Silicon Carbide
Silicon carbide, also known as carborundum, is a ceramic product made up of silicon and carbon atoms bonded in a crystal lattice. It has the chemical formula SiC. It was first discovered by a young scientist named Dr. Edward Goodrich Acheson, who was trying to make synthetic diamonds.
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Applications of Silicon Carbide
Silicon carbide is extremely hard, with low density, low thermal expansion, and high thermal shock resistance. Not susceptible to harm by molten salts, alkalis, or acids, it also displays extremely high levels of chemical inertness. Because of its superior characteristics, silicon carbide can be labeled as an engineering, technical, or advanced ceramic. It is popular for use in the high stress environments of industrial and commercial settings. Some of the sectors in which silicon carbide is most commonly used include the abrasion, automotive, electrical conduction, semiconductor, and structural industries. It is a common component of brake discs, bearings, seals, heat exchangers, and grinding machines. In addition, in grit form, it is often used to create decorative glassware and the ground glass used in photographic equipment.
Because it has zero porosity, silicone carbide is much less likely to trap cleaning solutions or harmful particles and does not allow toxins or contamination to escape into the environment. Silicon carbide is also easy to clean and can endure rigorous cleaning processes. It is used endlessly to make products, such as: heating elements, electric systems, abrasive tools, cutting tools, automobile parts, foundry crucibles, jewelry, thin filament pyrometry, nuclear fuel cladding, nuclear fuel particles, electronic circuit elements, power electronic devices, automobile parts and structural elements. It is used just as endlessly to assist in applications related to: astronomy, steel production, catalyst support, graphene production and carborundum printmaking. There can be no doubt that silicon carbide and silicon carbide products are worthwhile investments. Interested parties should contact an experienced and skilled silicon carbide distributor today. Some of the best ones around are listed right here on this page.
Manufacturing Process of Silicon Carbide
Silicon carbide is rarely found in nature and, therefore, it is more commonly produced synthetically. When it is found in nature, it is found as the mineral moissanite. Moissanite was discovered in 1893 by French chemist Henri Moissan. Mostly, moissanite is found in meteorites. When synthesized, as it usually is, it is made via either the Acheson process or the Lely process. The first method, named after its inventor, Dr. Edward Goodrich Acheson, involves heating a mixture of powdered carbon and silica or quartz sand to high temperatures and then gradually decreasing said temperatures. In addition to synthesizing silicon carbide, this method increases porosity. The Lely process, or Lely method, is named after its inventor, Jan Anthony Lely. It works by heating particles in an argon atmosphere similar to the one utilized inside an Acheson furnace. In doing so, it sublimates the particles.
Other possible methods of synthesization include thermal decomposition and chemical vapor deposition. When done in a low-heat and inert atmosphere, the thermal decomposition of polymethylsiloxane generates pure silicon carbide. In addition, using this method, manufacturers can pre-form the polymer before allowing it to turn into a ceramic. Chemical vapor deposition works well in the production of cubic silicon carbide. Unfortunately, however, the process is very expensive, so interested parties would do well to avoid this method unless absolutely necessary. Once formed, the grains or crystals of silicon carbide may be bound into any number of products. Methods available to aid manufacturers in product formation include deposition, sintering, fusing, firing, hipping, hot pressing, pressure casting, slip casting, and injection molding.
Material Properties of Silicon Carbide
Regardless of how it is formed, the purity of a sample of silicon carbide can be determined by the color of its crystals. The most pure samples have colorless crystals, or crystals of green or pale yellow. Tainted samples may have brown, black, or blue crystals. Some of the substances commonly responsible for such discolorations include iron, nitrogen, and aluminum. All three substances will decrease the electrical conductivity of a silicon carbide product. In general, however, silicon carbide has a purity of over 99.9995%. The three most commonly produced commercial grades of silicon carbide are sintered silicon carbide (SSC), nitride bonded silicon carbide (NBSC), and reactive bonded silicon carbide (RBSC). However, several other grades exist as well, such as SiAlON bonded silicon carbide and clay bonded silicon carbide. The latter is generally reserved for refractory applications, and manufacturers typically make and/or keep several variations of it on site. RBSC maintains good properties at high heats and, therefore, it is also used for refractory applications.
Engineering Properties of Silicon Carbide*
Silicon Carbide
|
Mechanical
|
SI/Metric (Imperial)
|
SI/Metric
|
(Imperial)
|
Density |
gm/cc (lb/ft3)
|
3.1
|
(193.5)
|
Porosity |
% (%)
|
0
|
(0)
|
Color |
—
|
black
|
—
|
Flexural Strength |
MPa (lb/in2x103)
|
550
|
(80)
|
Elastic Modulus |
GPa (lb/in2x106)
|
410
|
(59.5)
|
Shear Modulus |
GPa (lb/in2x106)
|
—
|
—
|
Bulk Modulus |
GPa (lb/in2x106)
|
—
|
—
|
Poisson’s Ratio |
—
|
0.14
|
(0.14)
|
Compressive Strength |
MPa (lb/in2x103)
|
3900
|
(566)
|
Hardness |
Kg/mm2
|
2800
|
—
|
Fracture Toughness KIC |
MPa•m1/2
|
4.6
|
—
|
Maximum Use Temperature
(no load) |
°C (°F)
|
1650
|
(3000)
|
Thermal
|
|
|
|
Thermal Conductivity |
W/m•°K (BTU•in/ft2•hr•°F)
|
120
|
(830)
|
Coefficient of Thermal Expansion |
10–6/°C (10–6/°F)
|
4.0
|
(2.2)
|
Specific Heat |
J/Kg•°K (Btu/lb•°F)
|
750
|
(0.18)
|
Electrical
|
|
|
|
Dielectric Strength |
ac-kv/mm (volts/mil)
|
—
|
semiconductor
|
Dielectric Constant |
—
|
—
|
—
|
Dissipation Factor |
—
|
—
|
—
|
Loss Tangent |
—
|
—
|
—
|
Volume Resistivity |
ohm•cm
|
102–106
|
dopant dependent
|
*All properties are room temperature values except as noted.
The data presented is typical of commercially available material and offered for comparative purposes only. The information is not to be interpreted as absolute material properties, nor does it constitute a representation or warranty for which we assume legal liability. User shall determine suitability of the material for the intended use and assumes all risk and liability whatsoever in connection therewith.
More Silicon Carbide Information
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