QSAM's Enhanced Boron Nitride Ceramics
Boron nitride ceramics, usually the hexagonal BN only, is a popular machinable ceramic material especially for metallurgy and vacuum chambers. Features of boron nitride material include: high thermal conductivity, machinable, low porosity, electrical insulation, extremely high working temperature in certain atmosphere, low wettability to molten metals and low coefficient of thermal expansion. However, as a soft machinable material, mechanical strength and wear resistance for boron nitride is relatively low. In order to get better mechanical strength, manufacturers of boron nitride ceramic materials (e.g. Saint Gobain, Momentive, QSAM…) usually develop enhanced BN materials, with additive such as aluminum nitride, zirconia, and silicon nitride.
As an example, the aluminum nitride enhanced material, which a relatively high percentage of aluminum nitride was added into the BN matrix, such as BIN77 of Momentive, or QSAM’s ALN-BN, are specifically enhanced to obtain higher hardness and wear resistance. For ALN-BN, it also designed to enhance the wear resistance to molten nickel in stainless steel or nickel based alloys.
Another example is ZCBN, which is the composite of boron nitride and zirconia. Due to the high wear resistance of zirconia, it is a quite nice material for break rings in metal casting.
A common feature for enhanced/composite boron nitride is much better wear resistance than the pure BN material. It will demonstrate much longer usage life in vacuum vapor deposition equipment when it need to be cleaned by sand blasting.
However, by adding a certain quantity of other ceramic materials, the maximum working temperature is limited by the additive. The low performance for low porosity and electric insulation are still great.