NaCl盐雾环境下Ti60合金的中温腐蚀行为

Corrosion Behavior of Ti60 Alloy in Fog of NaCl Solution at 600℃

利用增重测试、扫描电镜(SEM)、X射线衍射仪(XRD)和电子探针(EPMA)等分析技术,从氧化动力学、氧化膜相组成和微观结构方面,研究了Ti60合金在600℃下NaCl盐雾环境中的腐蚀行为。结果表明,Ti60合金在中温NaCl盐雾环境中腐蚀100 h后,其腐蚀速率远远低于在固态NaCl+H2O+O_(2)环境中的。在NaCl盐雾环境中表面形成双层腐蚀产物,外层相对致密,以Na_(2)TiO_(3)和TiO_(2)为主;内层为颗粒状,以TiO和Ti_(2)O为主。NaCl盐雾环境是富氧、富水蒸汽环境,更倾向于形成致密的TiO_(2),减缓材料的腐蚀。此外,Cl在氧化膜内层富集,并以“活性氧化”机制加速Ti60合金的腐蚀。

The corrosion behavior of Ti60 alloy in fog of NaCl solution at 600℃has been characterized by mass gain measurement,scanning electron microscopy(SEM),X-ray diffractometer(XRD)and electron probe microanalyzer(EPMA).The results suggested that the corrosion rate of Ti60 alloy in fog of NaCl solution is much lower than that with solid NaCl deposit in H2O+O_(2) atmosphere after 100 h corrosion at 600℃.The corrosion products formed in fog of NaCl solution are of two layer-structure,the inner layer consists of TiO and Ti_(2)O,while the outer one TiO_(2) and Na_(2)TiO_(3).The fog of NaCl solution is rich in O_(2) and water vapor,which should be favor thermodynamically for the stable existence of TiO_(2) oxide,further for the formation of dense oxide scale of TiO_(2),therefore,the corrosion rate of the alloy in the fog of NaCl solution is reduced.In addition,Cl concentrated in the inner layer of the corrosion products,and might accelerate the corrosion of Ti60 alloy in accord with"active oxidation"mechanism.