Influence of Hydrogen Peroxide on the Composition and Porosity of Oxide-Ceramic Coatings on Alloys of the Al–Si–Cu and Al–Cu–Mg Systems

We study the influence of hydrogen peroxide on the phase composition, thickness, and porosity of oxide-ceramic coatings obtained by plasma electrolytic oxidation on Al–Si–Cu and Al–Cu–Mg aluminum alloys. For these two systems, it is shown that the presence of H 2 O 2 , with a concentration of 5 g/liter, makes it possible to get a twofold increase in the thickness of the oxide-ceramic coating as compared with the original electrolyte. A subsequent increase in the concentration of hydrogen peroxide leads to a decrease in the thickness of oxide-ceramic coatings. The maximum content of corundum is obtained for hydrogen-peroxide concentrations of 5 g/liter for the Al–Cu–Mg system and 7 g/liter for the Al–Si–Cu system. The presence of silicon in the composition alloy results in the formation of sillimanite and quartz in oxide-ceramic coatings, which is accompanied by an increase in the volume of oxide-ceramic coatings. As the concentration of hydrogen peroxide in the electrolyte increases, the porosity of the Al–Si–Cu system decreases, whereas the porosity of the Al–Cu–Mg system does not change.