Abstract
Reinforced Inconel625 coatings have been successfully deposited by means of cold gas spray (CGS). Alumina has been simultaneously sprayed achieving a homogeneous distribution along the deposit with good cohesion between particles. The aim of this study was to investigate whether ceramic reinforcement could improve the mechanical and tribological properties of Inconel625 cold-sprayed coatings, while keeping the oxidation and corrosion resistance capacity. Furthermore, alumina particles were found to improve the spraying feasibility, by avoiding WC nozzle clogging during the process. A proper optimization of the spraying conditions was carried out in order to obtain the lowest possible porosity and best embedment of the alumina. Then, the mechanical and tribological properties as well as corrosion and oxidation behavior were characterized. Alumina acts as a reinforcement, improving the effects of abrasive and sliding wear. Regarding the oxidation and corrosion behavior, the coatings exhibit reasonably good oxidation resistance at temperatures up to 900 °C. The electrochemical corrosion performance in NaCl solution showed potentially lower noble corrosion values and corrosion current densities than bulk Inconel.
Highlights
Inconel alloys are oxidation- and corrosion-resistant materials well suited for service in environments subject to extreme pressure and heat
Inconel625 is a Ni–Cr–Mo alloy that was developed for high-temperature strength
Inconel625 and 718 coatings obtained by conventional thermal spray processes such as high-velocity oxy fuel (HVOF) have been extensively used in the power industry to improve the corrosion and wear resistance of metallic surfaces [4,5,6]
Summary
Inconel alloys are oxidation- and corrosion-resistant materials well suited for service in environments subject to extreme pressure and heat. Its highly alloyed composition provides a good level of general corrosion resistance in a wide range of oxidizing and non-oxidizing environments. Inconel625 and 718 coatings obtained by conventional thermal spray processes such as high-velocity oxy fuel (HVOF) have been extensively used in the power industry to improve the corrosion and wear resistance of metallic surfaces [4,5,6]. Most of the studies relate the corrosion activity to the presence of more or less oxidation and porosity content; for example, according to Planche et al, electrochemical activation time increases with the oxygen/fuel ratio used in the combustion, leading to a higher coating density due to a more difficult electrolyte penetration into the coating [6]
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