Highly Efficient Formation of Protective Composite Coatings Modified with Graphite on Light Alloys

An efficient, one-step method for formation of protective graphite ceramic coatings on light alloys (Al, Mg, Ti) has been developed. The method includes simultaneously high-frequency PEO-treatment and modification of ceramic coating with graphite formed in the electrolyte due to separation of dispersed particles from graphite counter electrodes under the action of plasma discharges and electroerosion. Studies of protective composite PEO-coatings obtained by the proposed method have shown that they are significantly superior in their performance properties to basic PEO-coatings not modified with graphite. Compared to basic PEO-coatings, the composite PEO-coatings had 10% higher microhardness, had one to two orders of magnitude higher wear resistance, three times lower coefficient of friction, and two times higher the corrosion resistance. Composite PEO-coatings also have hydrophobic properties. In addition, the proposed method is highly technological, extremely simple, and allows one to significantly reduce labor, material, and energy costs.