ULTRASONIC-ASSISTED ELECTRODEPOSITION OF CoMo/Al2O3 COMPOSITE COATING ON THE SURFACE OF STEEL AND ITS CORROSION RESISTANCE IN SIMULATED SEWAGE WATER
Abstract
The ultrasonic is applied during the electrodeposition process of CoMo/Al2O3 composite coating on 10# steel to enhance its corrosion resistance in simulated sewage water. The influence of ultrasonic power on the thickness, roughness, chemical composition, surface morphology, and corrosion resistance of the composite coating is investigated. In an aqueous solution, a co-deposition of cobalt and molybdenum can be induced to form CoMo alloy coating. The Al2O3 nanoparticles are incorporated into CoMo alloy to form CoMo/Al2O3 composite coating. When the ultrasonic power increases from 0W to 100 W, the electrodeposition rate of the composite coating increases from 63.25mg/h to 153.73mg/h, and the thickness of the composite coating also increases from 15.6μm to 28.1μm. The surface roughness of composite coating electrodeposited without ultrasonic is about 0.436μm. The CoMo/Al2O3 composite coating electrodeposited at 100W ultrasonic power exhibits the smallest surface roughness of 0.193μm and presents a denser surface morphology composed of 74.4% Co, 10.3% Mo, and 15.3% Al, resulting in better corrosion resistance with the smallest corrosion current density of only 9.7μA/cm2. However, when the ultrasonic power is 150W, the intense hydrogen evolution on the surface of the cathode reduces the density of the coating surface, which leads to the deterioration of corrosion resistance.
