ABRASIVES

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.