碳钢超声磷化及在模拟干热岩地热水中的耐蚀性能

he problem of corrosion of carbon steel in geothermal water limits the efficient and economic utilization of geothermal energy. Ultrasonic assisted phosphating of carbon steel was carried out in a bath with environmentally friendly hydroxylamine sulfate as an accelerant, but without any strong oxidation chemicals, aiming to enhance the corrosion resistance of the steel. The effect of process parameters such as ultrasonic irradiation, accelerant, pH and time on the corrosion performance of the phosphate coatings was studied by potentiodynamic polarization curves. The results showed that the grain size of phosphate coatings was reduced and the corrosion resistance could be enhanced by ultrasonic irradiation. The pH value of the phosphate bath and phosphating time could be considered as two key parameters affecting the corrosion performance of the phosphate coatings significantly, therefore the two parameters should be optimized. The protection performance of phosphating coatings formed under optimal conditions was evaluated by electrochemical impedance spectroscopy measurements. The charge transfer resistance of phosphate coatings is 3.39106 cm2, in the contrast, that for carbon steel is 1.44103 cm2.