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

采用电沉积法制作了IrOx pH传感器和电导率传感器，并对IrOx pH传感器的pH响应进行了表征。IrOx表现出超能斯特响应。 pH传感器的灵敏度大于Nernst方程的预测。优化电镀电流密度和溶液成分后，IrOx pH传感器的稳定性得到提高。设计了裂纹尖端溶液微取样系统，用于测量裂纹尖端溶液化学成分。微取样管路由PTFE管和二氧化硅微毛细管组成，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采样管线的最后一部分，可在微量采样过程中显着降低流速。

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.