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PROCESSING METAL MATRIX AND CERAMICS MATRICS COMPOSITE
WHAT ARE COMPOSITES?• Composites are created by combining two or more materials to produce a new material that retains important properties from the original elements Reinforcing fibers give composites the attributes of high strength and stiffness. Mostly Composites are produced by reinforcing a resin matrix (thermoplastic/thermoset) with fibers like glass fiber, aramid, carbon fiber and/or natural fibers. A common example of a composite is concrete. It consists of a binder as a cement and a reinforcement as a gravel.
Reinforcement Most composites have two constituents, a matrix and reinforcement. Reinforcement Composite Matrix The reinforcement is usually much stronger and stiffer than the matrix, and that gives the composite its good properties. The matrix hold the reinforcements in an orderly pattern, the matrix also helps to transfer load among the reinforcements. Reinforcements basically come in three forms: Particulate, Continuous fiber. Discontinuous fiber,
MATRIX• Matrix Surrounds the individual reinforcing elements protecting against surface damage. It maintains their relative positions. Prevents the propagation of brittle cracks between individual reinforcing elements . There are other types of matrices, such as• metal or ceramic, but plastics are the most . e.g.-thermoplastic and thermo setting polymers, metal, carbon etc.
Métal matrix composites (MMC) MMC are made by dispersing a reinforcing material into a metal matrix. The reinforcement surface can be coated to prevent a chemical reaction with the matrix. -- For example, carbon fibers are commonly used in aluminum matrix to synthesize composites showing low density and high strength. However, carbon reacts with aluminum to generate a brittle and water- soluble compound Al4C3 on the surface of the fiber. To prevent this reaction, the carbon fibers are coated with nickel or titanium boride.
Common matrix in mmc In structural applications, the matrix is usually a lighter metal such as aluminum, magnesium, or titanium, and provides a compliant support for the reinforcement. In high temperature applications, cobalt and cobalt-nickel alloy matrices are common
Reinforcement to MMC The reinforcement can be either continuous, or discontinuous.. Discontinuous MMC can be worked with standard metalworking techniques, such as extrusion, forging or rolling. In addition, they may be machined using conventional techniques, but commonly would need the use of polycrystalline diamond tooling (PCD).
Manufacturing Methods of MMC MMC manufacturing can be broken into three types: solid, liquid, and vapor. Solid state methods:- 1)-Powder blending and consolidation (powder metallurgy):- Powdered metal and discontinuous reinforcement are mixed and thenbonded through a process of compaction, degassing, and thermo-mechanicaltreatment (possibly via hot isostatic pressing (HIP) or extrusion). 2)-Foil diffusion bonding:-Layers of metal foil are sandwiched with long fibers, and then pressed through to form a matrix.
Liquid state methods FOR MMC 1)-Electroplating :- A solution containing metal ions loaded with reinforcing particles is co-deposited forming a composite material. 2)-Squeeze casting:-Molten metal is injected into aform with fibers preplaced inside it.
• 3)-Spray deposition:- Molten metal is sprayed onto a continuous fiber substrate.• Vapor deposition Physical vapor deposition: The fiber is passed through a thickcloud of vaporized metal, coating it.
APPLICATION OF COMPOSITESApplications of Métal matrix composites (MMC)–Carbide drills are often made from atough cobalt matrix with hardtungsten carbide particles inside.
Tank Armors .Some tank armors may be made from metal matrix composites, probably steelreinforced with boron nitride. Boron nitride is a good reinforcement for steel becauseit is very stiff and it does not dissolve in molten steel..
Honda , Toyotas automobiles hasused aluminum metal matrix compositecylinder liners in some of their engines,Specialized Bicycles has used aluminum MMC compounds for its top of the rangebicycle frames for several years. GriffenBicycles also makes boroncarbide-aluminum MMC bike frames,and Univega briefly did so as well.
Some automotive disc brakes use MMC. Modern high-performance sport cars, such asthose built by Porsche, use rotors made of carbon fiber within a silicon carbide matrixbecause of its high specific heat and thermal conductivity
Properties of MMC products• Tensile strength of composites is four to six times greater than that of conventional materials like steel, aluminum etc.• Improved torsion stiffness and impact properties .• Higher fatigue endurance limit (up to 60% of the ultimate tensile strength)• 30-45% lighter than aluminum structures designed for the same functional requirements .• Composites are less noisy while in operation and provide lower vibration transmission• Composites are more versatile and complex designrequirements
Ceramic matrix composites Ceramic matrix composites (CMCs) are a subgroup of composite materials as well as a subgroup of technical ceramics. They consist of ceramic fibers embedded in a ceramic matrix, thus forming a ceramic fiber reinforced ceramic (CFRC) material. The matrix and fibers can consist of any ceramic material, whereby carbon and carbon fibers can also be considered a ceramic material. Generally, CMC names include a combination of type of fiber / type of matrix. For example, C/C stands for carbon-fiber-reinforced carbon (carbon/carbon), or C/ SiC for carbon-fiber-reinforced silicon carbide. • REINFORCEMENT- SiC (Silicon carbide) • MATRIX-Cu Metal
Applications Of ceramic matrix composites Heat shield systems for space vehicles, which are needed during the re-entry phase, where high temperatures, thermal shock conditions and heavy vibration loads take place. Transparent concrete.
• CMC for high-temperature gas turbines such as combustion chambers, and turbine blades.• CMC for burners, flame holders, and hot gas ducts, where the use of oxide CMCs has found its way.• Disks breaks and brake system components, which experience extreme thermal shock
• Basic advantage of CMC is it withstand high temperature without damaging.• Long life offers excellent fatigue, impact, environmental resistance and reduced maintenance.• Composites enjoy reduced maintenance cost• Composites exhibit excellent corrosion resistance and fire retardant capability• Improved appearance with smooth surfaces and readily incorporable integral decorative melamine are other characteristics of composites• Composite parts can eliminate joints/fasteners, providing part simplification and integrated design.• 25% reduction in weight• 95% reduction in components by combining parts and forms into simpler molded parts.
Industries in Pakistan 1. EMCO Industries: 19-Km, Lahore Sheikhupura Road, Lahore Ali Ceramic Industries, Lahore, Pakistan 2-K.M., Sheikhupura Road, P.O. Kot Abdul Malik,, Pakistan Royalcosmo Group Of Companies(pvt) Addah Town Daska Road, Sialkot Pakistan Dynamic Tooling Services Office No.301, 3rd Floor, Royal Center, Blue Are, Fazal-EHaque Road, Islamabad, Pakistan