HIGH TEMPERATURE HOT CORROSION BEHAVIOR OF TiMOCN-29%Ni AND Cr3C2-25% NiCr COATING ON STAINLESS STEEL IN AN AGGRESSIVE ENVIRONMENT

The demand for coatings that can protect the base material from the influence of high temperature corrosion is nowadays increasing. For this reason, new coatings with potential to succeed in aggressive environments of energy, marine, food, etc. industries are being developed. TiMoCN-29% Ni (experimental coating) and Cr3C2-25% NiCr coatings were applied to the substrate material 1.4923 (P91) which is used as an effective material for structural components in power equipment. Evaluated coatings were deposited using optimized parameters of HP/HVOF (High Pressure / High Velocity Oxygen Fuel) thermal spraying technology. Resistance study of selected thermally sprayed coatings against high temperature corrosion was conducted in the corrosive environment of 60% V2O5 and 40% Na2SO4 at the temperature of 750 degrees C and in the environment of 59% Na2SO4, 34.5% KCl and 6.5% NaCl at temperatures of 525 degrees C and 575 degrees C. After the corrosion tests, the evaluated coatings were analyzed using optical and scanning electron microscopy (SEM) and subsequently the elemental composition (EDX) of each coating was conducted. Based on the results achieved, the experimental TiMoCN-29% Ni coating by the Japanese company Fujimi was further evaluated using X-ray diffraction. The obtained results prove that not all coatings deposited using HP/HVOF thermal spraying technology can be used as an appropriate protection for functional component surfaces.