Reactive vapor deposition of metal oxide coatings

The reactive deposition of metal oxide coatings has been achieved using an electron beam directed vapor deposition (DVD) approach. In this approach, a transonic helium carrier gas jet has been combined with electron beam evaporation to create and efficiently transport metal vapor to a substrate. Metal oxide coatings were then produced by adding oxygen to the carrier gas. The synthesis of multi-component oxide coatings could be achieved using either an alloy source or by simultaneous evaporation of metals from two or more sources. In the latter, the reactive carrier gas jet was used to facilitate vapor phase mixing of the evaporated fluxes. The preferred approach was found to be dependent on the vapor pressures of the individual source components. When large differences between the component vapor pressures exist, multi-source evaporation is preferred. Results are reported for the reactive deposition of zirconia from a single metal source and reactive deposition of yttria stabilized zirconia from two metal sources (Y and Zr). The phase and morphology are similar to those found in similar coating compositions created by the evaporation of a pre-compounded oxide. Very good compositional uniformity in the binary metal oxide films has been observed. Vapor transport modeling is used to explore the origin of the composition uniformity.