Two-source jumping beam evaporation for advanced EB-PVD TBC systems

The continuous increase of the turbine inlet temperature in gas turbines ne cessitates new TBCs with a temperature capability beyond the current partia lly yttria stabilized material coatings. The present paper focuses on two-s ource jumping EB-PVD processed novel candidate layers for future TBC applic ations. It is shown that mixtures of oxides with widely different vapor pre ssures can be manufactured by this technique. The microstructure of the lay ers depends strongly on deposition conditions and on materials properties a s well. Partial yttria stabilized zirconia coatings show no differences in microstructure and phase formation if deposited either by two-source jumpin g-beam or by one-source one-beam evaporation, while for ceria stabilized zi rconia coatings large differences mainly in chemistry are found; depending on the jumping frequency multilayers are formed. In mixed silica zirconia c oatings, crystalline zircon (ZrSiO4) was formed neither in the as coated co ndition nor after annealing. Finally, jumping beam experiments allowed a de tailed understanding of the growth kinetics of EB-PVD TBCs and the formatio n of a feather-like structure within the columns. (C) 2000 Elsevier Science B.V. All rights reserved.