ME381 Manufacturing Exam 1

The chemical formula for polyisoprene in natural rubber is:

C5H8

What elements are traditionally alloyed with copper to form (a) bronze and (b) brass?

(a) Sn and (b) Zn

What is considered a basic metal shaping process? Welding Electroplating Heat treating Casting

Casting

As the degree of crystallinity in a given polymer increases, the polymer becomes denser and stiffer, and its melting temperature decreases: T or F

False

Which one is NOT an application for Molybdenum? Die casting molds; Filament wire for incandescent light bulbs; Jet engine parts; Heat shields

Filament wire for incandescent light bulbs

Which the alloying elements increase hot hardness in steel: Mo, Co, W, P, Cr

Mo, W, Cr

Besides high carbon content, what other alloying element is characteristic of the cast irons? Silicon, Cobalt, Cadmium, Manganese

Silicon

A branched molecular structure is stronger in the solid state and more viscous in the molten state than a linear structure for the same polymer: T or F

T

The basic difference between low density polyethylene and high density polyethylene is that the latter has a much higher degree of crystallinity: T or F

True

Degree of polymerization is which one of the following sum of the molecule weights of the mers in the molecule proportion of the monomer that has been polymerized average number of mers in the molecule chain none of the above

average number of mers in the molecule chain

From which of the following ores is aluminum derived: cementite, alumina, scheelite, bauxite, hematite

bauxite

Which of the following is not an elastomer? butyl rubber styrene-butadiene rubber polyisoprene cellulose polyurethane polybutadiene

cellulose

Which of the following polymers are normally thermoplastic? Phenolics Cellulose acetate Polyisoprene Acrylics Polychloroprene Polyesters Polyethylene Nylon Polyurethane

cellulose acetate, acrylics, polyethylene, nylon

Which of the following alloying elements are most commonly associated with stainless steel (two best answers): tungsten chromium nickel molybdenum manganese

chromium and nickel

Which of the following is the most important cast iron commercially: gray cast iron ductile cast iron white cast iron malleable iron

gray cast iron

What property is titanium NOT noted for: high electrical conductivity; high temperature strength, corrosion resistance (due to the formation of a thin but tough oxide film), high strength-to-weight ratio

high electrical conductivity

What are some of the properties aluminum is NOT noted for: high temperature strength high thermal conductivity good corrosion resistance ( due to the formation of a tough oxide film on its surface) low density

high temperature strength

What properties does Boron add as an alloying element? Reduces cutting friction and decreases hardness; Largely increases hardenability and improves surface finish; Increases weldability and reduces corrosion; Increases wear-resistance and hot-hardness ability

largely increases hardenability and improves surface finish

Which one of the following metals has the lowest density: magnesium, tin, titanium, aluminum

magnesium

Which of the following metals has the highest density: lead, gold, platinum, tungsten, silver

platinum

Which of the following plastics has the highest market share: polypropylene, polyvinylchloride, polyethylene, phenolics, polysterene

polyethylene

The following repeat unit is for a polymer that is used in the fabrication of milk jugs. H H I I --C--C-- I I H CH_3 Name the polymer.

polypropylene (PP)

The following repeat unit is for a polymer that is used in the fabrication of soda bottles. O O H H II II I I --C--(())--C--O--C--C--O-- I I H H Name the polymer.

polythylene terephthalate (polyester, PET)

Which of the following is NOT a class of superalloys: nickel-based alloys, cobalt-based alloys, iron-based alloys, potassium-based alloys

potassium-based alloys

Which metal is NOT refractory: molybdenum (Mo) selenium niobium (Nb) tungsten (W) tantalum (Ta)

selenium