Interrelationships between thermal parameters/solidification microstructures with wear resistance and hydrogen generation of Al-Sn-(Mg;Zn) alloys

Abstract

This project aims to investigate the tribological and corrosion behaviors of alloys from the Al-Sn-(Mg;Zn) systems, with a particular emphasis on their potential for hydrogen (H2) generation, in order to develop correlations with the solidification microstructure. When varying solute content within the same alloy system, it is not common to have the possibility of application in different fields of interest, such as tribology and hydrogen generation. In terms of tribological aspects, while higher Sn contents (>10wt.%) are required to act as a solid lubricant, Mg and Zn contribute to increase the mechanical strength through the formation of second phases and/or being in solid solution in the Al matrix, thus favoring wear resistance. In terms of corrosion features, it should be noted that while the use of small Sn contents (~1wt.%) accelerate the hydrolysis reaction rate by forming galvanic cells and preventing the formation of the passive layer, Zn and Mg activate Al, that is, they decrease the anode potential, thus contributing to the effect of these cells in the generation of H2. Studies of alloys of Al-Sn-(Mg;Zn) ternary systems that systematize thermal and microstructural correlations to the tribological and H2 generation behaviors are practically non-existent in the literature, i.e., similar to the composition of a processing map. Thus, different compositions of Al-Sn-(Mg;Zn) alloys are intended to be solidified under unsteady-state conditions of heat flux and characterized by experimental thermal analysis and via numerical simulation, and by microstructural analysis via X-ray diffraction (XRD), optical microscopy and scanning electron microscopy associated with energy dispersive spectroscopy (SEM/EDS). It is also intended to establish growth relationships between quantitative parameters of the microstructure and solidification thermal parameters. Samples with different microstructural spacing will then be subjected to wear, H2 evolution and corrosion (linear polarization) tests in order to establish correlations between these microstructure parameters and wear performance and corrosion resistance to evaluate the generation and evolution of H2. (AU)