Effect of Si3N4 Ceramic Particulates on Mechanical, Thermal, Thermo-Mechanical and Sliding Wear Performance of AA2024 Alloy Composites

In this investigation, hybrid AA2024 - Si3N4 (0-6 wt.% @ 2%) - SiC (2 wt.%) - graphite (2 wt.%) alloy composites have been fabricated as per design using the stir casting method. This follows evaluation of physical, mechanical, thermal, thermo-mechanical, fracture toughness, and sliding wear performance as per standards. The density and material stability of the alloy composites improves with reinforcement content while porosity and thermal conductivity show a diminishing trend. The mechanical characteristics improve considerably with reinforcement. The alloy composite having 6 wt.% Si3N4 particulates show maximum mechanical characteristics like ultimate tensile strength (212 MPa), percent elongation (13%), flexural strength (645 MPa), micro-hardness (127 HV), and impact strength (85 J). Fracture toughness was found to improve with Si3N4 particulate content and with crack length. The storage modulus and damping capacity of the alloy composites have shown an increasing trend with reinforcement content while the loss modulus shows a reverse trend. The specific wear rate and friction coefficient tend to diminish with Si3N4 particulate content under steady state conditions. The normal load significantly influences the specific wear rate of the alloy composites under the Taguchi experimental design. Worn out surface morphology analysis shows wear mechanisms like surface fatigue, ploughing, micro-cutting, three-body abrasion, etc. responsible for surface damage. EDAX spectrum shows elemental presence and mapping and XRD analysis shows the presence and distribution of various phases of alloy composites and counter-surface disc. It could be the potential material for various components like gear, piston, cylinder liner, etc.