Engineered gradient structures in Al2O3-Ni composites: unlocking the potential of centrifugal slip casting for tailored microstructures and surface spinel formation

This study investigates the fabrication and characterization of Al 2 O 3 -Ni composites produced via centrifugal slip casting, focusing on the controlled formation of a surface NiAl 2 O 4 spinel phase. Two composite series were analyzed: Series I (45 vol.% solid phase) and Series II (50 vol.% solid phase), both containing 10 vol.% Ni by volume. Microstructural analysis revealed a gradient distribution of Ni, with Series I exhibiting more pronounced segregation and Series II displaying a more homogeneous structure. Rheological studies confirmed shear-thinning behavior, with higher solid content improving slurry stability. Stereological analysis demonstrated finer and more uniformly distributed Ni particles in Series II, influencing mechanical properties. The results highlight the impact of solid phase content on particle dispersion and spinel layer formation, offering insights for optimizing functionally graded ceramic-metal composites.