Comparison of Spray Techniques Depositing Fine Species

In the paper 3 different spray techniques for the deposition of ceramic powders, Suspension Plasma Spraying (SPS), Plasma Spray –Physical Vapour Deposition/Thin Film (PS-PVD/TF) and Aerosol Deposition (AD), are compared with respect to the used processing conditions and the obtainable microstructure. Both own results and from literature will be used. All the described techniques typically deposit finer species than those used in conventional thermal spray methods. Typically sizes are in the submicrometer range or even nanometer clusters or atomic species are used. The process conditions are significantly different and these process conditions lead to very different microstructures. Dense thin layers are possible by AD, PS-TF and partially by SPS, while columnar structures can be obtained by PS-PVD and SPS. Even true PVD type microstructures as well as segmented coatings can be obtained. A major objective of the paper is the development of a physical understanding between processing condition and microstructure.