%0 Journal Article
%A Hejrani, E.
%A Sebold, D.
%A Nowak, W. J.
%A Mauer, G.
%A Naumenko, D.
%A Vassen, Robert
%A Quadakkers, W. J.
%T Isothermal and cyclic oxidation behavior of free standing MCrAlY coatings manufactured by high-velocity atmospheric plasma spraying
%J Surface and coatings technology
%V 313
%@ 0257-8972
%C Amsterdam [u.a.]
%I Elsevier Science
%M FZJ-2017-01053
%P 191-201
%D 2017
%X In the present paper the high temperature oxidation behavior of a free standing NiCoCrAlY coating produced by high-velocity atmospheric plasma spraying (HV-APS) is investigated and compared with that produced by conventional low pressure plasma spraying (LPPS). Isothermal thermogravimetric experiments at 1000 and 1100 °C in synthetic air revealed a lower oxidation rate of the HV-APS than the LPPS coating. Both coatings formed oxide scales based on alpha alumina, however, in the LPPS coating incorporation of coarse mixed Y/Al-oxide pegs into the scale occurred, increasing the oxidation rate by providing short circuit paths for oxygen diffusion probably due to higher diffusivities in the mixed oxide and/or along the interfaces between mixed oxide and alumina. In the HV-APS coatings most of the yttrium was tied-up in sub-μm Y-containing oxide particles and only minor amounts of mixed Y/Al oxide precipitates were found in the alumina surface scale. Cyclic air oxidation tests at 1100 °C revealed a lower oxidation rate and better scale adherence for the HV-APS coating.The results thus show that HV-APS is a promising method for the processing of MCrAlY coatings. The specific yttrium distribution in form of fine oxide precipitates in the HV-APS material prevents the formation of deleterious Y-rich oxide pegs and promotes formation of a slowly growing, protective alumina scale with excellent adherence.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000398873100024
%R 10.1016/j.surfcoat.2017.01.081
%U https://juser.fz-juelich.de/record/826837