Wettability of aluminium with aluminium carbide (Graphite) in aluminium filtration

Abstract

Graphite filters have previously been employed based on petrol coke. Wetting between molten aluminium and graphite is studied. Al3C4 is formed at the interface between aluminium and graphite. In filtration of aluminium inclusions such as Al3C4 formed in the hall electrolysis are removed. Wetting between aluminium and Al3C4 (graphite) is determined in kinetic studies in the higher temperature range 1000-1200°C. The results are extrapolated down to temperatures employed in the industry around 700°C. The contact angle between aluminium and graphite decreases with time. It may be divided into three stages: removal of an oxide layer on aluminium, formation of Al3C4 at the interface, finally giving an equilibrium value for Al-Al3C4. This value is found to be around 126° at 700°C.