Pulsed electron beam treatment of MCrAlY bondcoats for EB PVD TBC systems part 2of 2: Cyclic oxidation of the coatings.

摘要

This paper discusses the effect of pulsed electron beam (PEB) treatment ofthermal sprayed MCrAlY bondcoats on the cyclic life of thermal barrier coatings(TBCs). Standard MCrAlY bondcoats were produced via HVOF, VPS and LPPS thermalspray methods. Some of the HVOF and VPS coatings were then given a PEB treatmentbefore all the samples were coated with an EB PVD 7-8 wt.% yttria partiallystabilized zirconia topcoat. The samples were all tested under cyclic oxidationconditions at 1150 à °C with 1 h at temperature and 15 min cooling, samples wereremoved after 20% coating spallation and prepared for cross sectional analyses.Cyclic testing revealed that although the PEB treatment had no measurable effecton the VPS sprayed samples, the HVOF coatings showed a significant increase inthe cyclic life after the PEB treatment. The effect of the PEB treatment on thevarious samples is discussed as well as its effect on TGO growth morphology. PEBtreatment of the HVOF bondcoat was found to reduce the rate of alumina growthand to suppress the formation of oxide pegs resulting in a smoother bondcoatinterface