METHOD FOR PRODUCING COMPOSITE SELF-LUBRICATING CERAMIC COATING ON PARTS MADE OF VALVE METALS AND THEIR ALLOYS Russian patent published in 2023 - IPC C25D11/00 

FIELD: plasma-electrolytic oxidation.

SUBSTANCE: production of protective ceramic coatings containing solid lubricating dispersed graphite particles. The method includes immersing a part as an anode and a counter electrode as a cathode in a bath with an aqueous alkaline electrolyte, and applying bipolar voltage and current pulses to the electrodes. A counter electrode made of graphite is used. Oxidation is combined with the formation of an electrolyte suspension in the bath due to the constant supply of dispersed graphite particles of 0.03-2 microns in size into the electrolyte, separated from the graphite counter electrode under the action of plasma discharges and electrical erosion, and their concentration is maintained in the range of 0.04-0.06 g/l when carrying out oxidation with a repetition rate of voltage and current pulses of 2-4 kHz, with amplitude values of anode voltage pulses of 520-1000 V and cathode voltage pulses of 200-350 V, with effective current densities in the anode circuit of 8-15 A/dm² and in the cathode circuit 10-20 A/dm². The temperature of the electrolyte-suspension is maintained in the range of 12-15°C.

EFFECT: obtaining wear- and corrosion-resistant ceramic coatings with antifriction and hydrophobic properties.

5 cl, 3 ex