Silicon nitride/silicon nitride whisker-reinforced composites

One of the major setbacks of ceramic materials is their inherent brittle nature which often leads to catastrophic failure, especially under impact and tensile stress conditions. Whisker-reinforcement of ceramic matrices has been shown to be an effective way of increasing toughness. However, the hot-pressing techniques being used at present are expensive. Si;An extrusion process was developed to align the whiskers such that they do not impinge on one another. This was done using a water soluble, cellulose based plasticizer. The process was sensitive to water content and mixing. Entrapped air caused problems in the extrudate, resulting in misaligned areas in the microstructure. Relative densities of 94.5% were obtained for composites having 15% whiskers. The toughness of this material was measured to be 13.5MPa.m;In this work Si...