| 摘要 |
Electroless plating High carbon steel strip is coated with nickel-phosphorus after the following cleaning operations; degreasing is trichlorethylene, cathodic cleaning in an aqueous alkali cleaner, the solids content of which comprises 85% trisodium phosphate, 10% sodium metasilicate and 5% wetting agent; washing and dipping in 10% aqueous hydro-chloric acid solution. The strip is immersed in a plating solution comprising:- .nickel chloride.30 gm./litre .sodium hypophosphite.10 gm./litre .sodium acetate.5 gm./litre .sodium citrate.21.75 gm./litre .sodium thiosulphate.0.006 gm./litre The solution is maintained at 90 DEG -95 DEG C. and the nickel content of the solution kept approximately constant by adding nickel chloride, sodium hypophosphite and sodium acetate. A deposit 0.002" thick is obtained after 5 hours immersion. Electrolytic plating Steel strip is cleaned as in the previous example, except that ultrasonic degreasing in perchloroethylene is used. The strip is immersed in an aqueous plating solution comprising:- .nickel sulphate.160 mg./litre .nickel chloride.46 gm./litre .phosphoric acid.50 gm./litre .phosphorous acid.22 gm./litre The solution is maintained at 70 DEG -80 DEG C, the anodes being of nickel and the current density being 20-40 amps./dm2. In less than 1 hour a deposit 0.002" thick is obtained. A coating of cobalt-phosphorus is obtained in an aqueous plating solution comprising:- .cobalt chloride.180 gm./litre .phosphoric acid.50 gm./litre .phosphorous acid.40 gm./litre The strip is connected as the cathode and cobalt anodes are used. The solution is maintained at 70 DEG C., the current density is 30 amps./dm2 and in less than an hour a deposit 0.002" thick is obtained. |
