Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Investigations on enhanced hardening of CuNi electrodeposited coatings obtained in the presence of micro-Al2O3 particles in a citrate-ammonia solution pH 9.2.
Submission Author:
Paulo Cezar Tulio , PR
Co-Authors:
Paulo Cezar Tulio, Raphael Souza
Presenter: Paulo Cezar Tulio
doi://10.26678/ABCM.COBEM2023.COB2023-0361
Abstract
Electrodeposited CuNi films on steel were obtained from citrate-ammonia pH 9.2 solutions with and without Al2O3 particles (3.4 microns) suspended on them. By microindentation hardness, improved mechanical strength of CuNi coatings obtained from solutions with Al2O3 (CuNi(Al)) was observed, especially at high constant cathodic current densities (ig). No occlusion of Al2O3 in CuNi matrix was verified, but Al2O3 particles affected Ni/Cu mass ratio and, therefore, the coating´s properties. At high ig, CuNi(Al) exhibited higher Ni/Cu mass ratios than CuNi(w) obtained without Al2O3 in the solution. X-ray diffraction was performed on the coatings. Through lattice parameter analysis and comparisons with EDS data using empirical Vegard´s law, at high ig, lattice parameters of CuNi(Al) coatings were smaller than those of CuNi(w), confirming higher Ni content. Since no occlusion of Al2O3 was observed in CuNi(Al), improved mechanical properties are explained in terms of the increased Ni content in CuNi(Al) compared to CuNi(w) and solid-solution strengthening. Ni is a metal harder than Cu and Al2O3 particles during electrodeposition enhanced hardening by increasing Ni content and not by forming a metal matrix composite at high ig. Coatings with enhanced mechanical strengthening can be employed for protection against erosion-corrosion.
Keywords
CuNi coatings, electrodeposition, Al2O3 (alumina), solid-solution strengthening;
