碳化硅的特性和应用

Silicon carbide is one of the hardest and strongest materials on Earth, known for its strength, thermal conductivity and acid resistance – qualities which make it suitable for applications across industries.

SiC is a naturally-occurring mineral known as moissanite; however, since 1893 it has been mass produced as powder and crystal form for use as abrasives and for other industrial and semiconductor substrate applications.

Characteristics

Silicon carbide boasts unique qualities that make it one of the most advantageous industrial materials. Notably, it is both hard and light among advanced ceramic materials; furthermore it boasts excellent thermal conductivity with low thermal expansion rates; additionally it easily manages erosion and abrasion – qualities which make it suitable for use in mill lining systems, cyclone components, spray nozzles and extruders.

Silicon carbide in its pure state is an electrical insulator. By adding controlled impurities, however, silicon carbide can be made to behave like a semiconductor device – aluminum, boron and gallium can create P-type devices while nitrogen and phosphorus give rise to N-type devices.

SiC transistors boast higher breakdown voltage and lower turn-on resistance compared to their silicon counterparts, which enables higher switching frequencies and smaller power electronics systems. Electric vehicle charging inverters may use SiC to decrease size and weight of their power management systems and increase driving range.

Properties

Silicon Carbide, more commonly referred to as SiC, is an exceptionally hard, synthetically produced crystalline compound composed of silicon and carbon that is chemically inert and corrosion resistant (though susceptible to attack from hydrochloric, sulphuric or other acids).

Silicon Carbide boasts many advantageous properties that make it a valuable material, including high strength and stiffness, low thermal expansion rates, resistance to oxidation and abrasion as well as keeping its elastic resistance even at high temperatures. Due to this combination of ceramic and semiconductor properties it makes an excellent material choice for structural ceramics as well as abrasives.

Pure SiC is a colorless crystal. By adding different amounts of impurities, however, its electrical properties can be altered to that of a semiconductor. Layered structures within crystals produce different polytypes of silicon carbide with unique crystal structures; most frequently found is 6H-SiC hexagonal crystal structure suited for power electronics due to its wide bandgap value of 1.12eV according to Wolfspeed.

Applications

Silicon carbide’s unique physical and electronic properties are revolutionizing power electronics. New devices crafted using SiC boast increased reliability, lower power losses, faster switching times and greater energy efficiency compared to their predecessors.

Pure silicon carbide behaves as an electrical insulator; however, doping with controlled impurities (called dopants ) allows it to conduct electricity under certain circumstances. Aluminum, boron and gallium doping produce P-type semiconductors; doping with phosphorus and nitrogen creates N-type semiconductors.

Silicon carbide’s atomic structure resembles that of carbon and silicon atoms bonded covalently together into two primary coordination tetrahedra, with four carbon and four silicon atoms covalently bonding to one another to form two primary coordination tetrahedra – each consisting of four carbon and four silicon atoms covalently bonded with each other – covalently bound by covalent bonds. It can be grown into various shapes; typically ground into fine powder then mixed with non-oxide sintering aids like organosilicon binders to form pasty mixture which can then be formed using cold isostatic pressing or extrusion processes – used extensively in cutting tools, structural materials (bulletproof vests/composites armor), automobile parts manufacturing, mirror material production as well as mirror material for astronomical telescopes.

Manufacturing

Silicon carbide is one of the hardest and strongest advanced ceramic materials, offering low thermal expansion rates, acid resistance, erosion resistance and excellent wear resistance.

Silicon carbide production involves various chemical reactions, but most commonly employs the Acheson Process. This involves heating a mixture of silica and coke at high temperatures until their chemicals react chemically and form crystals.

These crystals are then ground into a fine powder and combined with non-oxide sintering aids such as organosilicon binders to create a paste which is compacted and shaped via extrusion or cold isostatic pressing.

Silicon carbide is an indispensable material in modern lapidary, thanks to its hardness and durability. Its versatility has seen it used for everything from furnace linings, cutting tools and grinding wheels, wear-resistant parts in pumps and rocket engines, low on resistance power electronics components as well as thinner wafers due to a lower breakdown voltage.