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abrasive,material used to grind, smooth, cut, or polish another substance. Natural abrasives include sandsand,
rock material occurring in the form of loose, rounded or angular grains, varying in size from .06 mm to 2 mm in diameter, the particles being smaller than those of gravel and larger than those of silt or clay.
..... Click the link for more information. , pumicepumice
, volcanic glass formed by the solidification of lava that is permeated with gas bubbles. Usually found at the surface of a lava flow, it is colorless or light gray and has the general appearance of a rock froth.
..... Click the link for more information. , corundumcorundum
, mineral, aluminum oxide, Al2O3. The clear varieties are used as gems and the opaque as abrasive materials. Corundum occurs in crystals of the hexagonal system and in masses. It is transparent to opaque and has a vitreous to adamantine luster.
..... Click the link for more information. , and ground quartzquartz,
one of the commonest of all rock-forming minerals and one of the most important constituents of the earth's crust. Chemically, it is silicon dioxide, SiO2.
..... Click the link for more information. . Carborundum (silicon carbidesilicon carbide,
chemical compound, SiC, that forms extremely hard, dark, iridescent crystals that are insoluble in water and other common solvents. Widely used as an abrasive, it is marketed under such familiar trade names as Carborundum and Crystolon.
..... Click the link for more information. ) and aluminaalumina
or aluminum oxide,
Al2O3, chemical compound with m.p. about 2,000°C; and sp. gr. about 4.0. It is insoluble in water and organic liquids and very slightly soluble in strong acids and alkalies. Alumina occurs in two crystalline forms.
..... Click the link for more information. (aluminum oxide) are important synthetically produced abrasives. The hardest abrasives are natural or synthetic diamondsdiamond,
mineral, one of two crystalline forms of the element carbon (see allotropy), the hardest natural substance known, used as a gem and in industry. Properties
..... Click the link for more information. , used in the form of dust or minuscule stones.
A material of extreme hardness that is used to shape other materials by a grinding or abrading action. Abrasive materials may be used either as loose grains, as grinding wheels, or as coatings on cloth or paper. They may be formed into ceramic cutting tools that are used for machining metal in the same way that ordinary machine tools are used. Because of their superior hardness and refractory properties, they have advantages in speed of operation, depth of cut, and smoothness of finish.
Abrasive products are used for cleaning and machining all types of metal, for grinding and polishing glass, for grinding logs to paper pulp, for cutting metals, glass, and cement, and for manufacturing many miscellaneous products such as brake linings and nonslip floor tile.
The important natural abrasives are diamond, corundum, emery, garnet, feldspar, calcined clay, lime, chalk, and silica, SiO2, in its many forms—sandstone, sand, flint, and diatomite.
The synthetic abrasive materials are silicon carbide, aluminum oxide, titanium carbide, and boron carbide. The synthesis of diamond puts this material in the category of manufactured abrasives.