Eletrodeposição da liga Ni-Zn usando planejamento experimental.

Abstract

The amorphous metallic alloys has been much interest in recent years and their magnetic properties, mechanical properties and corrosion resistance have been widely disseminated. The Zn-Ni alloys are used in large proportions for presenting a greater degree of protection against corrosion and have improved mechanical properties and good thermal stability when compared with pure zinc deposits and other zinc alloys. This study aimed to obtain coatings of Zn-Ni and optimize operating parameters (current density and mechanical agitation of the electrolytic bath) using electrodeposition process for obtaining deposits resistant to corrosion, and to characterize their morphology and composition. As a tool for optimization of electrodeposition process was used the response surface methodology. The electrochemical bath used for the electroplating of Zn-Ni coating was comprised of chemical reactants of high purity which were as follows: ZnSO4.7H2O 57.5000 g / l NiSO4.6H2O 57.8270 g / l, Na2SO4 56 , 8000 g / l H3BO3 9.3000 g / l. The pH of the bath was maintained constant with a value of 2.5 and adjusted by adding sodium hydroxide or sulfuric acid. Was successfully obtained a Zn-Ni alloy. The deposits show variation in their silver stain black. It was observed that the current density was the variable that most influenced the process of electroplating. The best result was obtained with higher current density and lower agitation that the potential for corrosion and microhardness. The morphology of the alloy was influenced by the current density changed the average grain size of the coatings obtained.