Reactive binder jet additive manufacturing for microstructural control and dimensional stability of ceramic materials

Binder jet additive manufacturing (BJAM) is particularly suited to processing brittle materials such as ceramics as its process flow separates the steps of shaping and densification. Polymer binders are typically used in BJAM, including for the processing of ceramics. However, ceramic components in the green state are especially prone to distortion or fracture during sintering due to the low strength of polymer-bound parts after polymer decomposition and high sintering temperatures of ceramics. This paper presents the development and use of reactive metal salt binders for BJAM of ceramic components. Using aluminum oxide as the feedstock powder, we compare the performance of aluminum nitrate and magnesium nitrate metal salts as binders, and polyethylene glycol as a reference polymer binder. Test components are fabricated using a custom BJAM testbed, sintered, and characterized for density and deformation. The metal salt binders form solid interparticle bridges after decomposition, which provide continued strength to printed components during sintering. Additionally, increased densification results from the use of magnesium nitrate binders and reduced shrinkage results from use of aluminum nitrate binders, showcasing the utility of reactive binders that convert into ceramic sintering aids upon decomposition and sustain part strength during sintering.

Automated summary

This paper explores the development and use of reactive metal salt binders for BJAM of ceramic components. By comparing different binders, it demonstrates the importance of metal salt binders in maintaining part strength during sintering.