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Oxidation of HIPed TiC Ceramics in Dry O 2 , Wet O 2 , and H 2 O Atmospheres
Author(s) -
Shimada S.,
Onuma T.,
Kiyono H.,
Desmaison M.
Publication year - 2006
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.1551-2916.2005.00876.x
Subject(s) - isothermal process , analytical chemistry (journal) , ceramic , materials science , lamellar structure , hot isostatic pressing , weight change , mineralogy , chemistry , sintering , metallurgy , medicine , obesity , physics , chromatography , weight loss , thermodynamics
Isothermal oxidation of dense TiC ceramics, fabricated by hot‐isostatic pressing at 1630°C and 195 MPa, was performed in Ar/O 2 (dry oxidation), Ar/O 2 /H 2 O (wet oxidation), and Ar/H 2 O (H 2 O oxidation) at 900°–1200°C. The weight change measurements of the TiC specimen showed that the dry, wet, and H 2 O oxidation at 850°–1000°C is represented by a one‐dimensional parabolic rate equation, while the oxidation in the three atmospheres at 1100° and 1200°C proceeds linearly. Cross‐sectional observation showed that the dry oxidation produces a lamellar TiO 2 scale consisting of many thin layers, about 5 μm thick, containing many pores and large cracks, while H 2 O‐containing oxidation decreases pores in number and diminishes cracks in scales. Gas evolution of CO 2 and H 2 with weight change measurement was simultaneously followed by heating the TiC to 1400°C in the three atmospheres. Cracking in the TiO 2 scale accompanied CO 2 evolution, and the H 2 O‐containing oxidation produced a small amount of H 2 . A piece of single crystal TiC was oxidized in 16 O 2 /H 2 18 O to reveal the contribution of O from H 2 O to the oxidation of TiC by secondary ion mass spectrometry.