In the present work, the aluminum matrix composites reinforced with both SiC and graphite particles are joined using a friction stir welding (FSW) process. The wear characteristics of the welded joints were investigated at constant load of 50 N and a rotational speed of 1,000 rpm using a pin-on-disk wear testing apparatus. This study focuses on the influences of the FSW processing parameters (tool geometry, rotational speed, and welding speed) on the wear characteristics of the welded joint of the considered hybrid aluminum matrix composite under dry sliding conditions. The experimental results indicate that the wear resistance of the joint increases at high welding speeds (>45 mm/min) and/or low value of rotational speeds. Different tool pin profiles (square, octagonal, and hexagonal) are developed to perform the welding process, and the effects of the tool pin profile on the weldments were studied. It is found that joints welded with square pin profile have better wear resistance compared to the other pin profiles. The results demonstrate that the FSW processing parameters greatly affect on the wear resistance of the welded joints due to various microstructural modifications during welding that cause an improvement in the welded zone hardness and wear properties.

Low cost, low density and good thermal stability of hens’ eggshells make them a new reinforcement material. Further, eggshell (Es) is considered as a renewable eco-friendly material. Besides, its waste causes insect infestation and therefore pollution problems. Graphite (Gr) is one of the most commonly used reinforcements due to its self-lubricating properties. Hence, the current work aims to use the powder metallurgy technique to fabricate various aluminum matrix composites having different weight percentages of hybrid green particles (eggshells and graphite). Sintering additives such as magnesium and tin were used to improve the density. Firstly, the powders were manually mixed and cold compacted at 475 MPa and then sintered at 630 °C for 2 h. A pin-on-disk wear, Vickers hardness and compressive strength tests were used to investigate the mechanical and tribological properties. Scanning electron microscope (SEM) was used to characterize the morphology and microstructure of the produced composites as well as wear mechanisms. Energy-dispersive X-ray spectroscopy (EDX) test was used to investigate the elemental composition of the composites. The results showed that adding graphite to the aluminum matrix composite containing eggshell has a positive impact on the tribological properties of the composite up to a certain limit (1.5 wt%). However, the additional increase in graphite content has an adverse effect. Hybrid composites with 3 wt% eggshell show the best compressive strength and hardness, whereas hybrid composite with 9 wt% eggshell has the lowest compressive strength and hardness. The mass loss of the hybrid composite increases with the increase in the graphite weight percentages regardless of the eggshell weight percentages. The combination of SEM micrographs and EDX showed signs for three wear mechanisms: abrasive, adhesive and delaminated wear in the examined composites.

Chicken eggshell (Es) waste is an industrial byproduct, and its disposal constitutes a severe environmental risk. Eggshell is a new engineering reinforcement retaining excellent properties such as low density, renewable, eco-friendly, and high thermal stability. The current research aims to study the effects of eggshell particles addition on microstructures, mechanical and tribological properties of aluminium/eggshell green metal matrix composites (MMCs). In the present work Al–Es metal matrix composite is produced by powder metallurgy processes. SEM with EDX and XRD were used to examine the microstructures and the compounds that arise during the sintering process of the produced composites. Six tests were conducted on the produced samples including; dry wear test, micro Vickers hardness, and ultimate compressive strength. The results showed that the addition of 3 wt. % of eggshell improved wear resistance (65%), compressive strength (40%) and hardness (15%). At 6 and 9 wt. % of eggshell, negative results appeared.