| 摘要 |
PROBLEM TO BE SOLVED: To improve melt loss resistance and thermal shock resistance of a member to be directly brought into contact with a molten metal in casting facilities by forming a coating film consisting essentially of MgO.Al2O3 on the surface of a complex sintered compact composed of boron nitride of hexagonal crystal and MgO.Al2O3 spinel in a specific ratio. SOLUTION: A member for treating a molten metal comprises a complex sintered compact composed of 10-90 wt.% of boron nitride of hexagonal crystal and 90-10 wt.% of MgC.Al2O3 spinel. The sintered compact is obtained by mixing boron nitride powder of hexagonal crystal having preferably about 1-4 wt.% of oxygen content, with spinel powder or MgO powder and Al2O3 powder in the ratio of 2:3 to 1:9 by a ball mill, etc., by a ball mill, etc., baking the mixture by normal-pressure sintering in an inert atmosphere or hot, pressing at about 1,500-2,000 deg.C. A coating film consisting essentially of MgO.Al2O3 spinel may be formed on the surface of a complex sintered compact of the boron nitride of hexagonal crystal and MgO.Al2O3 spinel. The member for treating molten metal is especially useful for a protecting tube for measuring temperature, nozzle and tundish of casting facilities, weir, etc. |
