In the production process of silicon steel sheets, a core component of electrical equipment, insulation treatment is a crucial step that determines their performance. Proper insulation treatment can effectively reduce eddy current losses, enhancing the efficiency and stability of electrical equipment. Currently, there are several common insulation treatment methods for silicon steel sheets, as described below.
Coating insulation paint is the most widely used traditional method. Organic resin – based insulation paints, such as polyester resin and epoxy resin, are commonly preferred due to their excellent film – forming properties, insulation performance, and adhesion. During production, roll coating, spray coating, and dip coating each have their own advantages. Roll coating is suitable for large – scale continuous production, ensuring a stable and uniform coating thickness; spray coating allows for flexible control of the coating coverage, making it adaptable to silicon steel sheets with complex shapes; dip coating enables small – sized silicon steel sheets to be evenly coated with insulation paint. After coating, the sheets are dried and cured, forming a dense insulation film on the surface of the silicon steel sheets. For example, polyester resin insulation paint, when dried at 150 – 180°C for several hours, can effectively isolate the electrical connection between silicon steel sheets.
The chemical coating method generates an insulation layer through chemical reactions. In phosphating treatment, silicon steel sheets are immersed in a phosphate solution, forming a iron phosphate film on the surface, which not only provides insulation but also enhances the adhesion of subsequent coatings. Chromate treatment, which was once widely used, can produce high – quality insulation layers but has been gradually phased out due to the heavy metals it contains. Nowadays, chromium – free passivation technology has emerged. It uses metal salt solutions such as titanium and zirconium to form environmentally friendly insulation coatings, balancing performance and environmental protection.
Physical Vapor Deposition (PVD) is carried out in a high – vacuum environment and includes methods such as evaporation deposition and sputter deposition. Take sputter deposition as an example: high – energy particles bombard the target materials of insulation materials, such as silicon dioxide and silicon nitride, causing atoms or molecules to escape and deposit on the surface of silicon steel sheets, forming a uniform and dense insulation film. The insulation layer prepared by this method has high purity, strong bonding force with silicon steel sheets, and does not affect magnetic properties. However, due to its high equipment cost and low production efficiency, it is mainly used for high – end products.
Electrophoretic coating is based on the principle of electrochemistry. Silicon steel sheets are placed as electrodes in an electrophoretic bath containing insulating resin particles. Under the action of an electric field, the resin particles are deposited directionally. By adjusting parameters such as voltage, temperature, and time, the quality of the coating can be precisely controlled. The formed insulation layer has good uniformity, strong adhesion, and the production process is environmentally friendly with high paint utilization. It is increasingly used in the field of silicon steel sheets for automotive motors. Each insulation treatment method has its own unique advantages. Manufacturers need to comprehensively consider the application scenarios, performance requirements, and cost budgets of silicon steel sheets to select the most suitable method, enabling silicon steel sheets to fully demonstrate their performance advantages in electrical equipment and providing a reliable guarantee for the stable operation of the power system.
The above article systematically introduces the insulation treatment methods for silicon steel sheets. If you would like to learn about the latest research progress of these methods or the cost comparison among different methods, feel free to let me know.
