What is the difference between Cathode Electrolytic Oil and Anode Electrolytic Oil?
In metal surface treatment, we must first degrease the surface of the workpiece before the subsequent painting process, and electrophoretic coating is no exception. What method should be used to degrease it? At this time, an electrochemical degreasing method is often used. So what is electric degreasing oil? What is the difference between cathodic electrolysis oil and anode electrolysis oil? Then the Hongheshun electrophoretic paint manufacturer will reveal the answer for you.
Electrochemical degreasing, also known as electric degreasing, is to use parts as anodes or cathodes in alkaline solutions, and use stainless steel, nickel, nickel-plated steel, or titanium plates as the second electrode. Oil stain removal process. Electrochemical degreasing fluid is similar to alkaline chemical degreasing fluid, but it mainly relies on electrolysis to strengthen the degreasing effect. Generally, electric degreasing is more efficient and more complete than chemical degreasing.
Electric degreasing oil can be divided into two types: cathode degreasing oil and anode degreasing oil. Hong and Shun electrophoretic paint manufacturers will introduce the difference between these two types of electro-removal oil.
Cathode Electrolytic Oil
The characteristics of cathodic electric degreasing oil is that hydrogen will be precipitated on the workpiece, that is, 2H2O + 2e = H2 + 20H. When the cathodic electric degreasing is performed, the amount of hydrogen evolution is large, the dispersion is good, the bubble size is small, the emulsification is strong, and the oil removal effect is also good , Degreasing speed is fast, and does not corrode parts. However, the precipitated hydrogen will penetrate into the metal and cause the hydrogen embrittlement effect, so it is not suitable for degreasing of high-strength steel, spring steel and other brittle sensitive metal parts. In addition, when the electrolytic solution contains a small amount of zinc, tin, lead and other metal particles, there will be a layer of sponge-like metal on the surface of the part, which will contaminate the metal part and affect the bonding force of the coating. Therefore, it is not appropriate to adopt a single cathode electrolysis for the workpiece.
Anode electric release oil
The characteristic of anode electro-degreasing oil is that it will precipitate oxygen on the workpiece, that is, 40H- = 02 + 10 + 2H20 + 4e. When degreasing, the bubbles of the precipitated oxygen are small and large. Compared with the cathode electro-degreasing oil, its emulsifying ability is worse. Therefore, its degreasing efficiency is relatively low; on the other hand, the pH value of the anode surface solution is reduced due to hydroxide ion discharge, which is not conducive to degreasing. At the same time, the oxygen released during the degreasing of the anode will promote the oxidation of the metal surface, and even some greases will oxidize, making it difficult to remove. In addition, some metals may also cause anodic dissolution, so non-ferrous metals and their alloys or polished parts should not be treated with anode electrolysis. However, the anode electrochemical degreasing will not produce "hydrogen embrittlement", and there will be no precipitation of sponge-like substances on the plated parts.
Based on the above, it is not difficult to find that both degreasing methods have their own disadvantages. It is not suitable to use a single electric degreasing, so the two degreasing processes are often used in production, that is, Cathode-anode combined oil removal, complementing each other's strengths, makes the electric degreasing method more perfect.
So how do we come to joint degreasing? Then listen to Hong Heshun Electrophoresis Factory for your analysis.
In the case of combined degreasing, it is best to use catholyte first to degrease the oil and then use anode anode to degrease for a short time. This not only takes advantage of the high efficiency of cathode degreasing, but also eliminates the phenomenon of "hydrogen embrittlement". Because the hydrogen that penetrates into the metal during cathodic degreasing can be almost completely removed in a short anode degreasing. At the same time, the surface of the part will not be oxidized or corroded.
For ferrous metal products, the cathode and anode are mostly used for degreasing. For high-strength steel, thin steel sheets and spring parts, in order to ensure their mechanical properties, absolutely avoid "hydrogen embrittlement", generally only anode degreasing is performed. For non-ferrous metal parts that are easily dissolved on the anode, such as copper and its alloy parts, zinc and its alloy parts, soldering parts, etc., alkaline solution cathode degreasing without sodium hydroxide can be used. If anode degreasing is still required to remove impurities on the surface of the part, the electrolysis time should be as short as possible to prevent the workpiece surface from being corroded.
Shenzhen Hongheshun electrophoretic paint manufacturer has established an electrophoretic R & D team with more than 10 years of experience in the development and production of electrophoretic coatings. It is a technical enterprise integrating electrophoretic research and development and production, which can solve your technical problems in electrophoretic coating, Painting becomes so simple. Welcome to inquire about electrophoresis coating technology: 0755-89264486.