| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass material for fusion which contains no harmful material such as lead, exhibits excellent adhesion of an alumina substrate to silicon carbide and fixing performance of granular silicon carbide, is free from the occurrence of physical defects such as crack on a glass layer, has excellent heat resistance and acid resistanc and comprises a relatively inexpensive composition used in a common glass raw material and a tool for dressing obtained by using the glass material. SOLUTION: The glass material for fusion has an SiO<SB>2</SB>-Na<SB>2</SB>O-Al<SB>2</SB>O<SB>3</SB>-ZnO-B<SB>2</SB>O<SB>3</SB>-based composition and has 75×10<SP>-7</SP>/°C or less thermal expansion coefficient at a temperature ranging from room temperature to the glass transition point. The composition is preferably controlled to contain 60-72% SiO<SB>2</SB>, 7-11% Na<SB>2</SB>O, 0.5-6% Al<SB>2</SB>O<SB>3</SB>, 2-20% ZnO and 2-20% B<SB>2</SB>O<SB>3</SB>by mol. Wherein, the fixing performance of the granular silicon carbide is made inferior when the total content of alkaline earth metal oxide such as CaO is increased more than the impurity degree (<0.5 mol%). COPYRIGHT: (C)2005,JPO&NCIPI
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