The role of TiB2 particles in the creep and penetrating resistance of graphite-based composite

Abstract

In this work, the creep behaviors of the graphitic and graphite-TiB2 composite as cathode materials have been investigated at high temperature aluminum electrolysis for discussing the role of TiB2 particles in creep resistance and mechanical properties connected with the microstructural evolution involving electrolyte penetration and cracking. The graphite-TiB2 composite has superior creep resistance over the graphitic sample. The corresponding creep strain can be as low as ~0.2% after the high temperature electrolysis. The addition of TiB2 particles greatly densifies the prepared composite with low porosity, resulting in the reduction of penetrating channels. The well-wetted TiB2 particles by liquid Al generate a protective dense Al layer on the surface of composite, greatly blocking the electrolyte penetration. In turn, liquid Al may slowly penetrate into the composite via the cracks formed channels. The fracture strength of the graphite-TiB2 composite increases from 41.6 MPa to 48.9 MPa after creep test at high temperature loading. Such improved properties should be attributed to the combined mechanism with reduced micro-cracks, decreased penetrating channels and the reinforcement due to addition of TiB2 particles.