水化学对Zr-4合金氧化膜形貌的影响

Effect of Water Chemistry on Oxide Morphologies of Zircaloy-4

为了研究LiOH水溶液影响Zr-4合金耐腐蚀性能的机理,用扫描电子显微镜和扫描探针显微镜观察Zr-4合金样品在不同介质中腐蚀后氧化膜内外表面的形貌。实验结果表明:由于氧化过程体积膨胀,氧化膜中存在平行于界面的压应力。在压应力的作用下,氧化膜向外鼓起,并在垂直于平面的方向上产生张应力,导致氧化膜破裂,从而使腐蚀加速。LiOH水溶液浓度越高,这个过程越快。

To understand the degradation behavior of corrosion resistance in LiOH aqueous solution for Zircaloy-4, Scanning Electron Microscope (SEM) and Scanning Probe Microscope (SPM) are performed to observe the inside and outside surface morphologies of the oxide. Based on the results, it is suggested that there exists compressive stress parallel to oxide/matrix interface in the oxide film because of volume expanding during the oxidation of Zircaloy-4. The oxide film heaves due to compressive stress, which brings strain stress perpendicular to interface, the strain stress leads oxide film break and results in accelerating corrosion rate. The higher the concentration of LiOH aqueous solution is, the quicker the process is.