| 摘要 |
PROBLEM TO BE SOLVED: To provide molding sand having high heat resistance, excellent low expansibility and excellent friability and applicable even to the casting of a large-sized cast steel article having high pouring temperature, further, having excellent reusability to the sand and inexpensively produced in a high yield. SOLUTION: An Al<SB>2</SB>O<SB>3</SB>-SiO<SB>2</SB>based refractory raw material such as fired bauxite is melted. The melt is sprayed with gas such as high pressure air, and is cooled and solidified while being scattered in the shape of fine particles. Thus, a melted sphere having the chemical components of≥70 wt.% Al<SB>2</SB>O<SB>3</SB>and≤20 wt.% SiO<SB>2</SB>, comprising an alumina crystal phase as the main constituent in crystal constitution and having a particle size distribution of 30 to 3,000μm is formed. COPYRIGHT: (C)2005,JPO&NCIPI
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