Silicon carbide is produced in two main qualities depending on the raw materials-black and green Sic – where the green use higher purity raw materials and thus have a slightly higher purity. In some special abrasive and ceramic applications and green Sic are produced by Saint – Gobain Ceramic Materials.
Black Silicon Carbide
Green Silicon Carbide
Silicon Carbide (SiC) is a synthetic mineral most commonly produced in electrical resistance furnaces, by the Acheson process, named after the American E.G. Acheson who invented it in 1891. In an Acheson furnace, a mixture of carbon material (usually petroleum coke) and a silica or quartz sand is reacted chemically at high temperatures in the range of 1700 – 2500°C resulting in the formation of α-SiC following the main reaction:
The energy for the reaction is provided by the resistive heating of a graphite core done by connecting this core to two electrodes at both ends of the furnace.
SiC develops as a solid cylindrical ingot around the core, with radial layers ranging from graphite in the inside, to α-SiC (the highest grade material with coarse crystalline structure), β-SiC, metallurgical grade and finally un-reacted material on the outside. SiC can be produced as either black or green, depending on the quality of the raw materials.
After a cooling period, the SiC ingot is sorted accurately and further processed for different applications. The SiC crude material is carefully crushed, classified, sometimes milled again, and optionally chemically treated in order to obtain the specific properties for which it will be applied. These subsequent processing steps actually account for the bulk of our know-how and of the value we add to our products.
Properties of Silicon Carbide
SiC is a ceramic material with an outstanding hardness, only surpassed by diamond, cubic boron nitride and boron carbide. The material is highly wear resistant and chemically inert to all alkalies and acids. It is also highly heat resistant. These properties makes Silicon Carbide an outstanding abrasive and ceramic material to be used under extreme operating
• Density: 3.21 g/cm3
• Vickers hardness: 29 GPa
• Coefficient of Thermal expansion: 5·10-6/K
• Thermal conductivity: 50 to 100 W/m K
• Typical temperature resistance: 1500°C in air, 2400°C in inert atmosphere
• Specific heat: 750 J/kg K
SIKA I, II, IIA, III, IV, IVA
FEPA-specifications for Bonded F8 – F1200
FEPA-specifications for Coated P12 – P2500
JIS Abrasive Grain Size #8 - #8000
ANSI Sized 8 – 220 grit.
Black Silicon Carbide F16-220
Green Silicon Carbide F16-220