High Purity Metals

Silicon Carbide Balls: Silicon carbide (SiC) is composed of tetrahedral (structure) of carbon and silicon atoms with strong bonds in the crystal lattice. This produces a very hard and strong material. Silicon carbide is not attacked by any acids or alkalis or molten salts up to 800°C. In air, SiC forms a protective silicon oxide coating at 1200°C and is able to be used up to 1600°C. The high thermal conductivity coupled with low thermal expansion and high strength gives this material exceptional thermal shock resistant qualities.

Silicon Carbide Balls: Silicon carbide ceramics with little or no grain boundary impurities maintain their strength to very high temperatures. Chemical purity, resistance to chemical attack at temperature, and strength retention at high temperatures has made this material very popular as wafer tray supports and paddles in semiconductor furnaces. The electrical conduction of the material has lead to its use in resistance heating elements for electric furnaces, and as a key component in thermistors (temperature variable resistors) and in varistors (voltage variable resistors).

Silicon Carbide Balls: SiC whiskers, which are nearly single crystals, are produced (grown) using different methods, including the heating of coked rice hulls, reaction of silanes, reaction of silica and carbon, and the sublimation of SiC powder. In some cases a third element used as a catalyst, such as iron, is added to the reacting materials to facilitate the precipitation of the SiC crystals. In this arrangement, the mechanism for the SiC whisker growth is called the vapor liquid-solid (VLS) mechanism. SiC whiskers are in the order of microns in diameter and grow several hundred microns in length.

Silicon Carbide Balls: The ability of Silicon Carbide to withstand very high temperatures without breaking or distorting is used in the manufacture of ceramic brake discs for sports cars. It is also used in bulletproof vests as an armor material and as a seal ring material for pump shaft sealing where it frequently runs at high speed in contact with a similar silicon carbide seal. One of the major advantages in these applications being the high thermal conductivity of Silicon Carbide which is able to dissipate the frictional heat generated at a rubbing interface.

Silicon Carbide Balls: In general, SiC has excellent oxidation resistance up to 1650°C. Oxidation resistance, however, depends largely on the amount of open porosity and particle size, which determine the surface area exposed to oxygen. The higher is the surface area the higher is the oxidation rate. Kinetically, SiC is stable in air up to ~1000°C.