Processing and properties of nanophase SiC/Si3N4 composites

Silicon nitride (Si3N4) 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 Si3N4 has been s hown to improve the mechanical performance and is reviewed in this paper al ong with the currently accepted hypotheses for the improvement in propertie s. An improved method for synthesizing composite nanophase SiC/alpha-Si3N4 powders by carbothermal nitridation is presented along with a comparison of the processing and properties of nanophase composites obtained from conven tional mixed powders and from these carbothermally produced composite powde rs. It is shown that the composite powders offer a very attractive and vers atile process for producing nanophase composites in this system. Finally, r esearch needs in the area are addressed for producing high-quality, low-cos t nanocomposite materials. Multi-disciplinary teams having expertise in bot h synthesis and processing best carry out the research. (C) 1999 Elsevier S cience Ltd. All rights reserved.