Mats Lecture 2 Flashcards
What is Elasticity?
The ability for a material to return to its original shape after a force removal
What is Stiffness?
Resistance to Deformation
What is Yield Strength?
The point at which permanent (plastic) deformation starts
What is Ultimate Tensile Strength (UTS)?
The maximum amount of stress a material can handle before breaking
What is stress?
Force per area
What is Ductility?
Ability to undergo deformation before breaking
What is Hardness?
Resistance to wear
What is Thermal Expansion Coefficient?
How much a material expands when it is heated or cooled
What is Thermal (heat) Conductivity?
How well a material conducts heat
What is Specific Heat?
Amount of energy required to increase temperature
How is material classified?
Based on atomic/molecular structure
What are the main families in the material kingdom?
-Metals
-Polymers
-Elastomers
-Ceramics
-Glasses
-Hybrids (composites)
What is the first property of Metals?
Metallic solids are made up of atoms that share a “cloud” of valence electrons (metallic bonding)
What is the second property of Metals?
They have very good thermal and electrical conductivity because of metallic bonding
What is the third property of Metals?
High elastic stiffness
What is the fourth property of Metals?
Pure metals are soft and bendable (ductile)
What is the fifth property of Metals?
Metals can be strengthen
What are the ways metals can be strengthened?
-Alloying (mixing atoms of different elements)
-Strain Hardening (cold working)
-Heat Treating
What is the sixth property of Metals?
Usually have high fracture toughness
What is the seventh property of Metals?
Almost all metals are crystalline
What is the eighth property of Metals?
Metals can be shaped, joined and surface treated in many different ways
What are most elements in the periodic table?
Metals
What are metals usually found as?
Usually found in the form of metal oxides. Pure metals are seldom found in nature
How is metal extracted from its oxide?
-Coke is added and then it undergoes a process of melting or electrolysis
What are Polymers composed of?
-Are organic solids made up of long molecules containing a chain of carbon atoms
-These carbon atoms are connected by covalent bond C-C bonds
-The long molecules are usually joined to each other by weak hydrogen bonds or even weaker Van Der Waal bonding
What is the first property of Polymers?
-They are poor conductors of heat and electricity compared to metals
What is the second property of Polymers?
-Very lightweight (low density)
What is the third property of Polymers?
-Very low stiffness (approx 50x less than metals)
What is the fourth property of Polymers?
Not very strong but they have a very high strength to weight ratio
What is the fifth property of Polymers?
Very low melting temperatures (low service temperature)
What is the sixth property of Polymers?
Very easy to fabricate polymers into complex shapes
-They can be joined, shaped and surface treated for a very low cost
What is the first and second property of Elastomers?
-They are polymers but a very small number of the long molecules are joined together (cross linked) by covalent bonds
-As a result, they have the ability to undergo very large elastic deformation without breaking or deforming
What is the third property of Elastomers?
-Have very low stiffness (500x to 5000x lower than metals)
What is the first property of Ceramics?
they are non-metallic inorganic solids
What is the second property of Ceramics?
They are usually compounds made up of two or more elements
What is the third property of Ceramics?
They are held together by covalent or ionic bonds
What is the fourth property of Ceramics?
They have very low thermal and electrical conductivity
What is the fifth property of ceramics?
They have very high stiffness
What is the sixth property of Ceramics?
They have high strength
What is the seventh property of ceramics?
They are very brittle
What is the eighth property of Ceramics?
They are crystalline
What is the ninth property of ceramics?
Ceramics usually have high melting temperatures (therefore have high strength at elevated temperatures)
What is the tenth property of Ceramics?
It is difficult to make, shape, join or surface treat ceramic parts because of their brittleness and their very high melting temperatures
What is the eleventh property of Ceramics?
ceramic parts are very expensive
What do Ceramics usually constitute?
Ceramics are compounds usually consisting of at least 1 non metal constitute
What is the first and second property of Glasses?
-Mostly are non crystalline inorganic solids
-They are usually transparent
What is the third and fourth property of glasses?
-Glasses are held together by covalent or ionic bonds (same as ceramics)
-As a result, have very low thermal and electrical conductivity
What is the fifth property of Glasses?
They have lower strength, stiffness, and melting temperature than ceramics because of their lack of uniform atomic spacing
What is the sixth property of glasses?
-They are usually very brittle
What is the seventh and eighth property of glasses?
-It is easier to make parts from glasses than from ceramics because they melt at a lower temperature
-As a result, glass parts are less expensive than ceramic parts
What is hybrid material usually composed of? List them
Combination of two or more materials
-Glass Fibre Reinforced Polymers (GFRP, fibreglass)
-Carbon Fibre Reinforced Polymers (CFRP)
What group is the most commonly found material in nature?
Hybrid
What is wood composed of?
It is a hybrid of cellulose and lignin
What is bone composed of?
It is a hybrid of collagen (polymer(organic molecule)) and hydroxyapatite (glass)
Are hybrids expensive or inexpensive to make? List an example of an expensive composite and inexpensive composite
Usually are expensive
-Carbon-fibre composites are expensive
-Concrete and Plywood is inexpensive
What is the general taxonomy of the Kingdom of Materials/Processes
-Universe
-Family
-Class
-Sub-class
-Member
List the families for processes
-Joining
-Shaping
-Finishing
