FINAL
Examination Paper
(COVER PAGE)
Session
:
August 2024
Programme
:
Diploma in Mechanical Engineering (DMEN)
Diploma in Electrical and Electronics Engineering (DEEI)
Course Code & Title
:
EGM1185 : Materials Science
Date of Examination
:
06 December 2024 (Friday)
Time
:
09.00am – 11.00am
Duration
:
2 Hours
Instructions
:
Reading Time :
Nil
This paper consists of FOUR (4) questions. Answer all FOUR (4) questions in the answer
booklet
provided. All questions carry equal marks.
Materials Permitted
:
Scientific Non-Programmable Calculator
Materials Provided
:
Graph Paper, Formulae Sheet (Appendix A) & Periodic Table of
Elements (Appendix B)
Examiner(s)
:
Ts. Tajul Afiq, Mr Mohd Hafis
Chief Moderator
:
Mr Teo Chong Yaw
Committee Member(s)
:
Mr Teow Hsien Loong
This paper consists of 9 printed pages, including the cover page.
EGM 1185 (F) / Page 2 of 9
DIPLOMA IN MECHANICAL ENGINEERING PROGRAMME (DMEN)
DIPLOMA IN ELECTRICAL AND ELECTRONIC ENGINEERING PROGRAMME (DEEI)
EGM 1185: MATERIALS SCIENCE
FINAL EXAMINATION: AUGUST 2024 SESSION
Instructions: This paper consists of FOUR (4) questions. Attempt ALL questions in the answer
booklet provided. All questions carry equal marks.
QUESTION 1
(a) Describe and give TWO (2) examples of biomaterials.
(4 Marks)
(b) Table Q1(b) shows the atomic number of elements A and B. Based on the table answer the
following questions:
(i)
Identify the names of elements A and B.
(2 Marks)
(ii)
Write the electron configuration for elements A and B.
(2 Marks)
(iii)
With the aid of sketches, identify the type of atomic bonding that will be formed
between A and B atoms.
(5 Marks)
Table Q1(b)
Element
A
B
Atomic Number
20
9
EGM 1185 (F) / Page 3 of 9
(c) Figure Q1(c) shows a unit cells for Iridium (Ir). Find
(i)
the atomic radius of Iridium if the density is 22.4 g/cm3.
(5 Marks)
(ii)
the atomic packing factor (APF) for Iridium
(3 marks)
Figure Q1(c)
(d) Illustrate the following direction vectors in cubic unit cells and label the axes clearly.
(i)
[1̅10]
(2 marks)
(ii)
[3̅21̅]
(2 marks)
[Total: 25 Marks]
EGM 1185 (F) / Page 4 of 9
QUESTION 2
(a) With the aid of diagrams, explain the mechanism of the TWO (2) types of self-interstitials
due to the impurities defect in materials.
(8 Marks)
(b) Give THREE (3) volume defects in metallic materials.
(3 Marks)
(c) Indicate TWO (2) advantages of alloying metallic materials.
(4 Marks)
(d) A specimen of magnesium having a rectangular cross-section of dimensions 3.2 mm by 19.1
mm is deformed in tension and the data is shown in Table Q2(d).
(i)
Plot the data as engineering stress versus engineering strain.
(6 Marks)
(ii)
Find the modulus of elasticity.
(2 Marks)
(iii)
Identify the yield strength at a strain offset of 0.002.
(1 Mark)
(iv)
Identify the tensile strength of this alloy.
(1 Mark)
Table Q2(d)
Load (N)
0
1380
2780
5630
7430
8140
9870
12850
14100
14340
13380
12500
Length (mm)
63.50
63.53
63.56
63.62
63.70
63.75
64.14
65.41
66.68
67.95
69.22
70.49
[Total: 25 Marks]
EGM 1185 (F) / Page 5 of 9
QUESTION 3
(a) Figure Q3(a) shows the lead-tin phase diagram. For a 40 wt% Sn–60 wt% Pb alloy at 150 °C.
(i)
Indicate and illustrate the phase(s) present at this instant.
(2 Marks)
(ii)
Find the composition(s) of the phase(s).
(2 Marks)
(iii)
Find the mass fraction and volume fraction of the phase(s) present. At 150 °C, the
densities of Pb and Sn are 11.23 g/cm3 and 7.24 g/cm3 respectively.
(9 marks)
Figure Q3(a)
EGM 1185 (F) / Page 6 of 9
(b) Figure Q3(b) shows a Continuous-Cooling-Transformation (CCT) diagram (solid lines) for a
1080 steel which superimposed on an isothermal diagram. By using the CCT diagram,
(i) explain the properties of the steel after each of the cooling treatment A, B, and C.
(6 marks)
(ii) explain how the fine and coarse pearlites affected to the mechanical properties of the steel
alloy.
(6 marks)
Figure Q3(b)
[Total: 25 Marks]
EGM 1185 (F) / Page 7 of 9
QUESTION 4
(a) With aid of a diagram, explain the strengthening mechanism of sheet metal by the cold rolling
method and name the secondary process to increase the ductility of the sheet metal after the
cold rolling process.
(6 Marks)
(b) (i) Describe THREE (3) main stages in the creep phenomenon, and state TWO (2) factors that
make it necessary to consider creep in metal parts design.
(5 Marks)
(ii) By sketching a diagram, describe how increasing temperature, and applied stress can affect
the rate of creep in metal part.
(5 Marks)
(iii) Give TWO (2) recommendations to reduce the effect of creep in a highly loaded (static)
part over the long term of its service.
(2 Marks)
(c) A wire whose diameter is 3.5 mm must carry a 40 A, current. The maximum power dissipation
along the wire is 0.05 kW/m. Find the minimum allowable conductivity of the wire in (𝛺 𝑚)1
for this application.
(7 marks)
[Total: 25 Marks]
~The End~
EGM1185 (F)/ August 2024 Session/ formatted
EGM 1185 (F) / Page 8 of 9
APPENDIX A: FORMULA SHEET FOR MATERIAL SCIENCE
Avogadro’s Number
Potential Difference
𝑁𝐴 = 6.022 × 1023
Atomic Packing Factor
𝐴𝑃𝐹 =
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑎𝑡𝑜𝑚𝑠 𝑝𝑒𝑟 𝑢𝑛𝑖𝑡 𝑐𝑒𝑙𝑙
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑎 𝑢𝑛𝑖𝑡 𝑐𝑒𝑙𝑙
𝑉 = 𝐼𝑅
Power
𝑃 = 𝑉𝐼
Electrical Resistance
Density
𝜌=
𝑛𝐴𝑤
𝑁𝐴 𝑉𝑐
𝑅=
𝑙
𝜌
𝐴
Electrical Conductivity
Normal Stress
𝜎=
𝐹
𝐴
Strain
𝜀=
∆𝐿
𝐿0
Young Modulus
𝐸=
𝜎
𝜀
𝜎=
𝑙
𝐴𝑅
EGM 1185 (F) / Page 9 of 9
APPENDIX B: PERIODIC TABLE OF ELEMENTS