The Role of Different Atmospheric Plasma Spray Parameters on Microstructure of Abradable AlSi-Polyester Coatings

摘要

One of the approaches to increase the thermic efficiency of aerospace engines is the application of abradable coatings enabling minimization and control of the clearance between the stator and the rotating blades tips. The main purpose of this contribution is to define the role of different technological parameters utilized for atmospheric plasma spraying of AlSi-polyester coating on its resulting microstructure. Deposition of abradable coatings on the real engine parts is mostly dependent on spraying stand-off distance and on spraying angle. These two parameters influence not only the coating microstructure but also the deposition efficiency itself, which is directly connected with economical aspects of the coating production. The set of experimental samples with atmospheric plasma sprayed Ni-based bond coat and two in chemical composition same initial powders delivered from different powder manufacturers were used to spray thick AlSi-polymer top coats with different spraying stand-off distances and angles. Subsequently some of the samples were also heat treated to burn-out the polymer phase from the coating microstructure. The Rockwell HR15Y hardness was measured on all samples and the microstructure and coating thickness were evaluated by means of light microscopy and image analysis methods.