Temperature Dependence of CaO Desulfurization Mechanism in Molten Ni-Base Superalloy

Yuki Kishimoto*, Takaaki Kono, Takahide Horie, Tadaharu Yokokawa, Makoto Osawa, Kyoko Kawagishi, Shinsuke Suzuki, Hiroshi Harada

*この研究の対応する著者

研究成果: Article査読

3 被引用数 (Scopus)

抄録

Desulfurization phenomenon of Ni-base superalloy using a solid CaO was identified by adjusting the temperature of melt. Ni-base superalloy and NiS powder were heated together at 1400 °C, 1500 °C, and 1600 °C. Dense and porous CaO rods were inserted into the melts individually. After the rods were pulled out, CaO, CaS, and calcium aluminates were detected on the rods by X-ray diffraction analysis. Electron probe microanalysis showed that only Ca, O, Al, and S distributed at the melt/CaO interfaces. At 1500 °C and 1600 °C, Al and S were also detected at particle boundaries in the rods. S contents in the alloys decreased as the desulfurization time passed and the temperature was raised. There was no prominent correlation between the rod porosity and the S contents. The desulfurization reaction was suggested to be that CaO, Al, and S react to generate CaS and calcium aluminates. When the temperature is high enough, the calcium aluminates form a solid–liquid coexisting state. Effective diffusion coefficient, which shows the S diffusivity in the generated layer at the melt/CaO interface, depends on the temperature and can be expressed by the Arrhenius equation. It has been supposed that the desulfurization reaction mainly occurs on CaO, and a macroscale surface area controls the desulfurization rate.

本文言語English
ページ(範囲)1450-1462
ページ数13
ジャーナルMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
52
3
DOI
出版ステータスPublished - 2021 6

ASJC Scopus subject areas

  • 凝縮系物理学
  • 材料力学
  • 金属および合金
  • 材料化学

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