HIGH-TEMPERATURE REACTIONS BETWEEN SIC AND PLATINUM

Solid state reactions between SiC and platinum have been studied at temperatures between 900 and 1100-degrees-C. In the reaction zones, alternating layers of Pt3Si and carbon, and Pt2Si and carbon were formed at 900 and 1000-degrees-C, respectively. Both the Pt3Si and Pt2Si phases were stable at respective temperatures. Annealings at 1100-degrees-C, however, produced alternating layers of mixed Pt-silicides and carbon. The formation of platinum silicides gave rise to interfacial melting between SiC and platinum at all the temperature regimes. Laser Raman microprobe indicates that SiC decomposes into carbon and silicon at all the temperatures. The silicon reacts with platinum and forms platinum silicides, while the carbon forms clusters and stays unreacted. Based on the Raman results, the carbon exists in two different crystalline states depending upon its location from the SiC reaction interface. The reaction kinetics between SiC and platinum and the formation of periodic structure, respectively, are discussed based on the decomposition of the SiC and the phase separation of carbon from platinum silicides.