Additive manufacturing of pure copper via vat photopolymerization with slurry

Stereolithography (SLA) combined with a two-step post-processing method "oxidation-reduction" was developed to fabricate pure copper with high complexity. The copper slurries for SLA were prepared, and particularly the influence of volume fraction of copper on the properties of copper slurries was investigated. In the two-step post-treatment process, organics were removed by oxidation and copper powder was oxidized simultaneously, and then the oxidized copper was reduced into highly reactive copper particles, improving the sintering activity of the copper green body and enhancing the relative density of the sintered part. The results show that curing depth of the copper slurries decreased with the increase of volume fraction of copper. The viscosity of the pure copper slurry rises exponentially as the volume fraction of copper exceeded 50%. The highest volume fraction of pure copper slurry for SLA is 55%. The specimens exhibited an increase in hardness and electrical conductivity with the increase of volume fraction of copper. Specifically, the maximum values of hardness and conductivity of samples with 55 vol.% copper were HV 52.7 and 57.1%(IACS), respectively.