What's new in ceramics sintering? A short report on the latest trends and future prospects

Despite sintering has a history even longer than human civilization (its discovery dates back at least to 25,000 years ago), in the past decade, new exciting challenges have emerged in the field: reduction of environmental impact, densification of metastable phases, complete consolidation of ultra-refractory compounds, precise microstructural design to control properties of functional ceramics and integration between inorganic-organic compounds. In order to meet such challenges, new sintering routes employing electric fields/currents, water/solvents and external loads have been developed. The research also opened new questions about unexpected (and still not completely understood) interactions between electricity, presence of water/liquid, heating and diffusion processes. In this manuscript, we have rationalized the last-ten-years research in the field of sintering for the consolidation of ceramics. The processes are collected into three main groups: flash-like (sintering under relatively large electric fields and the material is internally heated by the Joule effect), spark plasma sintering-like (combination of pressure and limited electric field) and hydro-consolidation (sintering at temperature below ≈ 350 °C in the presence of a liquid under an applied pressure). This paper aims to point out common features and differences among different techniques. Finally, future research trends and new paradigm in material processing are anticipated.