Current Status and Development Trend of Cold Sintering Process

Densification of ceramic materials by conventional sintering process usually requires a high temperature over 1000., which not only consumes a lot of energy, but also forces some ceramic materials to face challenges in phase stability, grain boundary control, and co-firing with metal electrodes. In recent years, an extremely low temperature sintering technique named cold sintering process (CSP) was proposed, which can reduce the sintering temperature to below 400., and realize the rapid densification of ceramic materials through the dissolutionprecipitation process of ceramic particles by using the transient solvent in liquid phase and uniaxial pressure. The advantages of CSP, including low sintering temperature and short sintering time, have attracted extensive attention from researchers, since it was firstly reported in 2016. At present, CSP has been applied to the sintering of nearly 100 kinds of ceramics and ceramic-matrix composites, involving dielectric materials, semiconductor materials, pressure-sensitive materials, and solid-state electrolyte materials. This paper firstly introduces the low-temperature sintering techniques' development history, process and densification mechanism. Then, application of CSP in the field of ceramic materials and ceramic-polymer composites is summarized. Based on differences of solubility, application of CSP mainly on Li2MoO4 ceramics, ZnO ceramics, BaTiO3 ceramics, and their composites preparations are introduced. Auxiliary effect of the transient solvent on cold sintering process is emphatically analyzed. Moreover, the high pressure issue in the cold sintering process and the possible solutions are discussed. At last, future development trend of cold sintering process is prospected.

Automated summary

The conventional sintering process for ceramic materials requires high temperatures over 1000℃, which is energy-consuming and poses challenges in phase stability, grain boundary control, and co-firing. The cold sintering process (CSP) is an extremely low-temperature sintering technique introduced in recent years, which utilizes transient solvent in liquid phase and uniaxial pressure to achieve rapid densification of ceramics at temperatures below 400℃. CSP has attracted extensive attention due to its advantages such as low temperature and short sintering time. It has been successfully applied to sinter nearly 100 kinds of ceramics and ceramic-matrix composites, including dielectric materials, semiconductor materials, pressure-sensitive materials, and solid-state electrolyte materials.