Study On The Fabrication Of Hierarchical Nanoporous Silver And The Wettability Of Nanoporous Silver

Nano porous metal materials have broad application prospects in many ways due to the pore size effect.However,the single structure of nanoporous metal can not meet the new requirements in some aspects.In practical applications,it requires both large effective surface area and high chemical&physical activity which originates from small pores,as well as rapid mass exchange through macropores.Therefore,it is important to study the multilayered porous metal with small and large pores.Three Ag-Cu-Al alloys used for precursor were prepared by vacuum induction melting.The anodic polarization curves of precursor alloys in 0.1 mol/L H2SO4 solutions and 1 mol/L KOH solutions were measured by linear sweep voltammetry,and the electrochemical properties of the alloys were studied in two kinds of solutions.The crystal structure was measured by X ray diffractometer,the surface morphology of Ag-Cu-Al alloy before and after selective corrosion was obtained by scanning electron microscope andthe components were measured by INCA spectrometer.The results show that the three kinds of Ag-Cu-Al alloys have the Al2Cu phase of the tetragonal structure,the Al phase of the face centered cubic structure and the Ag3Al phase of the complex cubic structure.With the increase of silver content,the ratio of Al2Cu phase and Al phase decrease,and the ratio of Ag3Al phase increases.Nanoporous silver with multiple layers can be prepared by de alloying.The wettability of nanoporous silver surface was studied.Experiment shows that the surface shows hydrophilicity and lipophilicity.The contact angle of the deionized water on the nanoporous silver surface with different pore sizes changes with time is studied.The contact angle of deionized water will become 0° rapidly on the surface.In the time of 0-20 s,the contact angle decreases with prolonging time,and the decrease amplitude increases sharply as the pore size becomes larger.The hydrophilic surface of nanoporous silver converted to hydrophobic surface after stearic acid modification,and the contact angle changed to 128 degrees.It is shown that the hydrophobicity is obtained by the combination of micro&nano microstructure and the modification of stearic acid with low surface energy.After the surface modification,the wetting angle of the nanoporous silver surface stabilized with time and decreased slightly.Moreover,the wetting angle decreases with the increase of the dealloying time.The experimental results show that the contact angle decreases monotonically from the maximum to the minimum with the prolongation of the dealloying time(the pore becomes larger),that is,the roughness increases the wettability of the hydrophilic surface.In addition,the relationship between the contact angle of glycerol and the pore size of the nanoporous silver surface before and after modification was also investigated.In short,wettability of solid surfaces that controlled by chemical composition and geometric microstructure is one of the most important factors determining the use of materials or structures.