Carborundum grinding wheel

Silicon carbide, SiC or carborundum, has the diamond structure, and it is widely used as an abrasive in grinding wheels. These are made by crushing the SiC, adding clay, then heating the material in molds. Silicon carbide is prepared by the reaction... 

These are special mineral ingredients employed to impart abrasive power to rubber products, used for abrading, grinding or polishing such as rubber erasers and hard or soft rubber grinding wheels such as carborundum. 

Silicon combines with carbon to form silicon carbide or carborundum, SiC, and forms are known that have the wurtzite and zinc blende structures. It is a very hard, tough material that is used as an abrasive and a refractory. The powdered material is crushed after mixing with clay and heated in molds to make grinding wheels. It is prepared by the reaction... 

The sintered magnets are hard and brittle. They can only he machined by the techniques developed for Alnicos, ceramic magnets or semiconductors. They can he sliced with diamond impregnated blades, surface ground with carborundum or diamond grinding wheels, or cut on electric spark-erosion machines (EDM). This must he done in a demagnetized state. 

The first observation of silicon carbide was made in 1824 by Jons Jacob Berzelius. It was first prepared industrially in 1893 by the American chemist Edward Goodrich Acheson, who patented both the batch process and the electric furnace for making synthetic silicon-carbide powder. In 1894 he established the Carborundum Company in Monongahela City, PA, to manufacture bulk synthetic silicon carbide commercialized under the trade name Carborundum . Silicon carbide was initially used to produce grinding wheels, whetstones, knife sharpeners, and powdered abrasives. Despite being extremely rare in nature, when it occurs as a mineral it is called moissanite after the French chemist Henri Moissan who discovered it in a meteorite " in 1905. 

Carborundum, SiC, is widely used as an abrasive in industrial grinding wheels. It is prepared by the reaction of sand, Si02, with the carbon in coke Si02 + 3 C — SiC + 2 CO. How many kilograms of carborundum can be prepared from 727 kg of coke that is 88.9% carbon ... 

Carborundum is rjsed mainly for fast work when much glass needs to be removed, and for grinding quartz. It is cheaper and harder than emery. It can be graded by particle size the coarsest normally used is 90 mesh. The medium size is about 180 mesh, and the fine about 300 mesh, with very fine of 600 and 900 mesh this last is usually unnecessary since better results can be obtained with jeweller s rouge. Carborundum is also often graded in F numbers F consists of 240 mesh and finer 2F of 280 and finer and 3F of 320 mesh and finer. Carborundum is used in the same way as emery, and has the advantage that carborundum wheels and blocks can be obtained. 

The product thus obtained consists of sharp iridescent crystals which are extremely inactive chemically. The most notable property of this material, however, is its hardness. Carborundum is almost as hard as diamond and is generally as an abrasive (i.e., in the manufacture of grinding stones and wheels, polishing papers and cloths, etc.). A lesser use lies in the incorporation of coarse Carborundum crystals into concrete or terrazzo floors to render them slipproof. 

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