Influence of particle size on the microstructure and mechanical properties of Al2O3-Ni composite formed by the CSC method with a magnetic field

This study investigates the influence of nickel particle size on the microstructure and mechanical properties of Al2O3-Ni composites, produced using the Centrifugal Slip Casting (CSC) method in conjunction with an external magnetic field. Two series were analyzed: Series I (12.2 mu m Ni particles) and Series II (4.8 mu m Ni particles). Series II exhibited superior densification with an apparent density of 4.33 f 0.17 g/cm3, relative density of 98.92 f 0.89 %, water absorption of 0.06 f 0.03 %, and porosity of 0.25 f 0.01 %. A gradient structure with four zones was observed, driven by centrifugal and magnetic forces. Hardness testing revealed a significant improvement in Series II, with Zone IV showing 1930 HV (18.93 GPa) compared to 1020 HV (10 GPa) in Series I, and higher hardness variability in Zones II and III attributed to improved particle packing and densification. Compression tests confirmed greater deformation resistance and structural integrity in Series II. Despite Ni size differences, Al2O3 grain growth was unaffected during sintering, suggesting that densification and hardness enhancement are primarily driven by Ni particle size. These findings highlight the significant role of particle size in tailoring the physical and mechanical properties of Al2O3-Ni composites for advanced applications.