1. Material Science and Materials Processing (Day 1) Class

2. What are the Three Classifications of materials?

3. Material Classifications
Natural materials:
Occur in nature
Organic: wood, cotton, hemp
Inorganic: stone, clay, metals
Synthetic:
Human-made: rubber, plastics, nylon, Teflon
Mixed materials:
Combination of natural and synthetic: plywood, paper…etc.

4. Types of Materials (Close-up)
Woods (Natural & Engineered)
Metal
Plastics
Ceramics
Composites

5. Types of Materials (Close-up)
Woods
Thickness of cell walls determines density.
Color is a function of the chemicals in its cell walls.
Grain is the way wood fibers grow.
(Engineered):
Made by combining particles and fibers of wood with adhesives: wood chips, plywood.
Advantages: more strength per pound

6. Types of Materials (Close-up)
Metal:
Structure determines properties
Good conductors of electricity and heat
These are factors that might influence material selection.
Categorized as:
Ferrous:
Contain iron: steel
Nonferrous:
Do not contain iron: aluminum

7. Types of Materials (Close-up)
Plastics:
Can be made into films, fibers, and solids; molded into a variety of products and shapes.
Most plastics are made from petroleum.
Plastics are polymers. Have an enormous amount of uses.
Have densities less than metals, greater than most woods, and similar to crude oil. (material selection)
Categorized as:
Thermoplastic: can be softened by heat, then hardened again by cooling.
Thermoset: cannot revert once heated and molded.

8. Types of Materials (Close-up)
Ceramics: (material selection)
Made from clay and nonmetallic inorganic materials
Have an atomic structure that forms a 3-D geometric shape
Compounds formed by combinations of metallic and nonmetallic elements
High melting points; high strength and hardness; resistant to wear; brittle; can be transparent, translucent, or opaque; low densities
Sometimes a better choice then metal because it tolerates heat well and is an electrical insulator.

9. Types of Materials (Close-up)
Composites:
Combination of two or more materials with different properties
Materials retain separate identities
Formed by using materials of two types:
Matrix material
Reinforcement material (fiber)
Often lighter and provide similar or greater strength applications
Cost of manufacturing is significantly higher.
Often used in decks because it is resistant to rotting and insect damage.
Categorized into three matrix types:
Polymer, metallic, and ceramic

10. Types of Materials (Close-up)
Why Composites?

11. What are some properties of materials?

12. Properties of Materials
Key ideas:
Materials are chosen based on properties that make them appropriate for particular applications.
Categories:
Physical, mechanical, electrical, chemical, magnetic, thermal, optical, and acoustic.

13. Properties of Materials
Mechanical:
Those that influence a material’s ability to endure and withstand applied forces
Mechanical Testing:
Strength
Hardness
Ductility
Elasticity
Plasticity
Malleability
Brittleness
Toughness
Yield Point

14. Elastic limit (yield strength)
Beyond the elastic limit, permanent deformation will occur.
The lowest stress at which permanent deformation can be measured.
Under repetitive stresses, cracks in a metal can develop and grow and cause failure even thought the elastic limit has not been reached.

15. Properties of Materials
Strength (forces):
Flexural

16. Failure of Materials
Buckling occurs when a given material is compressed until it gives way and collapses

17. Properties of Materials
Physical properties:
Density and freezing, melting, and boiling points
Density is a measure of how tightly atoms are packed together
Freezing, melting, and boiling points exist on a temperature continuum

18. Properties of Materials
Electrical properties:
Conductivity and resistivity
Magnetic properties:
Diamagnetic, paramagnetic, or ferromagnetic
Thermal properties:
Ability to conduct heat and expand when heated
Optical properties:
Ability to reflect, absorb, refract, or transmit light

19. Material Science and Materials Processing (Day 2) Class

20. Processing Materials Key ideas:
The term “processing” means transforming basic (raw) materials into industrial materials, and then into finished products.
Processing methods are categorized according to:
Mass change
Phase change
Structure change.
deformation of material
Consolidation of material
**Example: Processing trees into timber**

21. Processing Materials (cont’d.)
Mass change:
Cladding
Electroplating
Drilling
Sawing
Grinding
Turning
Phase change:
Casting
Pressing
Injection molding
Blow molding
Vacuum forming
Rotation molding

22. Processing Materials (cont’d.)
Structure-change:
Hardening
Annealing
Tempering

23. Processing Materials (cont’d.)
Deformation:
Forging
Rolling
Machine pressing
Extrusion
Drawing
Consolidation:
Fastening
Joining
Sintering
Composite materials
Coating

24. Processing Materials (cont’d.)
Example Processes:
Injection Molding: (Very Accurate) common industrial process used to manufacture parts.
Extrusion: process whereby a continuous stream of a product is made by squeezing softened material (just below its melting point) through a small opening called a die.

25. Processing Materials (cont’d.)
Example Processes:
Sintering: is a process where powdered materials are combined with a binding material and pressed into shapes in a mold under heat and high pressure.

26. Factors in Selecting Materials
Key ideas:
Materials are chosen based on their properties, as well as other factors.
Choice of material often reflects trading off competing benefits.
True costs of materials extend beyond the cost of the raw material itself.

27. Factors in Selecting Materials (cont’d.)
Properties determine suitability for applications:
Cost
Safety
Availability
Disposability
Environmental impact

28. Factors in Selecting Materials (cont’d.)
True cost of a material includes:
Cost of the raw material
Amount of energy and water needed
Amount of pollution generated
Human time and effort wasted

29. Factors in Selecting Materials (cont’d.)
Availability of materials is a primary.
Safety is also important.
Disposability and environmental impact drive decisions about materials.
Some materials can biodegrade.
Engineers also consider the energy it takes to process materials.

30. Factors in Selecting Materials (cont’d.)
Figure 4.70 Comparison of cost versus strength for structural materials.

31. Factors in Selecting Materials (cont’d.)