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Formation and Microstructure of Carbon‐Containing Oxide Scales by Oxidation of Single Crystals of Zirconium Carbide
Author(s) -
Shimada Shiro,
Nishisako Masaru,
Inagaki Michio,
Yamamoto Kazuhide
Publication year - 1995
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.1151-2916.1995.tb08358.x
Subject(s) - materials science , microstructure , scanning electron microscope , oxide , analytical chemistry (journal) , isothermal process , single crystal , microanalysis , foil method , transmission electron microscopy , carbon fibers , zirconium , zirconium carbide , mineralogy , crystallography , metallurgy , composite material , chemistry , nanotechnology , physics , organic chemistry , chromatography , composite number , thermodynamics
The isothermal oxidation of ZrC single crystals with (100) orientation was carried out at temperatures of 500°, 550°, and 600°C at an oxygen pressure of 2.6 kPa for times up to 240 h. A polished cross section of the oxidized crystal was observed by backscattered electron imaging in a scanning electron microscope. Quantitative chemical analysis for Zr, O, and C and their elemental profiles by the linescan method in the ZrC and oxide scale were performed by wavelength dispersive X‐ray microanalysis. A thin foil of a crystal oxidized at 600°C was examined by transmission electron microscopy. It was found that the oxide scale was divided into two regions, zones 1 and 2, which contained 14 to 23 and 7 to 10 at. % carbon, respectively. Zone 1 exhibited an almost compact, pore‐free matrix of c ‐ZrO 2 . In zone 2, some growth and aggregation of the c ‐ZrO 2 occurred, producing 5‐ to 20‐nm‐sized particles between which carbon should have been present. The thickness of zone 1 increased parabolically up to 240 h at 500°C and probably in an early period at 550° and 600°C, reaching a constant (about 2 (μm), in contrast to the thickness of zone 2, which increased linearly with time.