Comparison of the cyclic oxidation behavior of beta-NiAl, beta-NiPtAl and gamma-gamma prime NiPtAl coatings on various superalloys

Abstract

Abstract The influence of exposure temperature on the cyclic oxidation behavior of simple and platinum aluminide coatings on various superalloy substrates was investigated. Coatings of ��-NiAl, ��-NiPtAl and ��-��' NiPtAl were tested and compared in dry oxygen at 1050 - 1150�aC. There was a clear influence of substrate sulfur content on the oxidation behavior of ��-NiAl coatings at all three temperatures. The impact of substrate impurities, especially S content, was significantly reduced for ��-NiPtAl coatings at all three temperatures. Simple ���{��' NiPtAl coatings showed excellent oxidation behavior up to 1100�aC on some alloys, but were more sensitive to substrate composition, especially Hf content, than were ��-NiPtAl coatings.