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Suspension plasma spraying (SPS) deposition represents an innovative technique to produce coatings that exhibit improved properties. However, the key to obtain coatings with superior functional properties relies on the investigation of the suspensions as starting materials. For this reason, the present work deals with the suspension preparation for SPS process and its influence on the resulting coatings.Laboratory-prepared 60/40 wt% alumina-zirconia suspensions were concentrated to avoid energy loss and were then successfully deposited by SPS technique. The liquid used was water instead of ethanol due to economical, environmental and safety reasons. The preparation of the suspension plays an important role in SPS process since stable and well-dispersed water suspensions are difficult to obtain. For this reason, colloidal behaviour characterisation of the starting particles as well as rheological optimisation of the feedstock suspensions were addressed in this research.Suspensions with different solid loadings (up to 30 vol.% or 72 wt%) were deposited using several spraying distances. All coatings displayed a bimodal microstructure consisting in partially melted zones surrounded by a fully melted matrix. α-Al2O3 and t'-ZrO2 constituted the main crystalline phases, but differences in the microstructure and properties of the coatings were observed. From these results, some relations between starting suspension and spraying parameters with coating characteristics were found. Thus the optimal spraying distance becomes shorter when the suspension solid loading increases.

Estimation of the length of the manuscript (the pages of the manuscript should be numbered) Number of words Please fill outPlease fill out Length of the text 1) (using "word count") 3716 Number of Tables 1 × 150 3) Total number of words: 4000 words for a contributed paper (oral and posters), 8000 words for an invited paper and plenary paper. Manuscripts exceeding these word limits will not be considered for publication in the Proceedings volume. These too long papers could be submitted to the Editor of the journal for publication as regular papers. AbstractIn this work, aqueous suspensions feedstocks with different particle size distribution from submicron-and nano-sized YSZ powders were prepared. A previous colloidal characterisation allowed concentrated suspensions (~40 wt%) to be prepared. These suspensions were then successfully deposited by suspension plasma spraying (SPS) onto stainless steel substrates at different spraying distances. Coatings were characterised in terms of microstructure and mechanical properties (hardness and elastic modulus) by nanoindentation.All coatings displayed a two-zones microstructure formed by partially molten melted areas containing nanometer or submicrometer-sized particles surrounded by fully molten melted areas. These partially molten melted areas strongly increased as standoff distance lengthened. Mechanical properties worsened with spraying distance increase.The finer the feedstock particle size the more the spraying distance effect was. A clear correlation between mechanical properties and amount of partially molten melted areas has been proved. Thus the use of a mixture of nano/submicron-sized particles as a SPS feedstock can represent a good balance between suspension processability and final coating performance.