A kind of chromium-free insulating coating for grain-oriented silicon steel and preparation method thereof

Abstract

The invention relates to a chrome-free insulating coating for oriented silicon steel and a preparation method thereof. The technical scheme is: 15-35% of organic mixed resin, 10-30% of silica sol, 0.2-2.5% of aluminum dihydrogen phosphate, 0.1-4.0% of inorganic buffer, and 0.5-7.0% of silane coupling agent , the auxiliary agent is 0.1-1.0wt%, the alkylphenol polyoxyethylene ether is 0.1-0.5wt%, and the balance is water. According to the above chemical components and their contents, under stirring conditions, first add silane coupling agent and auxiliary agent to the organic mixed resin in order to obtain an organic emulsion; in addition, add aluminum dihydrogen phosphate, silica sol and alkylphenol in turn to the water Polyoxyethylene ether, stirred until the aluminum dihydrogen phosphate is completely dissolved to obtain an inorganic emulsion; then the organic emulsion and the inorganic emulsion are mixed and stirred to obtain a chromium-free insulating coating for oriented silicon steel. The chromium-free insulating coating for oriented silicon steel prepared by the invention has good stability, and has the characteristics of excellent adhesion, corrosion resistance and insulation.

Description

technical field [0001] The invention relates to an insulating coating for oriented silicon steel. In particular, it relates to a chrome-free insulating coating for oriented silicon steel and a preparation method thereof. Background technique [0002] Oriented silicon steel is the iron core material used in the manufacture of various transformers, transformers and other electromagnetic directional conversion products in the industry; The level of resistance directly affects the level of iron core loss during use. Although a layer of magnesium silicate bottom layer is formed on the surface of oriented silicon steel after high-temperature annealing, which has certain insulation properties, but the resistance of this layer of magnesium silicate bottom layer is too small to meet the use of large and medium-sized transformers; therefore, in order to ensure For insulation between laminates, the surface of oriented silicon steel needs to be coated with an insulating coating with e...

AI Technical Summary

Problems solved by technology

[0004] But the hexavalent chromium in the chromic anhydride and chromate used in the above-mentioned coatings will cause serious harm to the human body and the environment, and it is difficult to avoid the secondary pollution of chromium when recycling waste silicon steel products, and the use of chromate is getting more and more popular. With more and more restrictions, many countries have formulated relevant laws and regulations to strictly limit the use and discharge of chromate, and it has become an inevitable trend to ban the use of chromate on metal surfaces

[0005] Patent document KR20010082119 discloses a chromium-free oriented electrical steel and insulating coating, the insulating coating includes: magnesium phosphate; zinc phosphate; 0.5~12% boric acid or one of borates containing Na, Al, Ca, Li, Mg The coating results show that the coating has poor corrosion resistance

In Japanese Patent No. 2005068493, Kawasaki Steel proposes to replace chromic anhydride with inorganic salt and oxide solid particles respectively. The coating results show that although the coating has good corrosion resistance, its adhesion is average

Images