TY - JOUR
T1 - The Effect of CaO-MgO Mixture on Desulfurization of Molten Ni-Base Superalloy
AU - Horie, Takahide
AU - Kono, Takaaki
AU - Kishimoto, Yuki
AU - Kawagishi, Kyoko
AU - Suzuki, Shinsuke
AU - Harada, Hiroshi
N1 - Funding Information:
The authors are grateful to Dr. T. Yokokawa and Dr. M. Osawa, Superalloys and High Temperature Materials Group at NIMS, for their useful advice on this study. This study was financially supported by Japan Science and Technology (JST), and conducted as part of 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 Dr. T. Yokokawa and Dr. M. Osawa, Superalloys and High Temperature Materials Group at NIMS, for their useful advice on this study. This study was financially supported by Japan Science and Technology (JST), and conducted as part of 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:
© 2021, The Minerals, Metals & Materials Society and ASM International.
PY - 2021/8
Y1 - 2021/8
N2 - Desulfurization ability and hydration resistance of CaO-MgO mixture were studied by comparing CaO-MgO, CaO and MgO rods. In desulfurization experiment, Ni-base superalloy and NiS powder were melted together, and each rod was held in the melt for a prescribed time under 1600 °C. S content in the alloy was lower in CaO-MgO desulfurization than that in CaO desulfurization in every holding time up to 300 seconds. Almost no desulfurization effect was confirmed in MgO. From EPMA and XRD analyses, it is considered that CaO-Al2O3-MgO ternary compound and CaS were generated and coexisted in the CaO-MgO rod during the desulfurization process. In the CaO-MgO desulfurization, the compound contained MgO as its component, and that decreased the liquidus temperature of the compound. Therefore, it is considered that the fraction of liquid increased, and the effective diffusion coefficient of S in the compound was larger than in the CaO desulfurization. In hydration experiment, each rod was maintained in an enclosed vessel with weighing paper and a cup with water for a certain period. The mass increasing ratio of the CaO-MgO was almost equal to that of the CaO. From the above, it is clear that CaO-MgO is a better desulfurization agent than CaO.
AB - Desulfurization ability and hydration resistance of CaO-MgO mixture were studied by comparing CaO-MgO, CaO and MgO rods. In desulfurization experiment, Ni-base superalloy and NiS powder were melted together, and each rod was held in the melt for a prescribed time under 1600 °C. S content in the alloy was lower in CaO-MgO desulfurization than that in CaO desulfurization in every holding time up to 300 seconds. Almost no desulfurization effect was confirmed in MgO. From EPMA and XRD analyses, it is considered that CaO-Al2O3-MgO ternary compound and CaS were generated and coexisted in the CaO-MgO rod during the desulfurization process. In the CaO-MgO desulfurization, the compound contained MgO as its component, and that decreased the liquidus temperature of the compound. Therefore, it is considered that the fraction of liquid increased, and the effective diffusion coefficient of S in the compound was larger than in the CaO desulfurization. In hydration experiment, each rod was maintained in an enclosed vessel with weighing paper and a cup with water for a certain period. The mass increasing ratio of the CaO-MgO was almost equal to that of the CaO. From the above, it is clear that CaO-MgO is a better desulfurization agent than CaO.
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U2 - 10.1007/s11663-021-02208-4
DO - 10.1007/s11663-021-02208-4
M3 - Article
AN - SCOPUS:85107415568
SN - 1073-5615
VL - 52
SP - 2687
EP - 2702
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 - 4
ER -