Improved oxide spallation resistance of microcrystalline Ni-Cr-Al coatings

Journal Article · Sat Aug 01 04:00:00 EDT 1998 · Oxidation of Metals

DOI:https://doi.org/10.1023/A:1018871817578· OSTI ID:655365

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). State Key Lab. for Corrosion and Protection

Microcrystalline Ni-20Cr-3Al coatings were deposited on Ni-20Cr-3Al substrates by unbalanced magnetron-sputter deposition. The grain size of the coatings was varied by using different Ar pressures. Cyclic-oxidation testing was performed at 1100 C. It was found that (1) an external {alpha}-Al{sub 2}O{sub 3} scale formed on coating A (4.7 {micro}m thick, 50 nm grain size); (2) an external Cr{sub 2}O{sub 3} scale and internal Al{sub 2}O{sub 3} oxide formed on coating B (14 {micro}m thick, 500 nm grain size); and (3) an outer layer scale of Cr{sub 2}O{sub 3} + NiCr{sub 2}O{sub 4} and interior layer of Al{sub 2}O{sub 3} formed on the as-cast alloy. Extensive spallation of the Cr{sub 2}O{sub 3} + NiCr{sub 2}O{sub 4} scale took place on the as-cast alloy, but no obvious spallation occurred on the two coatings. Improvement of the spallation resistance of the scale is explained by effective diffusional creep of the coatings and the micropegging effect of the inward-grown oxides.

• OSTI ID: 655365
• Journal Information: Oxidation of Metals, Journal Name: Oxidation of Metals Journal Issue: 1-2 Vol. 50; ISSN OXMEAF; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
GRAIN SIZE
NICKEL ALLOYS
OXIDATION
PROTECTIVE COATINGS
SCALING
SPUTTERING
TEMPERATURE RANGE 1000-4000 K