When processing cast iron workpieces with alkaline zinc-nickel alloy additives, due to their unique processing methods, complex structure, and the tendency for the cast iron surface to rust easily, which is difficult to handle after rusting and has poor decorative properties, the surface performance of the cast iron needs to be improved during the electroplating process. Considering the particularity of cast iron, the following three points should be noted during electroplating:
1. During the high-temperature casting process, a non-conductive oxide film forms on the surface of cast iron, which hinders the deposition of zinc-nickel alloy coating. Therefore, before electroplating, the oxide scale on the surface of the workpiece should be thoroughly removed. Bigely suggests using a shot blasting machine to polish the surface. This not only effectively removes the oxide scale but also causes the high-carbon layer formed during casting to fall off, resulting in microscopic roughness, which is beneficial for improving the adhesion of the coating.
2. The cast iron substrate has a porous and loose structure, with numerous sand holes, a rough surface, and unevenness. As a result, the actual surface area is much larger than the macroscopic area, leading to a much lower actual current density compared to the displayed current density. Therefore, in the electro-galvanizing nickel alloying process, the current density should be 1 to 2 times higher than that of other steel substrates. By subjecting the surface to a sudden activation through a high current, the loose surface can be covered by a dense coating.
3. The acid washing and ultrasonic cleaning processes should be strengthened. During the processing of cast iron parts, there will be a large amount of grease, lubricating oil, and coolant residues, as well as oxides and other insoluble contaminants formed by the sand particles and iron filings remaining from the casting molds during storage. Moreover, cast iron parts inherently contain a large amount of graphite. Therefore, in the electro-galvanizing of nickel alloy, the pre-treatment processes such as acid washing and ultrasonic cleaning should be enhanced to form a uniform, clean, highly conductive, and easily electroplated zinc-nickel alloy coating.
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.
