| Austenitic stainless steel could be contaminated by carbon steel if they contact with each other directly during the process of machining, transportation or assembly. Thus, the corrosion resistance of Austenitic stainless steel will be influenced. As we known, Because of severe rugged work environment and long active time, the corrosion resistance of Austenitic stainless for nuclear reactor coolant pump is strictly important. Therefore, this work focuses on the contamination of Austenitic steel, Z2CN18-10, which is used for nuclear reactor coolant pump, by carbon steel. Corrosion test of FeCl3 and Anodic Polarization Curve test are performed after contamination and remove contamination by pickling and passivating in this work. The results present that the carbon steel attached to the surface of the stainless steel doesn't have obviously effect on the long-term general corrosion rate. The carbon steel particles embedded into the Austenitic steel significantly reduce its pitting corrosion potential and increase the tendency of pitting corrosion. HNO3 passivation can partly counteract the decrease of pitting corrosion potential value of the contaminated Austenitic stainless steel samples, but which is still much lower than that from the samples of uncontaminated but passivated in the same way. In addition, the effects of carbon steel contamination on nuclear radiation field and thermal conductivity of fuel cladding are discussed.Because of excellent corrosion resistance, zirconium and zirconium alloys are widely used in nuclear industry and chemical industries. With the development of industry and technology, the corrosion resistance and other properties are increasingly demanding. In order to improve their corrosion resistance and explore the corrosion mechanism, plasma nitriding and air oxidation are carried out for Zr705 respectively, the nitriding temperature are 600℃and 900℃, the oxidation temperature are 550℃,650℃and 750℃.The nitriding behaviors of Zr705 at 900℃and 600℃are investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Anodic Polarization Curve and Friction Wear Testing Machine. The results showe that the plasma nitring treatment of Zr705 increased its corrosion resistance significantly in lmol/L sulfuric acid, which is mainly due to the existence of ZrN+ZrO2 composite layer. The plasma nitring treatment of Zr705 can reduce the friction coefficients of initial mild wear regime and increase the initial mild wear regime and transitional wear regime. Scanning Electron Microscopy (SEM) analysis and Anodic Polarization test are used to investigate the thickness of the oxidized layer and the corrosion resistance of oxidized Zr705 alloy, which exposed in air at the temperatures of 550℃,650℃and 750℃. Also X-Ray Diffraction (XRD) is used to analyze the mechanism of corrosion resistance. Results show that the thickness of the oxide layer increases with the increasing of the oxidation temperature. Both monoclinic ZrO2 and tetragonal ZrO2 are detected in the oxide layer, which are oxidized at 550℃,650℃and 750℃, and further analysis presents that the monoclinic ZrO2 is the major phase. The Anodic Polarization test shows the corrosion potential of the oxided Zr705 alloy is lower than the as-produced, and the higher the oxidation temperature, the lower the corrosion potential, which due to the effect of the ratio of tetragonal ZrO2 in the oxidation layer. The tetragonal ZrO2 in the oxidation layer would not only act as a barrier against diffusion of oxygen ions, but also can effectively reduce the corrosion rate of matrix alloy by corrosion solutions and different anions.
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