Effect of Varied Kaolin Content on the Mechanical Properties of Aluminium-Kaolin Particulate Composites

This study examines the effect of varying kaolin particle content on the mechanical properties of aluminium matrix composites fabricated using stir casting. Aluminium matrix composites have attracted substantial interest as lightweight structural materials for automotive and aerospace applications, and the use of locally sourced Nigerian kaolin as a reinforcing phase offers a cost-effective alternative to imported ceramic reinforcements. Kaolin particles obtained from deposits in Kankara, Katsina State, North West Nigeria, are sieved to a particle size of 75 micrometres, heat-treated, and incorporated into a commercially pure aluminium matrix at weight fractions of 0, 5, 10, 15, and 20 percent. Specimens are cast using a laboratory stir casting apparatus, machined to standard dimensions, and tested for tensile strength, hardness, impact energy, and wear resistance following ASTM D638, E10, and G99 standards. Optical microscopy and SEM analysis are performed to assess particle distribution and interfacial bonding. Results indicate that hardness and wear resistance improve progressively up to 15 percent kaolin addition, while tensile strength and impact energy exhibit an optimal peak at 10 percent reinforcement. Beyond 15 percent, agglomeration effects reduce mechanical performance. The study concludes that kaolin-reinforced aluminium composites with 10 to 15 percent reinforcement offer viable performance for light-duty structural applications. Keywords: aluminium matrix composite, kaolin, stir casting, mechanical properties, Katsina State.