Introduction to Materials Engineering

Question 1

Physical properties fall into four general groups:

Answer 1

1) Mechanical
2) Thermal
3) Electrical, magnetic, and optical
4) Chemical

Question 2

Define elasticity

Answer 2

Ability of a material to return to its original shape after force removal

Question 3

Define stiffness

Answer 3

Resistance to deformation

Question 4

Define yield strength

Answer 4

At the point that permanent (plastic) deformation starts

Question 5

Define UTS

Answer 5

Ultimate tensile strength, the maximum amount of stress a material can withstand before breaking

Question 6

Define ductility

Answer 6

Material’s ability to undergo deformation before breaking

Question 7

Define hardness

Answer 7

Resistance to wear

Question 8

Define thermal expansion coefficient

Answer 8

How much a mterial expands when it is heated/cooled

Question 9

Define thermal (heat) conductivity

Answer 9

How well a material conducts heat

Question 10

Define specific heat

Answer 10

Aount of energy required to increase temperature

Question 11

What are the 6 main families of the material kingdom?

Answer 11

• Metals
• Polymers
• Elastomers
• Ceramics
• Glasses
• Hybrids (composites)

My Pretty Elephant Can’t Get High

Question 12

What are the five-ish properties of metals?

Answer 12

• Good thermal and electrical conductivity
• High elastic stiffness
• High fracture toughness
• Ductile, in pure state / strengthened by alloying/strain hardening/heat treating
• Mostly crystalline

Question 13

Define fracture toughness

Answer 13

Describes the resistance of brittle materials to the propagation of flaws

Question 14

How is a metal M extracted from its oxide “ore”?

Answer 14

Coke is added to the metal ore and the reactants are subjected to heat and/or electricity.

Question 15

What are polymers?

Answer 15

Organic solids made up of long molecules containing a chain of carbon atoms

Plastics are a sub-category of polymers

Question 16

Differentiate between thermoplastic and thermosetting polymers.

Answer 16

THERMOPLASTIC
- structure: amorphous
- IMF: weak hydrogen bonds
- recyclability: yes
- heat resistance: no

THERMOSETTING
- structure: crystalline
- IMF: strong covalent cross-links
- recyclability: no
- heat resistance: yes

Question 17

What are some properties of polymers?

Answer 17

• Poor thermal and electrical conductivity
• Low elastic stiffness
• Low fracture toughness
• Low melting point
• Can be both crytalline and amorphous

Question 18

What are elastomers? Properties?

Answer 18

Elastomers are slightly cross-linked polymers. They undergo large elastic deformation without deforming. They have very low stiffness.

Question 19

What are the properties of ceramics?

Answer 19

• Usually compounds of 2+ elements
• Held together by covalent or ionic bonds
• Low thermal and electrical conductivity
• High stiffness, strength, melting temperatures
• Very brittle
• Crystalline
• Ceramic parts are expensive!!

Question 20

Properties of glasses

Answer 20

Very similar to ceramics but
- Amorphous
- Lower strength, stiffness, and melting temps
- Less expensive than ceramic parts

Question 21

Properties of hybrid

Answer 21

• Combination of 2+ materials
• Almost all natural materials are hybrids
• Often expensive to make

Question 22

Processes are organized

Answer 22

Universe
Family
Class
Member
Attributes

Question 23

How are material families grouped?

Answer 23

Material families are based on structure and structure determines properties - so family members have similar properties.