Electrochemical Corrosion Behavior of High Velocity Oxy-Fuel (HVOF) Superalloy Coatings On Ductile Irons

In this study, alloyed and unalloyed ductile irons (DI) were coated with two different Ni-based superalloy materials by HVOF method. Microstructure and phase analyzes of the coatings were performed by using SEM, EDX, XRD methods.  The electrochemical corrosion behavior of alloyed and unalloyed DI is investigated in 3.5% (w / v) NaCl solution. As a result of the characterization studies, it was observed that a dense non-porous coating layer of about 80 μm thickness was obtained on the cast iron samples and continuous adhesion was provided between the coating and the substrate. It has been determined that the cast iron coated with AMDRY 9624 contains γ and β intermetallic phases and the coating produced with AMDRY 9951 commercial powder contains only γ phase. As a result of coating process, the corrosion rate of the alloyed and unalloyed spherical graphite cast irons is reduced. Also, the corrosion rate of the coating produced with AMDRY 9951 is higher than the coating produced with AMDRY 9624. The presence of intermetallic phases in the coating produced with AMDRY 9624 increased the corrosion resistance of the coatings.