Effects of the liquid phase content on the microstructure and properties of the ZrW₂O₈ ceramics with negative thermal expansion fabricated by the cold sintering process

The liquid phase promotes the sintering densification during cold sintering process (CSP) and has crucial effects on the cold-sintered materials. Herein, ZrW₂O₈ ceramics with negative thermal expansion (NTE) were successfully fabricated by the CSP at 180 °C and 340 MPa, in which the effects of liquid phase content (0 − 35 wt%) on the microstructure and properties were analyzed in detail. No decomposition phases are detected, and the density and Vickers hardness of the cold-sintered samples first increase with the liquid phase content up to 25 wt%, then keep almost constant with the liquid phase content further increasing. Moreover, the homogeneous microstructure and fine NTE are obtained with the threshold value of 25 wt%. Also, the fundamental mechanism of the liquid phase effects during CSP is revealed. This study can guide the further fabrication of the ZrW₂O₈-containing composites utilizing CSP, especially for the precise control of the liquid phase content.