Uniform corrosion of zirconium alloy 4 under isothermal oxidation at high temperature

Many studies have suggested that oxygen at the metal/oxide interface could play a detrimental role on the gas-side oxidation rate of zirconium alloys. However, mechanism of the role of oxygen is not clearly understood yet. Recently it has been shown that oxygen may lower the stress built up in the metal/oxide interface during the oxidation and thus promote the oxide phase transformation, leading to the oxidation enhancement. In this paper, isothermal oxidation of zirconium alloy 4 or zircalloy-4 at high temperature has been studied. High temperature oxidation carried out at tube furnace in air atmosphere at 400, 500 and 600 degrees C. Oxidized sample was characterized by X-ray diffraction and optical microscope. In this study, kinetic oxidation of zirconium-4 at high temperature has also been studied. X-ray diffraction examination show that the oxide scale formed during oxidation of zirconium alloys is ZrO2. Characterization by optical microscope showed that microstructure of zirconium alloys 4 relatively unchanged after oxidation. Kinetic curves of oxidation of zirconium alloy 4 showed that increasing oxidation temperature will increase oxidation rate.