Remarkable progress has been made on simulating equipments and experimental techniques in high temperature high pressure water in recent years. A series of high temperature water equipments have been designed and established in our laboratory, covering temperature range of R.T. to 700oC, pressure range of 0.1 to 35 MPa, and flow rate range of 0 to 30 L/h. In particular, in-situ optical observation, Raman spectra analysis, electrochemical measurement, acoustic emission monitoring and constant loading have been realized simultaneously in high temperature high pressure water environments. Several high temperature measuring electrodes and a high temperature pH calculation/measurement technique were developed. By using the above experimental equipments and techniques, corrosion, electrochemistry and corrosion fatigue behaviors of nuclear-grade stainless steels, nickel-based alloy and low-alloy steels were investigated carefully. Electrochemical corrosion thermodynamic and dynamic of the above materials in high temperature high pressure water were clarified. Effects of temperature, pH value and water chemistry were examined. Characteristics of corrosion-product scales or passive films formed on the above materials in high temperature water and supercritical water were characterized. Related corrosion mechanisms were discussed and proposed. A fatigue evaluation model and its engineering application method have been proposed to predict or evaluate fatigue life or safety margin of nuclear structural materials in serving high temperature water. Based on the above fundamental research work, 14 technical papers have been published in CORROSION SCIENCE and 4 China invention patents have been granted in the past three years.
Thermodynamic analysis of Zn-injected water chemistry on corrosion resistance of Fe-Cr-Ni alloy in high temperature high pressure water environments.
Structure of corrosion-product scale on stainless steel in SCWO environment (500oC/ 250 h)
(a) TEM image of cross-section of corrosion-product scale (b) SAED of Zone A (c) SAED of Zone B (d) SAED of Zone C (e) SAED of Zone D. The right two are the HRTEM images of (Fe,Cr)2O3 with the incident electron beam parallel to the  direction and (Fe,Cr)3O4 with the incident electron beam parallel to the  direction respectively.