纳米化对Ag-50Ni在H3PO4介质中腐蚀电化学行为影响

通过电化学极化曲线方法和电化学交流阻抗谱(EIS)技术对比研究了不同晶粒尺寸的Ag-50Ni合金在不同浓度的H3PO4介质中的耐腐蚀性能。结果表明:2种尺寸的Ag-50Ni合金在不同浓度的H3PO4介质中主要呈单容抗弧特征,其中纳米尺寸的Ag-50Ni合金在H3PO4浓度分别为0.0,0.1及0.5 mol/L中呈双容抗弧特征,表明电极表面腐蚀受电化学反应控制。随着H3PO4浓度的增加,合金的自腐蚀电位向负方向移动,传递电阻逐渐减小,腐蚀电流密度逐渐增大,表明腐蚀速度加快。在同一种浓度腐蚀介质中,常规尺寸Ag-50Ni合金的腐蚀电流密度低于纳米尺寸Ag-50Ni合金,表明晶粒细化后抗腐蚀性能降低。

On corrosion electrochemical behaviors of nanocrystalline bulk Ag-50Ni alloy in H3PO4 solution

Corrosion electrochemical behaviors of Ag-50Ni alloy with different grain sizes in H3PO4 and Na2SO4 solution were studied by using potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique.Research results show that EIS plots of the Ag-50Ni alloy are mainly composed of single capacitance loop,however,the EIS plots of the nano-sized Ag-50Ni alloys represent two capacitance loops when the concentration of H3PO4 is 0.0,0.1 and 0.5mol/L respectively,which illustrates that the corrosion processes are controlled by electrochemical reaction.With the increment of H3PO4 concentrations of media,their corrosion potentials of alloys move to the negative direction,corrosion current densities increase gradually,while transfer resistance decrease gradually.Corrosion current densities of nanocrystalline Ag-50Ni alloy increases and corrosion rates become fast as compared with the corresponding coarse grained Ag-50Ni alloy.Thus,corrosion resistances of nanocrystalline Ag-50Ni alloy decrease.