Ag_(15)Cu_(85)二元合金制备纳米多孔银的去合金化工艺研究

Study on Dealloying Process for Preparation of Nanoporous Ag by Ag_(15)Cu_(85) Binary Alloy

采用冷辊旋凝凝固法制备Ag含量为15at%的Ag-Cu二元合金薄带。在5wt%硝酸溶液中,通过去合金法制备纳米多孔银。利用X射线衍射仪(XRD)与扫描电镜(SEM)分析纳米多孔银的相组成和微观形貌。研究了Ag-Cu合金腐蚀温度以及腐蚀时间对纳米多孔Ag微观结构及形貌的影响。结果表明:初始合金薄带是由α-Cu(Ag)相与中间相ζ-Ag2Cu相组成。去合金后得到的合金薄带中ζ-Ag2Cu相和α-Cu(Ag)相完全消失,仅剩fcc-Ag相;随着腐蚀时间的延长,腐蚀介质从合金表面逐渐渗透到内部,使得纳米孔洞/韧带结构特征尺寸逐渐均匀;而去合金化温度由30℃升高到90℃,Ag原子表面扩散率随之增大,活性组元的腐蚀速率加快,获得纳米孔洞结构所需的时间缩短,并且结构更均匀化。90℃进行试验最佳,节能省时。

The Ag-Cu binary alloy ribbons with Ag content of 15at%were prepared by using single roller melt-spinning method.The nanoporous Ag was fabricated by dealloying method in 5 wt%HNO3solution.The phase constituent and micro-morphology of nanoporous Ag were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM).The influences of Ag-Cu alloy corrosion temperature and corrosion time on the microstructure and morphology of nanoporous Ag were studied.The results show that the initial alloy ribbons are composed of two phases:α-Cu(Ag)andζ-Ag2Cu.In the alloy ribbon obtained by corrosion,α-Cu(Ag)phase andζ-Ag2Cu phase disappear completely,only fcc-Ag phase remains.With the increase of corrosion time,the corrosion electrolyte penetrates from surface to the interior of alloy,which can result in the homogenization of feature size of the nanometer orifice/ligament structure.When dealloying temperature increases from 30℃to 90℃,the surface diffusivity of Ag surface increases with temperature increasing,and the corrosion rate of active component increases.The required time for preparing nanoporous Ag is shorten obviously and the structure is more homogeneous.The90℃is the optimum temperature for testing,because it can save energy and time.