Amélioration de comportement tribologique d’un alliage d’aluminium par un alliage de surface déposé par voie électrochimique

Abstract

The aim of this thesis work is to improve the tribological behavior of an aluminum alloy using an produced surface alloy. To this end, nickel coatings are electrodeposited on Al-5Mg substrates for varying durations in a Watt bath, then heat treated at 450, 500 and 550°C, with times ranging from 1 to 40 hours depending on the diffusion temperature, in order to improve the mechanical properties of aluminum alloys. Various characterization techniques were employed to assess the and tribological behavior of the surface alloy developed. Microstructural studies, carried out by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), revealed that heat treatment leads to the formation of variable amounts of Al₃Ni₂ and Al₃Ni intermetallic phases. Microindentation with a Berkovich indenter was used to the hardness of the while wear tests were carried out using a ball-plane tribometer in alternating translation mode. The results show that the coated and treated substrates have a significantly higher hardness than the original Al-5Mg substrates, due to the growth of intermetallic phases (Al, Ni). Furthermore, the time taken to deposit nickel in the bath, as well as the annealing temperature and duration, influence the type, thickness and crystallinity of the intermetallic phases formed. Finally, the coefficient of friction of coated and heat-treated samples stabilizes between 0.3 and 0.36.