Week 1 Flashcards
Describe valence of the atoms in a metallic bond.
Valence electrons are free to drift through the entire material, forming a “sea of electrons” surrounding net positive ionic cores.
What are the 6 material property types?
Mechanical Electrical Thermal Magnetic Optical Deteriorative
Define the following term:
Processing
Different ways for shaping materials into useful components or changing their properties
Define the following term:
Synthesis
The process of which materials are made from naturally occurring or other chemicals
State any two applications in which single crystals are used.
Electronic and optical applications.
What are some of the materials and mechanical properties of metals and alloys?
Metals and alloys have relatively high strength, high stiffness, ductility or formability, and shock resistance.
The myriad materials in the world primarily fall into four basic categories; what are
they?
Metals
Polymers/plastics
Ceramics
Composites
What is the purpose of the classification for functional materials?
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.
Define the following term:
Structure
The arrangement of atoms or ions in a material
Define the following term:
Microstructure
The structure of a material at the microscopic level
Which of the 4 material classes has the highest strength?
Metals
Why are covalently bonded materials generally less dense than those that are bonded
ionically or metallically?
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.
Describe the behaviour of the atoms in a crystalline material.
Atoms are arranged in a 3D, periodic array.
What is material engineering?
An engineering-oriented field that focuses on how to transform materials into useful devices or structures.
Give an example of a composite material.
Concrete, plywood, fibreglass, and wood and bone (naturally occurring
composites).
Which of the 4 material classes has the lowest strength?
Polymers
Describe the behaviour of atoms in an amorphous material.
In an amorphous material, the atoms only have short range order.
How is a metallic bond formed?
Electrostatic attraction between metal cations and delocalised electrons.
What is material science?
A field of science that emphasises studies of relationships between
the microstructure, synthesis and processing, and properties of materials.
Are crystalline materials anisotropic or isotropic?
Anisotropic.
What are materials called that have one or more different types of material
fabricated into one component?
Composite materials
Describe the enabling materials property of polycarbonate for eyeglass lenses and why it is so.
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.
Define the following term:
Composition
The chemical make up of a material
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?
- 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.
What are the different levels of structure of a material?
Sub-atomic
Atomic
Microscopic
Bulk
Describe the enabling materials property of a cobalt chrome molybdenum alloy for hip implants and why it is so.
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.
What is the difference between the microstructure and the macrostructure of a
material?
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.
Are amorphous materials anisotropic or isotropic?
Isotropic.
