Ultrafast pressureless sintering of high conductivity Ni-based cermets inert anode for Carbon‐free electrolytic aluminum

Abstract

Cermet is a promising inert anode material to solve the problem of high carbon emission and bearing C-F harmful gas generation of primary aluminum produced from bauxite using molten electrolysis with carbon anode. However, a major challenge for traditional methods is to ensure that the cermet inert anode simultaneously has good conductivity, corrosion resistance, and strength. Herein, a new ultrafast pressureless sintering (UPS) method is developed to greatly improve the conductivity of metal ceramic inert anode materials while ensuring good corrosion resistance and strength. In a departure from conventional practice that metal phase undergoes local enrichment accompanied by irregular formation of ceramic particles at low heating rates, here UPS achieves rapid diffusion and uniform distribution of metal phase at regular ceramic particle interfaces during liquid phase sintering. The new method is applicable to Ni-based cermet and the production of Ni-based cermet inert anode with excellent conductivity in a few tens of seconds has been demonstrated, which is able to improve the quality of cermet inert anode requiring a low energy input. The conductivity of cermet produced by the applied UPS process is 15-fold higher than that of other pressureless sintering processes with low heating rates. These Ni-cermet inert anodes exhibit high corrosion resistance and density with excellent mechanical properties. This rapid sintering technique facilitates the structural design of inert anodes and develops a pathway of new systems with scalable, efficient, and high-quality sintering of composite materials.