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

用电沉积法制备了IrOx pH传感器和电导传感器，并对其pH响应进行了表征，表明IrOx具有超能斯特响应特性。优化了电沉积电流密度和溶液组成，提高了IrOx pH传感器的稳定性。设计了用于测定裂纹尖端溶液化学的裂尖溶液微采样系统，该微采样系统由聚四氟乙烯管和二氧化硅微毛细管通过两个接头连接而成。聚四氟乙烯管用于允许使用小型控制阀。硅胶微毛细管用作采样线的最后部分，可在微采样期间显著降低流速。

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.