Experimental Study of the Effect of Mechanical Agitation of the Electrolyte Solution on the Formation of Nanostructured Coatings

• DOI: https://doi.org/10.22533/at.ed.1153312611033

• Palavras-chave: electrodeposition, nanostructured coating, chromium nanoparticles, mass transport, electrolyte hydrodynamics.

• Keywords: electrodeposition, nanostructured coating, chromium nanoparticles, mass transport, electrolyte hydrodynamics.

• Abstract:

  This study experimentally analyzes the influence of mechanical agitation of the electrolyte on the formation of nanostructured coatings obtained by electrodeposition of chromium nanoparticles onto the surface of AISI 1020 steel, considering that the hydrodynamic conditions of the electrolytic bath directly influence mass transport and the availability of the deposited material at the electrode–electrolyte interface. The study is based on the principles of mass transport and on the hydrodynamic characterization of the system using the Reynolds number, a parameter that allows the electrolyte flow regime to be related to the mechanisms of dispersion and transport of nanoparticles in suspension. For the experimental setup, an electrolyte containing chromium nanoparticles at a concentration of 100 ppm was prepared, and three mechanical agitation conditions corresponding to 30 rpm, 60 rpm, and 120 rpm were evaluated, while keeping the electroplating parameters constant. Initial observations of the hydrodynamic behavior showed that at 30 rpm, sedimentation of the feed material occurs due to insufficient dispersion of the nanoparticles in the electrolyte, while at 120 rpm, radial redistribution of the particles toward the vessel walls occurs due to increased hydrodynamic forces, reducing their availability in the deposition zone. In contrast, at 60 rpm, a homogeneous suspension of the feed material was obtained, favoring the transport of nanoparticles toward the electrode surface. The coatings obtained were characterized using scanning electron microscopy ( ), showing that this condition produces homogeneous deposits of uniform thickness, while the conditions at 30 and 120 rpm generate uneven coatings. The results demonstrate that the hydrodynamics of the electrolyte control mass transport and the availability of nanoparticles at the electrode–electrolyte interface, allowing the establishment of an optimal stirring condition for obtaining homogeneous nanostructured coatings and providing experimental evidence of the importance of controlling hydrodynamic conditions in nanoparticle electrodeposition processes.