Energy efficient sintering of high-performance ceramics

Developing high-efficiency sintering technologies with mild conditions is crucial for reducing the energy consumption and manipulating the performance of ceramics. However, sintering ceramics at low temperatures in short times without pressure is challenging because of their high melting points. Inspired by microwave resonance and dissolution‒precipitation phenomena, an energy efficient sintering, microwave cold sintering process (MW-CSP), is proposed here to densify high-performance ceramics with significantly reduced sintering times and temperatures under pressureless conditions during the sintering stage. A range of ceramics, including chlorides, oxides, phosphates, and molybdates, with various applications, have been shown to be well sintered by MW-CSP. The transmission electron microscopy (TEM) and phase-field simulation results demonstrate that the combination of the transient liquid phase and microwave resonance improves the driving force of sintering. Compared with those of other pressureless sintering technologies, the mechanical and dielectric properties of the selected materials are improved by 50%–95%, whereas the energy consumption of MW-CSP is dramatically reduced by more than 97%. These findings highlight the great potential of MW-CSP in efficiently densifying high-performance ceramics, opening up possibilities for energy-saving sintering.