Five common defects and solutions of square tube electroplating

Today, let's talk about the corresponding solutions for five common defects in square tube electroplating.

1. The surface thickness is uneven

When the pH of the plating solution is too high, and the wetting agent is too much, the wetting agent is easy to interact with Ni2+ to generate insoluble compounds, which are randomly adsorbed on the surface of the square tube, resulting in uneven thickness of the coating. To solve this problem, a small amount of activated carbon can be added to absorb part of the wetting agent, and after filtration, dilute sulfuric acid is used to adjust the pH to the process specification.

2. Peeling and blistering

There are three reasons for this: (1) The presence of Zn2+ and N03- impurities in the plating solution not only causes black streaks and other phenomena in the coating, but also increases the internal stress of the coating, resulting in brittle cracking of the nickel layer, which eventually falls off in powder form; (2) Saccharin is the main component in the light aid. When self-preparation of light aids, too much saccharin is added, which will increase the internal stress of the nickel layer, causing the nickel layer to peel off; (3) Poor pre-plating treatment. There are residual oxide scale and other debris on the surface of the square tube, which causes the nickel layer to peel and blister.

There are also three ways to solve the cause: 1) Strengthen the pretreatment work, and strictly prohibit residual oxide scale and oil stains on the surface; 2) Use corrugated iron as the cathode, and conduct electrolysis treatment under stirring conditions until it is removed. In addition to N03-, use a large-area anode and a small-area cathode to electrolyze with a current density greater than 1.4-dm2 for 1~2h, and then reduce to 0.2A/dm2 to continue electrolysis until the coating is normal; 3). Water Dilute the plating solution and supplement the corresponding amount of main salt, boric acid and main brightener.

3. Pinhole pitting

The reasons are: (1) Too little wetting agent. The hydrogen bubbles generated by the electrode action tend to stay on the surface of the cathode, and Ni2+ is continuously discharged and deposited around the hydrogen bubbles, and the nickel layer gradually thickens: when the nickel layer is too thick to withstand the hydrogen bubbles, the bubbles will automatically burst, and the nickel layer is not deposited. There are pits, that is, pinholes or pits, where the air bubbles are located; (2) there is air in the pump. For the non-continuously filtered plating tank, the pump on the filter is used for mobile use, and the pump always contains a certain amount of air. When the filter is used, the air remaining in the pump is not completely removed, and these air follow the work of the pump And enter the coating to become air bubbles, resulting in the same failure caused by too little wetting agent; (3) There are organic impurities such as animal glue, oil stains, etc. in the coating, these non-conductive organic impurities will adhere to the surface, and Ni2+ cannot be in it. top discharge deposition. Where the organic impurities are not adhered, the plating layer continues to deposit and thicken. As a result, pit-type pinholes or pits are formed; (4) After adjusting the plating solution with a wetting agent, there are still pits in the plating layer, and it is necessary to consider whether the Fe3+ content is too much. Fe3+ is colloidal in the plating solution, which is difficult to filter and remove. When it adheres to the surface of the rectangular tube, the plating layer will appear pitted.

4. The coating is not bright

There are three reasons why the coating of the square tube is not bright: (1) The brightener is too small, the main salt content is too low, the anode plate is too short and too few, the deposition speed and migration speed of nickel ions cannot reach a balance, resulting in insufficient coating brightness ; (2) PH and temperature are too high. At this time, the main salt is easily hydrolyzed into Ni(OH)2 precipitation, and part of Ni(OH)2 is mixed in the coating, resulting in insufficient brightness of the coating; (3) The acid copper plating is not cleaned, and there is a layer of alkaline on the surface at this time. film, nickel is deposited on the film layer, resulting in the coating not reaching the mirror brightness.

The solution is: 1). After acid copper plating, it should be thoroughly cleaned, and if necessary, dilute sulfuric acid can be used to remove the film; 2) Adjust the pH with dilute sulfuric acid, and reduce the temperature to the process specification; 3). Supplement the main brightener, correspondingly Supplementary light aids are also required. Adjust the main salt and other components according to the process requirements, and increase the anode nickel plate.