Thermal properties of MoSi 2 with minor aluminum substitutions

Abstract

Mo(Si 1− x Al x ) 2 compositions ( x = 0–0.1) have been prepared by a modified SHS route under uniaxial hydrostatic pressure. Oxidation studies carried out by thermal analysis and sheet resistivity indicate an improvement in the low temperature (700–900 K) oxidation resistance with increasing aluminum addition. Dilatometric results show a decrease in the α value up to x = 0.05 substitution. With the aluminum substitution, both thermal expansion coefficient and thermal conductivity show decrease in their values except in the biphasic region. The x = 0.05 composition containing both C11 b and C40 phases is a promising material for high temperature thermal barrier coating as it shows higher oxidation resistance and a similar K/ α value as compared to pure MoSi 2.