Influence of thermal-spray procedure on the properties of Cr3C2-NiCr coating

A Cr3C2-NiCr coating (5 y 106 mum.), was thermal-spray projected using different procedures (plasma, HVOF and HFPD) onto stainless steel specimens. This type of coating is normally used as protection against heat, corrosion and erosion actions encountered in superheater and reheater tubes in power plant boilers. The microstructures, porosities, oxide contents and microhardnesses of the coatings were determined. Thermal fatigue tests under Simulative power plant service conditions were conducted in in experimental combustion chamber and, finally, the adhesion between the substrate and the coating layer was evaluated by means of tensile tests. The obtained results are discussed, and special attention was paid to the specific characteristics of the different spraying procedures.