1. Material Properties 1. Why do pans have non-metal handles?
2. Why is a space shuttle covered in ceramic tiles?
3. Why is cement better in compression and string better in tension?

2. Materials Types of Materials Atomic Structure
Bonding/Material Structure
Bulk Material Properties
Material Testing

3. Solids 1. Crystals/Metals (Fe, Cu, Al, quartz)
Atoms and molecules are systematically arranged during solidification
2. Glasses and Ceramics (sand, brick, window glass)
High viscosity during solidification prevents crystallization
3. Polymers (rubber, plastics, DNA, proteins)
Long chains of simple molecular structures.
4. Composites (plywood, cement and rebar)
Use of two or more materials to obtain desired engineering properties

4. Atomic Structure
What does an atom look like and what are its components?
How big are the electrons shells compared to the nucleus?

5. Atomic Structure 1) Composition: 2) ~10-10m across = 0.0000000001m
A) Nucleus: protons(+) and neutrons(o)
B) Electrons(-)
2) ~10-10m across = m
3) Neutral charge
#electrons = #protons
4) Electrons orbit around the nucleus
5) Reactivity with other atoms depends on # of electrons in outermost shell
6) Electrons in outermost shell are called “valence” electrons

6. Bonding Primary Bonding
Ionic: transfer of electrons between metal and non-metal ion (NaCl and ceramics)
Covalent: localized sharing of electrons
(ceramics, diamond, glass, wood)
Metallic: delocalized sharing of electrons
(metals)
Secondary Bonding
Van der Waals: weak forces that attract neutral molecules to another other in gases
Hydrogen Bonding: attractive force between molecules arising from the interaction between hydrogen atom and N, O, or F

7. Bonding 1. Why are metals ductile and ionic solid (ceramics) brittle?
2. How does a material react to pushing or pulling?
3. How do atoms react to pushing or pulling?

8. Material Properties Stress and strain Hooke’s law Plastic deformation
Springs, paper clip, silly putty
Plastic deformation
Necking

9. Stress-Strain Curve
What would the stress-strain curve look like for a ceramic material?
What about for polymer?
How would temperature affect the polymer?

10. Materials Testing Compressive Strength:
The maximum compressive stress a material can withstand without failure
Crushing or buckling failure
Failure depends on the material’s geometry and support
Euler buckling load
Testing spaghetti

11. Materials Testing Fracture Strength:
Bending Test
What’s going on in the center of the material?
Lab: Measure deflection of spaghetti under a given load.
Tensile Strength Test
Lab: Measure fracture strength of sample under tension

12. Charpy V-notch Test
Toughness: resistance to fracture of a material when stressed (defined as area under stress-strain curve)
Amount of energy absorbed in fracture
Classifies material as either brittle or ductile
Brittle: absorbs small amount of energy
Ductile: absorbs large amount of energy