Cold sintering process for ZrO₂-based ceramics: significantly enhanced densification evolution in yttria-doped ZrO₂

We recently developed a novel technique of cold sintering process (CSP) to obtain dense ceramics at extraordinarily low temperatures. In this communication, we demonstrate the feasibility of applying CSP to zirconia-based ceramics. As exemplified by 3Y-TZP ceramics, a significantly enhanced densification evolution is observed. Water is simply utilized as a sintering aid to assist the ceramic densification under an applied external pressure. The low-temperature advantage of CSP outstands in contrast to the densification curves compiled from other sintering techniques. A gradual monoclinic-to-tetragonal phase transformation is revealed in correspondence to the densification development, as well as contributes to the mechanical hardness evolution. A Vickers Hardness reaches ~10.5 GPa after annealing the cold-sintered ceramics at 1100°C, which is comparable to those values reported in the previous studies at higher sintering temperatures. Such a sintering methodology is of significant importance as it provides a roadmap for cost-effective processing of zirconia-based ceramics and composites that enable broad practical applications.