APPLICATION OF PARTING AGENT FOR HIGH-TEMPERATURE ANNEALING DIRECTIONAL ELECTROMAGNETIC STEEL SHEET

摘要

PURPOSE:To inhibit the sintering of a directional electromagnetic steel sheet during its high-temperature annealing, by electrostatically applying the powdery body of anhydrous magnesia clinker having a specified particle size to the surface of the steel sheet. CONSTITUTION:A directional electromagnetic steel sheet is annealed at a high temperature above 1,000 deg.C to grow the azimuth of (110)[001]by secondary recrystallization. In this case, the powdery body of anhydrous magnesia clinker having the distribution of particle sizes adjusted in a manner such that it contains at least 80% or more a powdery body having a particle size of 5-149mum is electrostatically applied at a ratio of 3-20g/m2 to form the layer of a parting agent for annealing. The granular body of said magnesia clinker may be electrostatically applied, after aqueous suspension containing a treating agent based on calcined magnesia is applied to the surface of the steel sheet at a ratio of 0.5-3g/m2 to form a coating film. Consequently, the directional magnetic steel sheet having an excellent magnetic property is obtained without being seizured during the high-temperature annealing.