Toward understanding the reaction between silicon carbide and iridium in a broad temperature range

The reaction between iridium and SiC in the 1000°C–1900°C temperature range was studied in details. The rate of this reaction was found to depend not only on temperature, but also on the grain sizes of the initial reagents, oxygen impurities in SiC, as well as the Ir: SiC ratio. The use of fine-grained initial reagents accelerates the reaction, whereas oxygen impurities in SiC powders slow it down. For the Ir: SiC ratio = 1:1, the IrSi silicide phase became dominant at 1400°C and remained the main phase at temperatures up to 1900°C. For the 3:1 ratio, Ir₂Si was the main phase at 1900°C. It was suggested that stabilization of this phase is due to the quenching effect. No Si-rich silicide phases were detected in the 1000°C–1900°C temperature range. The coefficients of thermal expansion of silicide phases were determined by high-temperature X-ray diffraction analysis.