How to avoid peeling of the coating during the production process using hard chromium additives

How to avoid peeling of the coating during the production process using hard chromium additives

Mon Jul 17 16:26:31 CST 2023

A customer inquired that during the production process of using hard chromium plating additives, the phenomenon of coating peeling often occurs due to poor adhesion of the coating. So, how can we effectively avoid the occurrence of this skin explosion phenomenon?

Based on on-site experience and the characteristics of the hard chromium additive Cr-2 in the product, Bigley Technology has conducted an analysis and can adopt the following four measures:

1. For workpieces with complex shapes, impact current can be used, which means that when the workpiece enters the groove, a current several times higher than the normal current density is applied to the workpiece for a short period of time to increase cathodic polarization. A layer of chromium will quickly deposit on the surface of the workpiece, and then the normal current will be restored for plating.

2. For alloy steel or high carbon steel workpieces with a thick oxide film on the surface, anodic etching can be used when plating hard chromium or continuing to plating chromium on a chromium plating layer with a longer power outage time. That is, the workpiece is first subjected to a short period of etching treatment to dissolve the oxide film electrochemically and form a micro rough surface.

3. For alloy steel containing nickel and chromium, a stepped power supply method can be used. Due to the presence of a thin and dense oxide film on its surface, hard chromium plating can affect the adhesion between the coating and the substrate. One layer of workpiece should first be anodized in the plating solution, then converted to a cathode, and electroplated with a current that is decimal times normal (usually controlled at around 3.5V). Afterwards, the current density should be gradually increased to the normal range every 20-30 minutes, so that a hard chromium coating with good adhesion can be obtained on the surface of the workpiece.

4. When plating hard chromium on construction workpieces, preheating before plating can be used, that is, the workpiece needs to undergo preheating treatment before electroplating, so that the temperature of the workpiece is close to the plating solution (the temperature change of the plating solution should be controlled within ± 2 ℃ as much as possible), otherwise it will affect the adhesion of the chromium coating and the temperature of the plating solution.

So, in the production process of using hard chromium additives, we can adopt the above four measures to effectively avoid phenomena such as coating cracking, reduce defect rates, and improve production efficiency. If you are interested in hard chromium additives, you can contact Bigley customer service to obtain free samples and detailed technical information!

If you want to learn more about chromium plating, you can click to view the "Electroplating Encyclopedia".