Solar powder metallurgy: An efficient processing of copper foams

Powder metallurgy methodology and a novel solar sintering process are combined to successfully produce porous copper foams with varying porosities from 50 to 70% vol. Firstly, pure copper powder was mixed with saccharose particles acting as spacer-holder and compacted into cylindrical shapes. Saccharose dissolution time, which ranged from 8 to 32 h, was inversely related to the target porosity. Concentrated solar energy, focused using a Fresnel lens, was applicated for the sintering of the remaining copper structures at 850 °C for 10 min. Comparing to conventional sintering in electrical furnace (1075 °C for 8 h), the solar sintering process achieved a full densification at a lower temperature and in a much shorter time. Density, pore size, and porosity morphology and distribution were analysed. The final copper foams exhibited uniform pore distribution and achieved porosities close to the target values, with roughly half of the porosity being open. Additionally, the compressive strength of the solar sintered foams matched, and in some cases, surpassed, that of conventional sintered foams. The utilization of concentrated solar energy has allowed to obtain high quality and densification copper foams with a good combination of mechanical properties and lightweight.