Material process development for the fabrication of heterogeneous titanium structures with selective pore morphology by a hybrid additive manufacturing process

Abstract This paper addresses a new methodology to fabricate cellular structures with embedded close pores distributed in controlled fashion. A hybrid additive manufacturing system integrating binder jetting and material extrusion was employed to selectively incorporate a sacrificial polymer into the structures followed by a post-processing step to decompose the polymer. Four different polymer compositions mixture of bisphenol-A ethoxylated diacrylate and cellulose acetate butyrate (CAB) were prepared. From determining the rheological and interfacial properties of the polymers, the composition with the highest CAB concentration (20 wt%) demonstrated lowest permeation inside powder porous media (0.03 m 2 /s). The significance of the results is in retaining the quality of green substrate via a decrease in influence of the polymer shrinkage stress due to a reduction in the polymer - powders interface. The effect of binder jetting and design parameters on the quality of green samples manufactured by embedding the optimized composition revealed the direct influence of binder saturation level, layer thickness, and the number of powder layers covering encapsulated polymers. In the heat treatment of the samples (up to 1400 °C), a high level of accuracy (1% error margin) in morphology of cavities, resulted from the decomposition of polymers (400 °C), was achieved.