PURPOSE: To industrially produce a grain-oriented silicon steel sheet having a very small iron loss by forming an oxide coating film by a sol-gel process on the surface of a grain-oriented silicon steel sheet after finish annealing.
CONSTITUTION: A silicon steel sheet is finish-annealed to grow secondary recrystallized grains and an oxide coating film is directly formed by a sol-gel process on a forsterite coating film formed on the surface of the steel sheet. The oxide coating film may be formed by the sol-gel process on the base iron exposed to the surface of the steel sheet and smoothened. A grain-oriented silicon steel sheet having a small iron loss can be produced at a low cost with high productivity. When a sol of alkoxide of a metal having a lower coefft. of thermal expansion than the steel, e.g., Si, Al, Zr or Ti or a sol of spodumene (Li2O-Al2O3-SiO2 mixture) having a negative coefft. of thermal expansion is used, the formed oxide coating film has a remarkable iron loss reducing effect.
SAIKI GORO
KANAI TAKAO
| JPS61235514A | 1986-10-20 |