| 摘要 |
An aqueous bath for electroplating NiP coatings comprising, generally, a solution containing nickel salts, either a mixture of nickel sulfate and nickel chloride or an all nickel chloride source, sodium hypophosphite and boric acid. Thiourea is added to an all chloride bath solution for decorative applications or other applications requiring enhanced brightness. Upon dissolution of the bath constituents, the bath pH is adjusted up to a value of 3.5 to 4.5 with sodium hydroxide and maintained for at least 15 minutes at or above room temperature, preferably in the range of 40° to 50°C, which prevents the oxidation of the hypophosphite anions. The bath pH is then reduced to the operating range of 2.0 to 3.0, preferably 2.2 to 2.6. |
