OXIDATION OF ZIRCONIUM IN AIR
The oxidation reaction of zirconium in air was studied in the temperature range 650 to 850 un. Concent 85% C. The reaction was followed up by measurements of weight change, chemical analyses of nitrogen absorbed in the oxidized specimens, and electron microscopic observations of the surface and cross section of specimens. Above 750 un. Concent 85% C, a significant breakaway phenomenon in the oxidation rate was observed, and the rate changed from an initial cubic or parabolic law to a linear one. Analyses of nitrogen indicated that the absorbed nitrogen, concentrated in the metal phase near the metal/oxide interface, could not be stable in the post-break away stage. The results of electron microscopic observations indicated that the cracking in the inner oxide layer did have a correlation with the change in kinetics, but the cracking at the surfuce had no correlation to it. Electron micrographs of cross sections also showed that the metal phase near the oxide layer had a greatly different appearance in structure in the post-breakaway stage from that in the initial stage. The mechanism of heavy break-away phenomenon in oxidation zirconium in air was discussed on the basis of the observations in electron micrographs with emphasis on the function of nitrogen. (auth)
- Research Organization:
- Mitsubishi Atomic Power Industries, Inc., Saitama, Japan
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-023370
- OSTI ID:
- 4724707
- Journal Information:
- Trans. Japan Inst. Metals, Journal Name: Trans. Japan Inst. Metals Vol. Vol: 3
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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