纳米晶Cu-20Ag-20Cr合金在H_2SO_4溶液中的腐蚀电化学行为  

Corrosion Electrochemical Behavior of Nanocrystalline Cu-20Ag-20Cr Bulk Alloy in H_2SO_4 Solutions

作　　者：尹晓桐 王奕丹[1] 李昌蔚[1] 贾中秋 吴松晓 曹中秋[1] 

机构地区：[1]沈阳师范大学化学与生命科学学院,沈阳110034

出　　处：《材料导报》2015年第24期68-72,97,共6页Materials Reports

基　　金：国家自然科学基金(51271127);辽宁省高等学校优秀人才支持计划资助项目(LR2011032)

摘　　要：利用机械合金化法通过控制球磨时间分别制备出粗晶和纳米晶Cu-20Ag-20Cr合金粉末,采用真空热压法分别制备了粗晶和纳米晶Cu-20Ag-20Cr块体合金。使用PAR273与M5210电化学综合测试仪通过测定两种Cu-20Ag-20Cr合金在不同浓度H_2SO_4溶液中动电位极化曲线和交流阻抗谱(EIS)等研究了晶粒细化对其腐蚀电化学行为的影响,发现随着H_2SO_4溶液浓度的增大,粗晶和纳米晶Cu-20Ag-20Cr合金的自腐蚀电位负移;向中性Na2SO4溶液中加入0.02mol/L H_2SO_4,腐蚀电流密度明显增大,但随着H_2SO_4溶液浓度的增大,腐蚀电流密度变化不大。晶粒细化后,Cu-20Ag-20Cr块体合金的腐蚀电流密度变大,活性溶解增强,腐蚀速度加快;当H_2SO_4的浓度为0.50mol/L时,两种Cu-20Ag-20Cr合金均发生了钝化,纳米晶Cu-20Ag-20Cr合金表面形成钝化膜时的维钝电流密度明显小于粗晶Cu-20Ag-20Cr合金,表明晶粒细化后,合金的钝化性能得到改善,稳定性增强;在H_2SO_4溶液中,两种Cu-20Ag-20Cr合金的交流阻抗谱均在高频处呈连续的圆弧,在低频端出现了"扩散尾",在中性Na2SO4溶液中容抗弧的曲率半径最大,加入H_2SO_4溶液后,容抗弧的曲率半径显著变小,随着H_2SO_4溶液浓度的增大,容抗弧曲率半径的大小变化不大。Coarse grained and nanocrystalline Cu-20Ag-20 Cr alloyed powders were prepared by mechanical alloying method through controlling ball milling time.Two corresponding bulk alloys were also obtained by hot pressing technique.The corrosion electrochemical behavior of coarse grained and nanocrystalline bulk Cu-20Ag-20 Cr alloy in H2SO4 solutions were studied by means of PAR273 and M5210electrochemical synthesis test system through potentiodynamic polarization curves and electrochemical impedance spectroscopies（EIS）technique.Results showed that with the increment of H2SO4 concentrations,free corrosion potentials of two Cu-20Ag-20 Cr alloys move negatively.The corrosion current densities increased significantly when 0.02mol/L H2SO4 solution was added to Na2SO4 solution and changed a little with the increment of H2SO4 concentrations.Moreover,the corrosion current densities of Cu-20Ag-20 Cr alloys became higher,active resolution increased,and therefore corrosion rates became faster when the grain size decreased.Two Cu-20Ag-20 Cr alloys produce passive phenomena in 0.5mol/L H2SO4 solutions and the passive current density of nanocrystalline bulk Cu-20Ag-20 Cr alloy was lower than that of the corresponding coarse grained bulk Cu-20Ag-20 Cr alloy.This indicates that passive properties of the alloy are improved and the chemical stability increases when the grain size is decreased.EIS plots of two Cu-20Ag-20 Cr alloys are composed of capacitance arc at high frequency ranges and diffusion tail at low ranges.With the increment of H2SO4 concentrations,the radius of capacitance arc change a little.

关 键 词：晶粒尺寸 电化学腐蚀 钝化 极化曲线 交流阻抗谱 

分 类 号：TG113.23[金属学及工艺—物理冶金]