MatSE 259 - Third exam Fall 2005
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Only one correct answer for each question
Turn in test questions paper with answer sheets
For problems 1-4, match with a-e below
a. 
polyester
b. 
nylon
c. 
polyurethane
d. 
polyethylene
e. 
Bakelite
1. Polyester a
2. Polyethylene d
3. Nylon b
4. Bakelite e
5. Which polymer in a-e above is branched? d
6. Which polymer in a-e above polymerizes by addition? d
7. Which polymer in a-e above has an ester group? a
8. Which polymer in a-e above is not thermoplastic? e
9. Below is shown one of the welded joints in a 6061-T6 (Al w/ Mg & Si) bicycle frame. Diamond pyramid hardness values, determined after the welding, at various points near the weldment (region C) are given. Which region is overaged? The diagram on the next page should help jog your memory on age hardening.
10. Which shows the microstructure of a ductile cast iron?
a.
graphite flakes - grey iron
b.
graphite nodules - ductile iron
c.
CM + P - white iron
11. What purpose does chromium serve in chromium plating?
a. to smooth the metal surface
b. to make the metal surface look good
c. to protect the metal underneath
d. to prevent crevice formation
12. Determine the best quenching medium to obtain a hardness of RC37 at a depth of 0.2 from the surface in a 2" diam. 4640 bar. The 4640 Jominy curve is given below.
a. water
b. oil
c. air
d. brine
13. Reason for use of a ceramic cutting tool
a. can't afford the more expensive types of tools
b. the work material is very soft
c. the work material is very hard
d. need a tool that doesn't fracture easily
14. For the corrosion example shown below, what type of cell is probably NOT responsible for the corrosion?
a. concentration in this case, oxygen concentration (crevice present)
b. dissimilar metals
c. non-homogeneous residual stress
d. none of the above
15. Best method for suppressing corrosion in an underground carbon steel water line
a. cathodic protection - make steel cathodic through imposed voltage (w/ inert anode)
b. sacrificial anode - not best....would have to dig up & replace anodes periodically
c. Cr plating - too expensive
d. sensitization - ??
e. passivation - can't...just get rust
16. Candidate material for induction hardening - need steel w/ good hardenability
a. 1020 - C too low
b. 6061-T6 - not a steel!! (see problem 9)
c. 1008 - C too low
d. 4340 - this is the only really hardenable grade....0.4 C + alloy elements
17. Quench and temper not required
a. pack carburizing
b. gas carurizing
c. nitriding - nitride case is inherently hard
d. carbonitriding
18. Corrosion "microcell"
a. deep scratch in galvanized coating
b. deep scratch in noble metal coating
c. 6061-T6 - T6 ageing gives tiny precipitate particles in Al matrix
d. bent nail
e. deep scratch in painted steel surface
19. Below are side and end views of a portion of a polyvinyl chloride (PVC) molecule. The large spheres represent the chlorine atoms. The molecule is
a. attacktic
b. atactic
c. syndiotactic
d. isotactic
e. monotactic
20. Which is correct?
a. when scratched, noble metal coatings corrode
b. when scratched, the metal underneath a noble metal coating doesn't corrode
c. when scratched, sacrificial metal coatings corrode
d. when scratched, the metal underneath a sacrificial metal coating corrodes
e. no corrosion occurs when coating scratched
21. What is the polymer molecule shown below
a. a polyester
b. polypropylene
c. nylon
d. polyethylene - no branches, no functional groups
e. branched polyethylene
22. Which stainless steel can be sensitized?
a. 321 Ti ties up carbon
b. 347 Nb ties up carbon
c. 304L almost no carbon for Cr carbide formation
d. 304 - C available for Cr carbide formation in grain boundaries
e. all of the above
23. Molecular weight of a polyethylene chain containing 8000 ethylene units (C -12, H - 1)
a. 8000
b. 1012
c. 28
d. 112,000
e. 224,000
24. Which is a block copolymer?
a. nylon
b. polyethylene
c. Bakelite
d. polypropylene
e. none of the above
25. Everyone got this right!!!