Silicon carbide Acheson process

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. 

The conventional production method for SiC - the reaction of coke and sand (Acheson process) -does not involve soluble or fusible intermediates. For many applications of silicon carbide this fact is not necessarily a disadvantage, but for the preparation of ceramic composites such intermediates are required. 

Acheson (1) A process for making silicon carbide from sand and coke, in an electric furnace, at 2,200 to 2,400°C ... 

Silicon carbide is manufactured industrially by the electrochemical reaction of high purity quartz sand with carbon in an electric resistance furnace (Acheson process) ... 

Silicon carbide is remarkable for its unusually large variety of different morphologies, which differ in their stacking sequences of hexagonal and rhombohedral layers. All hexagonal and rhombohedral forms are often simply described as a-SiC. The commercially available SiC produced by the Acheson process is a-SiC. 

In another process metallic silicon is evaporated in an electrical arc and reacts with methane to silicon carbide. A disadvantage of all gas phase processes is their high cost compared with the Acheson process. 

The classical route to SiC, the so-called Acheson process, has recently been described thoroughly by Schwetz [169]. It is well known that high-purity quartz sand and petroleum coke are used to get silicon carbide corresponding to the summarizing equation for this strongly endothermic carbothermjd reduction process (ArH = 618.5 KJ moP ) ... 

Acheson, Edward Goodrich (1856-1931), was an American chemist who worked with Thomas Edison before establishing his own laboratory. He developed a process for producing silicon carbide while trying to make synthetic diamonds. In 1891 he founded The Carborundum Co. to produce SiC for abrasives and was granted a patent in 1893 for SiC. In 1926, the U.S. Patent Office named his patent for SiC one of the 22 patents most responsible for the industrial age. 

Polycrystalline silicon carbide obtained by the Acheson process exhibits a large number of different structures (polytypes), some of which dominate. These can be classified in the cubic, hexagonal, and rhombohedral crystal systems (Table 1). 

Acheson process An industrial process for the manufacture of graphite by heating coke mixed with clay. The reaction involves the production of silicon carbide, which loses silicon at 4150°C to leave graphite. 

Polycrystalline silicon carbide obtained by the Acheson process exhibits a large number of different polytypes, some of which dominate. More than 200 different polytypes are currently known these can be classified into the cubic, hexagonal, and rhombohedral crystal system, and all have the same density of 3.21 gcm . Written polytype nomenclature [11] indicates the number of layers in the repeating layer pack by a numeral, while the crystal system is denoted by the letters C, H, or R. 

The Acheson process is still the major production process. In the US, over 115,000 metric tons of silicon carbide were produced in 1994 with a value estimated at 40 million, much of viiich was for abrasives and metallurgical uses.1 1... 

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. 

The Acheson process. This process, invented by Edward Goodrich Acheson in 1893, was extensively used for making silicon carbide and was the only industrial process available for... 

Karl Bayer first separated alumina from bauxite ore. This method, known as the Bayer process, is stiU used to purify alumina. In 1893, Edward Goodrich Acheson, an American chemist, electronically fused carbon and clay to create carborundum, also known as synthetic silicon carbide, a highly effective abrasive. 

Carborundum (Edward Goodrich Acheson) Attempting to create artificial diamonds, Acheson instead synthesizes silicon carbide, the second hardest substance known. He will develop an improved graphite-making process in 1896. 

Silicon carbide is produced most often by the Acheson process, discovered in 1891 by Edward Goodrich Acheson. Later in 1891 he formed Carborundum Corporation to manufacture Sic abrasives. In this process current is passed through a mixture of carbon and sand causing the reaction SiOj -H 3C — SiC + 2CO. When carried out at 2600°C or higher the result is alpha the beta form can be achieved at 1500 to 1600°C. ... 

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