Disclosed herein is a component in a combustion system comprising a composite, the composite comprising silicon carbide; and a refractory metal silicide comprising a phase selected from Rm.sub.5Si.sub.3, Rm.sub.5Si.sub.3C, RmSi.sub.2, and a combination thereof; wherein Rm is a refractory metal selected from molybdenum, tungsten, and a combination thereof. Also disclosed is a process for preventing slag, ash, and char buildup on a surface, comprising disposing a first surface of the composite on the surface; replacing a component comprising the surface with a component consisting of the composite; or a combination thereof.