锆合金在HCl和H2SO4溶液中的耐蚀性能研究

采用化学浸泡、电化学测试和物理检测技术,研究了HCl和H2SO4溶液中锆合金的腐蚀行为.结果表明,锆合金在还原性的HCl和低浓度H2SO4溶液中,具有优异的耐蚀性,而在高浓度的氧化性H2SO4溶液中腐蚀速率显著增大.物理检测结果显示,腐蚀的锆合金表面均匀地覆盖着弥散分布的微小颗粒状ZrO2.还原性的HCl和低浓度H2SO4溶液中ZrO2膜保持了原有的致密性,增强了锆合金的耐蚀性能.而高浓度H2SO4溶液中,在其强氧化作用下,锆合金基体/膜界面处不断生成ZrO2.当膜增加到一定厚度时,氧化膜的晶格参数与金属的晶格参数不一致,产生内应力,降低了氧化膜的附着力,直至氧化膜破裂,露出新鲜的锆合金表面.继之,新鲜的锆合金再次被氧化,以此循环往复,导致锆合金在浓H2SO4溶液中腐蚀加剧.

Study on Corrosion Resistance of Zirconium Alloy in HCl and H2SO4 Solutions

Corrosion behavior of zirconium alloy was studied by chemical immersion, electrochemical tests and physical analysis techniques. The results showed that zirconium alloy had excellent corrosion resistance in reductive HCl and low concentration H2SO4 solutions. While in high concentration H2SO4 solution, corrosion rates of zirconium alloy increased remarkably. Physical analysis techniques surface analysis results indicated that tiny grain-like ZrO2 granularly distributed on homogeneously the corrosive zirconium alloy surface. It was stable in reductive HCl and low concentration H2SO4 solutions. Thus, the corrosion resistance of zirconium alloy was strengthened. In high concentration H2SO4, for the strong oxidation of H2SO4, ZrO2 was formed continuously at the zirconium alloy/layer interface, and the thickness of this layer increased gradually. When the thickness reached certain thickness, crystal lattice parameter of the oxidation layer was not in accordance with that of the metal matrix, and inner stresses appeared, which resulted in the breakdown of the layer. And the exposed fresh zirconium alloy was oxidized by high concentration H2SO4. This process repeated regularly, which increased corrosion rate of zirconium alloy in high concentration H2SO4.