Sintering of Zirconium Diboride and Phase Transformations in the Presence of Cr3C2
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 a sintering activator for ZrB2 sintering reduces the hot pressing temperature 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, such as 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 with 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 the vanishing eutectic liquid phase, which is consumed to forming new high-refractory compounds (phases based on zirconium carbide and chromium borides).
Keywordshot pressing in vacuum compacting kinetics X-ray phase analysis contact interaction diffusion zone structure and phase formation X-ray diffraction analysis vanishing eutectic phase chemical microinhomogeneity chromium carbide zirconium diboride chromium boride zirconiumchromium carboboride
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