Introduction to the Main Problems of Electroless Nickel Plating on Electric Heating Tubes

Introduction to the Main Problems of Electroless Nickel Plating on Electric Heating Tubes

Due to its advantages in uniformity, hardness, wear resistance, and corrosion resistance, as well as its comprehensive physical and chemical properties, the electroless nickel coating has a wide range of applications. With the continuous development and changes of related industries, chemical nickel plating technology is also constantly evolving to meet more complex and demanding usage conditions. At the same time, technology needs to be improved and problems need to be solved. Here are how to solve common problems in chemical nickel plating. Let's take a look together with Changzhou Stainless Steel Chemical Nickel Factory.

1. Pitting and pinholes in the coating.

The surface condition of the plated parts is poor. If mechanical impurities, oxide scales, etc. are not completely removed, the pH value of the chemical plating solution and the instability of the plating solution may cause pitting and pinholes in the coating. The surface roughness of the parts should be minimized as much as possible. The brighter the basic surface, the brighter the chemical nickel layer, and the fewer pinholes in the coating. (Note: Do not adjust the pH value of the plating solution during plating. The plating solution should be circulated and filtered. An appropriate amount of stabilizer can also be added. In chemical nickel, the more important surfaces of the parts should be facing downwards or at 90 ° to the horizontal as much as possible.)

2. Uneven coating thickness.

Due to the different angles between the surfaces of the parts and the horizontal plane, the rate of hydrogen gas discharge varies during chemical nickel plating. The hydrogen gas generated on the part can quickly leave, while the hydrogen gas generated on the downward surface needs to rise along the surface to the edge before leaving, thereby reducing the actual contact time between the surface and the plating solution, resulting in uneven coating thickness. (Note: When the surface of the part is approximately perpendicular to the horizontal plane, the rise of hydrogen gas along the surface of the part can also cause the upper coating to be slightly thinner than the lower one.) In addition, in all areas that hinder the smooth discharge of hydrogen gas, it is possible to cause the coating to be thin and the surface to have more pinholes. For large-sized parts, it is recommended to use the up and down swing method as much as possible during the plating process, and to use the plating solution in a flowing state to facilitate the discharge of hydrogen gas.

3. Spot on the surface of the coating.

After multiple practices and analyses, it has been found that the appearance of spots on the surface of the coating is not related to the deionized water of the chemical plating solution, but rather to the adhesion of certain organic "impurities" on the surface of the plating piece, which cannot be cleaned thoroughly, thus changing the formation and growth behavior of the Ni-P alloy coating on the surface of the part, forming this uneven "spot". Later, different cleaning agents were used to strengthen the pre plating cleaning, eliminating the phenomenon of "spots" on the coating surface and restoring a uniform and bright surface appearance.

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