The magnesia for the annealing separable medicine of the directivity electromagnetic steel and production manner null of the directivity electromagnetic steel sheet which is superior in magnetic property and coat

摘要

PROBLEM TO BE SOLVED: To provide a technique capable of stably improving magnetic characteristics and film characteristics by improving magnesia which is an essential component of an annealing and separating agent. ;SOLUTION: The magnesia, which is 35 to 120 seconds in citric acid activity and 0.30 to 4.50 μm in average grain size, contains 0.20 to 0.90 mass % CaO, 0.02 to 0.75 mass % SiO3 and 300 to 2000 mass ppm B, further has a surface Cl content of 0.005 to 0.045 mass % and a total Cl content of 0.008 to 0.060 mass % and is 0.50 to 0.95 in the ratio s-Cl/t-Cl of the surface Cl content (s-Cl) and the total Cl content (t-Cl), is used as the essential component of the annealing and separating agent.;COPYRIGHT: (C)2001,JPO