阳极氧化钽酸锂薄膜在NaOH溶液中的腐蚀行为研究

通过阳极氧化法在高纯钽片表面制备了钽酸锂复合薄膜，采用浸泡失重法和电化学测试法考察了镀膜前后样品在10% (质量分数) NaOH溶液中的腐蚀行为。利用X射线衍射仪、扫描电子显微镜及能谱仪分别对薄膜的物相组成、表面及截面形貌、膜层厚度进行了测试分析。结果表明，阳极氧化后得到的复合薄膜由钽酸锂和氧化钽组成；该薄膜与基体之间结合良好，厚度约3 μm；镀膜后样品的质量腐蚀速率至少减少了6倍，腐蚀电流密度下降了2个数量级，腐蚀96 h后样品表面没有明显变化。而对比的纯钽样品却发生了严重的腐蚀反应，生成了很多长条状和多棱柱状的腐蚀产物Na₃TaO₄、Na₂Ta₂O₆和Na₈Ta₆O₁₉。

Corrosion Behavior of Anodic Oxide LiTaO3 Thin Film in NaOH Solution

Lithium tantalate (LiTaO₃) thin film was synthesized on high purity tantalum foil in molten LiNO₃via anodic oxidation. Then corrosion behavior of the LiTaO₃ coated Ta foil was studied in 10% (mass fraction) NaOH solution by means of immersion corrosion test and electrochemical measurement. While the LiTaO₃ coated Ta foil before and after corrosion test was characterized with X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively. Results showed that the anodic oxidation thin film consists of LiTaO₃ and tantalum oxides. The film was 3 μm in thickness and well bounded to the Ta matrix. The corrosion rate of the anodic oxidation thin film coated Ta foil was 1/6 that of the plain Ta foil, correspondingly, the corrosion current density of the former was two order magnitude lower than that of the later. Moreover, the morphology of the anodic oxidation thin film coated Ta foil remains unchanged even after 96 h immersion test. In contract, the plain Ta foil underwent severely corrosion with formation of rod-like and prism-like corrosion products of Na₃TaO₄, Na₂Ta₂O₆ and Na₈Ta₆O₁₉.