The bright nickel layer on stainless steel is a slightly yellowish, silvery-white metal which is harder than copper, zinc, tin, cadmium, gold and silver, but lower than chromium and rhodium metals. Bright nickel has a high chemical stability in air and a good stability to alkalis. Stainless steel through the use of bright agent, without polishing directly plated bright nickel, in order to improve the surface hardness, wear resistance and leveling, in the appearance of stainless steel and other nickel-plated parts consistent appearance, and to avoid corrosion between stainless steel and other bright nickel contact potential difference.
Stainless steel plating bright nickel solution in the bright agent in recent years the development of rapid, many varieties. In summary, the development of brightening agent has gone through four generations. The first generation is also the most primitive product for saccharin plus butylene glycol. It was possible to plate bright nickel with a very high leveling property. Its use flourished in the 1960s and 1970s. However, due to the instability of butynyl glycol in the nickel plating bath, the life is short, organic impurities accumulate quickly, need to deal with the nickel bath often, so, through epichlorohydrin or propylene oxide and butynyl glycol twinning, the synthesis of the second generation of nickel plating bright agent, such as BE, 791 bright agent, the situation has improved, BE and 791 retain the alkyne group, and later progress will be pyridine group polymerization up, the formation of the third generation of products, the light is faster, brighter. Out of the light faster, less bright agent dosage, longer service life. Now further use of nickel plating bright agent intermediates a variety of combinations of new bright agent has been developed to the fourth generation of products. It uses less, faster light, longer processing cycle, and stronger deep plating ability.
Stainless steel bright nickel plating process: organic solvent oil removal → chemical oil removal (sodium oxide 40g / L, sodium carbonate 30g / L, trisodium phosphate 50g / L, OP-emulsifier 3mL / L, temperature 80 ~ 90 ℃, time 30min) → water washing → cathode electrolytic activation (hydrochloric acid aqueous solution 1 +1, room temperature, Dk1 ~ 3A/dm2, time 5min, anode cloth wrapped carbon fine plate ) → flash nickel plating (nickel chloride 180~220g/L, hydrochloric acid 120g/L, room temperature, current density 4A/dm2, time 5~lOmin, anode nickel plate) → washing → activation [sulphuric acid 5%(V), time 5s] → washing → bright nickel plating (time 5~lOmin, or time required according to thickness) → washing → passivation (potassium dichromate 1s0g/L, sodium dichromate 150g/L, sulfuric acid 30~50mL/L, room temperature, time 20~25s) → water washing → water washing → hot water washing → shaking dry → drying → acceptance.
