Cord Plasma Spray (CPS), a New Robust Process with the Potential to Produce Advanced Coatings in IGT and Aero Applications

Abstract Overcoming difficulties associated with feeding very fine particles (typically < 5 microns) into the plasma plume has been the main motivation for development of suspension plasma spray (SPS) process for more than two decades. This approach has led to exciting advances and demonstrated the ability to obtain columnar microstructures, fine porous coatings and dense layers. While these results have led to a constantly growing interest within the research community, implementation of SPS technology at industrial scale comes with challenges. A novel technique for thermal spraying of very fine and non-flowable powders is presented as promising alternative to SPS: the cord plasma spray (CPS) which combines a specifically designed solid-shape consumable (cord) and an axially-fed plasma torch. In this approach, the cord acts as a carrier of the fine particles that are released in the spray stream while the organic binder is almost instantaneously pyrolyzed. The proof-of-concept experiments were led with the Yttria-stabilized Zirconia (YSZ) coating material and showed that this process is suitable to generate a wide range of coating microstructures relevant for the field of thermal barrier coatings (TBC) among. The advantages of this new approach are presented, as well as its perspectives and potential for industrial applications.