Surface hydrate-assisted low- and medium-temperature sintering of MgO

Abstract

MgO was readily densified by cold sintering at 180 °C with the help of its surface hydrate, but the product contained a considerable amount of Mg(OH)2. By increasing the sintering temperature to 450 °C to remove Mg(OH)2, pure MgO with a relative density of 93% was achieved. The effects of processing parameters such as Mg(OH)2 amount, initial liquid phase content, uniaxial pressure and dwelling time on densification behavior were investigated. Densification was achieved through a series of processes, including hydration of MgO, decomposition of Mg(OH)2, particle rearrangement, grain boundary diffusion and recrystallization of newly formed MgO. This work provides a novel approach to solve the challenge of densification in most oxides by means of a cold sintering process.