T225NG和T42NG钛合金在水中的氧化行为和表面分析

研究了T225NG和T42NG钛合金在高温高压水蒸汽中腐蚀后的氧化膜形貌及结构特征。测出了两种合金的氧化曲线，并拟合出了其氧化动力学方程；对试样表面进行了金相分析、表面形貌扫描电镜观察及X射线衍射分析。结果表明：T225NG和T42NG合金的氧化动力学规律，其中前者的耐蚀性明显优于T42NG合金。经过高温高压水蒸汽腐蚀后，在两种合金表面形成了均匀、致密的氧化膜，且以金红石型TiO2为主，并伴有少量的锐钛矿型TiO2形成；还可观察到明显的氧化膜形核并长大的结晶学特征，而两种合金的金相组织没有明显变化。

Oxidation Behavior and Surface Analysis of T225NG and T42NG Titanium Alloys in Vapor

The appearances and structural characters of oxides of T225NG and T42NG alloys after corroded in water vapor under high temperature and high pressure were studied. The oxidation curves of the two Ti alloys were drawn, and the dynamic equations of oxidation were gotten with fitting method. And then the microstructure, surface morphology and oxides phase composition of the specimens were also studied by optical microscope, scanning electron microscope and X ray diffraction analysis. The results show that the oxidation dynamic equations of T225NG and T42NG alloys are followed as g =0.6644 t 0.6939 and g =0 6976 t 0.5231 separately, and the corrosion-resistance of T225NG is better than that of T42NG. After corroded under water vapor at high temperature and high pressure, the homogeneous and compact oxide film which consist of the most TiO 2 of rutile type and less TiO 2 of anatase type are formed on the sueface of the two Ti alloys. And the crystallograghy for nucleating and growing up of surface grains can be also observed obviously, but the change of structures of the two Ti alloys have not found obviously before and after corrosion.