Hydrogen removal treatment after plating

Hydrogen removal is particularly important for electroplating products, because in the electroplating system, the plated metal ions get electrons on the cathode, and hydrogen ions also get electrons to generate atomic hydrogen. , It penetrates into the metal coating and makes the coating loose. When left for a period of time, the atomic hydrogen will combine to generate hydrogen gas and expand in volume. This will cause the coating to produce pinholes, bubbling or even falling off and other undesirable defects. If it penetrates into the substrate It will also lead to hydrogen embrittlement of the entire component, especially for high-strength steel, once hydrogen permeates, it will easily lead to the embrittlement of the component. Therefore, after electroplating, heat treatment at a certain temperature for several hours to drive out the hydrogen penetrating under the plating layer or in the base metal.

Compared with passivation treatment, the method of hydrogen removal treatment is relatively simple and simple. Generally, the method of heat treatment is used to expel the atomic hydrogen. For the commonly used galvanized components, usually in an oven with a fan In this process, keep the temperature at 220°C for 2 hours. This process is usually before passivation, so that it will not cause cracking of the passivation layer due to hydrogen drive. Stainless steel electroless plating after nickel After a heat treatment at 400°C for 1.5h, it can significantly increase its hardness and reduce brittleness. After the Fe-Mn alloy coating undergoes hydrogen removal treatment at 100°C, 150°C, 200°C for 1.5 hours, the tensile bond strength has increased by 49.5%, 75.5% and 121.8%, respectively. It can be seen that the hydrogen removal treatment can improve the performance of the coating. Important role.

It can be seen from the above that hydrogen removal treatment usually selects an optimal temperature range (usually between 200-300℃) and time (usually 2~3h) for heat treatment, but there are slight differences for different coatings. And different treatment temperature and treatment time also have a certain influence on the performance of the coating. Therefore, the hydrogen removal must ensure that the atomic hydrogen that penetrates into the coating or the metal matrix can be effectively removed without causing the coating to crack.