【作者】 周邦新； 孙国成； 姚美意； 谢世敬； 李强； 张金龙；

【Author】 ZHOU Bang-xin;SUN Guo-cheng;YAO Mei-yi;XIE Shi-jing;LI Qiang;ZHANG Jin-long;Key Laboratory for Microstructures,Shanghai University;Institute of Materials,Shanghai University;

【机构】 上海大学微结构重点实验室； 上海大学材料研究所；

【摘要】 选用Nb含量不同的Zr-4,N18和成分接近ZIRLO的3号锆合金厚板(2 mm)样品,用高压釜在360℃/0.01 M LiOH水溶液中和400℃过热蒸汽中腐蚀后,分别测量样品3个不同面上氧化膜厚度随腐蚀时间的变化,用这种方法来评价耐腐蚀性能。实验结果表明,在LiOH水溶液中腐蚀时,Zr-4合金氧化膜的生长呈现显著的各向异性,在轧面(S_N)上氧化膜的生长速率会发生转折,转折后的生长速率明显加快,耐腐蚀性能很差,但是在垂直于轧向的截面(SR)和垂直于横向的截面(S_T)上氧化膜的生长速率并没有明显的变化,耐腐蚀性能很好。N18和3号合金中添加Nb后完全抑制了氧化膜生长的各向异性特征,S_N,S_R和S_T面上氧化膜的生长速率几乎没有差别,都具有较好的耐腐蚀性能,不过随着Nb含量的增加,氧化膜的生长速率会明显加快。3种样品在400℃过热蒸汽中腐蚀时,氧化膜的生长都没有明显的各向异性特征,随着Nb含量的增加,氧化膜生长速率也会明显加快。本文解释了为什么Zr-Sn-Nb锆合金在LiOH水溶液中腐蚀时的耐腐蚀性能比Zr-4优良,但是含Nb高的Zr-Sn-Nb锆合金在400℃过热蒸汽中腐蚀时的耐腐蚀性能又会比Zr-4差的原因,并从氧化膜显微组织的演化与耐腐蚀性能的关联性讨论了其中的机理。更多还原

【Abstract】 Three different zirconium alloy plates in 2 mm thickness with different Nb contents,i.e.Zircaloy-4,N18 and No.3 alloy with similar composition of ZIRLO,were adopted for the experimental materials.Corrosion tests were carried out in static autoclaves at 400℃/10.3 MPa in superheated steam,and at 360℃/18.6 MPa in lithiated water with 0.01 M LiOH.The corrosion resistance on different surfaces of the plate specimens,i.e.the surface perpendicular to the normal direction(S_N),the surface perpendicular to the rolling direction(S_R) and the surface perpendicular to the transverse direction(S_T) of the plate specimens,was evaluated by measuring the thickness of oxide layer respectively after different period exposure.The results show that the anisotropic growth of oxide layer on different surfaces of the specimens corroded at 360℃ in lithiated water is more prominent for Zircaloy-4 than that for N18 and No.3 alloy.The thickness of oxide layer develops much faster on S_N surface than that on S_R and S_T surfaces for Zircaloy-4 specimens.There is a marked transition of the oxide growth rate on S_N surface at about 80 days exposure,and after transition the oxide growth rate increases to show a worse corrosion resistance.But the transition of oxide growth rate is not obvious on S_R and S_T surfaces for the same Zircaloy-4 specimen,and the corrosion resistance on S_R and S_T surfaces is much better than that on S_N surface.For N18 and No.3 alloy specimens,the anisotropic growth of oxide layer on different surfaces of S_R,S_T and S_N is restrained by the addition of Nb during corrosion testing at 360℃ in lithiated water.The corrosion resistance is much better on S_N surface of N18 and No.3 alloy specimens than that on S_N surface of Zircaloy-4specimens.The oxide thickness on different surfaces of S_R,S_T and S_N is about the same for either N18 or No.3 alloy specimens corroded in lithiated water,but the oxide growth rate increases with the increase of Nb content.For three different alloy specimens corroded in 400 ℃ superheated steam,the growth rate of oxide layer on S_N,S_Rand S_T surfaces shows no different for the same alloy specimen,but it increases with the increase of the content of Nb.In present work,it is elucidated that the corrosion resistance of Zr-Sn-Nb alloy specimens corroded in lithiated water shows much better than that of Zircaloy-4 specimens,but the corrosion resistance of Zr-Sn-Nb alloy specimens with higher Nb content is worse than that of Zircaloy-4 specimens corroded in 400 ℃ superheated steam.And the mechanism is discussed based on the relationship between the microstructural evolution of oxide layer and the corrosion resistance of zirconium alloys.更多还原