cap 2 materiales

Question 1

1. Metals, ceramics, semiconductors, and polymers are the four major groups of which type of materials?

a. Construction materials.
b. Engineering materials.
c. Raw materials.
d. Crystalline materials.

Answer 1

b. Engineering materials.

Question 2

2. An example of a substitutional alloy, one where a specific atom in a metal has been replaced by another from a different element, would be:

a. plain carbon steel.
b. brass.
c. tungsten carbide.
d. silver.

Answer 2

b. brass.

Question 3

3. A basic property of metal that allows it to be extensively deformed under compression without fracturing at room temperature and relatively high strain rates is called:
   a. tensile strength.
   b. creep resistance.
   c. fracture toughness.
   d. malleability.

Answer 3

d. malleability.

Question 4

4. Large quantities of metals are used in engineering materials because of:

a. their wide variety of mechanical properties and ability to conduct electricity and heat
b. the high cost of extracting them from ore.
c. the rarity and complexity of extracting them.
d. their low fracture toughness.

Answer 4

a. their wide variety of mechanical properties and ability to conduct electricity and heal

Question 5

5. That type of engineering material has the ability to keep its strength at high temperature (higher than most metals and polymers), and is resistant to most chemicals because of the strength and stability of its bonds?

a. Plastics.
b. Composites.
c. Ceramics.
d. Pure alloys.

Answer 5

c. Ceramics.

Question 6

6. Thermistors are made from which of the following?
   a. Nano-conductors.
   b. Composites.
   c. Intrinsic semiconductors.
   d. Extrinsic semiconductors.

Answer 6

b. Composites.

Question 7

7. Diodes, light-emitting diodes, and transistors are
   all examples of which of the following?

a. Nano-conductors.
b. Composites.
c. Intrinsic semiconductors.
d. Extrinsic semiconductors.

Answer 7

c. Intrinsic semiconductors

Question 8

8. Recycling and re-melting are two of the big advantages of which type of polymer?

a. Thermoplastic.
b. Thermosetting.
c. Epoxy.
d. Covalent.

Answer 8

a. Thermoplastic.

Question 9

9. Examples of natural composites would include which of the following?

a. Concrete, cement, and brick.
b. Wood and granite.
c. Silk, beeswax, and bamboo.
d. Sandstone, coal, and slate.

Answer 9

b. Wood and granite.

Question 10

10. The properties of composites are greatly influenced by the type of matrix and:

a. the time the matrix is allowed to cure.
b. the type, shape, and size of the reinforcement materials used.
c. the color of the matrix when exposed to ultraviolet light.
d. the size of the object being manufactured.

Answer 10

b. the type, shape, and size of the reinforcement materials used.

Question 11

11. Despite the advances in the use of composite materials, the largest quantity of composites comprises:

a. fiberglass.
b. carbon fiber.
c. concrete.
d. plywood.

Answer 11

c. concrete.

Question 12

12. Nearly inert, porous growth, surface reactive, and absorbable are all examples of what broad classification of engineering materials?

a. Noble metals.
b. Biomaterials.
c. Nano-materials.
d. Bionic ceramics.

Answer 12

b. Biomaterials.

Question 13

13. Materials that change shape with temperature, change dimension with application of an electrical impulse, or respond to strain by producing a magnetic field are called:

a. nanocrystalline materials.
b. proprietary response materials.
c. smart materials.
d. activated materials.

Answer 13

c. smart materials.

Question 14

14. The number of protons in the nucleus of an atom is referred to as which of the following?

a. Neutral number.
b. Atomic or Z-number.
c. Isotope number.
d. Electron-proton number.

Answer 14

b. Atomic or Z-number.

Question 15

15. Regarding the elements on the periodic table, a neutral atom has:

a. the same number of protons as neutrons.
b. the same number of protons as electrons.
c. only neutrons.
d. only protons.

Answer 15

b. the same number of protons as electrons.

Question 16

16. Atoms of the same element that have a different number of neutrons in their nucleus are referred to as:

a. rare earth elements.
b. metalloids.
c. halogens.
d. isotopes.

Answer 16

d. isotopes.

Question 17

17. Ionic, covalent, and metallic bonding are all examples of what general type of chemical bonding?
    a. Strong bonds.
    b. Weak bonds.
    c. Permanent bonds.
    d. Temporary bonds.

Answer 17

a. Strong bonds.

Question 18

18. Which type of bond is always found in compounds that contain both metallic and nonmetallic elements?
    a. Covalent.
    b. Metallic.
    c. Ionic.
    d. Dipole-dipole.

Answer 18

c. Ionic.

Question 19

19. Two atoms that are covalently bonded will share at least:

a. two electrons.
b. one electron.
c. two protons.
d. one proton.

Answer 19

b. one electron.

Question 20

20. The three most common lattice structures for metals include which of the following?

a. Body-centered cubic, diagonal close-packed, hexagonal open-packed.
b. Body-centered cubic, face-centered cubic, diagonal close-packed.
c. Body-centered cubic, hexagonal close-packed, diagonal close-packed.
d. Body-centered cubic, face-centered cubic, hexagonal close-packed.

Answer 20

d. Body-centered cubic, face-centered cubic, hexagonal close-packed.

Question 21

21. Iron has a body-centered cubic structure at room temperature, but as it is heated this structure changes to:

a. hexagonal close-packed.
b. body-centered tetragonal.
c. face-centered cubic.
d. hexagonal close-packed.

Answer 21

c. face-centered cubic.

Question 22

22. A material that has no well-defined crystalline structure is often described as in nature.
    a. ductile
    b. amorphous
    c. polymorphous
    d. triaxial

Answer 22

b. amorphous

Question 23

23. Prior to the onset of yield, the ratio between stress (amount of force per unit area) and strain (change in length per unit length) is known as:
    a. Avogadro’s number.
    b. fatigue limit.
    c. modulus of elasticity.
    d. phase diagram.

Answer 23

c. modulus of elasticity.

Question 24

24. If an entire piece of material is only one crystal, its properties will vary with direction. That material is said to be:

a. allotropic.
b. anisotropic.
c. isotropic.
d. plastic.

Answer 24

b. anisotropic.

Question 25

25. If an entire piece of material is made up of small crystals that are randomly oriented and its properties are identical regardless of direction, that material is said to be: a. allotropic. b. anisotropic. c. isotropic. d. elastic.

Answer 25

c. isotropic.

Question 26

26. Temporary deformation of a material when stress is applied, which fully reverses when stress is removed, is also known as: a. plastic deformation. b. elastic deformation. c. thermal expansion. d. viscous deformation.

Answer 26

b. elastic deformation.

Question 27

27. Permanent deformation of a material when a stress is applied and then removed is also known as: a. plastic deformation. b. elastic deformation. c. magnetic deformation. d. piezoelectric deformation.

Answer 27

a. plastic deformation.

Question 28

28. A(n) ________ phase .diagram graphically illustrates the relationship between temperature, composition, and the phases present in a particular alloy system. a. crystal b. isothermal c. equilibrium d. atomic bonding

Answer 28

c. equilibrium

Question 29

29. An iron-carbon mixture with more than 2.11% carbon is commonly referred to as: a. steel. b. stainless steel. c. cast iron. d. primary iron.

Answer 29

c. cast iron.

Question 30

30. Heating a piece of material to a specific temperature range, holding at that temperature for a period of time, and cooling it slowly at a specific cooling rate describes what metal-working process? a. Quenching. b. Carburizing. c. Forging. d. Annealing.

Answer 30

d. Annealing.

Question 31

31. Annealing to remove strain hardening due to previous cold working and to restore ductility so that additional cold working on the product can be performed is called: a. full annealing. b. process annealing. c. normalizing. d. stress relief.

Answer 31

b. process annealing.

Question 32

32. The technique used to provide uniformity in grain size and composition throughout the thickness of steel prior to further processing is called: a. full annealing. b. process annealing. c. normalizing. d. stress relief.

Answer 32

c. normalizing.

Question 33

33. When some alloys are aged at room temperature or at a slightly elevated temperature, it increases the mechanical properties due to the precipitation of alloying elements. This procedure is called: a. precipitation hardening. b. cold hardening. c. cold working. d. precipitation softening.

Answer 33

a. precipitation hardening.

Question 34

34. The degradation of a material, or deterioration of physical properties, due to a reaction with its environment describes: a. abrasion. b. corrosion. c. fracture. d. fatigue.

Answer 34

b. corrosion.

Question 35

35. The most common type of corrosion, which is caused by a chemical or electrochemical reaction that deteriorates the entire exposed surface of the material, is referred to as: a. localized corrosion. b. pitting. c. flow-assisted corrosion. d. general corrosion.

Answer 35

d. general corrosion.

Question 36

36. Corrosion that occurs under gaskets or seals, inside cracks or seams, or in spaces filled with deposits and under sludge piles is called: a. filiform corrosion. b. crevice corrosion. c. galvanic corrosion. d. erosion corrosion.

Answer 36

b. crevice corrosion.

Question 37

37. Corrosion that occurs as a result of localized attack at or near the grain boundaries in a metal or alloy is called: a. crevice corrosion. b. general corrosión. c. intergranular corrosion. d. fretting corrosion.

Answer 37

c. intergranular corrosion.

Question 38

38. The imperfection of crystals that are missing or have a few extra atoms is referred to as a: a. line defect. b. point defect. c. line dislocation. d. screw dislocation.

Answer 38

b. point defect.

Question 39

39. When the crystalline lattice is deformed in a spiral form, the dislocation is called: a. line defect. b. point defect. c. line dislocation. d. screw dislocation.

Answer 39

d. screw dislocation.

Question 40

40. When a material is "cold worked" at room temperature, causing plastic deformation, it becomes harder to deform. This process is called: a. cold hardening. b. case hardening. c. strain hardening. d. stress hardening.

Answer 40

c. strain hardening.

Question 41

41. A material that is plastically deformed (rolled, pressed, drawn, extruded, and so on) above its recrystallization temperature is said to have been: a. heat treated. b. hot worked. c. pressure treated. d. pressure worked.

Answer 41

b. hot worked.