Study On Corrosion Of The SUS304Stainless Steel By Means Of Ultrasound

304stainless steel is a structural material widely used in long-term nuclear power industry, which localized corrosion, such as pitting corrosion, stress corrosion and crevice corrosion, often occurred in actual service process. It limited the application of304stainless steel largely. Choose a suitable corrosion inhibitor, It is especially important to choose a suitable corrosion inhibitor to promote the resistance of pitting corrosion of304stainless steel. Ultrasound is usually applied to depolarization, enhance electrical analysis current and electrode pretreatment in the process of metal corrosion. But the research about ultrasound affect mental corrosion and inhibition, the effects of mental corrosion rate caused by the combined effect of ultrasound and inhibitors are very few. This article investigated ultrasound and inhibitors impacted304stainless steel corrosion behavior, which with theoretical and practical double meaning.This study measured hydroxyl radical content which produced by ultrasound cracking water molecules in anaerobic conditions. Meanwhile, analyzing the factors influencing hydroxyl radical content. The technique based on weight loss test, electrochemical methods and Environmental Scanning Electron Microscope (ESEM) analysis methods were applied to study the304stainless steel corrosion behavior under different conditions such as ultrasonic, water bath and stir, with potassium dichromate and sodium molybdate as corrosion inhibitors. Then the inhibitory performance of corrosion inhibitor was evaluated. At the same time, X-ray photoelectron spectroscopy (XPS) analyzed the the constituent elements and the distribution of valence state of passivation film on the stainless steel.Results showed that the ultrasonic cavitation made water molecules into hydroxyl radical in Fricke solution under anaerobic conditions. The content of free radicals effected by the factors such as the irradiation time, temperature, the ultrasonic intensity and the dissolved gas. The results obtained by the method of the stainless steel weight loss test, electrochemical methods and the Environmental Scanning Electron Microscope (ESEM) were basically identical. Under ultrasound condition, potassium dichromate preferably inhibited the corrosion of304stainless steel, while sodium molybdate increased the corrosion of stainless steel. In the low stirring rate(less than400rpm), the inhibition rate of potassium dichromate was high. As the stirring rate increasing (more than400rpm), the inhibition rate reduced. X-ray photoelectron spectroscopy (XPS) analyzed the constituent elements and the distribution of valence state of passivation film on the stainless steel, founding that the main elements of the stainless steel surface were O, Cr, Fe and Ni. Cr, Fe and Ni are respectively form oxide or hydroxide.