METHOD OF TREATING BRASS PRODUCTS PRIOR TO CHROME-PLATING Russian patent published in 1994 - IPC

FIELD: chemistry, particularly, electroplating. SUBSTANCE: essence of this method resides in annealing workpiece at temperature of 250 C for 2 h, degreasing its surfaces using trisodiumphosphate added with potassium or sodium silicate solution, pickling workpiece in 100 to 150 g/l sulfuric acid solution, electrochemically treating workpiece in strong solution of chrome anhydride (300 to 350 g/l) added with 10 to 15 g/l ammonium sulfate, chemically finishing workpiece in diluted solution of chrome anhydride (80 to 100 g/l) added with 15 to 20 g/l calcium sulfate and 10 to 15 g/l calcium sulfate, electrochemically nickel-plating (application of nickel substratum) workpiece in 250 to 300 g/l nickel sulfate solution and prescribed additives, and finally electrochemically chrome-plating workpiece in chrome anhydride solution (220 to 240 g/l) with sulfate additive (1.8 to 2.2 g/l). EFFECT: higher corrosion resistance. 2 tbl