Solution for forming insulation coating and grain-oriented electrical steel sheet

A grain-oriented electrical steel sheet comprising an insulation coating formed by:

• applying a solution comprising an aqueous solution consisting essentially of a phosphate solution and colloidal silica to at least one surface of the steel sheet, and baking the steel sheet at a temperature of 750-1000° C. to form an insulation coating on the at least one surface of the steel sheet,
• wherein silica particles of the colloidal silica are surface-modified by aluminate or a solution of the colloidal silica includes aluminate,
• the aqueous solution is free of chromium,
• the phosphate solution consists essentially of one or more selected from aluminum phosphate, magnesium phosphate, and manganese phosphate, and
• the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn.

A grain-oriented electrical steel sheet comprising an insulation coating formed by:

• applying a solution comprising an aqueous solution consisting essentially of a phosphate solution and colloidal silica to at least one surface of the steel sheet, and baking the steel sheet at a temperature of 750-1000° C. to form an insulation coating on the at least one surface of the steel sheet,
• wherein silica particles of the colloidal silica are surface-modified by aluminate or a solution of the colloidal silica includes aluminate,
• the aqueous solution is free of chromium,
• the phosphate solution consists essentially of one or more selected from aluminum phosphate, magnesium phosphate, and manganese phosphate,
• an amount of the phosphate solution is 25-75 mass % and an amount of the colloidal silica is 75-25 mass % of a total solid mass when the amounts of the phosphate solution and the colloidal silica are calculated in anhydrous form, and
• the insulation coating consists of phosphorous, silicon, oxygen, and at least one selected from Al, Mg, and Mn.