| 摘要 |
PURPOSE:To provide an ultralow iron loss by annealing in nonacidic atmosphere after coating a special surface layer on the mirror-finished surface of a finish- annealed unidirectional silicon steel plate which contains C, N. CONSTITUTION:After the surface of a directional silicon steel plate is mirror- polished in average roughness of center line of 0.4mum or less and a surface layer of one type selected from elements of group IVa - group VIIIa except Ti, group VIII except Fe, group IIIB and group IVb except C is coated, for example, by depositing preferably 0.1-2.0mum thick, and carbonized an nitrided to form a mixed thin film made of a carbide and nitride on the surface of the steel plate. Here, 0.001-0.01wt% (merely designated by %) of C and 0.0005-0.01% of N are contained in the unidirectional silicon steel plate after finish-annealing, a surface layer is coated on the mirror-finished surface of the steel plate, then annealed in nonacidic atmosphere to accelerate to anneal C and N in the steel plate. |
