Effect of Pulse Voltage in Plasma Electrolytic Oxidation on Structure of Ceramic Coatings on 2024 Aluminium Alloy

Ceramic coatings on the surface of 2024 alloy were prepared by plasma electrolytic oxidation(PEO) in the electrolyte solution rich in ultra-fine SiC powder. The effects of the pulse voltages on the thickness, growth mechanism, structures and corrosion behavior of coatings were systematically discussed. The results show that the thickness of the ceramic film increased slowly with increasing the pulse voltage, when the pulse voltages were lower than 400 V. The current density-time curves were very different when the pulse voltages were lower than 400 V and higher than 400 V. With the increase of the pulse voltages, three different surface morphologies of ceramic coatings were formed, and they exhibited different corrosion potentials and current densities in 3.5% NaCl solution.