Processing and properties of nanophase SiC/Si3N4 composites

Silicon nitride (Si(3)N(4)) is currently the premier ceramic material for high-stress, high-temperature applications such as gas turbines, turbochargers, and engine valves. The incorporation of nanophase SiC into Si(3)N(4) has been shown to improve the mechanical performance and is reviewed in this paper along with the currently accepted hypotheses for the improvement in properties. An improved method for synthesizing composite nanophase SiC/alpha-Si(3)N(4) powders by carbothermal nitridation is presented along with a comparison of the processing and properties of nanophase composites obtained from conventional mixed powders and from these carbothermally produced composite powders. It is shown that the composite powders offer a very attractive and versatile process for producing nanophase composites in this system. Finally, research needs in the area are addressed for producing high-quality, low-cost nanocomposite materials. Multi-disciplinary teams having expertise in both synthesis and processing best carry out the research. (C) 1999 Elsevier Science Ltd. All rights reserved.