Silicon carbide(Carborundum) Powder for Ceramics
Silicon carbide(Carborundum) Powder is the main raw material for silicon carbide composite ceramics. The superb thermal and chemical performance helps ceramic enhance strength, anti-corrosion, and thermal resistance.
Silicon carbide (SIC) ceramics have excellent characteristics such as:
strong oxidation resistance,
good wear resistance,
high hardness,
good thermal stability
high-temperature strength
small thermal expansion coefficient
high thermal conductivity
thermal shock resistance
chemical corrosion resistance
Therefore, it has played a great role in the fields of petroleum, chemical industry, machinery, aerospace, nuclear energy, and so on. For example, silicon carbide ceramics works as various bearings, balls, nozzles, seals, cutting tools, gas turbine blades, turbocharger rotors, reflective screens, and rocket combustion chamber liners. The excellent performance of silicon carbide ceramics is closely related to its unique structure.
Silicon carbide Powder is a compound with a strong covalent bond, and the ionic property of the Si-C bond in silicon carbide is only about 12%. Therefore, silicon carbide powder has high strength, a large elastic modulus, and excellent wear resistance. Pure SiC will not be eroded by acid solutions such as HCl, HNO3, H2SO4, and HF and alkali solutions such as NaOH. Oxidation happens when heated in air, but SiO2 formed on the surface during oxidation will inhibit the further diffusion of oxygen, so the oxidation rate is not high. In terms of electrical properties, silicon carbide has semiconductor properties, and the introduction of a small number of impurities will show good conductivity. In addition, SiC has excellent thermal conductivity.
Silicon carbide gets α and β Two crystal forms. The β- crystal structure of SiC is a cubic crystal system. The Si and C constitute face-centered cubic lattice respectively. For α-SiC, there are more than 100 polytypes of SiC, such as 4h, 15R, and 6H. 6H polytype is the most common one in industrial applications. There is a certain thermal stability relationship among various types of SiC. When the temperature is lower than 1600 ℃, SiC β- In the form of SiC. When the temperature is higher than 1600 ℃, β- SiC slowly transforms into α- Various polytypes of SiC. 4h SiC is easily formed at about 2000 ℃; Both 15R and 6h polymorphs need a high temperature above 2100 ℃ to form easily; For 6h SiC, it is very stable even if the temperature exceeds 2200 ℃.
There are several options of silicon carbide powder for SiC ceramics. Black(Or Green) silicon carbide Fraction 0-1mm,1-2mm,2-3mm, F14,F16,F24 always suitable for sintered SiC ceramics as aggregate. Black (Or Green) silicon carbide powder 40 microns, and 3.5micron are suitable for filling in SiC ceramics.