Preparation Of Nanoporous Copper And Effects Of The Corrosive Environment On Its Morphology

Nanoporous metal material is a type of porous materials which has Nanopores.Compared with traditional porous metal materials,it has smaller diameter and higher ratio surface area.Nanoporous metal material has special physical,chemical and mechanical properties.Therefore,It has both functional and structural dual functions.Nanoporous copper is known for its catalysis in the water gas shift reaction.At the same time, nanoporous metal material has the properties of superior electric and thermal conducti- vity in electrode material.Nanoporous copper is harmless to the people bec- ause of characteristics of structure which can be used as filter.Dealloying is a type of electrochemical corrosion process.When elements of alloy has huge difference in electrode potential, the high active elements has been selective dissolved in a corrosive environment,leaving behind the low active elements. Dealloying is the most effective way for preparation of nanoporous metal material.The method is simple.The pore structure is interconnected spongy structure.it has the hole to be even and small.In this paper,the different methods were adopted to prepare alloys then dealloy to preparating Nanoporous copper.The combinative method of arc melting and dealloying technique was adopted to prepare nanoporous copper. Nanoporous coppers were successfu- lly prepared by Cu_xMn_1-x(x=0.2,0.3).However,there are no holes in Cu_xMn_1-x(x=0.4)after dealloying.When Cu content reached a certain concentration, the dealloying only happens on the surface because the Cu diffusion prevents the reaction of the dealloying.Al-Cu alloy was preparaed by rapid solidification method. Nanoporous coppers were preparaed by dealloying method in 20% sodium hydroxide solution. After dealloying, Cu₃₈Al₆₂ which has low Al content has smoothly and even surface and homogeneous distribution of the pores.the average diameter is 40nm.Comparing these two different preparation methods of the precursor alloy,the precursor alloy greatly affects the pore structure after dealloying.The different applications had different requirements on the aperture.We can change the corrosion of time,temperature,etching solution concentrati- on,and the etching solution to controlling the pore sturcture.The results show that Cu_0.3Mn_0.7 alloys dealloy in sulfuric acid , hydrochloric acid, and NH4Cl solution showing different pore structure.In NH₄Cl solution,the porous copper has smaller pore diameter,uniform pore morphology and homogeneous distribution.The nanoporous copper was created by dealloying at different time.Corrosion rate increases with the increasing of time, and then decreases.Then with the continually increased corrosion time,the pore diameter increases and the pore wall becomes coarse.The nanoporous copper was created by dealloying under different temperature.Then with the increased temerature,the pore diameter increases and the pore wall becomes coarse. At the same time,with the temperature increases,the porous morphology of copper are not even. The pore diameter increases at the lower or higher concentration of solution.The dissolution rate of Mn and a diffusion speed of Cu together determined the final structure of porous。...