An analysis of the elastic properties of a porous aluminium oxide film by means of indentation techniques

The elastic modulus of thin films can be directly determined by instrumented indentation when the indenter penetration does not exceed a fraction of the film thickness, depending on the mechanical properties of both film and substrate. When it is not possible, application of models for separating the contribution of the substrate is necessary. In this work, the robustness of several models is analyzed in the case of the elastic modulus determination of a porous aluminium oxide film produced by anodization of an aluminium alloy. Instrumented indentation tests employing a Berkovich indenter were performe data nanometric scale, which allowed a direct determination of the film elastic modulus, whose value was found to be approximately 11 GPa. However, at a micrometric scale the elastic modulus tends toward the value corresponding to the substrate, of approximately 73 GPa. The objective of the present work is to apply different models for testing their consistency over the complete set of indentation data obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation. This approach shows the continuity between the two scales of measurement thus allowing a better representation of the elastic modulus variation between two limits corresponding to the substrate and film elastic moduli. Gao's function proved to be the best to represen the elastic modulus variation

Effect of nanosilica additive particles on both friction and wear performance of mild steel/CuSn/SnBi multimaterial system

This paper presents an experimental study of the tribological behaviour of a multimaterial system using conventional powder metallurgy process with SiO2 nanoparticles. Four configurations were studied with and without SiO2. The tribological properties of the sintered materials were analysed by wear experiments at lubricated conditions on a ball disc wear test rig. The results are compared with those of conventional material for journal bearing. These show less variation of the friction coefficient and less wear rate for the materials with SiO2 compared to the ones without SiO2 and to those of the reference material. The dominant wear mechanism is adhesive wear, accompanied by mild abrasive wear

Coupled effects of substrate microstructure and sulphuric acid anodizing on fatigue life of a 2017A aluminum alloy

International audienc