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

• Published in: Additive manufacturing Vol. 73; p. 103670
• Main Authors: Kolli, Samanwitha, Beretta, Margherita, Selema, Ahmed, Sergeant, Peter, Kestens, Leo A.I., Rombouts, Marleen, Vleugels, Jozef
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.07.2023
• Subjects: Additive Manufacturing; Copper; Material Extrusion; Multi-step AM; Sintering; Multi-step AM; Additive Manufacturing; Material Extrusion; Copper; Sintering
• ISSN: 2214-8604; 2214-7810
• DOI: 10.1016/j.addma.2023.103670

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 ∼98% dense Cu after pressureless sintering in pure H2 atmosphere at 1050 °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 µm) 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%.