Electrodeposited Ni/MWCNT-Al2O3 Composite Coating: Morphology and Tribology Studies

This work focuses essentially on the incorporation of hybrid MWCNT-Al2O3 particles into the Ni matrix through the electrodeposition process. Indeed, pure Ni coating and Ni/MWCNT-Al2O3 composite coating are applied to brass substrates, under the Direct (DC) and Pulse Current (PC). The effect of MWCNT-Al2O3 particles associated with the current conditions and the frequency of pulse current on the surface morphology and wear resistance of Ni matrix is investigated. The results showed that the current regime plays a key role in the microstructure of Ni matrix, the coating roughness and the wear resistance. Indeed, the PC regime gives rise to finer Ni grains and a smoother and more resistant coating to wear compared to the DC regime. The MWCNT-Al2O3 particles hinder the uniformity and continuity of the Ni matrix surface and increase its roughness. All the coatings reveal a friction coefficient superior to that of the brass substrate. However, they reduce the substrate wear depth. Furthermore, the incorporation of MWCNT-Al2O3 particles enhances the wear resistance of the Ni matrix in the case of DC regime compared to that of pure Ni coating. The PC regime with a frequency of 100 Hz causes the best wear resistance of the Ni matrix.