Study On Fabrication And Mechanical Properties Of Porous Silver By Dealloying

Porous silver materials have been fabricated by dealloying of Ag-Zn alloys in H2SO4 solution. The composition of precursor Ag23.1Zn76.9 alloy, porous structure and fracture surface morphology of porous silver have been investigated by means of x-ray diffraction, scanning electron microscopy and the energy dispersive X-ray spectrum analysis. The effect of the acid-treatment on the porous structure of porous silver, and the relations of meso-hardenss values, microhardness values, bending strength values, Young's modulus values and the porous structure of porous silver have been also studied.In 0.01 M H2SO4 solution and 0.05 M H2SO4 solution at 0.2 VSCE and 0.3 VSCE respectively, the corrosion way of Ag23.1Zn76.9 alloy is nonuniform. And in 0.1 M H2SO4 solution, the corrosion way of Ag23.1Zn76.9 alloy is uniform. The porous silver with the ligament and pore sizes of 70-230 nm has been fabricated by dealloying.Ag23.1Zn76.9 alloys have been dealloyed in 0.1 M H2SO4 solution at 0.05 VSCE, 0.15 VSCE, 0.2 VSCE, 0.3 VSCE and 0.4 VSCE, the macroscopic shrinkage by 2.5 %, 4.5 %, 4.5 %, 8.6 % and 16.1 % during dealloying respectively.The precursor porous silver has been fabricated by Ag23.1Zn76.9 alloys dealloyed in 0.1 M H2SO4 solution at 0.05 VSCE. In the acid treatment, the porous silver has been immersed in 35 mass% concentrated HCl solution and 20 vol. % H2SO4 solution. The ligaments and pores of the porous silver have been coarsened with the increase time of the acid-treatment. The porous silver with the ligament and pore sizes of 160-400 nm has been fabricated by the acid treatment.In this study, the meso-hardness value has nothing to do with the porous structure of porous silver, the microhardness value has been decreased with the increasing porosity, the bending strength and Young's modulus values have been decreased with the increasing average size of pore. Form the fracture surface morphology of porous silver, the porous silver is crack, the ligament of porous silver is ductility.Predicted by Gibson and Ashby's scaling laws, the yield strength of the ligament is 771 MPa, approach the theoretical strength, and higher than macroscopic yield strength of Ag; the Young's modulus of the ligament is 194 GPa, equal to the Young's modulus of bulk Ag single crystals.