Thermal expansion of siliconated pyrolytic carbon

The lattice and bulk thermal expansions perpendicular to the layer plane of siliconated pyrolytic carbon, PC(Si), produced by pyrolyzing a mixture of propane gas and silicon tetrachloride vapour at the deposition temperatures of 1440 to 2025° C, have been measured over the temperature ranges 20 to 550° C and 20 to 960° C, respectively. The expansion behaviours of PC(Si) are related to the density and the degree of preferred orientation of crystallites, as is the case for pyrolytic carbon without silicon PC. At a deposition temperature of about 1700° C, the bulk thermal expansion coefficient of PC(Si) is about three times as large as that of PC.