Tutorials

Failure Analysis-Q11

2009-09-09T10:00:00.000-07:00

Local universities graduates are encouraged to take parts in business opportunity in Malaysia. As materials engineering graduate, knowledge and skills in failure analysis seems having a large potential to be commercialised internationally. To set up a consultation firm that specialist in failure analysis services of engineering materials, you have to apply RM500,000 from Graduate Entrepreneur Schemes. To realize this intention, you have to make a proposal based on following inquiries.

a) Explain the definition of failure in term of materials engineering?

[10 Marks]

Inability of a materials or a components to

perform the intended function
Meet performance criteria although it may still be operational
Perform safely and reliably even after deterioration.

Examples

Yielding
Wear
Buckling (elastic instability)
corrosion
fracture

b) In term of economy, convince the Graduate Entrepreneur Schemes evaluation committee panels on the important and the value of failure analysis that will be offered to potential industry customers.

[40 Marks]

# Identify corrective actions based on a determination of the root cause of the failure.

# Minimize future failures of the same type.

# Tool that can be used to

Ø reduce maintenance costs,

Ø increase system availability,

Ø reduce the potential losses involved in catastrophic failures.

# Potential savings will vary on a case by case basis.

# Used to identify the party at fault.

3 Financial losses resulting from a failure can often be recovered when

Ø deficiencies in design,

Ø workmanship or

Ø materials

can be identified as the root cause of the failure.

c) In your proposal, list down and justify the procurement of the scientific equipments that necessitate to purchased to implement failure analysis consultation services

[30 Marks]

1) Photography

2) Optical Microscopy up to 600X

3) Scanning Electron Microscopy (SEM) over 10,000X

4) Chemical Analysis

Ø SEM/EDS

Ø Spark Emission Spectroscopy

Ø Fourier Transform Infra Red (FTIR)

5) Mechanical Testing

Ø Hardness, micro-hardness, tensile, shear, physical testing

6) Stress Analysis / FEA

Ø Magnitude, principal direction, sensitivity

7) Instrumentation

Ø Strain Gages, accelerometers, thermocouples, ect.

8) Non-Destructive Testing (NDT)

b) Recommend the types of potential industries that needs your consultation services

[20 Marks]

Upstream and Downstream Oil & Gas
Petrochemical
Refining
Power generation
Marine
Medical Instruments
Commercial Properties
Government Agency
Alloy Producers
Equipment Manufacturers
Ship and Ship Building
Water and Wastewater

Failure Analysis: MidTest - Marking Schema

2008-09-23T19:28:00.000-07:00

A process engineer responsible for the operation of petrochemical plant noticed a significant pressure drop which indicates that the boiler tubes might have experienced some damage problem. Primary witness report by inspection engineers found that the water content in steam tanks was reduced by as much as 15%. There are the some pitting marks were observed at tensioned side at the bend area of the boiler tube (refer Figure 1) results the vaporizing out of water vapour. The tube was then removed and sends to your consultancy firm for further investigation.

To initiate the failure investigation, you have to make a site visit to that petrochemical plant to get some background information. Identify the important information needed from plant engineers that helps you getting some primary clues. [30 marks]

1. Location,

2. name,

3. Part No,

4. Description,

5. Manufacturer or fabricator

6. Function of item

7. Maintenance procedures

8. Maintenance history

9. Cleaning procedures

10.Cleaning history

11.Operational procedures (temp./ pressure etc)

12. Type of materials (Chemical composition)

13. Operational documentation (standard, temp./ pressure etc)

14. Service deviations

15. Normal stress orientations

16. Extent of incident

17. Precipitating events

18. Drawings

19. Photographs

20. Previous inspections reports,

21. Opinions of related personnel

ii) Considering chemical composition of boiler tube as shown in Table 1,

a) What your hypothesis regarding the root cause of the tube failure [25 marks]

1. Residual stress resulted from bending works

2. Corrosion attacks originate from water, believed resulted from application of untreated water

3. Lower content of Mo (lower pitting index no.) contributes to pitting corrosion

4. All of the above factors contribute to the stress corrosion cracking (SCC).

b) Calculate the tube pitting index number [20 marks]

Pitting Index (PI) = wt.% Cr + (3.3)(wt.% Mo)

= 17.585 + 3.3(0.396) = 18.89

c) Recommend the new materials to prevent the same future failure. [25 marks]

Further upgrades are out of the realm of the stainless steels and into high-alloys steel. Eg Pitting resistance metals such as

Ø high-molybdenum SS

Ø Incoloys,

Ø Inconels, or

Ø Hastelloys

Jawatan Kosong sebagai Pegawai Penyelidik

2008-08-25T20:34:00.000-07:00

Saya memerlukan seorang pembantu penyelidik bagi menjalankan kerja-kerja penyelidikan dalam bidang kakisan yang bertajuk “Development of Biofriendly Sacrificial Anode from Magnesium Alloys for Underground Structure Corrosion Protection”.

Syarat Umum

Diploma/ Ijazah sarjanamuda Kejuruteraan atau Sains dalam bahan, fizik @ kimia
Mempunyai semangat tinggi dan minat yang mendalam dalam bidang kakisan dan penuangan logam Magnesium
Mempunyai kenderaan sendiri
Mempunyai daya kreativiti yang tinggi
Gaji: RM 1700 sebulan (Ijazah Sarjanamuda)
Tempoh kontrak 1 tahun
Mempunyai kemahiran analitik
Sanggup bekerja di UniMAP, Perlis
Perhubungan komunikasi yang baik sesame manusia

Tanggungjawab

Mempelajari dan memahani konsep elektrokimia kakisan
Membuat penyelidikan dalam makmal berkaitan elektrokimia kakisan
Memfabrikasi aloi Magnesium menggunakan teknik peleburan dan penuangan logam
Membangunkan aloi Magnesium yang berkeupayaan menghasilkan open circuit potential dan anode efficiecy melebihi 1.8V vs SCE
Sanggup outstation ke institusi penyelidikan lain untuk menjalankan analisis komposisi kimia dan analisis lain yang perlu.

Jika berminat sila hubungi saya seperti maklumat dibawah;

Shaiful Rizam Shamsudin
Pusat Pengajian Kejuruteraan Bahan
Universiti Malaysia Perlis (UniMAP)
Tel: 04-9798663
H/P: 019-6405116
E-mail: rizam@unimap.edu.my @ srizam@gmail.com
Skype: srizam

Replica-Q14

2008-08-22T02:31:00.000-07:00

What is the qualitative thermal degradation indexes considered in metallographic analysis?

Tendency to pearlite/ bainite spheroidisation

Coarsening of precipitates in the ferritic matrix and at grain boundaries,

Broadening of denuded zones (no precipitates) along grain boundaries.

Replica-Q13

2008-08-22T02:29:00.000-07:00

What is Creep or creed deformation?

Creep is a phenomenom of a sample to deform against time at particular temperature. Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to levels of stress that are below the yield strength or ultimate strength of the material. Creep is more severe in materials that are subjected to heat for long periods, and near the melting point

Replica-Q12

2008-08-22T02:20:00.000-07:00

Replica-Q11

2008-08-22T02:03:00.000-07:00

What are the deterioration mechanisms that could be detected by using in-situ metallography

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graphitization

spheroidazation of pearlite

creep

thermal fatigue

hydrogen attack

carburization

grain boundary oxidization

embrittlement of microstructure etc.

Replica-Q10

2008-08-22T01:54:00.000-07:00

Why microstructural crack analysis is important?

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Possible to make a correct determination of crack type.

Important to determine whether the crack is the original defect or caused by service conditions or damage.

Once the crack type is identified, the proper corrective action, such as

Eliminating a corrosive environment

Reducing stress levels

Re-examine the services condition & make a preventive actions

Replica-Q9

2008-08-22T01:05:00.000-07:00

An inspection engineer responsible for the operation of petrochemical plant boiler observed a significant pressure drop which indicates that the boiler tubes might have experienced some damage problem. Preliminary report by process engineer states that the tubes were operated since 15 year ago. For temporary period, they decide to implements the fitness for service inspection to certify that boiler system component was fully ready to operate reliably.

Taking into consideration the microstructural condition of boiler system component in the aged petrochemical plant, propose the best assessment technique to certify that boiler system component was fully ready to operate reliably
Give your reasons for the above proposed method.
Recommend the best interval inspection package on boiler system component that would satisfies the plant engineers.
If you decide to perform replica assessment, identify the important information needed from plant engineers for assessment interpretation

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i) The condition assessment shall be implemented by in-situ metallography or replication
assessment method.

ii) This in-situ metallography method will be ensure;

The fitness for service for the safety of operators/ workers/ contractors and/ or local communities as well as environment

All equipment operates reliably

Remaining life of metal structure or component which help the prediction when equipment should be re-inspected for the long-term & continuous productive operations

Degree of overheating or other damage mechanisms manifested by microstructural changes.

Assessment of surface flaws to determine if there are any cracks presented on boiler system component which help predicting the root cause of failure resulted by damage mechanism such as creep, fatigue, stress or corrosion.

Information that supports emerging conditions to ensure optimal use of plant & resources

iii) The best practice of interval inspection is according to Nordtest Method. NT NDT 010: High Temperature Components in Power Plants: Remnant Lifetime Assessment, Replica Inspection. based on Neubauer microstructure evolution as shown in Table below.

Grade/ Class	Microstructure Characteristic	Recommendation Action
Grade/ Class	Microstructure Characteristic	Recommendation Action
0/1	No cavity	No Action
0/1	No cavity	No Action
2	Single cavities	Reinspect after 20,000hrs of operation/ inspection interval 3-5 years
3	Coherent cavities	Reinspect after 15,000hrs of operation/ inspection interval 1~1.5 years
4	Microcracks <2mm>	Repair/ Replace of reinspect after 10000 hrs of operation/ inspection interval 0 - 0.5 years
5	Macrocracks >2mm detected by NDT	Immediate Repair/ replace

iv) The important information needed from plant engineers for assessment interpretation are as follows;

Objective of In-situ metallography; in this case - condition assessment,

Material of construction with exact specification

Location of replication with sketch

Process parameters and design parameters

Service life of the component at the time of replication.

Any history of previous failures at the location of replication.

Replica-Q8

2008-08-22T00:58:00.000-07:00

What are the Critical Point in Boiler Tubes ?

Bends

T-sections

Reducting section

Valves

Rigidly-held pipes

hangers

Replica-Q7

2008-08-22T00:50:00.000-07:00

What are the components that subjected to in-situ metallography?

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Boiler tubes

Furnace

Superheaters

Steam piping

Turbine

Heat exchanger

Pressure Vessel

Replica-Q6

2008-08-22T00:46:00.000-07:00

There are wide differences in the techniques of in-situ metallography (replication technique) against laboratory metallography. These differences get highlighted when in-situ metallography is actually carried out. Together with your experiences in lectures, laboratory works and industrial training, list down on this issue.

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The nature of metal and alloys under investigation,

Field conditions,

Geometry and location of area intended for in-situ metallography,

Purpose of the in- situ metallography,

Selection of polishing equipment and method,

Selection of etching method,

Technique of replication,

The details required from the replica,

Types of microscopy to be used,

Technique of viewing the replica and

Interpretation of results.

Replica-Q5

2008-08-22T00:40:00.000-07:00

In-situ metallography is used on vessels or structures that have been exposed to temperatures in excess of their design limits, and materials that have been in a corrosive atmosphere. What does in-situ metallography reveal?

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Displays flow pattern lines indicating hot or cold working

Grain structure is viewable

Characteristic structure such as pearlite’s lamellae

Exposes whether alloys have segregated during solidification

Microscopic characteristics give insight into macroscopic properties

Replica-Q4

2008-08-22T00:27:00.000-07:00

The object of in-situ alloy metallographic method is to allow viewing of the surface microstructure of operating components. Elaborate the application of this non-destructive technique?

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Remaining life of metal structure or component studies, which help predict when equipment should be re-inspected.

Damage assessment from creep mechanisms or fire damage to determine if it an item is safe to use after being exposed to fire.

Heat treatment condition evaluations to assess if the component has been properly heat-treated.

Composition verifications.

Classification of cast irons without sacrificing any components.

Degree of overheating or other damage mechanisms manifested by microstructural changes.

Assessment of surface flaws to determine if they are cracks, laminations or seams.

The cause of cracking which help predicting the root cause of failure where it resulted from corrossion, creep, fatigue, stress etc.

Fitness for service to ensure that all equipment operates with safety and reliably

Replica-Q3

2008-08-22T00:16:00.000-07:00

As an NDE technique, in-situ metallography is ideal for assessing the remaining life of power and petrochemical plants. Why this technique is important to industries?

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To ensure the safety of operators/ workers/ contractors and/ or local communities as well as environment

To ensure that all equipment operates reliably

To ensures long-term & continuous productive operations

To provide information that supports emerging conditions to ensure optimal use of plant & resources

To be applied for microstructural analysis when examining large components that cannot be easily moved or destructive sample preparation is difficult or not permissible.

Replica-Q2

2008-08-22T00:08:00.000-07:00

On field testing, metallography can be applied non-destructively by replication technique. Briefly explain, what is the replication technique and it objective?

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Replication means, the act or process of duplicating or reproducing something.

Replication in metallography, is the use of thin plastic films to nondestructively duplicate the microstructure of a component. The film is then examined at high magnifications using metallurgical microscope (or SEM).

The object of this nondestructive testing method is to allow viewing of the surface microstructure of operating components.

Or the answer could be like this

The sample is ground, polished, etched, replication & inspected in the field to identify microscopic defects

Tests metals currently in use, instead of metals being mass produced

Addresses potential failure problems of industrial equipment

The objective is to determine the microstructural deterioration & damage of engineering alloys subjected to various environments

Replica-Q1

2008-08-22T00:01:00.000-07:00

What is Metallography?

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Metallography is the science and art of preparing a metal surface for analysis by grinding, polishing and etching to reveal it's microstructure constituent

Failure Analysis-Q10

2008-08-16T10:57:00.000-07:00

Slide 4

What are objectives of failure analysis and explain how it can be implemented ?

There are 3 primary objectives;

The first objective is to examine the objective evidence presented by the failed components and, from that evidence, determine the failure mechanism.

ii)

The second objective is to determine the primary cause, or what is commonly called the root cause, of the failure. This is accomplished by examining design and operational issues to determine what specific factor, or factors, was responsible for the failure.

iii)

The third objective, recommendation of corrective actions that will prevent similar failures, can be accomplished once the root cause of the failure has been identified.

Failure Analysis-Q9

2008-08-15T03:37:00.001-07:00

“ Microstructural examinations were conducted on boiler tube from local petrochemical plant for assessment on the reusability of the tube. Tube diameter was measured along the tube and it was shows that there is no bulges on the as received tube. The boiler tube was found bending at fire side area (Figure 1). The structure has equated grains consisting of pearlite and ferrite. Microstructure examination revealed that the grain size at the bend was slightly bigger as compared to grains at far from than the bend side area. There is no change in structure of grain at both areas; it means that the temperature applied to the tube was not higher than the limit of permissible temperature of the tube. According to the different in grain size, it means that temperature at the bent area was also different with the straight area of the tube. Temperature gradient should be existed along the tube due to the different in temperature. The bending in the tube was caused by the temperature gradient.”

Slide 25

Figure 1 Schematic diagram shows the condition of bending and metallographic spot on the tube surface marked as R1, R2, R3 & R4

From the statement above, plan your investigation procedures to implement failure analysis on the boiler tube. Give your reason for each procedures

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1) Obtaining background data

To investigate the basic information that possible to be a primary clues of the root cause analysis.
These importance information are including its location, manufacturer, function of component, operational condition, maintenance and cleaning history as well as opinions of related personnel

2) Visual examination followed by closed-up photographs by digital camera.

Since many of the subsequent steps in the evaluation will involve destructive examinations, the as-received photographs provide an archival record of the original condition of the failed component prior to cutting and sectioning
The as-received photographs also provide an effective place to indicate the locations from which the various samples used in the destructive examination were obtained

3) Chemical composition analysis by using XRF or spark emission spectrometer

Analysis of the chemical composition of the component is a routine part of a failure analysis
The analysis is used either to determine if the material meets the specified composition limits (in this case, boiler tube is carbon steel) or to identify an unknown material

4) Dimension measurement by vernier calliper

The operational condition of boiler tube normally involves a high temperature stress. Thus as-received boiler tubes should have to document their dimension along the tube to investigate the occurrence of bulging on the tubes resulted by its operational condition. However there’re no bulging occur on the sample

5) The straightness of the tubes is carried by rolling the tube on the flat & smooth surface.

Any bending or uneven on the tube can be identified when unstable rolling is observed resulted by high temperature operational condition that probably hits the one side of the tubes.

6) Determination of failure mechanism & recommendations

Without identification of the failure mechanism, it is usually impossible to determine the root cause of the failure, which forms the basis for recommendations for immediate action whether the components should be replaced or not and to eliminate or reduce the frequency of future failures.
Determination of the failure mechanism is considered a critical step in the failure investigation. In this particular case, the failure was caused by the occurrence of temperature gradient on the tube.

Slide 25

Failure Analysis-Q8

2008-08-14T21:52:00.000-07:00

Visual observation, optical microscope and scanning electron microscope are three (3) major tools that play an important role in determining the success of a root-caused analysis. Explain the each their roles in determining the (a) ductile and (b) brittle failure

[Pemerhatian mata kasar, mikroskop optik dan mikroskop elektron imbasan adalah tiga (3) alat utama yang memainkan peranan penting dalam menentukan kejayaan analisis punca-penyebab. Terangkan peranan setiap alat tersebut dalam patahan mulur dan rapuh]

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Ductile Fracture

Brittle Fracture

Visual Observation

- Necking or plastic deformation

- Dull and fibrous fracture surface

- Shear lips

Visual Observation

- Little/no plastic deformation

- Shiny, course, crystalline fracture surface

- Chevrons

Optical Microscopic

- Plastic distortion of grains

- Irregular trans-granular fracture

Optical Microscopic

- Minimal deformation

- Inter-granular or trans-granular

SEM Microscopic

- Micro-voids elongation in direction of load

- Singular crack with limited/no branching

SEM Microscopic

- Cleavage or inter-granular

- Discontinuity or stress riser at origin

Failure Analysis: Q7

2008-08-14T21:44:00.000-07:00

In term of design, describe or explain the methods to control corrosion failure

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i) Allow for the penetration action of corrosion along with the mechanical strength requirements when determining the appropriate metal thickness

ii) Weld rather than rivet containers to reduce crevice corrosion. If rivets are used, choose a rivet material that is cathodic to the materials being joined.

iii) If possible, use galvanically similar metals for the entire structure. Avoid dissimilar metals that can cause galvanic corrosion. If galvanically dissimilar metals are bolted together, separate them with nonmetallic gaskets and washers.

iv) Avoid excessive stress and stress concentrations in corrosive environments to prevent stress-corrosion cracking, especially when using susceptible materials such as stainless steels and brasses.

v) Avoid sharp bends in piping systems to prevent erosion corrosion.

vi) Design tanks and other containers for easy draining and cleaning.

vii) Design systems for easy removal and replacement of parts that are expected to fail in service, such as pumps in chemical plants.

viii) Design heating systems such that hot spots do not occur.

Failure Analysis - Q6

2008-08-14T21:18:00.002-07:00

A process engineer found a significant pressure drop and realizes one of the plant heat exchanger might have experienced some problem. After several inspections, he found that one of the tubes in the E-1406A heat exchanger was experiences leaking. The tube was then removed and a group of UniMAP final year student was given a task to further investigate this failure problem. According to the daily report made by personnel incharge, the tube side was contains vapor and liquid of hydrochloride acid (HCl), ethylene dichloride (C₂H₄Cl₂), and vinyl chloride monomer (C₂H₅Cl₂), while the shell side contains the flow of untreated cooling water (Figure 1).

After some investigation is done, several findings were found;

i) The tube side was coated by 25 mm polypropylene

ii) The shell side of the tube was covered by brownish deposit layer

iii) The tube material was carbon killed steel as stated in plant design.

iv) The failure of the tube was resulted by pitting corrosion that initiated from shell side surface.

v) No microcracking or branching cracks were observed and it confirms that the failure was not due to overloading or any excessive external stresses on the tube.

vi) There are the reductions of the solute atoms in the stainless steel matrix during corrosion attack.

vii) Microanalysis at pitting region shows the present of chloride and the failure was believed resulted by untreated cooling water.

From the statement above, plan root-caused analysis procedures that should be taken and give reason for each of procedures. Suggest your own recommendation to prevent the future failure.

[Seorang jurutera proses mendapati kejatuhan tekanan yang tinggi dan menyedari salah satu daripada penukar haba logi berkemungkinan telah mengalami masalah. Selepas beberapa pemeriksaan, beliau mendapati salah satu tiub dalam penukar haba E-1406A telah mengalami kebocoran. Mengikut laporan harian yang dibuat oleh kakitangan bertugas, sebelah dalam tiub mengandungi wap dan cecair asid hidroklorik (HCl), etilina diklorik (C₂H₄Cl₂) dan monomer vinil klorida (C₂H₅Cl₂), semetara sebelah luar tiub mengandungi aliran air penyejukan tak terawat (Rajah 1). Tiub tersebut kemudiannya dikeluarkan dan satu kumpulan mahasiswa tahun akhir telah diberi tugas untuk siasatan lanjut masalah kegagalan ini. Setelah siasatan dilakukan, beberapa penemuan telah dijumpai;

i) Tiub sebelah dalam disaluti dengan 25 mm polipropilena

ii) Tiub sebelah luar diselaputi dengan lapisan mendakan keperangan

iii) Bahan tiub adalah keluli carbon termati seperti yang dinyatakan dalam rekabentuk logi

iv) Kegagalan tiub adalah disebabkan oleh kakisan lubang yang bermula daripada permukaan sebelah luar

v) Tiada mikrorekahan atau rekahan cambah diperhatikan pada mikrostruktur tiub dan mengesahkan bahawa kegagalan tidak disebabkan oleh lebihan berat atau kewujudan tekanan luar pada tiub

vi) Terdapat penurunan atom-atom terlarut dalam matriks keluli kalis karat semasa serangan kakisan.

vii) Mikroanalisis pada rantau lubang menunjukkan kehadiran klorida dan kegagalan adalah dipercayai disebabkan oleh air penyejukan tak terawat.

Daripada pernyataan di atas, rancang prosedur-prosedur analisis punca-penyebab yang sepatutnya diambil dan berikan alasan untuk setiap prosedur. Cadangkan tindakan pencegahan untuk mengelakkan kegagalan sama di masa hadapan.

Figure 1: Schematic diagram shows the pitting corrosion on the heat exchanger tube.

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Procedures	Reason
1) Obtaining background data	• To investigate the basic information including its location, manufacturer, function of component, operational condition, maintenance and cleaning history as well as opinions of related personnel that possible to be a primary clue of the root cause analysis.
2) Visual examination followed by closed-up photographs by digital camera.	§ The as-received photographs provide an archival record of the original condition of the failed component prior to cutting and sectioning § Also provide an effective place to indicate the locations from which the various samples used in the destructive examination were obtained. § In this case, visual examination found the failed tube was experiences pitting corrosion which exhibited by large transverse cracks, holes and pitting profile.
3) Chemical composition analysis by using XRF or spark emission spectrometer	§ Analysis of the chemical composition of the component is a routine part of a failure analysis § The analysis is used either to determine if the material meets the specified composition limits. § In this case, heat exchanger tube materials is meets the specified composition limits of 316L stainless steel.
5) Metallographic examination by optical microscope. i) As-polished microstructure ii) Etched microstructure Prior to metallographic viewing, there are several works need to carried out such as cutting, sectioning, mounting, grinding, polishing & etching.	§ In as-polished condition, the presence of defects such as inclusions and voids or microstructural anomalies at the crack initiation site is examined. § In this case, as-polished microstructure is presented to investigate the direction pitting attack whether it comes from tube side or shell side. In this case, pitting corrosion from shell side. § Specific etchant has to be developed to delineate specific microstructural features. § Once etched, the microstructure of the material can be determined and the relationship between the microstructure and the damage can be examined. § In this case, no transgranular or intergranular microcracking is detected. Hence, the failure is not due to overloading or any excessive external stresses on the tube.
6) Fractographis analysis (SEM) and microanalysis (EDS)	§ SEM analysis is carried out to identify of the fine scale features fracture mode. § However in this case, no plastic deformation were observed and the surface fracture shows the tube material is ductile. It confirms that the failure is not due to overloading or any excessive external stresses on the tube. § Identification of the chemical species present in the corrosion deposits plays a critical role in identifying the root cause of the corrosion and in this case, the present of chloride element in EDS result is strongly believed result by untreated that used as a coolent.
7) Determination of failure mechanism & recommendations	§ Without identification of the failure mechanism, it is usually impossible to determine the root cause of the failure, which forms the basis for recommendations for immediate action whether the components should be replaced or not and to eliminate or reduce the frequency of future failures. § Determination of the failure mechanism is considered a critical step in the failure investigation. In this particular case, the failure was caused by the occurrence of temperature gradient on the tube.

Failure Analysis-Q5

2008-08-14T19:27:00.003-07:00

Describe the process of fracture of metals and differentiate between ductile and brittle fracture

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The process of fracture:

• The specimen elongates, forming a necked region in which cavities form.

• The cavities coalesce in the neck center, forming a crack which propagates toward the specimen surface in a direction perpendicular to the applied stress.

• As the crack approaches the surface, its growth direction shifts to 45º with respect to the tension axis. This redirection allows for the formation of the cup-and-cone configuration and facilitates fracture.

*Ductile fracture*	*Brittle fracture*
Plastic deformation	Small/ no plastic deformation
High energy absorption before fracture	Low energy absorption before fracture
Characterized by slow crack propagation	Characterized by rapid crack propagation
Detectable failure	Unexpected failure
Stable crack	Unstable crack
Eg: Metals, polymers	Eg: Ceramics, polymers

Failure Analysis-Q4

2008-08-14T19:16:00.000-07:00

Generally, two types of fracture failure (ductile and brittle fracture) are based on the ability of a material to experience plastic deformation.

In term of plastic deformation, explain the characteristics ductile and brittle fracture.

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A ductile fracture surface has a dull , fibrous appearance and often resembles a “cup-and cone” configuration.

A brittle fracture surface typically appears shiny with flat facets which are created during cleavage fracture.

Failure Analysis-Q3

2008-08-13T23:08:00.000-07:00

What are the steps should be taken to investigate the the root cause of component failure

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1. Collecting background data
2. Visual Examination
3. NDT evaluation
4. Fractographic examination by SEM
5. Chemical composition analysis
6. Mechanical Properties
7. Macroscopic Examination
8. Metallographic Examination
9. Microhardness evaluation
10. Summarize findings
11. Root cause determination
12. Failure mechanism
13. Propose recommendation or preventive action to overcomes future failure
14. Report writing

Failure Analysis-Q2

2008-08-13T22:23:00.000-07:00

Explain why analysis of a failed component is important

____________________________________________________________________________________

The important of failure analysis are as stated below
==>Identify corrective actions based on a determination of the root cause of the failure.
==> Minimize future failures of the same type.
==> Tool that can be used to reduce maintenance costs
** increase system availability
** reduce the potential losses involved in catastrophic failures.
** Used to identify the party at fault.
==> Financial losses resulting from a failure can often be recovered when deficiencies in design, workmanship or materials can be identified as the root cause of the failure.

Failure Analysis-Q1

2008-08-13T20:35:00.000-07:00

One of the important and practical aspects of materials selection in the design, development and production of new components (or parts/ structures) is the possibility of failure of the component (or parts/ structures) under normal operation.

a) In term of materials selection and design, define the failure of materials or components and give five (5) types of that failure.

_________________________________________________________________
Failure is defined as inability of materials or components to
i) perform the intended function
ii) Meet performance criteria although it may still be operational
iii) Perform safely and reliably even after deterioration.

---------------------------------------------------------------------------------------------
Examples
i) Fracture
ii) Corrosion
iii) Wear
iv) Yielding
v) Buckling (elastic instability)

Fwd: TAWARAN BIASISWA NATIONAL SCIENCE FELLOWSHIP (NSF) (Oleh: Pejabat Pengajian Ijazah Tinggi - Norzaililah Zainoddin)

2008-06-11T02:32:00.000-07:00

Berita baik... jom kita mohon biasiswa NSF

No. Rujukan : UniMAP/ICT/Post:06/08 (1186)
Tarikh : 11 Jun 2008

Assalamualaikum dan Salam Sejahtera,

MAKLUMAN KEPADA SEMUA STAF DAN PELAJAR UniMAP

Sukacita dimaklumkan bahawa Kementerian Sains, Teknologi dan Inovasi (MOSTI) telah membuka tawaran skim biasiswa National Science Fellowship (NSF) bagi tahun 2008. Butiran berkenaan skim tersebut adalah seperti dilampiran.

Maklumat lanjut sila layari laman web http://www.mosti.gov.my .

Sekian, terima kasih

NORZAILILAH ZAINODDIN
Assistant Registrar
Postgraduate Studies Office

tel : (6 04) 9798331
fax: (6 04) 9798334
email: zaililah@unimap.edu.my

Fwd: Third Announcement

2008-05-28T19:24:00.000-07:00

Dear colleague,

I would like to invite you to submit a paper to the MMC2008, which will be held at Universiti Kebangsaan Malaysia on 3- 4 December 2008 .

MMC 2008 is a national event on metallurgy and related field, and is a continuity of NMC 2007, NMC 2006 and 2004 Metallurgical Conference.

The purpose of this conference is/are to provide national platform for networking between metallurgical local scientists and researchers. To establish an avenue to present ideas and research studies and to share and discuss research findings and disseminate knowledge in the area of metallurgy.

Submitted papers will be published in conference proceeding and selected presented papers will be published in Sains Malaysiana or International Journal of Mechanical and Materials Engineering (cited by Scopus) after normal reviewing procedure. It is my great pleasure if you also can invite your college and postgraduate student to join the conference. In addition, the conference fee is very competitive for the field in the country.

Malaysian Metallurgical
Conference 2008 Secretariat
School of Applied Physics
Faculty of Science and Technology
Universiti Kebangsaan Malaysia
43600 Bangi, Selangor
Tel: 03- 89213873 , 03- 89213404 ,
03- 89213405
Fax: 03- 89213777
Email: metallurgy2008@gmail.com
Website:
http://multimedia.eng.ukm.my/jkmb/mmc2008

Penjelasan gambar siswi muslim memegang anjing & babi

2008-05-21T18:06:00.001-07:00

Assalamualaikum warahmatullahi wabarakatuh

Kepada yang berkenaan,

Semoga sentiasa dalam lingkungan rahmat dan kasih sayang Allah swt. Saya merasa terpanggil untuk memberikan sedikit maklumbalas berkenaan beberapa gambar yang diedarkan menerusi
internet yang menunjukkan seorang siswi Fakulti Perubatan Veterinar UPM yang bergambar berdekatan serta memegang/menyentuh anjing dan babi.

Email ini saya tulis secara panjang lebar dengan harapan huraiannya dapat difahami dengan jelas dan tidak disalah tafsirkan. TETAPI buat mereka yang tidak mempunyai masa yang banyak untuk membaca cukuplah saya katakan TIADA APA-APA MASALAH PADA GAMBAR TERSEBUT!. IA TIDAK MENGHINA ISLAM SEBALIKNYA MENERANGKAN BAHAWA UMAT ISLAM BOLEH MENYENTUH ANJING DAN BABI. ADALAH MENJADI TANGGUNGJAWAB MANUSIA SEBAGAI KHALIFAH UNTUK MENGURUSKAN KESELESAAN HIDUP HAIWAN INI DENGAN MEMASTIKAN KEBEBASAN DAN KESIHATANNYA TERJAGA.

Tiada nas yang mengatakan menyentuh anjing dan babi itu haram. Yang haram ialah memakannya. Kita perlu jelas pandangan Islam terhadap 2 makhluk ini. Kedua-duanya adalah ciptaan Allah, dan Allah tidak menjadikan sesuatu itu sia-sia, sebaliknya setiap sesuatu itu ada hikmahnya. Adakah Allah menciptakan anjing dan babi ini untuk dipandang hina oleh umatnya?

Sebelum meneruskan perbincangan, izinkan saya memberi sedikit pengenalan diri, saya merupakan salah seorang graduan Doktor Perubatan Veterinar tahun 2006. Kini menyambung
pelajaran dalam bidang master fisiologi di Fakulti Perubatan Veterinar UPM semester pertama. Sebelum ini, bersekolah di Sek. Men. Keb. Agama Kuala Selangor. Saya bukanlah orang yang paling sesuai untuk memberi penjelasan kerana yang terbaik adalah mereka yang mendalami ilmu agama agar dapat menjelaskan dengan menyatakan nas-nas serta tafsiran yang tepat
serta mendalam. Walaubagaimanapun saya akan cuba menjelaskan dengan pengetahuan agama sedikit yang saya ada dan hasil daripada perbincangan secara peribadi dengan ustaz-ustaz serta seminar yang pernah kami adakan di fakulti sendiri berkenaan dengan isu ini.

Pertamanya, sebagai seorang doktor veterinar (doktor haiwan) sememangnya kami mungkin akan berhadapan dengan situasi merawat anjing atau babi. Bagi doktor veterinar atau ringkasnya vet, yang bekerja di klinik-klinik haiwan kebanyakannya akan merawat anjing dan juga kucing. Walaubagaimanapun terdapat sesetengahnya yang menghadkan rawatan kepada kucing sahaja. Berkenaan dengan babi, kebiasaannya tiada vet muslim yang akan bekerja di ladang ternakan babi. Walaubagaimanapun, bagi vet yang bekerja di jabatan perkhidmatan haiwan, adakalanya mereka akan ke ladang ternakan babi untuk membuat pemeriksaan bagi memastikan ladang tersebut mengamalkan amalan pengurusan ladang yang baik supaya bebas daripada penyakit-penyakit berbahaya seperti penyakit Nipah yang merebak pada tahun 1999 yang turut membahayakan nyawa manusia. Terdapat juga vet yang bekerja di makmal yang memproses sampel-sampel yang datang daripada babi atau anjing seperti darah, najis, organ-organ dan sebagainya

Justeru, dalam kurikulum Doktor Perubatan Veterinar, pelajar akan terlibat mengendalikan anjing dan babi. Bermula dengan organ-organ haiwan tersebut dalam amali bagi subjek anatomi
dan fisiologi sehinggalah kepada mengendali, merawat dan membuat post mortem terhadap haiwan tersebut secara seluruhnya apabila memasuki tahun para-klinikal dan klinikal. Secara
umumnya saya bersetuju dengan perkataan 'desensitization ' yang digunakan oleh salah seorang yang menghantar email tersebut kepada saya. Sebagai vet, proses ini perlu kerana kami tidak
sepatutnya jijik untuk merawat pesakit kami kerana itu merupakan tanggungjawab kami yang juga terkandung dalam ikrar yang dilafazkan oleh setiap vet ketika bergraduan.

Apabila memasuki tahun ke 4, pelajar vet akan mengikuti subjek pengenalan terhadap klinik. Dan subjek klinik pada tahun ke 5. dalam kedua-dua subjek ini pelajar akan dibahagikan kepada
kumpulan-kumpulan yang kecil dan kumpulan ' kumpulan ini akan bergilir membuat praktikal dalam amalan-amalan yang telah ditetapkan. Pelajar-pelajar ini akan membuat praktis selama
seminggu dalam setiap amalan. Amalan-amalan ini termasuklah amalan haiwan kesayangan yang melibatkan rawatan terhadap anjing dan amalan ternakan babi yang memerlukan pelajar ke ladang ternakan babi untuk membuat pemerhatian, diagnosis penyakit serta rawatan. Daripada apa yang saya lihat, gambar-gambar yang diedarkan menerusi internet itu adalah
gambar yang diambil oleh pelajar ketika praktikal sama ada dalam subjek pengenalan klinik atau subjek klinik ini. Pada pandangan saya, pelajar itu berkongsi gambar ' gambar tersebut secara
umum dalam internet bukanlah bertujuan menghina agama atau sebagainya, sebaliknya sekadar berkongsi suatu pengalaman yang mungkin tidak dilalui oleh orang ramai.

Berkenaan dengan isu menyentuh, memegang, merawat anjing dan babi yang dikategorikan sebagai najis 'mughollazoh ' iaitu najis berat dalam feqah, ianya bukanlah haram seperti mana yang dikatakan oleh sesetengah masyarakat melayu. Ramai yang bertanya kepada saya bagaimana saya sebagai seorang muslim boleh menyentuh anjing dan babi yang haram disentuh?. Berdasarkan pelajaran feqah yang saya pelajari sejak sekolah rendah agama
hinggalah sekolah menengah, menyentuh najis 'mughollazaoh ' tidak haram. Apa yang dinyatakan oleh hukum feqah ialah apabila kita menyentuh najis 'mughollazoh ' kita dikehendaki
menyucikannya dengan bersamak iaitu membasuh dengan air yang telah dicampurkan dengan tanah sekali dan membilasnya dengan air 'musta 'mal ' (air yang bersih dan suci) sebanyak 6x.
Yang haram berkaitan dengan anjing dan babi ialah memakannya bukan menyentuhnya.

Sebagai seorang melayu, saya maklum pandangan masyarakat melayu yang merasakan 'geli ' atau jijik terhadap anjing dan babi. Mungkin ini adalah disebabkan nilai yang diwarisi daripada
ibubapa yang mungkin berasal daripada usaha untuk mengelak daripada tersentuh anjing dan babi yang mana proses menyucikannya dilihat sebagai agak leceh dan jika tidak dilakukan akan menjejaskan ibadah. Saya sendiri, walaupun telah jelas berkenaan dengan hukum menyentuh anjing dan babi, merasa kekok dan sedikit 'geli ' apabila kali pertama memegang jantung babi apatah lagi ketika kali pertama mengangkat anjing untuk diletakkan di atas meja pemeriksaan yang mana tekniknya memerlukan kita merapatkan badan anjing tersebut
ke badan sendiri kerana itu merupakan teknik yang selamat bagi mengelakkan kecederaan yang tidak dingini dalam proses mengangkat tersebut. Namun, kita perlu jelas pandangan Islam
terhadap 2 makhluk ciptaan Allah ini. Adakah Allah menciptakan anjing dan babi ini untuk dipandang hina kerana itu ianya diistilahkan sebagai najis berat? Jika ya mengapa terdapat
hukum feqah yang menyatakan haiwan buruan yang dibunuh oleh anjing buruan yang terlatih halal dimakan dengan syarat pemburu berniat kerana Allah ketika melepaskan anjing buruan tersebut.

Bagaimana pula dengan kisah seorang pelacur yang diampunkan dosanya dan dimasukkan ke dalam syurga hanya kerana memberi minum kepada seekor anjing yang kehausan dengan menggunakan kasutnya?

Anjing dan babi juga merupakan makhluk ciptaan Allah yang mana termasuk dalam tanggungjawab manusia sebagai khalifah di muka bumi untuk menguruskannya. Sebagai makhluk ia juga seperti manusia memerlukan makanan apabila ia lapar, minuman apabila haus dan ia perlukan rawatan apabila ia sakit, walaupun mungkin dari sudut keutamaannya berbeza dengan manusia. Justeru saya melihat apa yang dipelajari oleh vet berkenaan dengan anjing dan babi serta kewajipan merawatnya termasuk dalam perkara fardhu kifayah dan ia memenuhi sebahagian tanggungjawab manusia sebagai khalifah.

Walaubagaimanapun menjadi tanggungjawab vet untuk mengetahui tuntutan agama yang perlu dipenuhi dalam kerjayanya. Vet dan pelajar doktor perubatan veterinar perlulah berhati-hati dan tidak sambil lewa dalam soal kesucian tubuh badan dan pakaian kerana ianya akan menjejaskan ibadah. Yang terbaik ialah mengasingkan pakaian kerja dengan pakaian harian terutamanya pakaian untuk solat jika tidak mahu menyamak pakaian kerana khuatir pakaian akan rosak dan sebagainya. Bagi orang awam pula tidak perlu risau kerana najis ini 'tidak berjangkit ' maksudnya jika seorang vet hanya membasuh tangannya dan telah
membersihkan zat najis tersebut selepas bertugas tetapi masih belum menyamak tangannya, ia tidak 'berjangkit ' jika anda bersalaman dengannya kerana tiada zat najis (warna, bau dan rasa)
pada tangan vet tersebut. Tetapi vet tersebut perlu menyucikan tangannya dengan bersamak sebelum solat. Hal yang sama jika anda bersalaman dengan orang bukan Islam yang mungkin memelihara anjing di rumahnya. Begitu juga dengan tapak kasut anda yang memijak mukabumi yang pernah dipijak oleh anjing atau babi. Tidak perlu risau dan terlalu was-was selagi tiada zat najis.

Walaubagaimanapun terdapat cadangan daripada sesetengah ustaz untuk menyamak seluruh badan sekali sekala bagi orang awam dan mungkin berkala bagi vet seperti sebulan sekali supaya jika terdapat najis 'mughollazoh ' pada badan yang tidak diketahuinya, ia dapat disucikan. Namun saya kira ini adalah sekadar satu pandangan bukan kewajipan yang baik untuk mereka
yang was-was praktikkan. Sebenarnya terdapat pelbagai persoalan - persoalan yang timbul yang berkait dengan kerjaya vet seperti bagaimana vet muslim merawat kuda yang terlibat dalam lumba kuda, apakah hukumnya?, bagaimana pula dengan bayaran upah perkhidmatan
yang diterimanya? adakah ianya halal? Begitu juga jika vet muslim memberi perkhidmatan nasihat untuk memperbaiki usaha perladangan babi, bagaimanakah hukumnya? Adakah ianya berdosa kerana membantu orang memakan babi? Bagaimana jika membuat pembedahan yang panjang sehingga terlepas solat? Adakah sama seperti pembedahan manusia yang membolehkan solat tersebut dijamakkan?

Banyak lagi soalan-soalan yang datang samada daripada orang awam, dikalangan vet atau pelajar vet sendiri yang saya sendiri tidak mampu menjawabnya dengan ilmu agama yang cetek ini. Saya kira perkara yang sama juga berlaku atau akan berlaku dalam bidang kerjaya anda jika anda mencarinya 'ini kerana Islam itu adalah cara hidup yang syumul, elemennye terdapat dalam semua bidang, dan yang indahnya, Islam sudah pun ada jawapannya, terpulang
pada kita untuk menyelidik dan memahaminya dengan panduan dan tunjuk ajar daripada mereka yang ahlinya.

Akhirnya, sebagai seorang muslim, marilah kita bersama mengambil tanggungjawab untuk memperbetulkan salah faham masyarakat khasnya masyarakat melayu berkaitan dengan isu ini. Perkara ini banyak dipertikaikan oleh masyarakat yang bukan Islam terutamanya
mereka yang kuat memegang nilai kebajikan haiwan. Seorang senior saya dalam projek tahun akhirnya yang berkenaan dengan kebajikan haiwan, menjalankan satu soal selidik. Salah satu
daripada soalannya adalah 'jika anda melihat seekor anjing yang tersepit kakinya, adakah anda akan menolong melepaskan kakinya? Nyatakan alasan bagi setiap jawapan anda '. Sebagai
seorang muslim saya merasa sedih dan malu apabila terdapat satu jawapan yang menyatakan 'Tidak, kerana saya seorang Islam '. Senario ini harus kita ubah kerana sebagai seorang Islam kita perlu menjaga 3 hubungan iaitu hubungan dengan Allah, hubungan sesama manusia dan hubungan dengan makhluk yang lain. Sesungguhnya Islam itu syumul, segalanya sudah pun digariskan panduannya, terpulang kepada kita untuk mencari, memahami dan mengamalkannya.

Wallahua'lam

Saya mengalu-alukan mereka yang ingin mengemuka pandangan,
memperbetulkan fakta atau berkongsi maklumat baru berkenaan
dengan hal ini. Anda bolehlah menghantar email kepada
lapanjuta@yahoo. co.uk. Sekian moga bermanfaat untuk semua.

Terima kasih.

Dr. Mohd Dzulhamka Kamaluddin
DVM, UPM

Disemak oleh,
Prof. Dr. Rasedee Abdullah
Pensyarah
Fakulti Perubatan Veterinar
Universiti Putra Malaysia

Little Knowledge is dangerous!!!

2008-04-27T23:33:00.000-07:00

Penghujung puasa 2006, rumah saya ada mengalami masalah elektrik. Selalunya akan panggil anak buah saya untuk memperbaiki, tetapi dia sangat sibuk dengan kerja-kerja elektrik di Klang.

Lalu seseorang yang mendakwa tahu tentang elektrik memperbaikinya. Saya memerhatikan dengan rasa pelik dan bimbang. "Hendak mengenali keperibadaian seseorang, lihatnya hasil pekerjaannya." Memang sah, dia tak tahu apa-apa pasal elektrik — hanya setakat dengar-dengar dan lihat-lihat sahaja. Hasil kerjanya 'asal siap' dan menyakitkan mata.

Kalau misalnya saya tanya berapa 'ohm' rintangan elektrik untuk arus ulang-alik dalam ruimah, pasti dia akan nganga dan mula mereka sendiri jawapan. Tahu sedikit adalah merbahaya. Merbahaya pada saya sekeluarga — boleh menyebabkan litar pintas, terbakar rumah saya. Little knowledge is dangerous. Berguru kepalang ajar, bagai bunga kembang tak jadi.

Tepat sekali, sehari sebelum Raya, anak buah saya datang memeriksa semula dengan membawa peralatan. Dia lulusan BMI (UniKL) dalam bidang elektrik. Sekali tengok saja dia berkata, "Acik bernasib baik." Maksudnya betapa bahayanya hasil pekerjaan orang yang tahu sikit-sikit berasaskan dengar-dengar dan lihat-lihat.

Peluang belajar di Malaysia ini sentiasa terbuka luas. Latihan amat penting. Tidak ada manusia yang boleh berjaya jika enggan belajar. Sekiranya malas nak belajar akan menepati kata-kata Isaac Newton, "Little knowledge is dangerous" — merosakkan dan membahayakan diri sendiri. Kalau setakat diri sendiri yang rosak dan jahanam tak mengapa tetapi mengakibatkan orang lain.

Contoh yang paling dekat untuk saya ialah penulisan buku. Banyak buku yang merosak di pasaran akibat dari orang yang enggan belajar. Hasil tulisan orang yang tahu sedikit berdasarkan dengar-dengar dan lihat-lihat sahaja — tidak mahu mendalami, belajar hingga selesai. Tahu sedikit adalah merbahaya — tepat sekali ia membahayakan pembaca. Bahaya atau tidak pendapat bahlul, "Jual air kacang soya boleh jadi jutawan"? Bahaya atau tidak pendapat jual produk melalui internet di Malaysia ini boleh menjadi jutawan? Bahaya atau tidak kononnya pasaran hartanah masih sihat lagi? Bahaya atau tidak kata-kata dari Dr Hang Tuah (Dr. Ayam) yang berbunyi, "Cantik itu penting tapi janganlah dipentingkan sangat." Pelik atau tidak seorang yang selayaknya berkelulusan PhD mengeluarkan kata-kata yang rasanya pakar bahasa pun tak faham. Memang amat membahayakan. Kalau bahaya tersebut terkena diri sendiri tak mengapa — ini orang yang tak bersalah menerima bahaya akibat kebahlulan, main agak-agak, dengar-dengar.

Penulisan seperti berceramah. Ada dua elemen paling penting iaitu 1) Kandungan ceramah 2) Cara berceramah. Ada seorang penceramah Cina dari Singapura yang saya anggap tolol, salah 100 peratus. Katanya, "Bukan penting apa yang nak diperkatakan, yang penting cara mengatakan." Sebab itu kebanyakan penceramah di Malaysia dan Singapura bila berceramah hanya mementingkan angin, gelak-gelak, penglipur lara (macam ceramah Fadzilah Kamsah) — sebab mengutamakan cara penyampaian bukan kandungan ceramah. Kedua-duanya amat penting — cara penyampaian dan kandungan ceramah.

Cara penulisan sama penting dengan isi penulisan. Cara penulisan diutamakan bagi memastikan pembaca tak bosan membaca hingga selesai. Ingat, pembaca mengeluarkan wang untuk membeli buku, jadi pastikan pembaca mendapat pulangan setimpal (atau lebih) dari buku yang dibeli. Kalau baca tak selesai, penulis gagal dalam cara penulisan. Dia perlu belajar lagi. Dia perlu mengamalkan 'modeling' membaca buku-buku best-seller. Dia juga perlu hadir kursus penulisan PTS. Dia mesti melayari Universiti PTS untuk belajar lagi.

Itu cara penulisan untuk memastikan pembaca membaca perenggan pertama hingga ayat terakhir dalam buku. Kandungan penulisan juga penting, sangat penting, sama penting dengan cara penulisan. Rajin membaca tidak mencukupi untuk mendapat bahan penulisan. Kena rajin bertanya, rajin merantau, rajin bergaul, rajin melayari internet, rajin berforum. Untuk menulis "Digital Fotress", Dan Brown, penulis best-seller, telah menghabiskan banyak masa untuk berforum di internet kerana beliau ingin mendapatkan istilah-istilah, fungsi elektronik, matematik dan sains.

Jika kandungan penulisan main agak-agak, akhirnya diri sendiri yang malu. Nama akan menjadi busuk untuk tahun-tahun akan datang. Sebagai contoh, ramai yang mencebik bila mendengar nama Billy Lim kesan dari buku angin beliau.

Belajarlah. Nak bersampan biar tahu mendayung. Datanglah ke kursus mingguan PTS. Percuma. Mungkin kerana percuma ia tidak dihargai. Pernah syorkan kepada Arief supaya berbayar biar dihargai kerana ada yang telah berpuluh kali menghadiri kursus tapi masih lagi tidak mampu menghasilkan seperenggan buku. Mungkin kalau berbayar akan berbeza — dihargai dan berasa rugi jika tidak menghasilkan buku.

PTS tidak terdesak dengan mengadakan kursus penulisan sebaliknya supaya penulis yang bernaung di bawah label PTS berkualiti dan menepati standard PTS. Supaya tidak tergolong dalam "Tahu sedikit adalah merbahaya." Biar tahu hingga selesai. Supaya buku terbitan PTS tidak hanya berasaskan dengar-dengar sahaja. Kalau terdesak, terbitkan saja manuskrip yang diterima setiap hari. Berlambak manuskrip yang diterima.

Juga supaya standard dan kualiti kekal -- tidak menerbitkan buku angin. Pembeli hendakkan ilmu bukan angin. Supaya terhindar dari menerbitkan buku Dr. Ayam (PTS telah mengesan 2 Dr Ayam yang cuba-cuba mengendeng di PTS).

Jangan jadi seperti industri MLM sekarang ini. Rosak kerana ada yang merosakkan. Rosak kerana ramainya yang "tahu sedikit" di dalam MLM. Untuk menggambarkan kerosakannya dan kisah "tahu sedikit" — tanyalah kepada mereka yang terlibat di dalam MLM — "Apa elemen penting dalam pemasaran?" (MLM adalah sistem pemasaran). Pasti tidak akan terjawab. Sebab itulah hendak mencari orang yang berjaya di dalam MLM seperti mencari gagak putih di kalangan gagak hitam. Hendak mencari jutawan di dalam MLM seperti mencari gagak belang-belang di kalangan gagak putih. Hendak mencari penipu, kaki kelentong, kaki lembik, kaki spring, leader katak dalam MLM adalah seperti mencari mencari gagak hitam di kalangan gagak hitam juga.

Maksud saya — betapa pentingnya latihan di dalam MLM. Itu yang saya perjuangkan sejak dahulu. Sebelum dan semasa menyertai MLM mestilah berilmu, ada latihan khusus. Latihan amat penting. Hendak jadi cikgu masuk maktab atau universiti dulu. Hendak kerja kilang belajar mengendalikan mesin terlebih dulu. Masuk MLM tiba-tiba jadi pandai — tiba-tiba meletakkan segala rupa Dr. Prof. Sir di depan nama. MLM adalah sistem pemasaran jadi latihan hendaklah ditekankan tentang pemasaran. Tentang bagaimana cara memasarkan produk. Bukan panggil Fadzillah Kamsah menyampaikan penglipur lara. Bukan kursus tiga hari tapi dalam kursus hanya ada penglipur lara, semangat, pijak-pijak badan, aura taik, menangis dan sebagainya. Tak perlu apa yang disebut "Seminar Motivasi". Yang utama sekali ialah pengetahuan tentang pemasaran, bagaimana memasarkan produk. Mana ada pijak-pijak badan dalam modul pemasaran? Di mana nak letakkan penglipur lara dalam modul pemasaran?

Tahu sedikit adalah bahaya. Jadi, jangan bertangguh untuk tahu banyak atau tahu benar-benar tahu.

TAWARAN BIASISWA KERAJAAN REPUBLIK MESIR TAHUN 2008

2008-04-24T21:00:00.001-07:00
Adalah saya diarahkan menarik perhatian Y. Bhg.Dato/ Datin/Tuan/Puan kepada perkara di atas.
2. Dengan hormatnya dimaklumkan bahawa Kerajaan Republik Mesir telah mempelawa calon-calon berkelayakan dari Malaysia ntuk memohon biasiswa bagi mengikuti pengajian di peringkat ljazah Pertama,Sarjana dan Doktor Falsafah,dan kursus Bahasa Arab di Universiti Al-Azhar. Program ini dibiayai oleh Kerajaan Mesir dan bertujuan untuk mengeratkah hubungan diplomatic diantara negara-negara OlC.

3. Sehubungan itu, kerjasama pihak Y. Bhg. Dato'/Datin/T uan/Puan adalah dipohon untuk menyebarkan tawaran biasiswa ini kepada pegawai dan kakitangand iinstitus miasing-masing dengan kadar segera. Permohonan daripada pegawai dan kakitangan Kerajaan hendaklah rnelalui Ketua Jabatan dan memenuhi syarat-syarat berikut:-

i) Telah disahkan dalam perkhidmatan pada tarikh tutup permohonan;
ii) Bersih daripada pertuduhan tatatertib dan bebas daripada dakwaan mahkamah;

iii) Mempunyai kelayakan yang sesuai dengarn bidang kursus yang ditawarkan;

iv) Telah mengisytiharkah harta; dan

v) Syarat-syarat lain yang dinyatakan dalam risalah.

4. Bersama-sama ini dilampirkan risalah yang mengandungi maklumat lanjut dan borang permohonan untuk makluman dan tindakan seterusnya. Tarikh tutup permohonan adalah pada 30 Mei 2008 dan segala permohonan hendaklah dipanjangkan kepada:-

Bahagian Biasiswa
Kementeria Pengajian Tinggi
Aras 4, Blok 1, Menara PjH
Pusat Pentadbiran Kerajaan Persekutuan
Presint2
62100 PUTRAJAYA
U/P: Cik Norkamilah Bt Zanial

Soalan Licik, Jawapan Cerdik,

2008-04-17T22:14:00.001-07:00

Seorang guru, Cikgu Murni (Umur: 22) menghadapi masalah dengan salah seorang muridnya (Abu). Lalu guru ini bertanya kepada murid tersebut : "Apa sebenarnya masalah awak, Abu?"

Lalu Abu menjawab, "Saya terlalu cerdik untuk berada di darjah 4, kakak saya menduduki UPSR dan saya lebih cerdik dari dia, maka saya seharusnya berada di tempat yang sama juga!".

Cikgu Murni dah tak tertahan. Dia bawa Abu ke pejabat pengetua. Sementara Abu menunggu di ruang tamu, Cikgu Murni terangkan keadaan tersebut kepada pengetua. Pengetua mengatakan yang dia akan berikan ujian kepada Abu dan jika Abu gagal menjawab, maka Abu harus kekal di darjah 3 dan berkelakuan baik. Abu dibawa masuk ke pejabat Pengetua dan Cikgu Murni terangkan pada Abu dan Abu bersetuju untuk ambil ujian yang akan diberikan.

Pengetua: Apa 3 x 3?
Abu: 9
Pengetua: Apa 6 x 6?
Abu: 36

Pengetua terus bertanyakan soalan2 berdasarkan tahap pencapaian murid2 UPSR dan si Abu mampu menjawab tiap soalan yang diberikan. Lalu pengetua memandang Cikgu Murni dan berkata, "Saya rasa murid ini sepatutnya berada di darjah 6", Lalu Cikgu Murni berkata pada pengetua, "Saya ada soalan saya sendiri, boleh tak saya ajukan pada Abu?". Pengetua dan Abu bersetuju.

Cikgu Murni: Apa yang lembu ada 4 di badan, tapi saya cuma ada dua?
Abu: (berfikir) Kaki

Cikgu Murni: Apa yang ada di dalam seluar kamu tapi tidak pada seluar saya?
Abu: Saku

Cikgu Murni: Apa yang bermula dengan huruf "K" akhir dengan "A", ianya berbulu, berbentuk oval, nyaman dan mengandungi lapisan nipis keputihan?
Abu: Kelapa

Cikgu Murni: Apakah yang masuk keras dan berwarna "pink", bila keluar lembik dan melekit?

Mata Pengetua terbuka luas dan sebelum sempat dia menahan, siAbu terus menjawab.

Abu: Gula-gula getah (Bubblegum)

Cikgu Murni: Apa yang mereka lakukan, lelaki secara berdiri, wanita secara duduk dan anjing secara tiga kaki?

Mata Pengetua sekali lagi terbuka sangat2 luas dan sebelum dia sempat hendak menahan si Abu terus menjawab.

Abu: Bersalaman

Cikgu Murni: Baik, sekarang saya akan ajukan soalan berbentuk siapakah saya, okay?
Abu: Baik Cikgu

Cikgu Murni: Awak memasukkan batang kedalam saya. Awak ikat saya untuk saya berdiri. Saya kebasahan sebelum awak.

Pengetua kelihatan resah dengan soalan yang diajukan oleh Cikgu Murni.

Abu: Khemah

Cikgu Murni: Jari memasuki saya. Awak menggesel-gesel saya bila awak teringatkan saya. Lelaki idaman akan mendapat saya dahulu.

Pengetua semakin resah dan tidak selesa. Lantas terus meneguk segelas Nescafe 3in1.

Abu: Cincin perkahwinan

Cikgu Murni: Saya ada bermacam-macam saiz. Bila saya sakit saya akan meleleh. Bila saya keluar, banyak tisu yang akan digunakan. Bila awak hembuskan saya, akan berasa lega.

Sekali lagi pengetua rasa amat resah dengan soalan yang di ajukan oleh Cikgu Murni dan ingin membantah, tapi si Abu mendahuluinya.

Abu: Hidung

Cikgu Murni: Saya batang yang keras. Hujungnya tajam. Saya akan datang dan masuk dengan lajunya.
Abu: Anak panah

Cikgu Murni: Sekarang saya akan ajukan soalan dalam Bahasa Inggeris, okay?
Abu: Okay

Cikgu Murni: What word starts with a 'F' and end in 'K' that means lot of heat and excitement?
Abu: Firetruck

Cikgu Murni: What word starts with a 'F' and ends in 'K' & if you dont get it you have to use your hand.
Abu: Fork

Cikgu Murni: What is it that all men have one of. It's longer on some men than on others, the pope does not use his, and a man gives it to his wife after they are married?
Abu: Surname

Cikgu Murni: What part of the man has no bones but has muscles, lots of veins and loves pumping?
Abu: Heart

Pengetua menghembuskan nafas kelegaan bila mendengar jawapan yang diberikan oleh si Abu, lantas berkata "Baik hantar murid ini ke Universiti Malaya; jawapan yang saya fikirkan semuanya salah".

P/s: Jika jawapan anda semua salah, anda adalah sama spesies dengan pengetua yang mempunyai pemikiran kuning.....hehehe

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Corrosion & Degradation of Materials

2008-03-13T03:21:00.001-07:00
1. Define corrosion as it pertains to materials.

Solution;

Corrosion is the deterioration of a material resulting from chemical attack by its environment.

2. What are some of the factors that affect the corrosion of metals?

Solution;

Some of the factors that affect the corrosion of metals are: the temperature and concentration of the reactants and products of a chemical attack; the state of mechanical stress in the metal; the presence of erosion in the metal; and the energy state of the metal.

3. A standard galvanic cell has electrodes of zinc and tin. Which electrode is the anode? Which electrode corrodes? What is the emf of the cell?

Solution;

Zinc has a more negative Eo potential of –0.763, as compared to tin’s potential of –0.136, and will thus serve as the anode. The zinc corrodes in an oxidation reaction.

The emf of the cell is obtained by adding the half-cell reactions together:

Anode reaction: Zn → Zn²⁺ + 2e^- E^o = - 0.763 V

Cathode reaction: Sn²⁺ + 2e^- → Sn E^o = - 0.136 V

_________________
E^o_cell = - 0.627 V

4. Consider a magnesium-iron galvanic cell consisting of a magnesium electrode in a solution of 1 M MgSO4 and an iron electrode in a solution of 1 M FeSO4. Each electrode and its electrolyte are separated by a porous wall, and the whole cell is at 25°C. Both electrodes are connected with a copper wire.

i) Which electrode is the anode?

ii) Which electrode corrodes?

iii) In which direction will the electrons flow?

iv) In which direction will the anions in the solution move?

v) In which direction will the cations in the solution move?

vi) Write an equation for the half-cell reaction at the anode.

vii) Write an equation for the half-cell reaction at the cathode.

Solution:

i) The magnesium electrode is the anode.

ii) The magnesium electrode corrodes since the anode in a galvanic cell corrodes (oxidizes).

iii) The electrons will flow from the anode, Mg, to the cathode, Fe.

iv) The SO₄_- anions will flow toward the magnesium anode.

v) The cations will flow toward the iron cathode.

vi) The oxidation reaction that occurs at the magnesium anode is: Mg ® Mg²⁺ + 2e⁻

vii) The reduction reaction that occurs at the iron anode is: Fe²⁺ + 2e⁻ ® Fe

5. Describe two methods by which cathodic protection can be used to protect steel pipe from corroding.

Solution:

Cathodic protection of steel pipe can be achieved by (i) an external DC power supply, or by (ii) galvanic coupling with a metal, such as magnesium, that is more anodic than the steel.

Cathodic protection of an underground tank by using impressed currents

Cathodic protection of an underground pipeline by using sacrificial Mg anode

Fundamentals of Metal, Steel, Alloy & Biometal

2008-03-13T02:53:00.000-07:00
1. What are the three (3) basic types of stainless steels?
Solution

The three (3) basic types of stainless steels are ferritic, martensitic, austenitic.

2. What are some applications for ferritic and martensitic stainless steels?

Solution

Ferritic stainless steels are used mainly as general construction materials requiring good corrosion and/or heat resistance. Examples include range hoods, restaurant equipment and combustion chambers. Martensitic stainless steels have comparatively low corrosion resistance but high strength and are thus used in applications such as machine parts, pump shafts, bearings and bearing parts, cutlery, and surgical tools.

3. What are the cast irons? What is their basic range of composition?

Solution

Cast irons are a family of ferrous alloys intended to be cast into a desired shape rather than worked in the solid state. These alloys typically contain 2 to 4 percent C and 1 to 3 percent Si. Additional alloying elements may also be present to control or vary specific properties.

4. What are some of the properties of cast irons that make them important engineering materials? What are some of their applications?

Solution

Cast irons are easily melted and highly fluid and do not form undesirable surface films or shrink excessively; consequently, they make excellent casting irons. They also possess a wide range of strength and hardness values and can be alloyed to produce superior wear, abrasion, and wear resistance. In general, they are easy to machine. Their applications include engine cylinder blocks and gear boxes, connecting rods, valve and pump casings, gears, rollers, and pinions.

5. Why are ductile cast irons in general more ductile than gray cast irons?

Solution

Ductile cast irons are, in general, more ductile than gray cast irons because their spherical graphite nodules are surrounded by relatively ductile matrix regions which allow significant deformation without fracture. In contrast, the gray cast irons consist of an interlacing network of graphite flakes which can be fractured easily.

6. Why does the graphite form spherical nodules in ductile cast irons instead of graphite flakes as in gray cast irons?

Solution

Graphite forms spherical nodules in ductile cast irons because the levels of phosphorus and sulfur are reduced significantly compared to those in gray cast irons; these two alloying elements prevent the formation of nodules and thus promote the formation of graphite flakes.

7. How Steel & Cast Iron Differ?

Solution

Steel

Cast Iron

§ Iron with C still in solution

§ Iron which some of the C has precipitate out & appears as flakes

§ C content; 1.6 ~ 2.0%

§ C content; 2.0 ~ 6.0%C

§ Ductile compare to C. iron

§ Brittle compare to steel

§ High strength

§ Poor Strength

§ Hard to machine

§ Easy to machine

§ Hard to control casting

§ Easy to cast

§ Low damping capacity

§ Good Damping Capacity

8. What are some of the important properties of unalloyed copper that make it an important industrial metal?

Solution

Properties of unalloyed copper, which are important to industrial applications, include high thermal and electrical conductivity, good corrosion resistance, ease of fabrication, medium tensile strength, controllable annealing properties, and general soldering and joining characteristics.

9. What are some of the properties that make aluminum an extremely useful engineering material?

Solution

Aluminum is an extremely useful engineering material due to its low density (2.70 g/cm3), good corrosion resistance, good strength when alloyed, high thermal & electrical conductivities and low cost.

10. What are some of the properties that make aluminum to be high prospect for transportation materials?

Solution:

To be used as engineering materials for transportation to reduce fuel assumption because its specific strength, which is quantified by the tensile strength-specific gravity ratio. Its TS is inferior to a more dense material (such as steel), on weight basis it will able to sustain a larger load.

11. What advantages do magnesium alloys have as engineering materials?

Solution:

As engineering materials, the primary advantage of magnesium alloys is their lightness; magnesium has the low density value of 1.74 g/cm3.

12. Why are titanium and its alloys of special engineering importance for aerospace applications?

Solution:

Titanium and its alloys are of special engineering importance for aerospace applications because of their high strength-to-weight ratios.

13. Define a refractory metals. Name the metal elements that are considered to be refractory elements?

Solution:

Refractory metals are metals with exceptionally high melting points; above 2450^oC for example; Niobium (columbium) (Nb), Tantalum (Ta), Molybdenum (Mo) and Tungsten (W)

14. Define a biometals. Name the metal/ alloys that are considered to be biometals and give examples.

Solution:

Biometals is a metal alloys that replace damaged biological tissues, restore function, and are constantly or intermittently in contact with body fluids.

Biometals Group

Example

Stainless Steel (SS)

§ 316 L SS

Cobalt-based alloys

§ Co-28 Cr-6 Mo cast alloy

§ Co-20 Cr-15 W-10 Ni wrought alloy

§ Co-35 Ni-20 Cr-10 Mo wrought alloy

§ Co-28 Cr-6 Mo cast alloy

Ti alloys

§ Pure Ti

§ α Ti alloy (Ti-Al, Sn, Zr)

§ α-β Ti alloy (Ti-6 Al-4 V, Ti-6 Al-7 Nb

15. Metals/ alloys used as surgical instruments are not classified as a biometals. Briefly discuss this issue.

Solution:

Because metals/ alloys used as surgical instruments are used in external prosthesis. In addition this instrument is not exposed to body fluids in continuous or intermittent manner

16. A striker from Liverpool FC team was badly injured resulted by hard tackling from Manchester United FC player. After getting some x-ray scanning by orthopaedic medical officer, it was found that there are few knee bone fracture and crack. The footballer has to take 9 month rest for a surgical operation on his knee to replace a damaging bone in order to restore it function back to normal. As a biomedical engineer you are responded to make some recommendations on the suitable materials for used as bone joint and fixation devices.

i) Taking into consideration the function of knee in a footballer profession, analyse the factors that may affect on the biometal performance.

ii) Recommend the suitable materials that would satisfy your requirements.

Solution:

i) Considering knee function for a footballer that may experience million cycles of stress on his knee bone in daily activity. Thus, the metal/ alloys should be able to endure large & variable (cyclic) stress in the highly corrosive environment of the human body.

The internal knee environment is highly corrosive and could degrade the implant materials, resulting in the release of harmful ions or molecules. Thus the characteristic of a biometal is biocompatibility. Thus the additional characteristic for knee implant is chemical stability, corrosion resistance, non carcinogenic & nontoxic when used in the human body.

ii) Biometal that may satisfy the requirement must be strong, fatigue & wear resistance and biocompatibility in a highly corrosive environment such as;

a) Stainless steel

b) Cobalt based alloys

c) Titanium alloys

Phase Diagrams

2008-02-26T18:12:00.000-08:00

1. Define (a) a phase in a material and (b) a phase diagram.

Solution

a) A phase in a material is a microscopic region that differs in structure and/or composition from another region.

b) A phase diagram is a graphical representation of the phases present within a materials system for a range of temperatures, pressures and compositions.

2. Refer to the pressure-temperature equilibrium phase diagram for pure water below, calculate the degrees of freedom are there

i) at the triple point?

ii) along the freezing line?

Solution

i) At the triple point, there are zero degrees of freedom.

ii) Along the freezing line of pure water, there is one degree of freedom.

3. In figure below, the pressure temperature phase diagram for H₂O. Apply the Gibbs phase rule at point A, B, and C; that is, specify the number of degrees of freedom at each of the points – that is, the number of externally controllable variables that need be specified to completely define the system

Solution

Gibbs phase rule in general form is, P + F = C + N, for this system, the number of components, C, is 1, whereas N, the number of non-compositional variables, is 2--viz. temperature and pressure. Thus, the phase rule now becomes

P + F = 1 + 2 = 3 or F = 3 – P where P is the number of phases present at equilibrium.

At point A, only a single (liquid) phase is present (i.e., P = 1), or F = 3 – P = 3 – 1 = 2 which means that both temperature and pressure are necessary to define the system.

At point B which is on the phase boundary between liquid and vapor phases, two phases are in equilibrium (P = 2); hence F = 3 – P = 3 – 2 = 1 or that we need to specify the value of either temperature or pressure, which determines the value of the other (pressure or temperature).

At point C, three phases are present—viz. ice I, vapor, and liquid—and the number of degrees of freedom is zero since F = 3 – P = 3 – 3 = 0. Thus, point C is an invariant point (in this case a triple point), and we have no choice in the selection of externally controllable variables in order to define the system.

4 What is a binary isomorphous alloy system? Give an example & sketch its phase diagram

Solution

The binary isomorphous alloy system is a two-component system in which the two elements are completely soluble in each other in the liquid and solid states and form a single type of crystal structure for all compositions.

Example - The Cu-Ni system

5. Describe how the liquidus and solidus of a binary isomorphous phase diagram can be determined experimentally.

Solution

The liquidus and solidus of a binary isomorphous phase diagrams can be determined experimentally by measuring cooling rate for several specific alloy compositions and plotting the corresponding liquid-solid curves. The phase diagram can then be constructed by plotting the liquidus and solidus temperatures versus composition of the alloys.

6. Explain how a cored structure in 70% Cu-30% Ni alloy is (i) produced and (ii) eliminated by heat treatment?

Solution:

i) A cored structure is produced in a 70% Cu-30% Ni alloy when the alloy is cooled rapidly; without sufficient time for complete solid-state diffusion, concentration gradients remain in the alloy structure.

ii) The cored structure can be eliminated in ingots and castings by heat treating at elevated temperatures. This homogenization process accelerates the required solid-state diffusion and thus produces a homogeneous structure in the alloy.

7. Consider an alloy containing 70 wt % Ni and 30 wt % Cu in Figure below

a) At 1350ºC make a phase analysis assuming equilibrium conditions. In the phase analysis include the following:

(i) What phases are present?

(ii) What is the chemical composition of each phase?

(iii) What amount of each phase is present?

b) Make a similar phase analysis at 1500ºC.

c) Sketch the microstructure of the alloy at each of these temperatures by using circular microscopic fields.

Solution:

(a)

i) The phases present are the liquid and solid (L + α).

ii) The chemical composition of liquid is wl = 62 wt % Ni while that of the solid is ws = 74 wt % Ni.

iii) The weight percent of solid and liquid are:

(b) At 1500ºC, the alloy is 100% liquid.

The microstructure of the alloy at these temperatures would look similar to the following sketches.

Atomic Structure & Bonding

2007-03-21T02:16:00.000-07:00
TUTORIAL 2: Question vs Solution

ENT 112 – Materials Engineering

Q1:

A gold wire is 0.70 mm in diameter and 8।0 cm in length. How many atoms does it contain? The density of gold is 19.3 g/cm3.

Solution:

First determine the mass of gold based upon the wire volume and the density of gold.

Q2:
A solder contains 52 wt % tin and 48 wt % lead. What are the atomic percentages of Sn and Pb in this solder?

Solution:

Q3:
Describe the ionic bonding process between a pair of Na and Cl atoms.
i) Which electrons are involved in the bonding process?
ii) After ionization, why is the sodium ion smaller than the sodium atom?
iii) After ionization, why is the chloride ion larger than the chlorine atom?

Solution:

i) The ionic bonding process between a pair of Na and Cl atoms involves a transfer of the outer 3s1 electron of the Na atom to the 3p vacancy in the Cl atom. Thus, the Na ion formed has the Ne electron configuration while the Cl ion has the Kr electron configuration.

ii) After ionization to the Na+, the Na atom becomes smaller because the electron-to-proton ratio of the Na atom is decreased when the Na+ ion forms. Also, the outer third shell no longer exists once the 3s1 electron is lost by the Na atom.

iii) After ionization, the Cl- ion is larger because the electron-to-proton ratio of the chlorine atom is decreased by the ionization process.

Q4:
Briefly describe the following types of primary bonding: (a) ionic, (b) covalent, and (c) metallic।
Solution:

(a) Ionic bonding arises from the electrostatic attraction between oppositely charged ions. In the process of ion formation, an electron or a number of electrons may be transferred from a highly electropositive element to a highly electronegative one. The ionic bond in solids is nondirectional.

(b) Covalent bonding is a primary type of bonding which arises from the reduction in energy associated with the overlapping of half-filled orbitals of two atoms. In this bond, there is an electron exchange interaction. The covalent bond is a directional type of bond.

(c) Metallic bonding is a primary type of bonding involving the interaction of the valence electron or electrons of one atom with many surrounding atoms. This interaction leads to a reduction in energy of the system considered. The valence bonding electrons of these bonds are sometimes regarded as an ‘electron gas’ bonding the positive ion cores (atoms less their valence electrons) of atoms. The metallic bond is nondirectional.

Q5:
If the attractive force between a pair of Cs+ and I- ions is 2.83 × 10-9 N and the ionic radius of the Cs+ ion is 0.165 nm, calculate the ionic radius of the I- ion in nanometers.

Solution:

Q6:
How can the high electrical and thermal conductivities of metals be explained by the “electron gas” model of metallic bonding? Ductility?

Solution:

The high electrical and thermal conductivities of metals are explained by the mobility of their outer valence electrons in the presence of an electrical potential or thermal gradient.

The ductility of metals is explained by the bonding .electron gas. which enables atoms to pass over each other during deformation, without severing their bonds.

Introduction to Materials Science & Engineering

2007-03-18T19:59:00.000-07:00
TUTORIAL 1: Question vs Solution

ENT 112 – Materials Engineering

1. What are materials? List eight commonly encountered engineering materials.

Materials are substances of which something is composed or made. Steels, aluminium, alloys, concrete, wood, glass, plastics, ceramics and electronic materials.

2. Define materials science and materials engineering.

Materials science is the subject which is concerned with basic knowledge of the internal structure, properties, and processing of materials. Materials engineering is the subject which is concerned with the use of fundamental and applied knowledge of materials so that materials can be converted into the products necessary to and desired by society.

3. What are the main classes of engineering materials?

Metallic, polymeric, ceramic, composite, and electronic materials are the five main classes.

4. What are some of the important properties of each of these engineering materials?

Metallic Materials
§ many are relatively strong and ductile at room temperature
§ some have good strength at high temperature
§ most have relatively high electrical and thermal conductivities

Polymeric Materials
§ generally are poor electrical and thermal conductors
§ most have low to medium strengths
§ most have low densities
§ most are relatively easy to process into final shape
§ some are transparent

Ceramic Materials
§ generally have high hardness and are mechanically brittle
§ some have useful high temperature strength
§ most have poor electrical and thermal conductivities

Composite Materials
§ have a wide range of strength from low to very high
§ some have very high strength-to-weight ratios (e.g. carbon-fiber epoxy materials)
§ some have medium strength and are able to be cast or formed into a variety of shapes (e.g. fibreglass-polyester materials)
§ some have useable strengths at very low cost (e.g. wood and concrete)

Electronic Materials
§ able to detect, amplify and transmit electrical signals in a complex manner
§ are light weight, compact and energy efficient

5. Define a composite material. Give an example of a composite material.

A composite material is a materials system composed of a mixture or combination of two or more materials. Two examples are carbon-fiber epoxy and fiberglass polyester materials.

6. List some materials usage changes which you have observed over a period of time in some manufactured products. What reasons can you give for the changes that have occurred?

The modern automobile is being constructed with more and more plastic materials and less metallic due to the lower cost and weight of plastics. The modern airplane is using more composite materials and plastics and less metallic materials to reduce plane weight. Modern electronics equipment uses a great number of solid state devices made with electronic materials. These materials are more compact, weigh less, and provide higher overall and energy efficiency. In many cases, they are the only type of material that can be used for specific applications such as complex computer memories.

7. What factors might cause materials usage predictions to be incorrect?
*If a war breaks out and, as a consequence, a raw material’s supply is cut off. For example, if a major war broke out in the Middle East, the price of oil would increase, and hence the price of plastic materials would also increase.
*If a major new discovery is made, some materials’ usage may change.
*If defects show up in a specific material after a certain length of its service, the material’s usage may decrease. For example, a high strength composite material used for aircraft may start showing some delimitation defects.

Steel	Cast Iron
§ Iron with C still in solution	§ Iron which some of the C has precipitate out & appears as flakes
§ C content; 1.6 ~ 2.0%	§ C content; 2.0 ~ 6.0%C
§ Ductile compare to C. iron	§ Brittle compare to steel
§ High strength	§ Poor Strength
§ Hard to machine	§ Easy to machine
§ Hard to control casting	§ Easy to cast
§ Low damping capacity	§ Good Damping Capacity

Biometals Group	Example
Stainless Steel (SS)	§ 316 L SS
Cobalt-based alloys	§ Co-28 Cr-6 Mo cast alloy § Co-20 Cr-15 W-10 Ni wrought alloy § Co-35 Ni-20 Cr-10 Mo wrought alloy § Co-28 Cr-6 Mo cast alloy
Ti alloys	§ Pure Ti § α Ti alloy (Ti-Al, Sn, Zr) § α-β Ti alloy (Ti-6 Al-4 V, Ti-6 Al-7 Nb