METHOD FOR APPLYING COATINGS TO PRODUCTS MADE OF ALUMINUM ALLOYS Russian patent published in 1994 - IPC

FIELD: mechanical engineering. SUBSTANCE: this method prescribes carrying out such steps as microarc anodizing in at least two or three solutions each containing 0.20 to 0.30 g/l sodium hydroxide and 2.5 to 7.05 g/l sodium silicate solution (in case of two solutions) and 0.41 to 0.50 g/l sodium hydroxide and 8.0 to 50.0 g/l sodium silicate solution in order of increasing alkalinity and concentration of salts with applying asymmetric alternating current at industrial frequency with equal duration in both positive and negative triangular pulses, with nonlinearly varying voltage from amplitude value to zero within width of each pulse. Ratio between amplitudes of voltage of positive and negative pulses is 0.01 to 0.4. EFFECT: high quality of coatings. 1 dwg, 2 tbl