The effect of an interfacial tantalum oxide layer on interactions in the Ta/Sn system

Liquid Sn is a corrosive agent for tantalum at high temperatures. Oxidation of tantalum is often used to form a surface protective oxide layer in order to improve its chemical resistance in the liquid metal. In this study the stability of tantalum oxide layer, obtained by thermal oxidation and plasma anodization of tantalum, in contact with liquid Sn was examined in the 700-1000 °C temperature range. It was established that the stability of the oxide layer is controlled by its dissolution into the substrate, which takes place along with the formation of non-stable Ta sub-oxides. It was found that the thermal oxide layer may provide sufficient protection against tantalum corrosion by liquid Sn up to 700 °C, whereas the protective layer obtained by the plasma anodization gives an adequate corrosion resistance up to 1000 °C.