Process optimization and characterization of dense pure copper parts produced by paste-based 3D micro-extrusion

The manufacturing of dense pure Cu components by 3D micro-extrusion, a Material Extrusion (MEX) Additive Manufacturing (AM) technology, was investigated. This technology is based on the extrusion of a highly viscous powder-loaded suspension or paste at room temperature. The present study focused on the development of a complete processing route for 3D micro-extrusion from feedstock paste formulation, optimization of printing parameters, and thermal post-processing conditions. A propanol-based feedstock paste with 95 wt% Cu powder loading was prepared by employing optimized mixing and degassing steps to produce similar to 98% dense Cu after pressureless sintering in pure H-2 atmosphere at 1050 degrees C for 5 h. Printing of green parts by 3D micro-extrusion of the developed paste with optimized printing parameters followed by the same post-processing conditions enabled the fabrication of 96-99% dense Cu components with high purity. Microstructural investigation of the paste and printed parts after thermal treatment revealed the presence of residual isolated spherical pores (<10 mu m) distributed within the grains, at the grain boundaries and in triple junctions. The final material has an electrical conductivity in the range 90-100 %IACS, a yield strength of 61 +/- 7 MPa, an ultimate tensile strength of 194 +/- 9 MPa and an elongation at fracture of 32 +/- 4%.

Automated summary

Investigation into the manufacturing of dense pure Cu components using the 3D micro-extrusion technology was conducted. The process involves extrusion of a high-viscosity powder-loaded suspension or paste at room temperature. The study focused on developing a complete processing route, optimizing printing parameters, and thermal post-processing conditions. The results showed that the technique successfully produced dense Cu components with high purity and good mechanical properties.