The only functional interface that has been identified and proven to enhance the toughness of a ceramic composite is graphite and hexagonal boron nitride. These materials oxidize at relatively low temperatures rendering their use limited to low temperature or very reducing environments. There are other materials currently under investigation but none have shown superior properties thus far. One example, fluorophlogopite is a layered structure oxide based upon an aluminosilicate structure which is not stable at high temperatures.Researchers at Arizona State University have developed a series of layered structure oxide compounds which can be used to increase the fracture toughness of the ceramic material by blunting the momentum of crack propogation through what would otherwise be a weak and brittle material. The important characteristic of these compounds is that they are mechanically weak in at least one crystallographic direction and are resistant to chemical changes in oxidative and mildly reducing environments and at high temperatures.
|Published - Jan 19 1996