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2680 |
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Thursday, September 29, 2011, Saal B2.1 4:50 PM Plasma Spraying 3 |
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Reconstitution of yttria stabilised zirconia nanopowders to obtain coatings by atmospheric plasma spraying |
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Enrique Sánchez* / Instituto de Tecnología Cerámica - Asociación de Investigación de las Industrias Cerámicas. Universitat Jaume I, Spain Carlos Feliu / Instituto de Tecnología Cerámica - Asociación de Investigación de las Industrias Cerámicas. Universitat Jaume I. , Spain Pablo Carpio/ Instituto de Tecnología Cerámica - Asociación de Investigación de las Industrias Cerámicas. Universitat Jaume I. , Spain Rodrigo Moreno/ Instituto de Cerámica y Vidrio, CSIC, Spain Maria Carmen Alcazar/ Instituto de Cerámica y Vidrio, CSIC, Spain Maria Dolores Salvador/ Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia , Spain Rut Benavente/ Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Spain Victoria Bonache/ Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Spain |
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This paper addresses the deposition of yttria-stabilised zirconia (YSZ) coatings on austenitic stainless steel coupons from nanostructured powders using air plasma spraying (APS) under different spraying conditions. However, nanosized powders need to be previously reconstituted into a sprayable size by a suitable method such as spray drying. A commercial suspension of nanosized YSZ was used as starting material. A highly concentrated YSZ-nanoparticle suspension was then obtained from this commercial suspension and YSZ-submicron powder. A binder and a plasticiser typically used in spray drying were also used. Both suspensions were then reconstituted into plasma sprayable powders. The reconstitution process was performed by spray drying, followed by thermal treatment in order to reduce porosity and enhance agglomerate sinterability. The reconstituted granules were characterised by XRD, SEM, granule and pore sizing techniques, and a flowability evaluation. The effect of suspension characteristics on granule morphology and porosity was examined. Finally, plasma spraying conditions were optimised to successfully deposit the reconstituted powders, yielding coatings that were well bonded to the substrate. The coatings were characterised by XRD and SEM, as well as by mechanical properties and erosion resistance evaluations. Microstructure observation showed that the coatings consisted of a fused matrix and partially-molten areas made up of initial nanoparticles. The influence of spray-dried granule characteristics on coating microstructure and, hence, on coating properties was also studied. |