A method of providing an anti-stick coating on non-oriented, semi-processed electrical steels to be subjected to a quality anneal.

摘要

A process of providing an inorganic anti-stick coating directly on non-oriented, semi-processed electrical steels by applying to such steels a coating solution containing Al<Sup>+++</Sup>, Mg<Sup>++</Sup> and H<Sub>2</Sub>PO<Sub>4</Sub>- in a specified relative relationship, the concentration of Al<Sup>+++</Sup>, Mg<Sup>++</Sup> and H<Sub>2</Sub>PO<Sub>4</Sub>- comprising 100 parts by weight calculated as Al<Sub>2</Sub>O<Sub>3</Sub>, MgO and H<Sub>3</Sub>P0<Sub>4</Sub>, respectively, on a water-free basis. The coating solution may additionally contain from 0 to 150 parts by weight of colloidal silica on a water-free basis. Chromic anhydride (CrO<Sub>3</Sub>) may be added to the coating solution to improve its wettability and improve the moisture resistance of the anti-stick coating. The coating solution is so diluted with water as to provide a uniform coating as thin as possible to prevent lamination sticking and having a coating weight of less than 2 gramns per square meter on each side. The coated electrical steel is subjected to a heat treatment to cure the anti-stick coating thereon.