OLIVEIRA, A. S.; Oliveira, Alison Silva; http://lattes.cnpq.br/9929189005375876; OLIVEIRA, Alison Silva.
Résumé:
Corrosion is termed as a spontaneous and natural process in which the materials tend to return to their more thermodynamically stable state, thus causing deterioration and degradation of the surface of the materials, affecting their properties. By means of these effects of the corrosive processes on the surfaces of the materials in particular of the metallic materials, the interest in the development of technologies capable of mitigating the damages caused by the corrosion was aroused. Among these technologies we have the use of metallic coatings obtained by electrodeposition. This technique allows obtaining coatings formed by pure metals or by the combination of two or more metals to form an alloy. In this work, the electrodeposition of ternary alloy formed by Mo, Co and Fe on Cu substrate was evaluated. Where a 3² factorial design was used with a repetition of the center point associated to the response surface methodology (RSM), for optimization of the alloy electrodeposition mechanism. By means of the factorial design, the influence of the operational parameters current density and bath pH on the properties of the metallic coating was evaluated. The results of the chemical composition showed that the reduction of molybdenum is favored with high current density and pH 8, since cobalt is favored in all current density range and pH 4, iron is also favored in any current density range and with pH higher than 4 and less than 8. The morphology of the alloy presented the formation of nodules with presence of micro cracks. The structure of the alloy presented an amorphous character in all the diffractograms. The alloy with the highest corrosion resistance was that obtained with a chemical composition of Mo 44 (wt.%), Co 30 (wt.%) and Fe 25 (wt.%) with a current efficiency of 11.93 (%). The polarization resistance was 10427.0 Ohm.cm² with corrosion current density of 4.462×10-6 A/cm², under conditions of 20 mA/cm² current density with pH 8, the micrograph of its surface presented micro nodules with formation of micro-cracks.