NON-CHROMIUM COATING AGENT FOR A GRAIN-ORIENTED ELECTRICAL STEEL SHEET, PREPARATION METHOD THEREOF, ELECTRICAL STEEL SHEET USING THE SAME, AND MANUFACTURING METHOD THEREOF

摘要

The present invention relates to a coating agent, to a preparation method thereof, and to the use thereof, and more particularly, aims to manufacture a grain-oriented electrical steel sheet having great tensile stress caused by an insulation film. To achieve the aim, the coating agent of the present invention consists of phosphate, colloid silica, and hematite sol, and cobalt hydroxide or boric acid is added to the coating agent. The method for preparing a coating agent of the present invention includes a step of preparing a silica-hematite mixture solution (1) by injecting hematite sol into colloid silica and stirring the mixture, as well as a step of preparing a mixture solution (2) by gradually injecting phosphate into the silica-hematite mixture solution (1) prepared in the previous step. Further, the present invention provides a grain-oriented electrical steel sheet wherein the steel sheet having a surface coated with the coating agent has a coating tension of 0.30~1.02 kg/mm2, and provides a method for manufacturing a grain-oriented electrical steel sheet, including the steps of applying the coating agent to a grain-oriented electrical steel sheet such that the amount of coating agent applied on the dried coated film of the steel sheet is 0.5~6.0 g/m2, and performing heat treatment in two stages. The coating agent of the present invention is capable of forming a dense coated film when used in an electrical steel sheet or the like, and improving the adhesion property, film tension allowance, and abrasion resistance thereof as compared to conventional films.