%0 Journal Article
%A Huang, T.
%A Bergholz, J.
%A Mauer, G.
%A Vassen, R.
%A Naumenko, D.
%A Quadakkers, W. J.
%T Effect of test atmosphere composition on high-temperature oxidation behaviour of CoNiCrAlY coatings produced from conventional and ODS powders
%J Materials at high temperatures
%V 35
%N 1-3
%@ 1878-6413
%C Amsterdam [u.a.]
%I Elsevier Science
%M FZJ-2018-04906
%P 97 - 107
%D 2018
%X The oxidation behaviour of free-standing CoNiCrAlY coatings produced by low-pressure plasma spraying using conventional powder and oxide dispersion strengthened (ODS) powder containing 2 wt. % Al-oxide dispersion was investigated. Thermogravimetric experiments at 1100 °C in Ar-20%O2 and Ar-4%H2-2%H2O showed lower oxidation rates of the ODS than the conventional coating. In the latter material the scale growth was enhanced by extensive Y-incorporation of Y/Al-mixed oxide precipitates in the scale and apparently by Y-segregation to oxide grain boundaries. In the ODS coating the alumina dispersion bonded Y in the form of Y-aluminate thereby effectively suppressing scale ‘overdoping’. SEM/EBSD studies of all alumina scales revealed a columnar grain structure with the lateral grain size increasing approximately linearly with depth from the oxide/gas interface. For both coatings the alumina scale growth was slower in Ar–H2–H2O than in Ar–O2. The result is believed to be related to a lower oxygen potential gradient and to slower grain boundary diffusion in the scale forming in H2/H2O containing gas.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000435483900012
%R 10.1080/09603409.2017.1389422
%U https://juser.fz-juelich.de/record/851206