Characterization and enhancement of the indentation and scratch performances of Al/Al2O3 nanolaminates

The protection of certain materials against erosion is becoming increasingly important. Therefore, many research are currently done to build coatings with enhanced properties which can ensure a good protection of the substrates. In order to produce coatings that can sustain erosion, the goal is to have a combination of high strength and high ductility. This has been achieved through creating hybrid nanolaminates-coatings. In the context of the FNRS project: "Tough hybrid nanolaminates" several systems of crystalline/amorphous nanolaminates are studied. This work focuses on the investigation of the scratch and indentation resistance properties of several Al/Al2O3 nanolaminates. A comparison between several systems deposited by magnetron sputtering with various proportion of alumina, and several layers thicknesses was done. The scratch resistance, the critical load under certain loading conditions, the wear volume and the failure mechanisms were determined by a scratch test with a spherical tip of 5 microns. The mechanical properties of the different systems such as the hardness and Young modulus were determine through numerical indentation simulation via finite element analysis, with the use of two different tips: spherical and Berkovitch. Due to the low number of experimental samples performed as a result of the corona virus pandemic, the results only allowed to compare general trends of the materials. In all the tests, alumina outperformed the hybrid nanolaminates in terms of scratch resistance, hardness and Young modulus. Furthermore, other tests should be performed to complete the tribological characterization of the materials. Research must go on to measure the properties specific to erosion, in order to produce coatings fitted to their function.