HEAT-RESISTANCE AND PHASE-COMPOSITION OF TI-SI COATINGS ON NIOBIUM

A diffusion silicide coatings on refractory under thermal shock, A prospective method of improving their durability is the formation of multi-component coatings, Ti is one of the widespread components of such coatings. In this work, process of simultaneous diffusion saturation of niobium by Ti and Si in powder mixtures has been investigated, The coatings can be divided into two basic types: Nb-TI solid solutions and Nb and Ti silicides, The coatings of the first type obtained in Ti-Ti5Si3 powder mixtures. The complex silicide layers were observed in the packs with higher silicon activity (Ti5Si3-TiSi and TiSi2-TiSi mixtures). The activities of Ti and Si have been shown to be principal controlling factores in coating phase in composition. The coatings allows to increase heat-resistance of the niobium and niobium alloys up to 2000 degrees C (1,5 hour).