In-situ quantitative evaluation of the crack tip pH, conductivity, and Cl content on the environmentally assisted cracking of stainless steels in high temperature water

采用电沉积法制备了IrOx pH传感器和电导传感器，并对其pH响应特性进行了表征。pH传感器的灵敏度高于能斯特方程的预测值，通过优化电沉积电流密度和溶液组成，提高了IrOx pH传感器的稳定性。设计了一种裂纹尖端溶液微量取样系统，该系统由PTFE管和石英微毛细管组成，并通过两个接头连接。PTFE管用于允许使用小型控制阀。二氧化硅微毛细管用作取样管线的最后一部分，以在微量取样事件期间显著降低流速。

The IrOx pH sensor and conductivity sensor were fabribcated by using electrodepositon method.The pH response of the IrOx pH sensor were charactreized.The IrOx exhibits a super-Nernstian response. The sensitivity of the pH sensor is greater than the Nernst equation predicts.The stability of the IrOx pH sensor was improved after optimizing the electrdeposition current density and the solution composition. The crack tip solution micro-sampling system was designed and used to measure the solution chemistry of crack tip.The micro-sampling line consists of PTFE tube and a silica microcapillary tube that were connected through two unions. The PTFE tube is used to permit the use of a small control valve. The silica microcapillary used as the last part of the sampling line to reduce the flow rate significantly during a micro-sampling event.