| 摘要 |
PROBLEM TO BE SOLVED: To cast and form a slender hole by adding resin as bond to inorganic fiber which is a main component, and making it the core for casting. SOLUTION: The main component of the core must be inorganic fiber 10 to 200μm in diameter and 1 to 20mm in length. By adding 0.2 to 2 pts.wt. resin as bond to the inorganic fiber, and it is formed to make it the core. Mica is applied on the surface of the core. The shape of the core can be maintained by a bonding strength requiring when the inorganic fibers entwine one another, and the consumption of the bond is decreased. Gas generated by a thermal decomposition at the time of the casting is decreased. The generated gas is passed through a space among the fibers, and is easily discharged outside a casting mold. When the inorganic fiber is shorter than 10μm in diameter and is shorter than 1mm in length, its strength is lowered, a void among the fibers becomes small, and they make the gas generated at the time of the casting hard to discharge outside. When the inorganic fiber exceeds 200μm in diameter and 20mm in length, the void among the fibers becomes much, the core shrinks at the time of the casting, and a prescribed shape can not be maintained. When the quantity of the resin is little, the strength of the core is lowered, and when the quantity of the resin is much, much gas is generated at the time of the casting.
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