Hydrothermal oxidation of niobium metal

Masahiro Yoshimura; Seung Eul Yoo; Shigeyuki Somiya

Hydrothermal oxidation of niobium metal

Masahiro Yoshimura, Seung Eul Yoo, Shigeyuki Somiya

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

Reactions of niobium metal powder with high-temperature high-pressure water were studied in an open system under conditions of 300° - 800°C, 10 - 100MPa and 3-72h. Niobium pentaoxide (Nb₂O₅), niobium hydride (NbH_x), and NbO₂ were formed as products. Niobium changed into orthorhombic Nb₂O₅ and niobium hydride at 400°C under 100MPa for 3h. Only orthorhombic, or/and monoclinic Nb₂O₅ were obtained above 700°C under 100MPa for 3h. The formation of oxides and hydrides caused cracking on the surface above 400°C (100MPa, 3h) resulting in disintegration of grains above 500°C (100MPa, 3h). Partial crystal growth of Nb₂O₅ was observed above 700°C (100MPa, 3h). Temperature and reaction duration affected the hydrothermal oxidation of Nb metal, but pressure did not.

Original language	English
Pages (from-to)	29-35
Number of pages	7
Journal	Journal of the Ceramic Society of Japan. International ed.
Volume	96
Issue number	1
Publication status	Published - 1988 Jan 1

All Science Journal Classification (ASJC) codes

Engineering(all)

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title = "Hydrothermal oxidation of niobium metal",

abstract = "Reactions of niobium metal powder with high-temperature high-pressure water were studied in an open system under conditions of 300° - 800°C, 10 - 100MPa and 3-72h. Niobium pentaoxide (Nb2O5), niobium hydride (NbHx), and NbO2 were formed as products. Niobium changed into orthorhombic Nb2O5 and niobium hydride at 400°C under 100MPa for 3h. Only orthorhombic, or/and monoclinic Nb2O5 were obtained above 700°C under 100MPa for 3h. The formation of oxides and hydrides caused cracking on the surface above 400°C (100MPa, 3h) resulting in disintegration of grains above 500°C (100MPa, 3h). Partial crystal growth of Nb2O5 was observed above 700°C (100MPa, 3h). Temperature and reaction duration affected the hydrothermal oxidation of Nb metal, but pressure did not.",

author = "Masahiro Yoshimura and Yoo, {Seung Eul} and Shigeyuki Somiya",

year = "1988",

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T1 - Hydrothermal oxidation of niobium metal

AU - Yoshimura, Masahiro

AU - Yoo, Seung Eul

AU - Somiya, Shigeyuki

PY - 1988/1/1

Y1 - 1988/1/1

N2 - Reactions of niobium metal powder with high-temperature high-pressure water were studied in an open system under conditions of 300° - 800°C, 10 - 100MPa and 3-72h. Niobium pentaoxide (Nb2O5), niobium hydride (NbHx), and NbO2 were formed as products. Niobium changed into orthorhombic Nb2O5 and niobium hydride at 400°C under 100MPa for 3h. Only orthorhombic, or/and monoclinic Nb2O5 were obtained above 700°C under 100MPa for 3h. The formation of oxides and hydrides caused cracking on the surface above 400°C (100MPa, 3h) resulting in disintegration of grains above 500°C (100MPa, 3h). Partial crystal growth of Nb2O5 was observed above 700°C (100MPa, 3h). Temperature and reaction duration affected the hydrothermal oxidation of Nb metal, but pressure did not.

AB - Reactions of niobium metal powder with high-temperature high-pressure water were studied in an open system under conditions of 300° - 800°C, 10 - 100MPa and 3-72h. Niobium pentaoxide (Nb2O5), niobium hydride (NbHx), and NbO2 were formed as products. Niobium changed into orthorhombic Nb2O5 and niobium hydride at 400°C under 100MPa for 3h. Only orthorhombic, or/and monoclinic Nb2O5 were obtained above 700°C under 100MPa for 3h. The formation of oxides and hydrides caused cracking on the surface above 400°C (100MPa, 3h) resulting in disintegration of grains above 500°C (100MPa, 3h). Partial crystal growth of Nb2O5 was observed above 700°C (100MPa, 3h). Temperature and reaction duration affected the hydrothermal oxidation of Nb metal, but pressure did not.

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