Evaluation of thermal barrier coating systems on novel substrates

Testing was conducted on both plasma-sprayed (PS) and electron beam-physica l vapor deposited (EB-PVD) Y2O3-stabilized ZrO2 (YSZ) thermal barrier coati ngs (TBCs) applied directly to oxidation-resistant substrates such as beta- NiAl, oxide-dispersed FeCrAl, and NiCr. On an alloy that forms a very adher ent alumina scale, beta-NiAl + Zr, the coating Lifetime of YSZ in furnace c yclic tests was 6 or more times longer than on state-of-the-art, YSZ coatin gs on single crystal Ni-base superalloys with MCrAlY or Pt aluminide bond c oats. Coatings on FeCrAl. alloys appear to be a viable option for applicati ons such as the external skin of the X-33, single stage to orbit, reusable launch vehicle. Model chromia-forming bond coat compositions also show prom ise for power generation applications at temperatures where hot corrosion m ay be a major problem. In general, while this work examined unique material s systems, many of the same fundamental failure mechanisms observed in conv entional TBCs were observed.