Research On The Insulation Coating Adhesiveness Of Non-oriented Silicon Steel

Nowadays, in order to reduce eddy current losses during alternating magnetization and improve magnetism through reducing iron loss, non-oriented silicon steel, which is used widely in electromechanical manufacture, will be coated with a layer of insulating coating. By now, the problem of poor performance of coating adhesion had not been resolved in many enterprises. This paper aimed at resolving the poor performance of coating adhesion.On the basis of a large amount of literature and patent research, the paper initially studied the forming mechanism of insulation coating in non-oriented silicon steel and established the stripping modelof coating. Based on this model, the technical factors of coating adhesion was analyzed and technical solutions at the view of substrate and liquid formulations was given. In addition, this paper presented a new quantitative test methods for coating adhesion.Coating's forming is a complex processing of physical and chemical changes. Solvent have evaporated before 140℃. L-41# is oxidized to HCOOH by L-63# through CH3OH. Cr3+, as the deoxidize production, takes part in the crosslink processing with L-18# and forms the coating at 280-300℃. Many experiments show that crosslink of the liquid system is a key factor on coating's adhesion.According to the experimental results, the coating and the substrate adhere to each other physically. When the coating peels off, the interface peel off between coating and substrate and interlaminar peel off in coating itself exist at one time. In view of interface stripping, through the thermodynamics calculation, the influence for surface oxidation in dry and wet atmosphere is analyzed; Through experiment of roughness gradient, it is found that coating adhesion would get a gratifying level with nice magnetism performance at the same technological condition when the roughness of substrate is about 0.8μm. In view of interlaminar stripping, formula and the technics factor influencing adhesion has been determined through the DOE experiment. Synchronization adjustmen of L-18# and the L-B# , as the core improvement, has been carried out. The coating produced by new formula system has smaller young's modulus and remarkable anti-dehiscence performance. This result is consistent with the stripping model mentioned in this article.