Development of powder bed pre-debinding techniques for the manufacturing process of 3D-printed multi-material parts made of polyethylene-based ceramic, metal and metal–ceramic filaments

In this study the impact of different pre-debinding procedures on the shape stability of ceramic and metal–ceramic filament during the thermal treatment process were investigated. By using fine alumina powder and coke grit as support powders different pre-debinding conditions (atmosphere, grain size of the support powder) were tested. In further investigations the pre-debound filaments were compared to the filaments in as-extruded states. In total, five different filaments consisting of polyethylene-based binder system and ceramic or metal–ceramic solid phase were tested using four different debinding procedures. The shape stability analyses consisted of filament softening tests after each pre-debinding steps supported by DSC/TG thermal analyses. The SEM analyses were performed on sintered lanthanum-strontium-maganite and magnesium-aluminate spinel filaments and revealed strong relation between applied pre-debinding procedure and the stability of their internal structure. The results revealed that the presence of fine alumina powder in the pre-debinding procedure led to a significant enhancement of the filament dimensional stability. The research was concluded with the successful debinding and sintering of a complex multi-material demonstrator applying the most favorable pre-debinding procedure.