Ceramics and Composites in Extreme Environments

摘要

Ceramics and ceramic composites are stable in extreme conditions and for this reason are the materials of choice when environments exceed the thermal and chemical capability of super-alloys and other metallic materials. As an example, aluminum nitride is used as a material in the aluminum industry because it is chemically and thermally resistant to molten aluminum, and molten cryolite, whereas most metals and metallic alloys are not. Cutting tools for cast iron are often made of silicon nitride, which can withstand the temperatures and stresses generated at their cutting edge during the cutting operation. Finally, if a material is needed to withstand ultra-high temperatures (> 2000 ℃), ZrC or ZrB_2 might be the material of choice because of their high melting points and their resistance to oxidation at high temperatures. These are just three examples of the use of ceramics as engineering materials under conditions that would literally destroy metals.