扫描微电极法原位测量2024Al合金表面微区Cl^-浓度分布

Fabrication of Scanning Micro Cl^- Probe and in Situ Imaging of Cl^- at the Interface of 2024 Al Aloy/Solution

应用自研制扫描微电极测量系统和扫描微Ag/AgCl复合电极 ,原位测量含Cl- 溶液中 ,2 0 2 4Al合金在其局部腐蚀发生发展过程中金属 /溶液界面微区Cl- 离子的浓度分布 ,考察金属 /溶液界面微区Cl- 浓度分布对Al合金表面局部腐蚀行为的影响 .结果表明 ,扫描Ag/AgCl探针可实时跟踪腐蚀过程中金属表面氯离子浓度分布的动态行为 .当 2 0 2 4Al合金浸渍于含Cl- 溶液中 ,Cl- 离子在Al合金 /溶液界面呈不均匀分布 ,Cl- 主要在第 2相颗粒和铝基交界区域发生优先吸附和累积 。

Micro combination Ag/AgCl electrode with a tip measuring tens micron in diameter was fabricated. The probe satisfied in situ imaging of Cl - distribution at metal surface in chloride solution because of its excellent linearity between potential and Cl - concentration, rapid response, good stability and selectivity. With the aid of the home made Micro Electrode Scanning system and scanning Cl - probe, the effect of the [Cl - ] at 2024_Al/solution interface on localized corrosion process was investigated. It was demonstated directly that Cl - ion in solution immigrated toward, then adsorbed preferentially and accumulated at the junction between the Al_Cu_Mg secondary phase and Al matrix, the uneven distribution of Cl - accelerated the initiation and development of localized corrosion of 2024_al alloy in Cl - containing solution.