Week 1

Question 1

Describe valence of the atoms in a metallic bond.

Answer 1

Valence electrons are free to drift through the entire material, forming a “sea of electrons” surrounding net positive ionic cores.

Question 2

What are the 6 material property types?

Answer 2

Mechanical
Electrical
Thermal
Magnetic
Optical
Deteriorative

Question 3

Define the following term:

Processing

Answer 3

Different ways for shaping materials into useful components or changing their properties

Question 4

Define the following term:

Synthesis

Answer 4

The process of which materials are made from naturally occurring or other chemicals

Question 5

State any two applications in which single crystals are used.

Answer 5

Electronic and optical applications.

Question 6

What are some of the materials and mechanical properties of metals and alloys?

Answer 6

Metals and alloys have relatively high strength, high stiffness, ductility or formability, and shock resistance.

Question 7

The myriad materials in the world primarily fall into four basic categories; what are
they?

Answer 7

Metals
Polymers/plastics
Ceramics
Composites

Question 8

What is the purpose of the classification for functional materials?

Answer 8

Materials can be classified based on the most important function they perform, for
instance, mechanical(structural), biological, electrical, magnetic, or optical.

The classification is very important as it is helpful in recognising different materials and their characteristics.

Question 9

Define the following term:

Structure

Answer 9

The arrangement of atoms or ions in a material

Question 10

Define the following term:

Microstructure

Answer 10

The structure of a material at the microscopic level

Question 11

Which of the 4 material classes has the highest strength?

Answer 11

Metals

Question 12

Why are covalently bonded materials generally less dense than those that are bonded
ionically or metallically?

Answer 12

Covalently bonded materials are less dense than metallic or ionically bonded ones
because covalent bonds are directional in nature whereas metallic and ionic are not.

When bonds are directional the atoms cannot pack together in a dense manner yielding
a lower mass density then solids with non-directional bonds.

Question 13

Describe the behaviour of the atoms in a crystalline material.

Answer 13

Atoms are arranged in a 3D, periodic array.

Question 14

What is material engineering?

Answer 14

An engineering-oriented field that focuses on how to transform materials into useful devices or structures.

Question 15

Give an example of a composite material.

Answer 15

Concrete, plywood, fibreglass, and wood and bone (naturally occurring
composites).

Question 16

Which of the 4 material classes has the lowest strength?

Answer 16

Polymers

Question 17

Describe the behaviour of atoms in an amorphous material.

Answer 17

In an amorphous material, the atoms only have short range order.

Question 18

How is a metallic bond formed?

Answer 18

Electrostatic attraction between metal cations and delocalised electrons.

Question 19

What is material science?

Answer 19

A field of science that emphasises studies of relationships between
the microstructure, synthesis and processing, and properties of materials.

Question 20

Are crystalline materials anisotropic or isotropic?

Answer 20

Anisotropic.

Question 21

What are materials called that have one or more different types of material
fabricated into one component?

Answer 21

Composite materials

Question 22

Describe the enabling materials property of polycarbonate for eyeglass lenses and why it is so.

Answer 22

Compared to real glass, which is much heavier, polycarbonate is lighter and far
more resistant to impact. Wearing them both and comparing the two will
almost surely change the mind of someone using real glass on their eyewear.

Question 23

Define the following term:

Composition

Answer 23

The chemical make up of a material

Question 24

What properties should an engineer consider for a total knee replacement of a
deteriorated knee joint with an artificial prosthesis when selecting the materials for this
application?

Answer 24

• Biocompatibility – minimum rejection by surrounding body tissue;
• Chemically inert to body fluids;
• Mechanical strength to support forces generated; and
• Good lubricity and high wear resistance between articulating surfaces.

Question 25

What are the different levels of structure of a material?

Answer 25

Sub-atomic
Atomic
Microscopic
Bulk

Question 26

Describe the enabling materials property of a cobalt chrome molybdenum alloy for hip implants and why it is so.

Answer 26

This material is resistant to corrosion, it also does not give in easily to metal
stress. Its inherent strength and hardness makes it a reliable hip implant
material.

Question 27

What is the difference between the microstructure and the macrostructure of a
material?

Answer 27

The macrostructure is the structure of a compact substance, which consists of the
elements of the microstructure.

The microstructure is built depending on the conditions of crystallisation.

Question 28

Are amorphous materials anisotropic or isotropic?

Answer 28

Isotropic.