How to Make Silicon Carbide Powders

Silicon carbide, more commonly referred to as carborundum, is hard like diamond and highly wear resistant. Furthermore, its ceramic properties make it suitable for high temperature environments and voltage environments.

Lely process production results in powder form that can be cut into moissanite gemstones for use as gemstones, while manufacturers also employ it for use in manufacturing abrasive items and products requiring hardness.

Sources

Silicon carbide (SiC), also known as carborundum /krbnm/, is an extremely hard compound of silicon and carbon that forms naturally as the mineral moissanite and mass produced as an abrasive since the late 19th century. Bonding SiC together into hard ceramics or doping it with nitrogen, phosphorus, beryllium or aluminum can form either n- or p-type semiconductors.

Industrial SiC is typically produced through the Acheson Process of heating silica sand with carbon sources like petroleum coke to high temperatures in an open furnace, yielding either green or black-colored grains depending on their purity level.

SiC is known for its superior thermal conductivity and corrosion resistance. With low thermal expansion coefficient, high strength/hardness ratio, chemical stability and ease of machineability it serves as a prime raw material in many industrial applications such as high grade refractories/abrasives/ceramics [16].

Processing

Silicon Carbide (SiC) is a technical ceramic material with unique properties including chemical inertness at all temperatures, thermal shock resistance, and high sinterability. SiC is used in various technical ceramic applications including the manufacture of kiln furniture and fluid handling equipment as well as bearings and wear parts. Additional uses of SiC include diesel particulate filters and ballistic protection. Washington Mills offers crushing, grinding and classifying equipment capable of producing raw materials which meet ANSI, FEPA and JIS standards.

SiC powders may vary in grain size depending on their initial state and carbon source. A popular preparation process for SiC synthesis is through carbon-thermal reduction; this involves reacting a mixture containing one mole of SiO2 less than 200 mech with 1.5-3 moles of carbon source; acid leaching, heating and reacting the resultant solution will eliminate glass carbon from being produced.

SiC powders produced through XRD quantitative analysis are analyzed further using particle shape, granulometric composition and specific surface analysis. Important characteristics include particle shape, granulometric composition and specific surface. SiC particles typically exhibit flat, splintery structures with defected substructures characterized by dislocation grids on their borders – an undesirable characteristic which could negatively impact on sintering processes.

Characteristics

Silicon carbide offers many unique characteristics that allow it to be applied across various industrial fields. Notably, it’s extremely hard with a Mohs hardness rating of 9. Additionally, this material is chemically inert and offers great abrasion resistance, heat resistance up to high temperatures and has good tensile strength and low coefficient of thermal expansion properties – qualities which all add up to make silicon carbide suitable for many industrial uses.

Silicon carbide production processes have an immense effect on its properties and uses. Edward Goodrich Acheson developed the Acheson process, which involves heating a mixture of quartz sand, petroleum coke and wood chips to extremely high temperatures in order to cause chemical reactions which produce silicon carbide crystals – these crystals can then be crushed down into powder or cast into ingots for sale.

This abrasive powder is commonly employed by aerospace and automotive industries for honing and lapping parts to achieve precise dimensions and smooth finishes, while it also finds use in ceramics, glass production and the production of steel and other metals. Alter Technology created a radio circuit using this material that can withstand space’s extreme conditions.

Applications

Silicon carbide ceramic is an outstanding nonoxide material with various applications due to its hardness (Mohs hardness > 9), chemical inertness, low thermal expansion coefficient and resistance to both heat and impact. Silicon carbide finds use as wear-resistant parts in abrasives or wear-resistant parts in wear resistant parts refractories ceramics as well as semiconductor and electrical applications due to its thermal conductivity properties.

To produce SiC, manufacturers first combine amorphous silica with carbon at high temperatures – typically coal coke as the carbon source – before finely grinding and mixing with small amounts of bauxite to form a preform. Once doneping takes place for either nitrogen doping (n-type SiC) or doping with boron, aluminium, and gallium doping (p-type SiC), depending on their desired application.

Manufacturers then utilize this preform to produce cubic silicon carbide through either linking by reaction or chemical vapor deposition. Linking by reaction is the more commonly employed approach; this involves heating it to 1410 degC and doping it with nitrogen or boron for producing n-type SiC. Chemical vapor deposition requires significantly more energy and equipment for its process; linking by reaction requires much less.

Conductive semiconductor grade SiC powder is designed to meet the unique growth needs of various methods for growing third-generation n-type conductive silicon carbide single crystals. This type of powder has an optimal particle size distribution with few voids, offering product purity levels exceeding 6N.