Activated Sintering of Refractory Borides

Abstract

The interaction of titanium, zirconium, and tungsten borides with chromium is investigated. It is shown that the process occurs through contact melting involving intensive wetting of borides with interaction products at temperatures much lower than the melting points of components. The temperature dependences of contact wetting angles and phase composition of interaction products are studied. Chromium vapors that reduce the strength of chemical bonds in the lattice lead to a eutectic liquid phase with small contact angles of wetting of boron surface and create optimum conditions to activate sintering of boride systems. It is demonstrated that low-porous (1–2%) borides can form at sintering temperatures lower than the temperature of collective crystallization. The dependence of bending and compressive strength on sintering temperature is examined. Conditions for producing low-porous fine-grained materials are determined.