Sintering of Zirconium Dіboride and Phase Transformations in the Presence of Cr₃С₂

Abstract

The kinetics of sintering and phase interactions in the diffusion contact zones of Cr₃C₂ and ZrB₂ are investigated. It is found that using Cr₃C₂ as sintering activator for ZrB₂ sintering reduces the hot pressing temperatures from 2200 °C to 1500–1750 °C, depending on the Cr₃C₂ content. The phase formation accompanied with the formation of new high-temperature refractory compounds like zirconium carboborides, chromium borides and carboborides, and zirconium-chromium carboborides rapidly develops at the Cr₃C₂ and ZrB₂ interface within the diffusion zone. An intense diffusion of chromium and carbon into zirconium diboride accompanied by the formation of nonporous states in zirconium diboride (to a depth of 50–100 µm at 1360 °C) near diffusion contact zone is observed. It is established that the contact interaction during sintering in the diffusion zone results in the formation of eutectic liquid vanishes phase, which is consumed to forming the new high-refractory compounds (phases based on zirconium carbide and chromium borides).