New insights into the optimization of bimodal powder for the enhancement of green body densification via binder jetting

Abstract

Powder preparation plays a critical role in the densification of products fabricated via binder jetting (BJ) and strongly influences the performance of the end product. Bimodal powder mixing using particles of different sizes represents an effective approach to improve powder packing density. This study provides new insights into the densification of green bodies by optimizing bimodal powder mixing within the BJ process. Spherical alumina powder was used as the representative powder material. Three types of spherical alumina particles of different sizes were used as secondary particles and mixed with coarse spherical alumina powder at different proportions. Green bodies were subsequently produced from the prepared powder mixtures. The relative densities, microstructures, and pore size distributions were characterized for all green bodies. The relative density of the green body was significantly influenced by the incorporation of the secondary powder. Under optimized conditions, the addition of the secondary powder increased the relative density of the green body by a maximum of 24% compared with that of the green body without added secondary powder (relative density: 47.5%). This improvement suggests that secondary particles enhance the packing of matrix particles at specific binary mixing ratios during the BJ process.