Stability And Heat Resistance Of Silicide Coatings On Refractory Metals. I. Effect Of Subsurface Layer On Process Of Phase Redistribution In System Wsi sub 2 - W

The effect of a subsurface layer of metal silicide on the phase composition stability of high-temperature MeSi sub 2 -type coatings on refractory metals was investigated. Using the system Wsi sub 2 - W as a prototype it was experimentally determined that a subsurface layer of the tungsten disilicide, and the distribution profile of silicon in the diffusion zone upon high-temperature heating have a substantial effect on the formation of a barrier layer of lower silicide which determines the stability of the system as a whole. It is proposed that the search for more stable silicide coatings on refractory metals should be directed toward the creation of diffusion barriers on not only the inner interface MeSi sub 2 -Me, but also the external surface of the coating. The process of coating formation must be accompanied by the formation of a metal silicide on the external surface with the highest possible concentration of silicon. [Substrates: W.]