Densification behavior of microwave hybrid sintered Al2O3 bimodal powder mixtures and comparison with 3D modeling and simulation

Abstract In this study, slip casting and microwave hybrid sintering of Al2O3 bimodal powder mixtures were conducted to observe the effect on packing factor and densification behavior of different compositions. The powder mixtures contained up to 50 vol% fine particles. It was found that the green density increased remarkably with the addition of fine particles into coarse ones, and the composition having 30 vol% fine particles had the highest relative density of 72.7%. A similar behavior was also observed in sintered samples, where the sintered densities were also higher for bimodal compositions. Moreover, 3D modeling of the system was carried out, and the sintering behavior was simulated and compared with the experimental data. It was shown that with the same relative green density of 50% solid volume for all samples, the composition with 40 vol% fine particles exhibited the highest relative sintered density of 92.1%. The sintering behavior was also predicted for highly dense modeled structures, which could not be obtained experimentally, and pore analysis was performed. It was observed that the closed porosity increased with the addition of fine particles, while the pore size distribution significantly reduced, where 81.4 vol% pores had pore sizes of only up to 0.28 μm.