Abstract
A reactor and process are described that allow the variation of the plasma deposition conditions such that a wide range of coating properties can be obtained. The reactor consists of three plasma torches mounted such that the deposition precursors can be injected centrally into the merging jets. This reactor has been used to deposit the different layers of a solid oxide fuel cell, including the very dense (99.5% density) zirconia electrolyte layer. Investigation of the zirconia layer showed a microstructure which has characteristics of both plasma sprayed coatings and vapor deposited coatings. The region of particle heating and acceleration has been characterized with enthalpy probes resulting in velocity and temperature fields. Calculations have been performed to describe the particle heating histories. The results show that a significant fraction of the particles evaporate and condense at the surface thus contributing to the formation of the dense layer. This hybrid process combines the possibility of obtaining high density coatings as with a PVD process with the rapid deposition rate of a plasma spray process.
