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09 - COMPOSITE MATERIALS


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Composites
MATERIALS CONSISTING OF TWO OR MORE DISTINCT PHASES, phases that can give material excellent phisical and mechanical properties in addition to a higher price and sometimes, non-isotropic properties. Can be separated into [1] Traditional composites - woods, portland cement and [2] Synthetic composites - carbon and glass fiber composites. >>> EXPENSIVE COMPOSITES CREATE ANISOTROPIC BEAMS
Isotropic material
Material with the same properties in all directions.
Structure of composites
IN A COMPOSITE A MATRIX PHASE HOUSES REINFORCING PHASE, also called the embedded phase or the reinforcing agent that usually makes the result stronger than the sum of it's parts. The matrices can be [1] Metals - metal matrix composites, [2] Ceramics - ceramic matrix composites (ceramic matrix mixes only with ceramic reinforcing angents), [3] Polymer - polymer matrix composites. >>> SNOBBISH CERAMIC MATRIX REJECTS METAL AND POLYMER REINFORCERS.
Reinforcing phase
The reinforcer of the composite, skeletal or porous matrix. Common shapes: [1] Fibers, [2] Particles, [3] Flakes. >>> FLAKY FIBERS HUNT SMALL PARTICLES
Fibers
Reinforcement filaments of long, continuous or short, discontinuous length, arranged in 1d, 2d, 3d orientation, filaments that increase the material's tensile strength as their diameter gets smaller. Glass, kevlar, carbon steel can be used for such filaments. >>> THIN FILAMENTS WEAVE A STRONG PATTERN.
Whisker
A type of fiber reinforce, a thin, hairlike crystal of very high strength.
Particles
SMALL BITS OF MATTER THAT STRENGTHEN THE MATRIX, augmenting it's strength in two distinct ways: [1] Dispersion hardening - microscopic size particles at small amounts, less than 15%, restricting the dislocations in the matrix but not carrying much of the load. [2] Sharing the load - once particles get macroscopically big and increase to 25% or more, they share the load with the matrix, due to the bonding, that's how carbide blades have their structure. >>> MICROSCOPIC DISPERSION STOPS DISLOCATIONS PLAYFULLY, WHILE LOAD SHARING PARTICLES GET SCREWED OVER AND ACTUALLY HAVE TO WORK.
Flakes
TWO DIMENSIONAL PARTICLES THAT ADD STRENGTH AND STIFFNESS to materials, plastic molds for example. Platelet size is usually 10 to 1,000 microns long and 1 to 5 microns thick. >>> STRONG FLAKES MAKE GOOD RUBBER STICKS
Infiltrated phase
Some sort of a material that infiltrates a porous matrix. Metallic fillers sometimes used for parts made by powder metallurgy, or like in oil impregnated bearings and gears. >>> INFILTRATED OIL LUBES UP HARD GEARS
Interface
The interface between the matrix and the reinforcer: [1] Direct bonding between phases, [2] Addition of agent to bond between phases - adhesive to bond glass fibers to plastic, [3] Formation of interphase from a solution of a primary and a secondary phase - cemented carbides >>> INTERPHASED CARBIDES SHATTER GLUED GLASS FIBERS.
Properties of composites
Properties of the composites are determined by: [1] Materials of component phases, [2] Geometric shapes of constituents and structure of resulting mixture. [3] Manner in which phases interact with each other. >>> MIG >>> MATERIAL, INTERACTION, GEOMETRY
Rule of mixtures
The composite is a mix of the material, thus some of it's physical properties, such as mass, density, volume is a linear combination of original material's mass, density, volume. >>> PHYSICAL MASS INCREASES FAT VOLUME.
Fiber reinforced composites
Composites in which mechanical properties will vary depending on the direction and the length of the fibers. >>> DIRECTION AND LENGTH DEPENDED PROPERTIES
Laminar composite structure
LAYERS OF BONDED MATERIAL, like in plywood, tiers, snow skies, windshield glass, honeycomb sandwich, a structure that gains strength due to different properties and orientation of the layers. >>> DISTINCT LAYERS PRODUCE GOOD PROPERTIES.
Sandwich structure
Stiff, strong structure of light material between two strong layers, such as a foam or a honeycomb >>> STRONG SANDWITCH BREAKS BENDING TEETH
Metal matrix composites
MATERIALS WITH A METAL MATRIX REINFORCED BY A SECOND PHASE - [1] Ceramic particles (cermets). [2] Fibers of different materials - ceramics, metals, carbon, boron.
Cermets
A LOT, UP TO 96%, OF CERAMIC REINFORCER IN A METAL MATRIX, bonded by the solubility between phases at elevated temperatures. can be divided into: [1] CEMENTED CARBIDES - tungsten carbide(WC), titanium carbide (TiC), chromium carbide (Cr3C2) in binders such as cobalt and nickel, about 5%-15% of binder, [2] OXIDE BASED CERMETS - primarally allumina Al2O3 as a particulate, as in small particles, phase, particles usually embedded in chromium. -- Cermets are used in cutting tools, valve liners, bearing seals, spray nozzles. >>> CEMENTED CARBIDES AND OXIDE CERMETS GLADLY CUT HARD SAFES.
Fiber reinforced metal matrix composites
Strong fibers in a light metal matrix create a strong, light, anisotropic materials, fit for aircrafts, airspace, and turbine machinery, materials with their strength dependent on the fibers properties, dimensions, and orientation >>> STRONG FIBERS REINFORCE LIGHT METAL.
Ceramic matrix composites
Short, ceramic fibers or whiskers in a ceramic matrix reinforcing the matrix and removing some of the fragility of ceramics, as a matter of fact, some of the ceramic matrix composites that have been developed so far are used as cutting tools >>> CERAMIC WHISKERS PENETRATE FRAGILE MATRIX
Polymer matrix composites
A POLYMER MATRIX WITH FIBERS, PARTICLES, FLAKES REINFORCING MATERIALS, such as most plastic molding components, rubber reinforced with carbon black, and fiber reinforced polymers, the most commercially important PMC.
Fiber reinforced polymers
Polymer matrix with reinforcing fibers or a polymer/fiber alternating layers, can be very strong stiff in fiber direction, resistant to corrosion and fatigue, light, low thermal expansion ,and very anisotropic. Used in airplane skin parts, automotive body panels, PCBs, tennis rackets, boat hulls >>> STRONG FIBERS STIFFEN SOFT PLASTIC
Advanced composites
A PMC in which carbon, Kevlar, or boron fibers are used as the reinforcing material
Hybrid composite
A fiber reinforced polymer with two or more types of fiber materials.
Other PMCs
Polymer matrix composites, in addition to fibers, can contain particles, flakes, and short fibers as fillers or the ingredients of the second phase. Fillers can be divided into two categories: [1] Reinforcements - fillers that improve the quality of the material (strength, abrasion resistance, tear resistance): carbon black in rubber, wood flower in phenolics, [2] Extenders - fillers that bulk up the materials and reduce the cost - foamed polymers, like styrofoam. >>> STRONG REINFORCERS BULK UP FOAMY FOAM.
Processing of composites
Composite's phases are, usually, produced individually and then combined, be it in the sintering of metal/ceramic powders or embedding graphite threads in a polymer matrix. >>> COMBINE DUST OF DRAGON BONE AND PUKE OF A TOADSTOOL TO MAKE THE STRONGEST ERECTILE PILL