Utilizing the waste fly ash and spent catalyst residue as reinforcement for the development of sustainable composites and investigating its mechanical and microstructure behaviour

The current study focuses on reusing spent catalysts and fly ash, presenting an interesting and intriguing topic for the researchers. The waste catalyst and fly ash from the petroleum and coal industries were initially considered hazardous. One of the most common approaches to recycling spent catalyst and fly ash involves incorporating them into the aluminum matrix to improve the mechanical behaviour for specific applications. This study uses pure aluminum as the matrix material for synthesizing a hybrid composite using an ultrasonic-aided squeeze casting technique. The spent catalyst and fly ah particles were ball-milled before being utilized as reinforcing particles with varying concentrations (2 wt% and 4 wt%) and mean particle sizes of 221.75 nm and 201.25 nm, respectively. The microstructure and mechanical behaviour of the aluminum composites produced using both reinforcements were investigated and compared. The scanning electron microscope (SEM) analysis shows that using ultrasonic treatment in squeeze casting improves the uniform dispersion of the reinforcement nanoparticle. The optical microscope shows that incorporating nanoparticles, coupled with intensive ultrasonic treatment, reduces the grain size of α-Al dendrites. Energy dispersive X-ray analysis (EDAX) and X-ray diffraction (XRD) indicate that the fabricated nanocomposite is free from impurities, contaminants, and oxide formations. The hardness, compressive, and tensile tests were conducted on the prepared aluminum composites. The overall results show that Al+2 wt% spent catalyst+2 wt% fly ash composite improves hardness, tensile, and compressive strength by 98.55 %, 43.24 %, and 29.24 %, respectively, compared to the base pure aluminum. The strength of the aluminum composites has been evaluated using various strengthening mechanism techniques. The strengthening contributions are primarily due to the temperature mismatch between the waste reinforcement nanoparticles and the aluminum matrix. It is well known that metal-based composites strengthen dispersion, in which the dispersed particles hinder dislocation motion and significantly increase the composite strength. [Display omitted] •Aluminum composites were fabricated using two distinct percentages of waste fly ash and spent catalyst nanoparticles.•Impact of waste nanoparticles in the aluminum composite and the mechanical behaviour was evaluated and compared.•Hardness, compressive and tensile strength of the 2wt% composites with UV increas