Produções de revestimentos de ligas de Ni-Co com capacidades hidrofóbicas

Abstract

Coatings with Ni-Co alloys have a very wide range of applications in the industry, however, currently, a lot of research has been done in order to produce a Ni-Co coating with super-hydrophobic characteristics. The production of this type of coating becomes interesting to be applied in systems that are easily damaged by moisture, such as solar panels, it has also been used as an anti-icing coating, to protect the substrate in colder regions, among others. This work aimed to prepare a hydrophobic or even super-hydrophobic surface, aiming at a future application of this coating. This dissertation worked with 0.5 molar solutions of cobalt sulfate and nickel sulfate and 0.5 molar solutions of the complexing agent sodium tartrate. The electrodeposition process was done by direct current and simple pulsed current, varying the frequency and duty cycle on the pulse. From the chemical analyses, it can be observed that Co was deposited preferentially in relation to Ni, thus producing an anomalous deposition process. Observing the SEM images and the diffractograms, it was clear that cobalt was in greater quantity, especially when the deposit was made at higher frequencies. From the EDS, it is also possible to observe a morphology that would be interesting for the production of superhydrophobic coatings, a cauliflower-like structure was obtained at low frequencies, mainly in the 30% duty cycle, which indicates that this deposition modified the surface in order to create a hierarchical micro-nanostructure, necessary for the production of these films. Contact angle analysis showed us that all films deposited by pulsed current achieved hydrophobicity and that a deposition with silane could decrease its surface energy and create this superhydrophobic coating.