TY - JOUR
T1 - Desulfurization Model Using Solid CaO in Molten Ni-Base Superalloys Containing Al
AU - Kishimoto, Yuki
AU - Utada, Satoshi
AU - Iguchi, Taketo
AU - Mori, Yuhi
AU - Osawa, Makoto
AU - Yokokawa, Tadaharu
AU - Kobayashi, Toshiharu
AU - Kawagishi, Kyoko
AU - Suzuki, Shinsuke
AU - Harada, Hiroshi
N1 - Funding Information:
The authors are grateful to Mr. D. Kaneko (Meijun Gijutsu Shien) for the designing and development of the induction melting furnace specified for this experiment. I.mecs Co., Ltd is thanked for their precise work on the condition adjustment of the induction heating and for their continuous support. We thank TOUHOKU SOKKI CORP for organizing the development of the experimental apparatus. We also thank Drs. S. Kawada, and A. Iwanade, Materials Analysis Station, NIMS, for chemical analysis. Dr. T. Degawa is thanked for his achievement on the field of desulfurization process and for providing his book that helped the first study of the present research. This research was financially supported by Japan Science and Technology Agency (JST), under the Advanced Low Carbon Technology Research and Development Program (ALCA) project: “Development of Direct and Complete Recycling Method for Superalloy Turbine Aerofoils. (JPMJAL1302)”.
Funding Information:
The authors are grateful to Mr. D. Kaneko (Meijun Gijutsu Shien) for the designing and development of the induction melting furnace specified for this experiment. I.mecs Co., Ltd is thanked for their precise work on the condition adjustment of the induction heating and for their continuous support. We thank TOUHOKU SOKKI CORP for organizing the development of the experimental apparatus. We also thank Drs. S. Kawada, and A. Iwanade, Materials Analysis Station, NIMS, for chemical analysis. Dr. T. Degawa is thanked for his achievement on the field of desulfurization process and for providing his book that helped the first study of the present research. This research was financially supported by Japan Science and Technology Agency (JST), under the Advanced Low Carbon Technology Research and Development Program (ALCA) project: “Development of Direct and Complete Recycling Method for Superalloy Turbine Aerofoils. (JPMJAL1302)”.
Publisher Copyright:
© 2019, The Minerals, Metals & Materials Society and ASM International.
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Details of the desulfurization for molten Ni-base superalloys containing Al using solid CaO have been investigated, and the formula that explains the reaction rate has been developed. A cylindrical CaO rod was inserted into 500 g molten Ni-base superalloy TMS-1700 (MGA1700) containing 200 ppm S and held for a certain period at 1600 °C in each experiment. Sulfur content in the melt decreased with the increasing holding time of the CaO rod. Results of electron probe microanalysis show that Ca, O, S, and Al distribute in the same part of the melt/CaO interface as well as the particle boundaries of the CaO rods. The distribution of these elements suggests that CaO reacted with S in the melt to generate CaS, and Al reacted with O and CaO to form calcium aluminate slag. The desulfurization rate formula was obtained by the assumption that the rate-controlling process of the desulfurization is S diffusion through the generated layer composed of CaS and calcium aluminate slag. This formula expresses the amount of S in the melt by the diffusion term with the effective diffusion coefficient, which was obtained from the experimental results. Moreover, the time required for the desulfurization of 2 kg molten Ni-base superalloy PWA1484 using a CaO crucible, was calculated by this desulfurization rate formula which resulted in fair agreement with the actual result.
AB - Details of the desulfurization for molten Ni-base superalloys containing Al using solid CaO have been investigated, and the formula that explains the reaction rate has been developed. A cylindrical CaO rod was inserted into 500 g molten Ni-base superalloy TMS-1700 (MGA1700) containing 200 ppm S and held for a certain period at 1600 °C in each experiment. Sulfur content in the melt decreased with the increasing holding time of the CaO rod. Results of electron probe microanalysis show that Ca, O, S, and Al distribute in the same part of the melt/CaO interface as well as the particle boundaries of the CaO rods. The distribution of these elements suggests that CaO reacted with S in the melt to generate CaS, and Al reacted with O and CaO to form calcium aluminate slag. The desulfurization rate formula was obtained by the assumption that the rate-controlling process of the desulfurization is S diffusion through the generated layer composed of CaS and calcium aluminate slag. This formula expresses the amount of S in the melt by the diffusion term with the effective diffusion coefficient, which was obtained from the experimental results. Moreover, the time required for the desulfurization of 2 kg molten Ni-base superalloy PWA1484 using a CaO crucible, was calculated by this desulfurization rate formula which resulted in fair agreement with the actual result.
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U2 - 10.1007/s11663-019-01716-8
DO - 10.1007/s11663-019-01716-8
M3 - Article
AN - SCOPUS:85074500548
SN - 1073-5615
VL - 51
SP - 293
EP - 305
JO - Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
JF - Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
IS - 1
ER -