Effects of refined grains and doped nanoparticles on fabricating Al2O3 ceramics using binder jetting

Abstract

Adding sintering additives to fabricate alumina ceramics via the binder jetting (BJ) technique effectively enhances material properties. However, it is still limited by the disadvantages of low relative density and poor mechanical properties. This study proposed reducing matrix particle size and adding nanoscale particles using binder jetting to address the poor densification and strength of printed alumina (Al2O3) samples. Additionally, their effects on the mechanical properties and manufacturability of the material were explored. Numerical simulations were carried out before the experiments to predict the impact of particle stacking on the powder bed using the discrete element method (DEM). Then, filler particles with an average 40 μm size replaced the original 106 μm-sized Al2O3 particles. Subsequently, Al2O3 nanoparticle content in the samples was gradually increased, and the relevant properties of the sintered samples with different compositions were tested. Consequently, the size of the Al2O3 particles and the addition of Al2O3 nanoparticles significantly affects the physical and mechanical properties of the samples. The sample with 106 μm-sized particles has a compressive strength of 58 MPa, while reducing the particle size to 40 μm increases its compressive strength by 26 %. Moreover, the sample's compressive strength could reach up to 330 MPa, an increase of 513 %, and the hardness reaches 1215 HV (11.91 GPa) by expanding the Al2O3 nanoparticles content to 30 %. Additionally, using Al2O3 nanoparticles further reduces the sintering temperature, significantly improving the practicality of Al2O3 printing using binder jetting.