1. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering Summary of Material Science Chapter 1: Science of Materials Chapter 2: Properties of Materials Chapter 3: Material Testing Chapter 4: Alloys of Materials Chapter 5: Plain Carbon Steels Chapter 6: Heat Treatment Chapter 7: Cast Iron Chapter 8: Plastics/Polymers Chapter 9: Composite Materials Chapter 10: Ceramics Chapter 11: Semiconductors & Diodes Chapter 12: Biomaterials Chapter 13: Electrochemistry

2. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering COMPOSITE MATERIALS Alloys of metals and metals with non-metals could only occur if all the component materials were miscible, that is soluble in each other in the molten state. Composite materials can be made from materials that are not soluble in each other. Composite materials are not alloys.

3. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering COMPOSITE MATERIALS By combining two different materials we can produce a material that is greater than the sum of the parts. To act as one the materials must bond intimately, otherwise the reinforcement will weaken the matrix phase.

4. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering LAMINATION Brittle materials such as concrete and ceramics are strong in compression but weak in tension Tensile load Crack runs when load is applied Initial crack Laminate with good tensile properties Ceramic material Before load (a) Crack stops at the interface (b) Tensile load External tension Fibres holds ceramic in compression Surface crack Ceramic matrix (c)

5. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Reinforced Concrete Concrete itself is a particle-reinforced material. It consists of mortar made from cement and sand, reinforced with an aggregate of chipped stones. Also add fibre = steel

6. PLYWOOD (a) Load perpendicular to grain carried by natural cellulose tubes acting as reinforcement (b) Load parallel to grain causes wood to break as lignin bond is relatively weak Grain direction Adhesive film Lamination All placed together and joined

7. LAMINATED PLASTIC (TUFNOL™) Fibrous materials such as paper, woven cotton, cloth, and woven glass fibre cloth can be used to reinforce phenolic and epoxy resins. Tufnol™ composites are widely used for making bearings, gears and other engineering products, which have to operate in hostile environments or where adequate lubrication is often not possible, as in food processing and office machinery. In the electronic industry copper clad sheet tufnol™ is used for making printed circuit boards. It is also used for making insulators for heavy-duty electrical equipment in the electrical power engineering industry.

8. Dr. Joseph Stokes School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Glass Reinforced Plastic (GRP) The important composite material is produced when a plastic material, usually a polyester/epoxy resin, is reinforced with glass fibre in a strand or mat form. The resin is used to provide shape, colour and finish, whilst the glass fibre, which are laid in all directions, impart mechanical strength.

9. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Glass Reinforced Plastic (GRP) Load Matrix Reinforcement (area a) Reinforcement area fraction = n = number of reinforcements a = cross-sectional area of each reinforcement A = total cross-sectional area of composite Total cross-sectional area (A)

10. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Glass Reinforced Plastic (GRP) E-glass: Most common, high resistance to acids, originally for Electrical applications(Al 2 O 3 -B 2 O 3 -SiO 2 <1%Na 2 O) S-glass: More expensive, higher tensile strength, stiffer (SiO 2 -Al 2 O 3 -MgO).

11. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Glass Reinforced Plastic (GRP) Chopped Strand Plain Weave Long Fibre

12. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT Glass Reinforced Plastic (GRP) Surfacing tissue Former Laminating resin Tensile modulus (GPa) Tensile strength (MPa)

13. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering FIBRE REINFORCEMENT CARBON FIBRES Higher elastic modulus Lower density Higher strength-to-weight ratio Lightweight, high strength applications: Gas turbine fan blades Racing car body panels High performance tennis racket frames High performance golf club shafts. Compared to glass fibre

14. Dr. Joseph Stokes School of Mechanical & Manufacturing Engineering PARTICLE REINFORCEMENT Cermets Combine ductility & toughness of a metal with the hardness & compressive strength of a ceramic. Metal matrix and ceramic particles. Certain metal oxides & carbides can be bonded together and sintered into a metal powder matrix Cermets: CEramic Reinforced METalS. e.g. WC-Co:

15. Dr. Joseph Stokes School of Mechanical & Manufacturing Engineering PARTICLE REINFORCEMENT Cermets

16. Dr. Joseph Stokes School of Mechanical & Manufacturing Engineering PARTICLE REINFORCEMENT Cermet Alloy

17. Dr. Owen Clarkin School of Mechanical & Manufacturing Engineering PARTICLE REINFORCEMENT "Whiskers" and Dispersion Hardening 'Whiskers" are high aspect ratio crystals grown with very high strengths. They may have a diameter of only 0.5 to 2.0 microns, yet have a length of up to 20 millimetres. The properties of some whiskers are shown in table 9-4. Increase Toughness