研究論文
ニッケル基単結晶合金鋳造用耐火物へのジルコニアの適用の検討
1988 年 60 巻 11 号 p. 672-676
詳細
1988 年 60 巻 11 号 p. 672-676
Zirconia was examined with the application of the molding refractory for the single crystal casting of Ni-base super alloy.
Ni-base single crystal alloy, Alloy 454, was melt and held in the crucible of CaO stabilized zirconia at 1,500°C-1,540°C for 1-2 hours under the reduced pressure 2X10-4 Torr. The results were summerized as follows.
1) The surface of the ingot melted at 1,500°C was relatively clean. In the case melted at 1,540°C, black colored film was formed on the almost part of the obtained ingot. The thickness of the film was about 3.2μm for 1 hour holding and 6.8μm for 2 hours.
2) Zr was detected from the film and it considered to form by the significant increase of oxygen vacancy in zirconia.
The contaminated surface layer which contained 0.05-0.2%Zr was estimated about 20-30μm.
3) The decrease in weight of 1-1.5g was recognized by the evaporation during at 1,540°C. Cr content in the evaporated metal was higher about 25% than the original alloy.
