Method of deplating:
Chemical and electrochemical methods. It is usually preferred according to the chemical properties of the coating and the substrate.
There are two kinds of traditional chemical methods to remove Cu / Ni coating: concentrated nitric acid (adding sodium chloride) oxidation method and nitro compound (anti dye salt) method. The former has low cost and fast removal rate, but it produces a lot of nitrogen oxide gas, and it is easy to lead to excessive corrosion of the base metal; the anti dye salt, namely sodium m-nitrobenzene sulfonate, has no corrosion to the base metal, but needs high temperature removal, with long time and low efficiency; moreover, if it is used together with the highly toxic substance sodium cyanate, the operation is improper, and the harm is very serious. Now, this method is basically used in combination with potassium thiocyanate and ethylenediamine.
Development direction of deplating:
The electrodeposited coating is based on the use of some base metals in alkaline solution or solution containing chromium compounds, or the addition of corrosion inhibitors and other substances in acid solution, so that only the coating metal is anodized and dissolved. In recent years, the combined stripping solution containing coordination agent has been developed with high dissolution efficiency.
Although the deplating of unqualified parts is only a supplementary link in the electroplating production, the deplating of the hanger coating in the automatic production line is as important as the electroplating process of each coating. Once the hanger coating is not removed cleanly, it will directly affect the composition of the plating solution and the quality of the plated parts. Therefore, it is very important to keep the good effect of electrodeposition.