When using electroless nickel plating solution, adhesion is a very important property of the coating and also one of the key indicators for evaluating the quality of the plated parts. So, why do temperature and pH value affect the adhesion of the coating? Does intermittent plating stop have a significant impact on the bonding force? Why is it that heat treatment can enhance bonding strength, but the higher the temperature, the better? In this issue's article, we will answer these questions.
Plating process
The adhesion of the coating obtained by acid bath is higher than that by alkali bath. The former is approximately 415MPa, while the latter is only about 219MPa. The phosphorus content in the coating also affects the adhesion, as the composition, pH value and temperature of the electroless nickel plating solution are all related to the phosphorus content, and thus also influence the adhesion.
Fluctuations in temperature or pH value during the plating process can cause layered structures with different amounts of phosphorus, which will reduce the bonding force. In severe cases, interlayer peeling may occur.
Heat treatment
Appropriate heat treatment of the electroless nickel plating layer on carbon steel, stainless steel, copper and aluminum alloy substrates can enhance the adhesion of the coating. When the heat treatment temperature reaches as high as 700℃, although the hardness of the coating decreases, a thin diffusion layer appears at the interface between the substrate and the coating, which can enhance the adhesion.
When the coating on stainless steel was bent on an unheat-treated test piece on a 25t testing machine, it was found that when bent to 90°, cracks or even peeling occurred at the bent edge. However, after heat treatment, when bent to 180°, only micro-cracks appeared at the corners.
About us
Guangdong Bigely Technology Co., Ltd. ,founded in 2003, is a high-tech enterprise integrating R & D，production, sales and service, specializing in the production of electroplating chemicals. As a fast growing electroplating chemicals supplier in China, Bigely has over 20 years' experience in electroplating additives production and own production base of 5000 square meters. We can produce 15,000 tons of electroplating additives every year, which can fully meet the needs of customers.
If you need our high-quality electroplating additives, please contact us. We can provide you samples for test, and also provide a series of services.
