The study was led by Wolverhampton University's Additive Manufacturing of Functional Materials (AMFM) research group, part of the university’s Centre for Engineering Innovation and Research (CEIR).
It was initiated in response to increased industry demand for 3D printable heat transfer materials and devices. The team said that copper-silver alloys offer significant potential in enabling the next generation of aerospace, automotive and biomedical devices.
Silver has the highest thermal conductivity and thermal diffusivity performance properties of any metal, closely followed by copper. However, the high reflectivity and desired thermal conductive properties create challenges for laser 3D printing due to laser energy reflection and heat dissipation hindering material meltpool generation.
“Thermal management is challenging for many sectors and even small improvements in heat transfer can have a significant impact on reducing material waste while increasing component reliability and life,” said Dr Arun Arjunan, director of the CEIR at Wolverhampton University.
Arjunan added that emerging systems, such as those in electric vehicles (EVs), radio-frequency systems, high power light-emitting diodes, solar cells and solid-state laser light sources all have significant heat dissipation requirements and therefore innovative materials and advanced manufacturing technologies are essential.
Lead researcher John Robinson explained that in his previous role at Cookson Gold developing 3D printing laser processing parameters for precious metals, he saw significant demand for sterling silver for thermal management applications.
“As sterling silver is essentially a copper-silver alloy with 92.5 per cent silver content it is relatively expensive in comparison to copper and other available 3D printing metal materials,” he said. “However, for high value applications such as aerospace and space the enhanced performance may warrant the cost.”
According to the team, copper-silver alloys with 30 per cent silver content demonstrated 84 per cent, 100 per cent and 106 per cent higher yield strengths in comparison to commercially available copper, commercially pure copper and copper-chromium-zirconium while ultimate tensile strength was 91 per cent, 62 per cent and 82 per cent higher. Thermal diffusivity was also shown to increase by 6.2 per cent with silver addition.
Further studies will include 3D printed triply periodic minimal surface structures printed in copper-silver. The research group is also working with collaborators in establishing 3D printed high purity copper and silver with enhanced IEC electrical conductivity for electromagnetic applications.