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Sunday, 24 November 2013

Classification of Synthetic/Artificial Abrasives

Classification of Synthetic/Artificial Abrasives Points : Classification of SyntheticArtificial Abrasives, Silicon Carbide, Aluminum Oxide, Boron Carbide Three common synthetic/artificial abrasives include silicon carbide, aluminum oxide, and boron carbide oxide and boron carbide. 1. Silicon Carbide It is made by heating a mixture of powdered sand, coke, sawdust, and common salt in an electric furnace. It comes from the furnace in masses of beautiful bluish crystals like diamonds. The crystals are crushed into fine abrasive grains which are used in making grinding wheels, abrasive stones and coated abrasives (abrasive cloth).
Silicon carbide is harder. and more brittle than aluminum oxide abrasive. It is hard enough to cut aluminum oxide. It is generally used for polishing or grinding materials of low tensile strength, including the following: cast iron, aluminum, bronze, tungsten carbide,, copper, rubber, marble, glass, ceramics pottery, magnesium, plastics, and fiber. Silicon carbide is known by trade names such as Carborundum,
2. Aluminum Oxide It is produced by heating bauxite ore in an electric furnace an extremely, high temperatures. With the addition of small amounts of titanium greater toughness can be imparted to’ the aluminum oxide. The center of the solid mass formed in the furnace is aluminum oxide. It is broken up and crushed into the grains for making grinding wheels, abrasive stones and coated abrasives.
Aluminum oxide has properties somewhat different than silicon carbide. It is not as hard, but it is tougher and does not fracture easily. Aluminum oxide abrasives are recommended for grinding and polishing materials of high tensile strength, including the following: carbon steels, alloy steels, hard or soft steels, and malleable iron, wrought iron, and tough bronze. Approximately 75% of all grinding wheels in use today are made of aluminum oxide. Aluminum oxide is known by trade names such as Alundum, Aloxite, Borolon, Exolon, and Lionite.
3. Boron Carbide It is produced from coke and boric acid in an electric, furnace. It is known by the trade name Norb.ide, produced by the Norton Company It is harder than either aluminum oxide or silicon carbide and can cut either of them. However, it is not as hard as diamond. It is used in stick form to dress or true grinding wheels 10 in. or less in diameter. It is also used in powder form, instead of diamond dust, for lapping hardened steel or other very hard materials.

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