Circular manufacturing in Bound Metal Deposition: Quantifying ceramic carryover effects on recycled SS316L feedstock integrity and sintered-part performance

Bound Metal Deposition (BMD) is a sinter-based metal additive manufacturing technology that offers cost-effectiveness and enhanced process safety. In BMD, metal-binder green parts are produced by material extrusion, followed by debinding and sintering stages. Ceramic interface layers are often used to facilitate support removal. While BMD allows for defective green parts recycling, ceramic contamination hinders material circularity. In this study, the reuse and remanufacturing of defective SS316L green parts are investigated with a focus on ceramic carryover. Feedstock with controlled ceramic (Al₂O₃) inclusion levels (0, 1, and 5 wt.%) was prepared, and a full characterization workflow was applied to both feedstock and sintered parts. Recycled feedstock exhibited mass-loss behavior similar to the virgin material, confirming that standard extrusion, debinding, and sintering parameters remain applicable. After sintering, ceramic inclusions were found to reduce shrinkage by imposing rigid particle constraints on densification. SEM revealed a progression from dense, uniform surfaces to inclusion-rich regions with interfacial gaps and cluster-associated porosity. EBSD showed higher LAGB fractions and slight grain refinement with increasing ceramic content. Surface roughness analysis indicated amplified extreme topographic features, while microhardness increased with ceramic content and exceeded the virgin mean. These composition-microstructure-property relationships provide practical guidelines for recycling BMD feedstock while maintaining part quality.