Electron beam directed vapor deposition of thermal barrier coatings

Electron beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) are currently applied to gas turbine engine components to improve engine durability but, in the future, may be used to increase engine efficiency. These coatings are costly to apply in part because of the low evaporated materials utilization efficiency (a few percent) and the relatively slow rate of deposition (similar to 5-10 mu m min(-1)). Here, an emerging electron beam directed vapor deposition (EB-DVD) approach is explored as a method for producing these TBCs. The EB-DVD technique combines low vacuum (10(-3)-10 Torr)- electron beam evaporation with a carrier gas jet to rapidly create and efficiently transport evaporant to a deposition surface. Studies of the deposition of yttria partially stabilized zirconia (YSZ) and reactively formed zirconia coatings have been performed and the composition, microstructure, phase content and crystallographic texture of deposited layers are reported. The results indicate EB-DVD's ability to form compositionally controlled YSZ and zirconia coatings, with a 50% or greater materials utilization efficiency, at a rate in excess of 50 mu m min(-1). The EB-DVD films have a columnar microstructure, phase content and crystalline texture similar to that of the EB-PVD coatings used for high performance gas turbine applications. (C) 1998 American Vacuum Society. [S0734-2101(98)04406-6].