Abstract
Microcrystalline Ni-20Cr-3Al coatings weredeposited on Ni-20Cr-3Al substrates by unbalancedmagnetron-sputter deposition. The grain size of thecoatings was varied by using different Ar pressures.Cyclic-oxidation testing was performed at 1100°C. It wasfound that (1) an externalα-Al2O3 scale formed oncoating A (4.7 μm thick, 50 nm grain size); (2) anexternal Cr2O3 scale and internalAl2O3 oxide formed on coating B (14 μm thick, 500 nm grain size);and (3) an outer layer scale ofCr2O3 +NiCr2O4 and interior layer ofAl2O3 formed on the as-cast alloy.Extensive spallation of the Cr2O3+ NiCr2O4 scale took place on the as-cast alloy, but no obviousspallation occurred on the two coatings. Improvement ofthe spallation resistance of the scale is explained byeffective diffusional creep of the coatings and the micropegging effect of the inward-grownoxides.
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Liu, Z., Gao, W., Dahm, K.L. et al. Improved Oxide Spallation Resistance of Microcrystalline Ni-Cr-Al Coatings. Oxidation of Metals 50, 51–69 (1998). https://doi.org/10.1023/A:1018871817578
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DOI: https://doi.org/10.1023/A:1018871817578