While two various materials which neither react chemically nor dissolve in every other are combined together so they form a composite materials. Individual of the two constituents be used like a binder while another may be in micro or macro form. The major purpose for such a composite is made is to acquire a property that may not be exhibited via either constituent.
In engineering practice various composites are employed. The most understandable is reinforced cement concrete or RCC employed for building construction. In softer metal matrix, hard particles make composite materials of exceptionally good strength essential for metal cutting tools.
Fibre reinforced plastics or FRP by putting strong fibres in the weaker plastic material matrix form most significant materials employed in engineering practice. The glass and carbon fibres are commonly employed as reinforcement in a variety of plastics.
The ideal material for structural applications necessitates being strong, light and tough. The metals and their alloys satisfy these necessities to a great extent. The metals are not extremely light, so amply tough and strong. The plastics are not tough and strong but such are extremely light. Combining materials along with complementary properties produced composite materials centuries ago.
Egyptians during the days of Pharohs employed bricks reinforced along with chopped straw. Plant fibres were utilized for strengthening potteries in India and South America. Eskimos strengthened ice by employing moss as reinforcing constituent.
The glass fibres such serve like reinforcing constituent in softer plastic matrix are cheaply and conveniently drawn from bulk glass. Even with their higher strength than bulk glass they can't be employed in structure for their high brittleness. The softer plastic matrix has good adhesion along with brittle and extremely thin fibres of glass and protects them from atmospheric attacks via close them in a composite. The glass reinforced plastic renders itself along with convenience of simply moulding in varied geometry's shapes. The glass fibres laid in a mould beside longitudinal direction can be moulded via pouring molten plastic or even by brushing the plastic on framework formed by fibres of glass. Various products like kitchen sinks, motor car body parts, bath tubs, swimming pools and even airplane bodies can be build in GRP.
Carbon fibres were long identified for their electrical fragility and resistance. Though, the strong covalent bond among two carbon atoms would make carbon fibres exceptionally strong. This fact was identified to scientists also. During sixties various companies initiated commercial production of carbon fibres and hence their commercial application in reinforcing of plastic matrix was essentials. These fibres were found to improve high strength adhesive bonding along with epoxy resin resulting into FRP as strong as steel as but lighter than such aluminium.
Boron fibres seem to give strength higher than carbon fibres but are costlier. Various types of fibres that have been tried are those of silicon carbide and various ceramics. Although, the glass and carbon fibres, via far, are the main reinforcing fibres within plastic matrix.