Associate Degree of Applied Engineering …€¦ · Web viewTitanium Aluminium Zinc Tungsten Lead...
Transcript of Associate Degree of Applied Engineering …€¦ · Web viewTitanium Aluminium Zinc Tungsten Lead...
EXAM COVER SHEET Student name:
Student ID
Campus:
Associate Degree of Applied Engineering (Renewable Energy Technologies)
Subject number: ENMAT101A
Subject name: Engineering Materials and Processes
Semester 1, 2013 Final Exam
Time allowed 1:50 hours plus 10 minutes reading time
General instructions Marks
Write your answers using black or blue pen Total marks: 35% of Subject
Write your name and campus at the top of each page
All questions must be attempted.
No liquid paper (whiteout) can be used – if you make a mistake, just cross out your attempt.
Marks allocated for each question are shown throughout the examination paper. Total marks 100.
Examination aids permitted as indicated
Standard dictionaries
Bilingual dictionaries
Technical dictionaries
Programmable calculators
Non-programmable calculators
No No No No Yes
Other examination aids permitted
Writing implements (pens, pencils, erasers, highlighters) Ruler
Note: Reference information included at end
ENMAT101A Engineering Materials and Processes Semester 1, 2013
Student name: Campus:
Question 1 (8 marks total)
(a) Choose the non-ferrous metal that best matches the properties listed below. Mark with a single “tick” in each row (2 marks)
Tit
aniu
m
Alu
min
ium
Zinc
Tun
gste
n
Lead
Copp
er
Nic
kel
Low density, good electrical conductor, ductile. Alloys have high strength-to-weight ratio.
High electrical conductivity, ductile, can be soldered.
Corrosion resistant, used for surgical implants. Alloys have high strength-to-weight ratio at high temperature.High density, extremely high melting point, hard. Used in high speed steel and high temperature alloys.
High density, low melting point, soft. Used in batteries.
Easy to high pressure die-cast, corrosion coatings of steel.
Corrosion resistant. Makes special alloys for: high temperature, electrical resistance wire, low expansion.
(b) Explain why titanium is more corrosion resistant than aluminium. (1mark)
___
___
(c) What is the main property of magnesium for its use in engineering? (1mark)
___
___
(d) What is the main problem with using magnesium? (1mark)
___
___
(e) What is a Babbit metal and what is it used for? (1mark)
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
2
Student name: Campus:
(f) A catalytic converter in car exhaust systems improves emissions by completing reactions of unburnt hydrocarbons, reducing Nitrogen oxides and oxidising Carbon monoxide into CO2. Platinum works best, because it attracts the molecules to its surface so the reaction can take place. What other properties about Platinum are important here? What is a disadvantage of using Platinum? (2 marks)
___
___
___
___
___
(g) The mass airflow (MAF) sensor for this car has the following material label: PBT-GF30. Describe this code and any relevance to this operating environment. (2 marks)
PBT: ___
GF30: ___
Environment: ___
_________
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
3
Student name: Campus:
Question 2 (9 marks total)
(a) Brass is predominately an alloy of copper and _________________, while bronze is
predominately an alloy of copper and _________________ (1 mark)
(b) The Copper Zinc diagram:
From the diagram above, complete the following;
(i) What type of diagram is this? _________________ (0.5 marks)
(ii) The melting point of copper: _________________(0.5 marks)
(iii) The melting point of zinc: _________________(0.5 marks)
(iv) The melting point of brass: _________________ (0.5 marks)
(c) The majority of engineering brasses are in the range (circle the appropriate symbol/s) :
(1 mark)
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
4
Student name: Campus:
(d) With reference to the Cu/Zn diagram, explain what happens when molten cartridge brass (70/30 brass) slowly cools to 200oC. (2 marks)
___
___
___
___
(e) Explain what the letters represent, and what they have to do with copper and zinc. (1 mark)
___
___
___
(f) Why is de-zincification a problem? Give examples of what can be done about this in both the production of brass and when brass is in service. (2 marks)
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
5
Student name: Campus:
Question 3 (6 marks total)
(a) In the earth’s crust, aluminium is more common than iron. Explain why scrap aluminium is more than 10 times the price of scrap steel. (1 mark)
___
___
(b) Explain how aluminium resists corrosion. (1 mark)
___
___
(c) Explain the advantages and disadvantages of using aluminium for electrical wires. (1 mark)
___
___
___
(d) Explain artificial aging of Aluminium grade 7075T6, using information below. Describe what happens to the microstructure during the various stages of the process with regard to all the relevant data in the table below. (3 marks)
GRADEUTS
(MPa)YS
(MPa)Elongation
%
Annealing Temperature
oC
Solution Temperature
oC
Aging Temperature
oC
7075-O 228 103 17% 413 466-482 -
7075-T6 572 503 11% 413 466-482 121
___
___
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
6
Student name: Campus:
Question 4 (11 marks total)
(a) Match the most appropriate polymer to each diagram below (a) to (d). (2 marks)
(i) Natural Rubber
(ii) Epoxy
(iii) Low Density Polyethylene
(iv) High Density Polyethylene
(b) Which diagram/s (above) show thermoplastics _____ , and thermosets __ (1 mark)
(c) The melting point of a linear polymer increases with increasing molecular weight. What is the name of the intermolecular force of attraction that causes this? (1 mark)
___
(d) Explain the terms amorphous and crystalline when applied to polymers. List some of the physical differences between strongly amorphous and strongly crystalline polymers. Give an example of each. (3 marks)
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
7
Student name: Campus:
(e) Fill in the blanks in the table below. Briefly describe problems in the recycling of each plastic products and give examples of the end use of recycled scrap material. Identify the dominant material in the product and write the appropriate recycling code from the list below. (4 marks)
Product Material Code Problems / Recycled into ….
1. Carbonated drink bottle
2. Telephone
ABS
3. Electrical cable
5. Car tyre
6. Oil container
2
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
8
Student name: Campus:
Question 5 (6 marks total)
(a) According to the engineering definition, what is the difference between ceramic and glass? (1 mark)
___
___
___
(b) Hip replacement prosthesis: In the 1970’s the femoral head stem was stainless steel, and the socket (acetabular component) was Teflon. They lasted only a few years. A more modern one (below) has titanium alloy stem, ceramic ball and HDPE socket.
In the design above, describe the relevant properties of each material that make it a suitable choice in this application. (2 marks)
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
9
Student name: Campus:
(c) Identify the following ceramic materials: Amorphous Silicon Dioxide, Tungsten carbide, Titanium Nitride, Aluminium Oxide. (2 marks)
Product Material Properties required for the task
Saw
Grinding wheel
Drill
Optical fibres
(d) Explain the microstructure differences between amorphous and crystalline silicon dioxide. What is another name for the amorphous state? (1 mark)
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
10
Student name: Campus:
Question 6 (10 marks total)
(a) “Safety glass” can refer to laminated or toughened (tempered) glass. Briefly compare each in the table below. (4 marks)
Laminated Glass Tempered Glass
How it is made
Advantages for fabrication and
installation
Advantages in service and applications
Disadvantages
(b) Describe metallic glass and explain its mechanical properties. (1 marks)
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
11
Student name: Campus:
(c) Discuss the arguments (for and against) for the alleged proof that window glass flows over centuries to become thicker at the bottom and thinner at the top. How does this compare with the same claims for lead pipes and flashing? (1 marks)
___
___
___
___
(d) What does “float glass” mean? Describe how it is made. (1 mark) ___
___
___
(e) Solar panels can use monocrystalline, polycrystalline or amorphous cell technology. Identify each solar cell type below. Rank by entering 1,2 or 3 in each row. (2 marks)
Identify
Low cost
High solar efficiency
Quick payback of embodied energy
(f) Discuss performance / cost issues of using float, laminated and tempered glass for solar panels. What is the role of the glass? (1 mark)
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
12
Student name: Campus:
Question 7 (9 marks total)
(a) To make and set strong concrete there are many factors: Fill in the table below referring to cement properties such as strength, workability, curing time, shrinkage and cost. (6 marks)
What happens if too low or not enough
What happens if too high or too much
Cement ratio
Water Ratio
Curing Temperature
Curing Humidity
Sand (fine aggregate)
Gravel (coarse aggregate)
(b) Describe what a cermet is, and what the intended mechanical properties should be. (1 mark)
___
___
___
(c) Explain the mechanism of dispersion hardening. (Where small particles can strengthen a ductile metal matrix even when the particles are rounded). (2 marks)
___
___
___
Question 8 (14 marks total)
A frame for a high performance bicycle requires strength, stiffness and low weight.
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
13
Student name: Campus:
Compare alloy steels, aluminium, titanium and CFRP and explain the following: (Refer also to reference section Diagram 1: Strength vs Density and Diagram 2: Specific Stiffness vs Specific Strength).
(a) During the 1990’s, top class cyclists were racing on frames of all four materials – in the same race. Explain with reference to the chart above. (2 marks)
___
___
___
___
(b) Chrome Molybdenum steel frames are brazed while aluminium and titanium alloys are TIG welded. Explain the difference and why steel is done differently. (1 mark)
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
14
Student name: Campus:
___
___
___
(c) CFRP bike frames did not dominate until more recently. Explain with reference to the chart above, and your understanding of manufacturing processes. (1 mark)
___
___
___
___
(d) Rank the following fibre composites (enter 1, 2 and 3 in each row, where 1 = best). Briefly describe problems or disadvantages of each. (3 marks)
GRP Aramid CFRP
Strength
Stiffness
Low Weight
Briefly describe problems or
disadvantages
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
15
Student name: Campus:
(e) In this energy storage flywheel, a fibre reinforced composite is preferred over a steel flywheel. Why? Give as many reasons as you can. (False or irrelevant reasons will lose marks. E.g “Carbon is cheaper” = false. “Nicer colour” = irrelevant) (3 marks)
___
___
___
___
___
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
16
Student name: Campus:
(f) Failure of wind turbine blades. Give advantages and disadvantages of the material chosen for turbine blades. (4 marks)
Storm damage to turbine blades and tower Generator fire
Disadvantages Advantages
Manufacture
Operating performance
Minor repair and
maintenance
Major failure, recycling
Question 9 (9 marks total)
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
17
Student name: Campus:
(a) Adhesives can be classified according to the method of curing. Fill in the table below. (3 marks)
Cures by… How it works (brief) Example adhesive and application
Cooling
Chemical reaction
between 2 components
Evaporation
Surface curing
Anaerobic
Heat
(b) What does shelf-life mean, and what is the usual method of extending it? (1 mark)
___
___
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
18
Student name: Campus:
(c) Define soldering and brazing according to temperature. (1 mark)
Soldering: ___
Brazing: ___
(d) Name and briefly describe the four welding processes in the table below. (4 marks)
Name How it works Advantages/applications
MMAW
MIG
TIG
ERW
___
___
___
___
Question 10 (16 marks total)
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
19
Student name: Campus:
(a) Domestic water tanks are produced in four different materials: Concrete, steel, polyethylene and fibreglass. Briefly highlight (a few words each) the issues for/against each type of material. (6 marks)
Concrete Steel Polyethylene Fibreglass
Made by…
Transport and
installation
Water quality
Leakage and Repair
Special problems
Recycling
(b) In the solar industry, most of the racking system components (including the solar module frames) are aluminium. Bolts and nuts can be stainless steel, bronze, brass or galvanised steel.
(i) Explain galvanic corrosion with reference to the anodic table of metals. (2 marks)
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
20
Student name: Campus:
AnodicMagnesiumZincAluminium alloysLow alloy steelCast ironLeadAluminium bronze, brassCopperBronze (manganese, silicon)Nickel, SilverStainless steel 302, 304, 316, Alloy 20TitaniumGold, PlatinumGraphiteCathodic
(ii) Why is this type of corrosion more aggressive near the coast? Explain chemically. (1 mark)
___
___
___
(iii) Briefly describe four ways to counter galvanic corrosion in PhotoVoltaic system structures. (2 marks)
(c) Explain energy content (embodied energy) vs material cost. (Ref Diagram 3 and 4) (1 mark)
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
21
Student name: Campus:
_________
_________
_________
_________
(d) Why is it economic to recycle aluminium cans but less so for steel ones? (1 mark)
_________
_________
_________
(e) Describe how you would build a domestic home that has the lowest total of embodied energy + energy efficiency + re-use/recycling. Justify your answer. (Ref Diagram 3 and 4) (3 marks)
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
_________
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
22
Student name: Campus:
REFERENCE SECTION
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
23
Student name: Campus:
Diagram 1
Diagram 2
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
24
Student name: Campus:
Diagram 3
Diagram 4
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
25
Student name: Campus:
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
26
Student name: Campus:
© TAFE NSW Higher Education 2012Version: X | Day-Month-Year
27