Cutting silicon carbides

In 1885, Charles Martin Hall invented his aluminum process and Hamilton Young Castner in 1890 developed the mercury-type alkali-chlorine cell, which produced caustic (sodium hydroxide) in its purest form. Edward G. Acheson in 1891, while attempting to make diamonds in an electric furnace, produced silicon carbide, the first synthetic abrasive, second to diamond in hardness. Four years later, Jacobs melted aluminum oxide to make a superior emeiy cloth. Within two decades, these two abrasives had displaced most natural cutting materials, including naturally occurring mixtures of aluminum and iron oxides. 

Other ceramic cutting-tool materials include alumina, Si-Al-0-N, alumina-carbide composites and, more recently, a composite of silicon nitride reinforced with silicon carbide whiskers. This last material can be produced by chemical-vapor infiltration (CVI) and has high strength and toughness as shown in Table 18.3.Cl... 

Silicon carbide (SiC), nearly as hard as diamonds, is used as an abrasive in grinding wheels and metal-cutting tools, for lining furnaces, and as a refractory in producing nonferrous metals. 

Richmond, J., Hard-Switched Silicon IGBTs Cut Switching Losses in Half with Silicon Carbide Schottky Diodes, Cree Inc. Application Note, CPWR-AN03, 2003. 

Among the useful compounds of silicon are silicon carbide (carborundum) and silicon nitride, which are hard, tough materials used for making cutting tools, abrasives, and engineering... 

Composite Plating. An electroless nickel matrix can be used to securely bond diamonds to cutting tools, and electroless nickel—diamond composites are also used (see Tool materials). The NYE-CARB process gives a silicon carbide—electroless nickel composite that has extremely high abrasion resistance (49). Electroless nickel—Teflon composites are being promoted as low friction materials. 

Composites. Another type of electro deposit in commercial use is the composite form, in which insoluble materials are codeposited along with the electro-deposited metal or alloy to produce particular desirable properties. Polytetrafluoroethylene (PTFE) particles are codeposited with nickel to improve lubricity (see LUBRICATION AND LUBRICANTS). Silicon carbide and other hard particles including diamond are co-deposited with nickel to improve wear properties or to make cutting and grinding tools (see Carbides Tool materials). 

Cutting wheels or wires with abrasives Aluminum oxide abrasives Silicon carbide abrasives i r Diamond abrasives... 

High stiffness ceramic fibers such as alumina, alumina-silica, silicon carbide, boron, etc. are used as reinforcement fibers for polymeric, metallic, and ceramic matrix composites (Chawla, 1987). Silicon carbide whisker reinforced alumina composites are used as high speed cutting tools (Chawla, 1993). 

The practical utilization of silicon carbide and silicon nitride ceramics or of SiAlON in the above-mentioned application sectors has steadily increased in recent years. Ca. 400 t/a of SN-powder is currently consumed in the manufacture of SN-components. The main applications are for cutting tools, roller bearings, dosing and deliver pipes for aluminum processing, as well as a multiplicity of other components which enjoy the advantages of SN-ceramics. 

Examination of the Smithsonian skull similarly showed marks produced by high-speed rotary cutting and also retained trace amounts of the abrasive material. Although only traces were found, this was nonetheless enough to perform an X-ray diffraction analysis and identify it as silicon carbide, a synthetic abrasive invented at the end of the nineteenth century. 

Recycling this is discussed extensively in the CER. Examples include the use of reusable tote bins, waste heat recovery from cooling water for building heating, and the recovery of silicon and silicon carbide from cutting wastes. 

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