Non-chromium coating agent for a grain-oriented electrical steel sheet, preparation method thereof, electrical steel sheet using the same, and manufacturing method thereof

Abstract

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.

Description

technical field [0001] The present invention relates to a coating agent which does not contain chromium (Cr) and which exhibits corrosion resistance, excellent adhesion to materials, and interface characteristics when an insulating thin film is formed using the coating agent and improved tension, relating to a method for preparing the coating agent, a oriented electrical steel sheet using the coating agent, and a method for preparing the electrical steel sheet. Background technique [0002] The coating agent of the present invention is a chromium (Cr)-free coating agent and can be used for coating grain-oriented electrical steel sheets and the like. [0003] Grain-oriented electrical steel sheets contain 3.1% of silicon (Si) and have excellent magnetic properties in the rolling direction, and thus are used as core materials for transformers, motors, generators, and other electromagnetic devices, for example. [0004] Basically, a good insulating coating must have a uniform ...

AI Technical Summary

Problems solved by technology

However, the former method has problems in that the process of improving colloidal silica by its reaction with Fe, Al, etc. is extremely complicated, disadvantageous in terms of manufacturing cost, and not very effective, so it is difficult to apply this method to In the industrial field

The problem with the latter method is that, although it can be used more simply than the former method, it cannot sufficiently meet the level of high-grade grain-oriented electrical steel sheets that require higher corrosion resistance and film tension, simply because Introduced oxide prevents the appearance of free phosphoric acid when drying the coating agent to additionally improve the compactness and tension of the film

[0009] Therefore, no commercially available technology for oriented chromium-free coating agents satisfying all the desired physical properties has yet been proposed.

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