Oxidation behavior of sputter-deposited Ni-Cr-Al micro-crystalline coatings

Journal Article · Mon Mar 02 04:00:00 EST 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00346-7· OSTI ID:616394

Liu, Z; Gao, W; Dahm, K L ^[1]; Wang, F ^[2]

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1. Univ. of Auckland (New Zealand). Dept. of Chemical and Materials Engineering
2. Academia Sinica, Shenyang (China). Inst. of Corrosion and Protection of Metals

Unbalanced magnetron sputter deposition was used to produce Ni-20Cr-xAl (x = 2, 3, 5 wt%) coatings on the substrates of the same materials. The effects of coating grain size and Al content on oxidation behavior at 1,000 C have been studied. It was found that the oxidation products were determined by both grain size and Al content. {alpha}-Al{sub 2}O{sub 3} scales formed on the coatings containing as little as 2.4 wt% Al when the coating grain size was < 100 nm. The oxidation behavior was described using Wagner`s theory to include short-circuit diffusion. With the formation of {alpha}-Al{sub 2}O{sub 3} scale on coatings, the oxidation kinetics did not follow a parabolic law, but could be described with a new model that considered diffusion through both the lattice and grain boundaries. Based on the experimental results, a map showing the relationship between Al content, alloy grain size, and oxidation products has been established.

• OSTI ID: 616394
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
CORROSION PRODUCTS
GRAIN SIZE
NICKEL BASE ALLOYS
OXIDATION
PROTECTIVE COATINGS