How to electroplate aluminum after immersion plating

【China Aluminum Network】 In order to ensure good adhesion of the plating layer, after the aluminum is immersed, the copper or nickel should be pre-plated in a solution that is near neutral or weakly alkaline to prevent the etching solution from being electroplated. Impregnate the plating.

Pre-plating copper can be performed in a conventional pyrophosphate solution. After flashing, it should be flash plated at high current density for 1 to 2 minutes.

Pre-plating copper can also be carried out in a cyanide solution. The process specifications are as follows:

Copper cyanide (CuCN) 42g/L

Total amount of sodium cyanide (NaCN) 50 ~ 55g/L

Sodium cyanide free (NaCN) 5.7g/L

Sodium potassium tartrate (KNaC4H4O6·4H2O) 60g/L

Sodium carbonate (Na2CO3) 30g/L

Temperature 40~55°C

pH 10.2 to 10.5

Charged into the groove under 2.6A/dm2 flash plating 2min, in the 1.3A/dm2 plating 3 ~ 5min. Pre-plating of nickel is carried out in a neutral solution. The process specifications are as follows:

Nickel sulfate (NiSO4·7H2O) 140g/L

Ammonium sulfate [(NH4)2SO4]35g/L

Nickel chloride (NiCl2·6H2O) 30g/L

Sodium citrate (Na3C6H5O7·2H2O) 140g/L

Sodium gluconate 30g/L

Temperature 50～65°C

pH 6.8 to 7.2

Current density 2A/dm2

5min

However, when galvanizing aluminum, brass, silver, or chromium, the plating may not be pre-plated, but the lower tank must be charged.