Silicon carbide (also referred to as carborundum) is an advanced ceramic material. While naturally found as the extremely rare mineral moissanite, most Silicon Carbide (Carborundum) production occurs as powder or grains that can be bound together into tough and durable ceramic structures.
SiC is produced through an electric resistance furnace by melting raw materials such as quartz sand and carbon sources like petroleum coke into an electrochemical reaction that produces Green and Black-colored crystals.
Chemical Composition
Silicon carbide (SiC) is an extremely hard synthetic crystalline compound of silicon and carbon with the chemical formula SiC. First produced commercially in 1893 for use as a grinding and cutting abrasive, SiC is now one of the hardest known natural and manufactured materials with excellent wear resistance, chemical inertness towards both acids and alkalis, thermal properties as well as excellent wear resistance properties.
Henri Moissan from France and Edward G. Acheson from the US independently discovered carborundum around the same time, designing processes to manufacture it from silica sand and coal coke and giving it its trade name: Carborundum.
Modern silicon carbide production methods used by the abrasives, metallurgical, and refractories industries follow Acheson’s original technique for producing silicon carbide ingots for various industrial uses are similar. A mixture of raw silica sand and finely ground coke is combined in an electric resistance-type furnace near a graphite conductor using electric current; this causes chemical reaction that yields silicon carbide as well as carbon dioxide gas resulting in an ingot that must then be cut into sections and sorted according to grain size before being processed by cut and sorted again once cool down again before being cut up and cut for further use or reuse by another ingot-producing furnace.
Chemistry and crystallography play an essential role in defining the quality and uses of finished grains and powders. Grain sizes typically range from one micrometer to several millimeters; production methods range from self-bonding (using Si+C forms to join grains together) or silicon bonding for high temperature applications or ceramic and metalurgical use.
Physical Properties
Silicon carbide (SiC) is an insoluble substance with insolubility in water, alcohol and acids. Denser than ceramic materials but lighter than many metals, its color and appearance vary according to purity level.
Moissanite can be found naturally as a mineral in small quantities within the earth, though most graphite manufactured today is synthetic and manufactured through grinding carbon and silica sand in an Acheson graphite furnace at high temperatures of 2,550 degC (4,530 degF).
Raw silicon carbide stands out among its peers due to its hardness (Mohs hardness > 9), making it one of the hardest refractory materials with excellent wear resistance characteristics. Furthermore, it is chemically inert to alkalies and acids except hydrofluoric acid and boasts very high breakdown electric field strengths as well as good thermal conductivity properties.
One of SiC’s key characteristics is its resistance to oxidation, which allows it to operate in harsh environments. SiC has one of the lowest rates of oxidation among all metal carbides and even most refractory oxides; additionally it is a wide band-gap semiconductor so electrons need less energy to move between conduction band and valence band; this characteristic allows SiC to operate at higher voltages and switching frequencies.
Mechanical Properties
Silicon carbide is an outstanding material for mechanical applications due to its outstanding strength and durability. It boasts high fracture toughness – which measures resistance against crack propagation – as well as high Young’s modulus and flexural strength ratings, with low thermal expansion at temperatures reaching 1600degC.
Fusion processes used to produce raw silicon carbide result in an ingot that can be cast into various shapes using casting techniques known as refractory casting or refractory lining, such as graphite to protect it during its melting reaction and protect from heat exposure during melting reactions. Refractory casting has wide applications including industrial furnace linings, wear-resistant parts for pumps and semiconducting substrates for light-emitting diodes (LED).
Silicon carbide stands out among ceramic materials by being produced in many different grain sizes and compositions, which allows its manufacturers to achieve desired mechanical properties more easily. A finished product’s quality depends on factors like its ratio of Si to C content, grinding and sizing processes and type of sintering process used; Washington Mills utilizes various crushing, grinding and screening equipment in order to produce raw silicon carbide grains and powders tailored specifically for customer requirements.
Silicon carbide’s atomic structure consists of four-sided pyramids made up of silicon and carbon atoms bonded together via strong covalent bonds in its crystal lattice, giving it exceptional properties in various environments. For example, it does not attack by alkalis or basic salts up to 800degC and resists internal oxidation at higher temperatures.
Applications
Silicon carbide has many uses. It is found in applications as diverse as abrasives, advanced refractories and metallurgical raw materials due to its strength, wear resistance, high temperature tolerance and low coefficient of thermal expansion. Furthermore, silicon carbide may even serve as a catalyst carrier due to its interaction with oxygen and alkali compounds.
Edward Acheson of Edison’s assistant company Carborundum developed the most widely utilized method for producing raw silicon carbide; his fusion process. To use this method of production involves placing silica sand and carbon particles into a graphite electric resistance furnace with electric current running through carbon conductors before heating to 2200 degrees Celsius to create silicon carbide ingots.
Washington Mills employs the traditional Acheson process to manufacture fused silicon carbide crude for use in the abrasives, metallurgical, and advanced refractories industries. Our crushed, ground, and sieved equipment ensures particle sizes meet process specifications to create standard FEPA/ANSI sizes as well as custom particle size ranges with custom densities and chemistries – and more importantly we offer standard sizes from these ranges based on FEPA and ANSI dimensions!
Raw silicon carbide, more commonly referred to as Moissanite, offers exceptional abrasive qualities and can be used to produce cutting tools, grinding wheels and inserts made of tungsten carbide. Furthermore, due to its excellent temperature resistance and corrosion resistance properties it makes an excellent refractory material in steel production; and due to its low coefficient of expansion it provides insulation properties as well as electrical conductivity properties – ideal features when manufacturing these tools or inserts.
English 
Swedish