Deposition of thick oxide layers from solutions in a low pressure plasma reactor

The ceramic layer of a thermal barrier coating is usually deposited by plasma spraying or by EBPVD (Electron Beam Physical Vapour Deposition). To explore the potential of new oxide compositions in view of thermal barrier coating applications, these deposition techniques may be difficult to apply on account of the unavailability of suitable oxide powders for plasma spraying, for example, or the difficulty to determine the appropriate evaporation conditions for complex oxides in EBPVD.However a flexible technique has been developed, which enables to deposit a wide range of oxide compounds with minimal investment. This technique is based on the injection of micrometric droplets of solution containing the elements to deposit, into a plasma reactor equipped with a convergent nozzle.The first results concerning the deposition of thick oxide layers of Yttria-Stabilized Zirconia (YSZ) and that of a high temperature complex perovskite Ba3MgTa2O9 are given, with micro structural and chemical characterization (SEM, XRD, FTIR). YSZ grew into a layer 1 μm mn− 1 thick and exhibited vertical cracks from the surface to the substrate. The stoichiometry of the layer was in accordance with the composition of the precursors solution. The Ba3MgTa2O9 coating deposited was homogenous and presented cracks at the surface. The observation of the cross section revealed a layer up to 100 μm thick. Vertical cracks and lamellar porous microstructures, which could be favourable to thermal barrier applications, were visible along the cross section.