FIELD: mechanical engineering. SUBSTANCE: part of cylinder-piston group with composite coating containing aluminium and silicon oxides on part of surface section has thickness of coating equal to 50 - 100 μm and microhardness not less than 15 GPa after machining. Method of machining of part surface by oxidation in alkaline electrolyte using ac current comes to the following: anode voltage is applied to part under machining at moment of momentary voltage rise in supply circuit to 300-500 V, and mean negative (cathode) current value is set 20-40% higher than mean anode current value at cathode voltage amplitude less than circuit voltage amplitude. Step-down transformer is used for forming cathode voltage. Installation for machining working surface of cylinder has electrolyte intake and working reservoirs and pump for delivering electrolyte from one reservoir into the other. Working reservoir is formed by inner surface of cylinder under machining and covers pressed to cylinder at end faces in which channels are made to supply and let out the electrolyte. Auxiliary electrode is arranged inside cylinder along its axis. Installation has electrolyte cooling device placed in line along which electrolyte is delivered from one reservoir into the other. Coating, thus formed, reduces friction between piston and cylinder, operates reliably at high temperatures and pressures and does not prevent dissipation of heat flows from mated surfaces. EFFECT: enhanced quality of part coating. 8 cl, 2 dwg
