Avaliação do efeito anti-incrustante de revestimento de cobre depositado por diferentes técnicas de aspersão de alta velocidade

Abstract

Metal surfaces exposed to natural or marine water are susceptible to the adhesion of living microorganisms, a process known as biofouling. These biofilms adhered to the surface alter the characteristics of the surface, reducing hydrodynamic efficiency and thermal exchange in piping and heat exchangers, respectively, while accelerating the phenomenon of corrosion. The interest of researchers in studying antifouling coatings, or natural antifouling agents, has increased since the ban on the toxic substance tributyltin (TBT). In this work, pure Cu coatings were deposited using different variations of high-velocity oxy-fuel (HVOF) spraying (propane, kerosene, and ethanol fuel) and a cold spray technique. The samples were exposed to interactions with microorganisms to analyze the response of the metal surface of the sprayed Cu coatings, comparing their properties with those of stainless steel 304. The results indicate that the HVOF coating with propane exhibited the lowest oxide fraction and the best antifouling performance (99.99%) but had the highest corrosion rate of 0.069 mm/year and the lowest Vickers hardness (94 HV). The ethanol-sprayed coating demonstrated intermediate hardness (137 HV) and a corrosion rate of 0.033 mm/year, associated with moderate oxide formation and good antifouling performance (99.98%). The kerosene coating, in turn, showed the highest hardness (148 HV) and a corrosion rate of 0.035 mm/year, but with higher oxide formation, which impacted its antifouling performance (49.39%), despite its good mechanical performance. The cold spray coating exhibited the lowest porosity and a hardness of 109 HV, with a corrosion rate of 0.051 mm/year, standing out in corrosion tests with antifouling performance (99.97%). These results demonstrate that the fuels used in the HVOF process significantly influence the microstructure and properties of the coatings, with HVOFpropane standing out as the option with the lowest oxides for antifouling effect, while HVOF-ethanol and cold spray exhibited more balanced results in terms of hardness, electrochemical corrosion, and antifouling properties.