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Composites by Mind Map: Composites

1. A multi phase material

1.1. Matrix phase

1.1.1. Can be Metal Ceramic Polymer

1.1.2. Function Binds fibers together Medium in which externally applied stress is transmitted Protect individual fibers from surface damage Separates the fibers Barrier to crack propagation

1.1.3. Properties Ductile Elastic modules is much lower than that of a fiber

1.2. Fiber phase

1.2.1. High tensile strength

1.2.2. Types Whiskers Very thin crystal with extreme length-to-diameter ratio Among of the strongest known materials Extremely expensive Material Fibers Small diameters Either WIres Large diameters Material

2. Particle-reinforced

2.1. Large-Particle

2.1.1. Types Cermets Ceramic-metal composites Cemented carbide Concrete Too little water leads to incomplete bonding & to much results in excessive porosity Portlans Cement Concrete

2.2. Dispersion strengthened

2.2.1. Atomic/molecular interactions

3. Fiber-reinforced

3.1. Influence

3.1.1. Fiber length Critical fiber length lc = (σ*fd)/2tc length increases, fiber reinforcement becomes more effective If fiber length is > critical length Continuous, Discontinuous or Short fibers

3.1.2. Orientation & Concentration Discontinuous(short) Aligned Randomly oriented Continuos(aligned) Strength dependent on direction Mechanical responses depend on Longitudinal Transverse

3.2. Types

3.2.1. Metal matrix composites Ductile Advantages Higher operating tempratures Non flammabil Greater resistance to degradation Reinforcements Specific stiffness Specific strength Abrasion resistance Creep resistance Thermal conductivity Dimensional stability Materials Matrix Fibers

3.2.2. Polymer matrix composites Polymer resin as matrix and fibers as reinforce material Types Glass fiber-reinforced polymer Carbon fiber-reinforced polymer Aramid fiber-reinforced polymer Other fiber-reinforced material Polymer-matrix material

3.2.3. Hybrid composites When using 2 or more types of fibers in a single matrix Most common Carbon and glass fibers in polymetric resin

3.2.4. Carbon-Carbon composites Expensive Complex processing techniques High tensile moduli High tensile strength @2000°C Resistance to creep Relatively large fracture toughness High thermal conductivity Low thermal expansion

3.2.5. Ceramic matrix composites Brittle Several techniques are uses to retard crack propagation Phase transformation Ceramic wiskers Fabrication Hot pressing Hot isostatic pressing Liquid-phase sintering

3.3. Processing

3.3.1. Pultrusion Continuous length Constant cross-sectional shape Method Fibers are impregnated with thermosetting resin Rolled through a die to the acquire shape and resin/fiber ratio Passes through a curing die for final shape and cures resin matrix

3.3.2. Prepreg Preimpregnated fibers with polyester resin Directly molds and fully cures without adding resin Method Prepreg fibers start on rolls They get sandwiched and pressed between sheets of release and carrier paper by heated rollers A doctor blade spreads the resin The release and carrier paper are removed and the final prepreg is prepared for packaging

3.3.3. Filament winding Continuous reinforced fibers are accurately positioned in a predetermined pattern to form a hollow shape Method The fibers are fed through a resin bath Then wound onto a mandrel After appropriate number of layers is applied, curing is carried out Thereafter the mandrel is removed

4. Structural

4.1. Laminates

4.1.1. Composed of 2 dimensional sheets or panels

4.1.2. Each sheet has a preferred high-strength direction

4.1.3. Multi-layered structure

4.1.4. Common ingredients Carbon Glass Aramid

4.1.5. Common Techniques for post-lay-up Autoclave molding Pressure-bag molding Vacuum-bag molding

4.1.6. Common uses Aircraft Automotive Marine Building/civil-infrastructures

4.2. Sandwich panels

4.2.1. Combination of 2 outer sheets with a bonded inner core

4.2.2. Outer sheets are usually stiffer than inner Aluminum alloys Steel Stainless steel Fiber-reinforced plastics Plywood

4.2.3. Core material is usually lightweight and has a low modulus of elasticity Functions Provides continuous support Hold faces together Withstands transverse shear stresses Provides high shear stiffness Core materials Rigid polymeric foams Wood Honeycomb

5. Nano

5.1. Nano sized particles embedded in matrix material

5.2. Can be designed to have specific properties

5.2.1. Magnetic

5.2.2. Mechanical

5.2.3. Electrical

5.2.4. Optical

5.2.5. Thermal

5.2.6. Biological

5.2.7. Transport

5.3. Degree of change depend

5.3.1. Particle size

5.3.2. The increase in ratio of particle surface area to volume

5.4. Composition

5.4.1. Matrix Materials Metals Ceramics Epoxy resin Polyurethanes Polypropylene Polycarbonate Poly Silicone resin Polyamides Ethylene vinyl alcohol Butyl rubber Natural rubber

5.4.2. Nanoparticle Nanocarbons Single- & multi wall carbon nanotunes Graphene sheets Carbon nanofibers Nanoclays Layered silicated(most common montmorillonite) Particulate nanocrystals Inorganic oxides

5.5. Most popular

5.5.1. Gas-barrier coating Montmorillonite nanoclay particles Used to keep air and water in or out Food packaging Tires,balls ect

5.5.2. Energy storage Graphene nanocomposites are used in batteries Capacity is higher Life cycles are longer Double the power is available

5.5.3. Flame-barrier coatings Multi-walled carbon nanotubes dispersed in silicone matrices Flame barrier Abrasion & scratch resistant

5.5.4. Dental restorations Nano clusters composed of silica and zirconia High fracture toughness Wear resistant Short curing times Curing shrinkages

5.5.5. Mechanical strength enhancements Adding multi-walled carbon nanotubes into epoxy resin High strength and lightweight polymer Used in wind turbine blades

5.5.6. Electrostatic dissipation Multi-walled carbon nanotubes in polymers Used in transport in highly flammable fuels ect. To prevent static charges