Silicon carbide (SiC) is one of the hardest synthetic materials, second only to diamond. Due to its extreme hardness, wear resistance and heat resistance properties it makes SiC an invaluable material for abrasives and refractories applications.
Raw silicon carbide can be produced through the smelting of quartz sand, petroleum coke and wood chips in a resistance furnace, producing either black or green colored SiC as a byproduct.
Hårdhet
Silicon carbide is one of the hardest materials, second only to diamond and cubic boron nitride in terms of hardness. With a Mohs hardness rating of 9.5, silicon carbide is very difficult to damage or wear down and therefore ideal for applications requiring wear resistance such as abrasives or refractories. Furthermore, its excellent thermal conductivity and minimal temperature expansion make it suitable for aerospace and defense equipment that must withstand harsh environments like high temperatures or radiation exposure.
Edward Goodrich Acheson discovered silicon carbide by accident during an attempt at creating artificial diamonds in 1891. While heating a mixture of clay and powdered coke in an iron bowl, its glowing green hue led him to assume he had discovered an alloy composed of silicon and carbon similar to corundum mineral found naturally. Later Henri Moissan synthesized synthetic forms by dissolving silicon in hot carbon.
Silicon carbide has long been used as an industrial raw material and today can be found in numerous applications ranging from sandpaper, grinding wheels and cutting tools to making refractory linings for furnaces and wear-resistant parts for pumps and rocket engines. Furthermore, in electronics it serves as a semiconductor base material as it can withstand higher temperatures, pressures, frequencies than conventional semiconductors – as well as being doped with nitrogen, phosphorus beryllium or aluminum to form different kinds of semiconductors.
Termisk konduktivitet
Raw silicon carbide’s extraordinary hardness – second only to diamond and some synthetic compounds – makes it an indispensable material in numerous applications. Not only is its wear-resistance high, but its thermal conductivity, thermal expansion coefficient, semiconductor properties and electric field breakdown strength make it a prime candidate. Furthermore, depending on its raw materials composition it may come out black or green in appearance depending on production processes used.
Silicon carbide synthesis requires careful selection and testing of raw materials in order to control purity and quality of the finished product. Once selected, they are fed into a furnace where a carbonization reaction takes place at high temperatures of 2000-2500 degrees Celsius; before this step they are also pulverized and sieved to meet production process requirements in terms of particle size.
Workers handling silicon carbide should exercise extreme caution, to prevent skin and eye exposure as well as respiratory ailments. It should always be stored and transported in sealed containers in a cool environment, with emergency shower facilities readily available in case of exposure; in addition, workers should wash any contaminated work clothing prior to leaving work for home. In an ideal world, engineering controls would reduce exposure levels; however personal protective equipment may still be required depending on the task at hand.
Resistance to Chemical Reactions
Silicon carbide is one of the hardest materials available, boasting an Mohs hardness rating of 9-10 (second only to diamond and certain synthetic compounds). Furthermore, its heat resistance makes it suitable for refractory and wear-resistant applications while its electrical conductivity enables higher currents/voltages/energy loss transfers without disruptions to service provision.
Acheson process is the go-to method for manufacturing silicon carbide. Raw materials like silica sand and petroleum coke are combined in an electric resistance furnace before an electric current passes through them, initiating a chemical reaction between carbon from the coke and silicon from the sand that forms SiC. This reaction usually takes several days until an SiC ingot has formed which will then be refined, refined pulverized sifted shaped and finally manufactured into finished product.
At every step in this process, it is vital that workers take measures to protect them from exposure to silicon carbide dust. When working with silicon carbide dust, people should wear protective eyewear and clothing designed to block dust from entering their eyes or coming into contact with skin; any time dust does get onto exposed areas they should wash clothes immediately so as to prevent abrasions or other complications arising. Furthermore, workers must be mindful of any risks involved with bringing dirty work clothing home; emergency shower facilities provided by their company at the end of shift should also be utilized by workers when necessary.
Electrical Conductivity
Silicon carbide is a semi-metal, meaning it resides between metals (which conduct electricity) and insulators (which do not). At high temperatures, silicon carbide proves an excellent electrical conductor; however, its effectiveness depends on any impurities present within its composition.
Carborundum is produced through the reaction between silica sand and carbon in an electric furnace using a carbon electrode as the source of electricity, producing a mixture of Si and C which is heated to approximately 2,700 degC, where crystal formation begins resembling mineral corundum formation into silicon carbide crystals known as “carborundum.” Today this material can be found in abrasives, cutting tools and refractories; semiconductor substrates for light emitting diodes; among others.
Modern methods for producing the abrasive material involve mixing silica sand with powdered coke in a brick electrical resistance furnace and passing an electric current through its carbon electrode to chemically react with silica sand, yielding carbide material.
Raw material must first be ground to eliminate knife marks caused by slicing and to reduce surface roughness, followed by fine grinding to bring uniformity to its texture. A sintering aid is then added and pressure sintered in an atmosphere containing either argon or nitrogen; electrical conductivity of sintered materials depends on their composition and concentration during this step of sintering process.
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