Three-dimensional characterization of the pore structures in SiC formed by binder jet 3D printing, polymer infiltration and pyrolysis (PIP)

Abstract

Processing of binder jet printed refractory ceramics, including SiC, to high density remains a major challenge in additive manufacturing. Polymer Infiltration and Pyrolysis (PIP) has been applied to SiC made with large particle sizes and low sinterability, but the PIPed material struggles to reach high density even after many infiltration cycles. In this work, binder jetted α-SiC powders were PIPed up to 8 cycles and characterized after each cycle. By comparison with an exclude volume model, the infiltrated density showed a plateauing after 8 cycles. X-ray micro-computer tomography (μCT) was used to characterize the microstructure evolution in 3D. The reconstructed cross-sectional image indicated that large cracks, attributed to gas pressure build-up in burn-out, were formed as the number of infiltration cycles increased. Additionally, quantitative 3D data extracted from μCT images showed a large pore network existed in the interior of all samples and remained mostly open, even after 8 PIP cycles.