Hydrogen in chromium: Influence on the high-temperature oxidation kinetics in O{sub 2}, oxide-growth mechanisms, and scale adherence

Journal Article · Thu Apr 01 04:00:00 EST 1999 · Oxidation of Metals

DOI:https://doi.org/10.1023/A:1018866505708· OSTI ID:351477

Tveten, B; Norby, T ^[1]; Hultquist, G ^[2]

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1. Univ. of Oslo (Norway). Centre for Materials Science
2. Royal Inst. of Tech., Stockholm (Sweden). Div. of Corrosion Science

Oxidation of chromium in 20 mbar isotopically labeled molecular oxygen was studied at 900 C. The samples comprised specimens with as-received contents of hydrogen and specimens where this hydrogen had been eliminated by vacuum annealing. Two-stage oxidation was performed by exposure of the samples to {sup 16,16}O{sub 2} and {sup 18,18}O{sub 2}. Reaction rates were studied by measuring the change in oxygen pressure in a closed reaction-chamber with a mass spectrometer during oxidation. The oxide formed was characterized by secondary-ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). The adherence of the oxide scale to the underlying metal substrate is poor and the oxidation rate is initially slightly higher when the metal contains hydrogen prior to oxidation. It is shown by {sup 18}O depth profiles that chromium diffusion within the Cr{sub 2}O{sub 3} sale is increased and oxygen diffusion is decreased for metal containing hydrogen. It is believed that the poor adherence of the oxide scale, in this case, is due to low anion diffusion relative to cation diffusion, which leads to an insufficient portion of oxide growth at the metal-oxide interface.

• OSTI ID: 351477
• Journal Information: Oxidation of Metals, Journal Name: Oxidation of Metals Journal Issue: 3-4 Vol. 51; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM
DIFFUSION
HYDROGEN
KINETICS
OXIDATION
OXYGEN 18
SCALING
TEMPERATURE RANGE 1000-4000 K