Corrosion degradation behavior of alumina ceramics in hot sulfuric acid

Corrosion behavior of 93 wt% alumina ceramics was investigated. The weight, the bending strength and the thickness of corroded layer were measured after exposed in sulfuric acid at temperatures of boiling point and 90 °C. The weight decreased with time, but the weight loss rate became small. On the contrary, the thickness of corroded layer, which was determined by a porous zone depth formed on the surface of specimens as a result of dissolution of grain boundary phase, increased linearly with time. The bending strength decreased with an increase in the corroded layer depth. However, the morphology of fracture was inconsistent with the assumption that the corroded layer depth corresponds to a flaw dimension causing the failure. As large numbers of pore were observed on the fracture surface of specimens, it was suggested that a combined flaw of the pore and the corrosion layer governs the strength of corroded alumina.