Silicon Carbide – A Key Technology Material

Silicon carbide has recently made a resurgence as an important technology material. Once used primarily as an abrasive and in industrial furnaces, SiC is now used in long-lasting mechanical parts and ceramic products.

Sintered (SiC) material is a self-bonded, hard and durable substance made by heating silicon and carbon atoms together into a tetrahedral structure. Commercially available versions are widely available.

High Voltage Resistance

Silicon carbide occurs naturally as the rare mineral moissanite; however, most SiC is manufactured. With both ceramic and semiconductor properties making up its composition, SiC is one of the most adaptable refractory materials on the market today.

Due to their superior blocking voltage capabilities and lower specific on resistance, power MOSFETs make for an excellent alternative to FRDs and IGBTs for high-speed applications that involve switching currents of several kilovolts while keeping power losses to an absolute minimum.

SiC Schottky diodes and MOSFETs do not suffer from thermal runaway at extremely high temperatures, enabling them to achieve higher blocking voltages with much reduced on resistance compared to silicon devices.

High Temperature Resistance

Silicon carbide is an inorganic ceramic material, known for its superior mechanical strength, corrosion resistance, wear resistance, abrasion resistance and thermal conductivity. Additionally, it is insoluble in water, alcohol or acids – except hydrofluoric acid! – making it suitable for most organic and inorganic acids except hydrofluoric acid.

Natural moissanite deposits occur naturally, however large-scale production began in 1893 by Edward Goodrich Acheson while trying to synthesize diamonds. Acheson developed an electric furnace and established the Carborundum Company for mass production as an abrasive. Due to its high temperature resistance and chemical-attack resistance properties it is commonly used as blast furnace lining, copper smelting tank liners, and zinc furnace arc plates linings.

High Thermal Conductivity

This material can withstand temperatures of up to 1,800 C / 3,272 F without degrading and has low thermal expansion, making it suitable for chemical applications including the separation of corrosive chemicals such as phosphoric, sulphuric and nitric acids.

Pure silicon carbide is not an efficient electrical conductor, but this can be enhanced through doping it with nitrogen, boron or aluminum. Furthermore, silicon carbide’s wider band-gap helps it overcome limitations associated with traditional semiconductors in high voltage and temperature applications.

High Strength

Silicon carbide is one of the hardest and most durable synthetic materials known. While naturally found as moissanite mineral deposits in very minute quantities, mass-production began in 1893 for use in ceramic car brakes and clutches as long-term solutions.

SiC in its original state acts as an electrical insulator; however, when doped with impurities it becomes an active semiconductor with P-type characteristics while doping with boron yields N-type ones.

Reaction Sintering (RS) of SiC is an increasingly popular manufacturing process due to its low processing temperature, shape capability and high purity. Unfortunately, however, mechanical properties of RS-SiC such as strength and Young’s modulus tend to be lower than for regular sintered silicon carbide.

High Hardness

SiC is one of the hardest materials known to mankind, second only to diamond and cubic boron nitride. It is highly resistant to erosion, corrosion and acid, with high radiation hardness making it suitable for use as filters on sand filters.

SiC is found naturally as the rare mineral moissanite, first discovered in 1893 in Arizona’s Canyon Diablo meteorite. But most of what we use today is synthetically produced using reaction bonding and sintering processes.

Aluminium oxide is widely used in grinding wheels, cutting tools and refractory linings; additionally it provides excellent abrasion resistance in automotive applications and bulletproof vests.

High Wear Resistance

Silicon carbide is chemically inert, highly corrosion resistant and withstands temperatures up to 1600oC without degrading in strength or durability. Furthermore, its excellent oxidation resistance enables it to retain its integrity at such extreme temperatures.

Kumar et al. reported that SiC ceramics containing short carbon nanofibres demonstrated lower friction and wear when sliding against steel counterparts than those without such lubricants, with the latter due to stress concentration being limited by carbon film restriction.

Grain size of SiC ceramics can be reduced using sintering additives and adding an additional phase. Furthermore, thermal exposure treatment to crystallize intergranular phases may also help mitigate their adverse effect on tribological performance.

Long Life

Silicon is a proven material, yet its limits have become apparent in high-powered applications. SiC steps up by offering additional bandgap that enables electronics to function at higher temperatures, frequencies, and voltages.

SiC power devices are constructed to withstand corrosion, acid and high temperatures – perfect for oil and gas production. Their long filter life makes ceramic sand filters also ideal for use in electric vehicle charging stations or high altitude power installations like solar energy conversion systems.

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