Effects of temperature on the protective property, structure and composition of the oxide film on Alloy 625

The paper mainly investigated the protective property, structure and composition of the oxide film on Alloy 625 in a lithium borate buffer solution (pH300°C = 6.93) in the temperature range of 25–300 °C. The methods used were electrochemical measurements and XPS analysis. As temperature increased, the protective property of the oxide film degraded, and the structure varied from a singe-layer to double-layer. The oxide film consisted of Cr2O3 and Cr(OH)3 at 25 and 150 °C, while it contained Ni(OH)2, in addition to Cr2O3 and Cr(OH)3 at 250 and 300 °C. This was mainly attributed to the temperature-induced variation of composition and protective property of the barrier layer.