FIELD: chemistry.
SUBSTANCE: method of thermal protection of internal combustion engine piston comprises applying a heat-insulating coating on the piston bottom by the anode-cathode-micro-arc oxidation, wherein the coating comprises solid inclusions of phase α-Al2O3, dispersed in the matrix of phase γ-Al2O3 and mullite compounds 3⋅Al2O3⋅SiO2. The coating is applied in an electrolyte consisting of potassium hydrate solution, sodium silicate solution and distilled water, wherein the piston is anode, and a plate is cathode, fixed at a distance of 90-100 mm from the piston bottom, which is arranged parallel to the cathode, while the process is carried out for 90-120 min at an electrolyte temperature of 298°-318°K, an anode voltage of 295-315 B, a surface current density of 16-17 A/dm2, at a ratio of cathode and anode currents - 1:1, wherein the coating is applied to the piston bottom until the coating thickness is 100-160 mic, excluding the edge area with width of 2-3 mm on the perimeter of the bottom, afterwards mullite compound is removed from the surface coating mechanically until the coating thickness is 50÷110 mic.
EFFECT: method enables to produce thermal barrier coating on the piston bottom, capable of protecting the piston from destruction at thermal-cycle loads, with a reduction in labour intensity and power consumption of the method.
