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Preparation of Fine Monoclinic Hafnia Powders by Hydrothermal Oxidation
Author(s) -
Toraya Hideo,
Yoshimura Masahiro,
Somiya Shigeyuki
Publication year - 1982
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1982.tb10438.x
Subject(s) - monoclinic crystal system , hafnia , hydrothermal circulation , hydride , metal , materials science , phase (matter) , hydrothermal reaction , chemical engineering , closed system (control theory) , inorganic chemistry , mineralogy , chemistry , metallurgy , cubic zirconia , crystal structure , crystallography , organic chemistry , ceramic , engineering , physics , thermodynamics
Fine single‐phase monoclinic HfO 2 powders were prepared from Hf metal chips and high‐temperature high‐pressure water by hydrothermal oxidation in closed and open systems. In the closed system, Hf metal was converted to HfO 2 by treatment at ≥600°C under 100 MPa for 3 h. At 500°C half the Hf reacted to produce Hf hydride and a small amount of HfO 2 . In the open system, Hf metal scarcely reacted at 500°C, but at 600°C the reaction was more rapid than the corresponding run in the closed system.