Evaluating the sintering behaviors of ceramic oxide powders processed via binder jet additive manufacturing

Abstract

Binder jet additive manufacturing is well suited for fabricating large (order of cm) and geometrically complex ceramic preforms. However, the main challenge in producing ceramic oxide parts via binder jetting is the high-temperature postprocess tasked with eliminating internal porosity to achieve full densities. In this work, we demonstrate the ability to produce oxide ceramic parts with desirable densities by sintering binder jetted preforms. We investigate the sintering behavior of binder jetted preforms composed of three oxide powders with distinct morphologies: ball-milled alumina, gas-atomized silica, and sintered-agglomerated zirconia. We fabricate the preform samples using a commercial binder jetting system and a conventional die-pressing technique to understand the effect of starting densities. Furthermore, we parametrize the heating profiles to understand the effect of sintering temperature, sintering duration, and heating rate on each powder's densification behavior, microstructure, and phase composition. Results show the relatively low starting densities within the binder jetted preforms caused the onset sintering temperature to be higher than what is documented in conventional sintering studies. As expected, we observed sintered densities increase with respect to sintering temperature and duration. These findings were utilized to downselect sintering parameters capable of achieving high densities (>96%). Herein, this study validates the sintering of binder jetted preforms as a suitable way to manufacture ceramic parts, regardless of powder morphologies, thereby increasing the robustness of the supply chain involved in additive manufacturing of ceramic oxides.