Tribological Properties of Al 7075 Alloy and 7075/Al2O3 Composite Under Two-Body Abrasion: A Statistical Approach

Abstract

Tribological properties, i.e., wear rate, coefficient of friction (COF), and roughness of worn surfaces of an Al-Mg-Zn-Cu alloy and its composite reinforced with 20 wt % Al2O3 particles developed by stir-casting method have been studied and compared under two-body abrasion considering four independent control factors, i.e., load, abrasive grit size, sliding distance, and velocity each at three different levels. Design of test conditions and analyses of output responses have been performed employing standard Taguchi L27 orthogonal array, signal-to-noise ratio, analysis of variance technique, and regression method. Irrespective of wear conditions, composite exhibits lower wear rate and reduced COF with reference to base alloy owing to the load bearing ability and better wear resistance capability of Al2O3 particles. Roughness of worn surfaces of composite is, however, found to be higher over base alloy due to nonuniform abrasion in case of composite that generates the protruded Al2O3 particles on contact surfaces as the surrounding soft matrix is easily removed. For all three tribo-responses of both materials, the most influential factor is identified as grit size followed by load and then, grit size-load interaction except for the roughness of worn surfaces where the influence of sliding distance is also considerable. Linear regression models with excellent predictability have been developed for all tribo-characteristics separately for base alloy and composite. The predominant mechanisms of abrasion are identified as plowing and microcutting for base alloy, but delamination for composite.

Modelling of tribological responses of composites using integrated ANN-GA technique

“…For performing microstructural activities, specimens of particular dimensions were polished (without etching) under standard metallographic norms. 33 Optical and FESEM equipments coupled with energy dispersive X-ray spectroscopy (EDS) arrangement were utilized for realizing insights into microstructures. 33 Phases in the respective microstructures were indicated by a diffractometer through the generation of X-ray diffraction (XRD) profiles.…”

“…33 Optical and FESEM equipments coupled with energy dispersive X-ray spectroscopy (EDS) arrangement were utilized for realizing insights into microstructures. 33 Phases in the respective microstructures were indicated by a diffractometer through the generation of X-ray diffraction (XRD) profiles. 38 In inter-dendritic regions of microstructures of both BA and composites, elongated lean phase(s) were noticed (the inset in Figure 2(a), and (e)).…”

“…Subsequently, ANN based models for W rt , COF and RAS were developed considering generated experimental results and those reported elsewhere. 33–37 The developed ANNs models were employed as objective functions for multi-objective optimization through GA methodology. Finally, the criteria for designing improved DPAMCs as well as to indicate applicable tribo-conditions were emphasized and experimentally validated.…”

Identification and modelling of applicable wear conditions for stir cast Al-composite

“…With a reduction in the abrasive size, the number of abrasives increases for a specific area of an abrasive paper, leading to less stress generated on a single abrasive particle, since the normal load of same magnitude is shared among the higher number of abrasives. This results in a lower penetration ability of abrasives into the soft matrix [24,65]. Therefore, with an increasing abrasive size from 13 to 30 μm, the nature of alloy debris alters from short and fragile microchips to long and curly shaped microchips (Figs.…”

“…In case of the composite, ceramic reinforcements protruding from the matrix alloy result in a reduction of the real surface area of contact. Consequently, the degree of penetration of abrasives into the Al matrix diminishes leading to lesser removal of material, and thus an improvement in the wear resistance property [17,65].…”