What is the cause of fading or even blackening of zinc alloy die-casting parts after electroplating?

It is required to die-cast a batch of zinc alloy faucets. After electroplating copper, after polishing and electroplating, it always does not like copper. The color is like imitation gold plating. It is not successful after repeated times, and the plating of color will fade black. What is the method? Can solve the problem that the copper plating color is similar or close, and the black color fades after plating?

Electroplating processes and die cast surface quality can result in poor plating.

Mold castings should have good surface quality, no porosity, cracks, pores, bubbles, shrinkage holes, cold wires, pinholes, etc.; otherwise, the surface of the casting after electroplating is easy to foam, and the plating layer will be separated from the substrate.

When grinding and polishing before plating, be careful not to over-grind.

Due to the rapid cooling rate during the solidification process of Die casting, the die-casting surface becomes a dense hard layer, and the internal structure may have defects such as porosity and shrinkage.

Do not remove the fine surface during grinding, otherwise pitting and bubbles will occur during the plating process. In addition, the polishing wheel should not be pressed too tightly and overheated to prevent adhesion between the abrasive and the product, resulting in poor plating of the product.

Zinc is easily oxidized and forms an oxide film on the surface, which affects the performance of zinc.

Therefore, the oxide film is removed to have a reducing material, and the surface of the oxide film can be removed by an acid (e.g., hydrochloric acid) solution.

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