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2067 |
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Tuesday, May 04, 2010, Sophia Room 2:50 PM Young Scientists |
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Adhesion of nanostructured YSZ plasma sprayed coating on thin substrates |
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Romain Vert* / CEA Le Ripault
Laboratoire de Projection Thermique, FRANCE Erick Meillot / CEA Le Ripault - Laboratoire de Projection Thermique, France Armelle Vardelle/ SPCTS - University of Limoges, France Gilles Mariaux/ SPCTS - University of Limoges, France Christelle Dublanche-Tixier/ SPCTS - University of Limoges, France |
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The adhesion of plasma-sprayed coating is controlled, to a large extent, by the roughness and cleanness of the surface to be covered and its temperature during the spray process. Most of the plasma spray deposition procedures involve the roughening of the surface by grit-blasting prior to coating deposition. However, this stage induces compressive stresses (≈ 400 MPa) that result in the deformation of thin substrates. This work deals with a deposit procedure that makes it possible to achieve a good coating adhesion and cohesion on 1-mm thick substrates that exhibit a rather low roughness (Ra < 0.5 µm). Yttria-stabiliezd zirconia (YSZ) coatings were plasma-sprayed on different substrates that may be used in the thermal barrier systems implemented in next generation nuclear plants. This procedure involves the elaboration by plasma spraying (SPS) of a layer by using a suspension of nanoparticles (30-60 nm). As the adhesion mechanisms of the coating are not clearly understood yet, a parametric study was carried out to establish the relationship between the spray process parameters and coating cohesion and adhesion to the substrate. The mechanical properties were investigated by using a ball on disc tribometric test, a scratch test, and a nano-indentation technique while the microstructure was studied by using TEM, SEM and XRD. This paper will discuss the various mechanisms that could control the coating adhesion under the deposit conditions developed for the specific application of the coating. |