In the production process of using chemical nickel plating solution, it is inevitable that there will be unqualified workpieces. So how do we remove the chemical nickel plating layer from these workpieces?
Based on on-site experience and the characteristics of Ni-809 phosphorus electroless nickel plating solution in the product, Bigley Technology has analyzed that the electroless nickel coating of unqualified workpieces can be removed through the following two methods:
1. Chemical stripping method: The chemical stripping method does not corrode the workpiece and is suitable for workpieces with complex geometric shapes, and can achieve uniform stripping.
Formula 1: Concentrated HNO3, 20-60 ℃. This solution has low cost and fast speed (30-40%) μ M/h), with low toxicity. Suitable for workpieces with low precision requirements in size, to prevent water from entering. After the plating is removed, it should be quickly washed in hydrochloric acid and then cleaned with flowing water.
Formula 2: HNO3 (1:1), 20-40 ℃, fast fading rate (10 μ M/5-6min), suitable for stainless steel.
Formula 3: 1000ml/L concentrated HNO3, 20g/L NaCl, 10g/L urea (to inhibit the generation of NOX gas), 5g/L hexamethylenetetramine, room temperature, regression rate of 20 μ M/h.
Formula 4: Sodium m-nitrobenzenesulfonate 60-70g/L, sulfuric acid 100-120g/L, potassium thiocyanate 0.5-1g/L, 80-90, suitable for stripping of copper and copper alloy workpieces. When the stripping surface is dark brown, remove it and thoroughly clean it before removing the brown film (NaCN 30g/L, NaOH 30g/L, room temperature).
Formula 5: HNO3: HF=4:1 (volume ratio), appropriately heated in winter, fast fading rate, and non corrosive iron substrate. But HF must be analyzed with analytical purity (using industrial grade HF for tank preparation, which is prone to explosion).
Formula 6: Ammonium nitrate 100g/L, aminotriacetic acid 40g/L, hexamethylenetetramine 20g/L, pH=6, room temperature, regression rate 1/5min, low cost.
Formula 7: Sodium meta nitrobenzenesulfonate 110-130g/L, sodium cyanide 100-120g/L, sodium hydroxide 8-10g/L, trisodium citrate 20-30g/L, 80-90 ℃, suitable for the removal of chemical nickel coatings on precision steel parts.
Formula 8: Sodium m-nitrobenzenesulfonate 100g/L, NaOH 100g/L, ethylenediamine 120ml/L, sodium dodecyl sulfate 0.1g/L, 60-80 ℃. Adding sodium meta nitrosulfonate during adjustment can restore the regression rate to 80% of the regression rate.
2. Electrolytic stripping method: It can more conveniently and quickly remove the chemical nickel coating from the workpiece.
The formula is: NaNO3 100g/L, aminotriacetic acid 15g/L, citric acid 20g/L, thiourea 2g/L, sodium gluconate 1g/L, sodium dodecyl sulfate 0.1g/L, pH=4, room temperature, current density 2-10A/dm2, cathode made of 10 # steel, and the area ratio of cathode to anode is 23:1.
So, in the production process of using chemical nickel plating solution, we can use the above two methods to remove the chemical nickel plating layer from unqualified workpieces, effectively reducing the scrap rate of workpieces and thus saving production costs more. If you are interested in chemical nickel plating solution, please contact Bigley customer service to obtain free samples and detailed technical information!
If you want to learn more about chemical nickel plating, you can click to view the "Electroplating Encyclopedia".