Carborundum Co. - Specimen Stock CertificateInv# SE1741 Stock
Specimen Stock printed by American Bank Note Company.
Silicon carbide (SiC), also known as carborundum (//), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal since 1893 for use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests. Large single crystals of silicon carbide can be grown by the Lely method and they can be cut into gems known as synthetic moissanite.
Electronic applications of silicon carbide such as light-emitting diodes (LEDs) and detectors in early radios were first demonstrated around 1907. SiC is used in semiconductor electronics devices that operate at high temperatures or high voltages, or both.
Non-systematic, less-recognized and often unverified syntheses of silicon carbide include:
- César-Mansuète Despretz's passing an electric current through a carbon rod embedded in sand (1849)
- Robert Sydney Marsden's dissolution of silica in molten silver in a graphite crucible (1881)
- Paul Schuetzenberger's heating of a mixture of silicon and silica in a graphite crucible (1881)
- Albert Colson's heating of silicon under a stream of ethylene (1882).
Wide-scale production is credited to Edward Goodrich Acheson in 1890. Acheson was attempting to prepare artificial diamonds when he heated a mixture of clay (aluminium silicate) and powdered coke (carbon) in an iron bowl. He called the blue crystals that formed carborundum, believing it to be a new compound of carbon and aluminium, similar to corundum. Moissan also synthesized SiC by several routes, including dissolution of carbon in molten silicon, melting a mixture of calcium carbide and silica, and by reducing silica with carbon in an electric furnace.
Acheson patented the method for making silicon carbide powder on February 28, 1893. Acheson also developed the electric batch furnace by which SiC is still made today and formed the Carborundum Company to manufacture bulk SiC, initially for use as an abrasive. In 1900 the company settled with the Electric Smelting and Aluminum Company when a judge's decision gave "priority broadly" to its founders "for reducing ores and other substances by the incandescent method". It is said that Acheson was trying to dissolve carbon in molten corundum (alumina) and discovered the presence of hard, blue-black crystals which he believed to be a compound of carbon and corundum: hence carborundum. It may be that he named the material "carborundum" by analogy to corundum, which is another very hard substance (9 on the Mohs scale).
The first use of SiC was as an abrasive. This was followed by electronic applications. In the beginning of the 20th century, silicon carbide was used as a detector in the first radios. In 1907 Henry Joseph Round produced the first LED by applying a voltage to a SiC crystal and observing yellow, green and orange emission at the cathode. The effect was later rediscovered by O. V. Losev in the Soviet Union in 1923.
A stock certificate is issued by businesses, usually companies. A stock is part of the permanent finance of a business. Normally, they are never repaid, and the investor can recover his/her money only by selling to another investor. Most stocks, or also called shares, earn dividends, at the business's discretion, depending on how well it has traded. A stockholder or shareholder is a part-owner of the business that issued the stock certificates.