OLIVEIRA, J. A. M.; OLIVEIRA, JOSÉ ANDERSON MACHADO; OLIVEIRA, JOSÉ ANDERSON MACHADO DE; http://lattes.cnpq.br/0336606752365569; OLIVEIRA, José Anderson Machado.
Résumé:
The electroplating of metal alloys is a more sophisticated process than that of
pure metals, therefore, requires a further refinement of the operational parameters to
obtaining it. In the codeposition of alloys, the characteristics of the constituents are united
to obtain better quality deposits. The excellent properties
physical and chemical properties of tungsten added to nickel contribute to the increase
in the nobility of Ni-W alloys. The solutions used to obtain deposits
were prepared with distilled and deionized water, using high-quality reagents
analytical purity. As complexing agents, tartrate and oxalate were used
associated sodium The operational and composition parameters were evaluated
for the enrichment of tungsten in the Ni-W alloy. The pH of the solution was adjusted to
three values studied in this work: 7, 5 and 3. Sulfuric acid was added to
promote the solubilization of reagents and to evaluate the influence of pH on
chemical composition of the alloy. It was observed that the proportion between the metals Ni and W
vary according to the decrease in the pH value of the electrolyte solution. Being the
pH the only variable in the electrodeposition process, it is noted that the decrease in
even favors the increase in the mass percentage proportion of tungsten in the
obtained deposit. The heat-treated alloy at a temperature of 600 BC
an inversion in the mass percentage ratio between Ni and W, this fact can be
explained by the possible migration of nickel to the copper substrate in this
temperature. A considerable increase in alloy hardness was noted when
subjected to the treatment of 600 BC. The results obtained from the
polarization, obtained in 0.1 M NaCl medium, demonstrate the characteristics of
corrosion resistance of the studied alloys. An increase in the potential is observed
corrosion with decreasing pH, and consequently an increase in
polarization resistance. This behavior is associated with a higher content of W
in the alloy obtained in the lowest studied pH value.