| Electrical steel coating is a kind of covering coating used on the surface of electrical steel sheet. The application of electrical steel sheet was determined by the performances of the coating, which influences the quality and service life of the motors. The problem of the traditional electrical steel coating as pollution and toxicity could be solved by the water-soluble coating with water was used as main solvent, but the wettabilities of the coating against the electrical steel sheets and nano particles were reduced. The water-soluble polyester was prepared in the study, and the water-soluble coating was prepared based on it. The ultrasound was used to modified the polyester coating and Ti O2/polyester composite coating, in order to reduce the contact angle between the coating and the steel sheets. Si O2 particles were grafted by glycine, in order to increase the wettability between the nano fillers and the coating. The coatings with rather good wettability to the electrical steel and Si O2 nano particles were prepared during the study, and the mechanisms of wettability and performance enhancement were studied.The water-soluble polyester was synthetized first. The species and mole amounts of the raw materials were analyzed by the performances changes of the electrical steel coating. The performances of the coating and the water solubility were also affected by the reaction time after TMA added and the amount of DMPA. The best processes and formula were determined in the study, and the structure of the polyester was characterized by 13C-NMR and FT-IR, which indicated the polyester with high branching degree having a backbone formed by ester and benzene ring, and hydroxyl as side group.The water-soluble electrical steel coating was composed by the watersoluble polyester and amino resin. The amino resin amount was discussed by the influences on the mechanical, electrical performances, and the best amount of the amino resin is 20 wt% of the polyester. The polyester molecular chain were broken down and recombined by the high energy of ultrasound, and the MW of the polyester was divided into two grade by the GPC test. The contact angle of the coating irradiated by ultrasound for 5 hours against the electrical steel sheet was 13.6o, compared to the unirradiated coating fell 48.7%, as other performances were not changed. The RMS of the film was fallen from 6.51 nm to 3.77 nm, as the low MW polyester produced by ultrasonic irradiation could improve the RMS, which fell 42.1%.The Ti O2 amount of the composite electrical steel coating prepared by Ti O2 and polyester was 40 wt.% of the polyester weight, according to the coating performances tests and SEM. The contact angle of the composite coating irradiated by ultrasound for 5 hours against the sheet was 7.9o, fallen 79.03% compared to the coating without irradiated, and the performances of the coating was better too. The curing speed of the coating was increased by the photocatalystic function of Ti O2 according to the DEA test. The Ti O2 particles were coated by polyester molecular employ ultrasound, and form an adsorption layer, according to the TEM test.The composite coating with glycine modified Si O2 as the fillers was also prepared in this study. The method of SiO2 modified by glycine was discussed, the modified results were characterized by FT-IR, XRD, XPS and TEM. The results of the comparison among the coating filled with Si O2 modified by different methods indicated that glycine grafted could improve the wettability between the polyester solvent and the Si O2 particles. The performances of the Si O2/polyester coating were enhanced by the glycine modified, and the mechanism of the enhancement was the reunite of the particles was reduced and the wettability against polyester was enhanced. The thermal ability of the electrical steel coating was also enhanced by the Si O2 particles grafted by glycine. |
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