Copper additive manufacturing using MIM feedstock: adjustment of printing, debinding, and sintering parameters for processing dense and defectless parts

Abstract

In the present study, an additive manufacturing process of copper using extrusion 3D printing, solvent and thermal debinding, and sintering was explored. Extrusion 3D printing of metal injection moulding (MIM) feedstock was used to fabricate green body samples. The printing process was performed with optimized parameters to achieve high green density and low surface roughness. To remove water-soluble polymer, the green body was immersed in water for solvent debinding. The interconnected voids formed during solvent debinding were favorable for removing the backbone polymer from the brown body during thermal debinding. Thermal debinding was performed up to 500 °C, and ~ 6.5% total weight loss of the green sample was estimated. Finally, sintering of the thermally debinded samples was performed at 950, 1000, 1030, and 1050°C. The highest sintering temperature provided the highest relative density (94.5%) and isotropic shrinkage. Micro-computed tomography (μCT) examination was performed on green samples and sintered samples, and qualitative and quantitative analysis of the porosity confirmed the benefits of optimized printing conditions for the final microstructure. This work opens up the opportunity for 3D printing and sintering to produce pure copper components with complicated shapes and high density, utilizing raw MIM feedstock as the starting material.