PLASMA SPRAY - PHYSICAL VAPOR DEPOSITION (PS-PVD) FOR ADVANCED THERMAL BARRIER COATINGS

Plasma spray - physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland) to deposit coatings out of the vapor phase. In comparison to conventional vacuum plasma spraying (VPS) and low pressure plasma spraying (LPPS), PS-PVD uses a high energy plasma gun operated at a work pressure below 2 mbar, to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. In contrast to EB-PVD, due to the forced gas stream of the plasma jet, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume which allows shadowed areas and surfaces which are not in the line of sight to the coating source to be coated with new and unique microstructures. By using yttria partially stabilized zirconia (PYSZ) as the ceramic top coat, this presentation reports the comparison in engineering performance of PS-PVD coatings with industry-standard EB-PVD systems with regard a key parameters such as coating adhesion, thermal conductivity and erosion resistance, and reviews the progress made in the coating coverage on complex turbine hardware.