| 摘要 |
PURPOSE:To provide a crucible satisfactorily resistant to reducing reaction of Nd, Pr, Sm, La, Ce, and the like by constructing the crucible for melting highly reactive alloys with ceramics in which zirconia excellent in heat resistance is compounded in silica having a smaller coefficient of thermal expansion as a base. CONSTITUTION:Silica SiO2 has a very small coefficient of thermal expansion and hence does not produce any crack thereon due to expansion and contraction even after heating and cooling are repeated. Additionally, zorconia ZrO2 has a low wetting property for molten metal and is resistant to erosion by an Nd alloy melt and the like. Provided ZrO2 is compounded in SiO2 as a base, a material is yielded in which there is reduced production of any crack due to cooling and heating and there is produced a lower wetting property for the Nd alloy melt, etc. Further, once the melt makes contact with SiO2-ZrO2 ceram ics, a ZrO2 rich thin film is formed on a ceramics surface. The contents of SiO2 of the SiO2-ZrO2 ceramics are 50-80% by weight. Moreover, ZrO2 contents compounded into zircon ZrO2.SiO8, etc., are 20-50% by weight, with SiO2 + ZrO2 97.5% by weight. |
