TY  - JOUR
AU  - Hejrani, E.
AU  - Sebold, D.
AU  - Nowak, W. J.
AU  - Mauer, G.
AU  - Naumenko, D.
AU  - Vassen, Robert
AU  - Quadakkers, W. J.
TI  - Isothermal and cyclic oxidation behavior of free standing MCrAlY coatings manufactured by high-velocity atmospheric plasma spraying
JO  - Surface and coatings technology
VL  - 313
SN  - 0257-8972
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2017-01053
SP  - 191-201
PY  - 2017
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000398873100024
DO  - DOI:10.1016/j.surfcoat.2017.01.081
UR  - https://juser.fz-juelich.de/record/826837
ER  -