TiO2纳米粒子对铝锂合金微弧氧化膜结构及性能的影响

为改善微弧氧化膜层的耐蚀性及力学性能，向电解液中添加TiO₂纳米粒子后对2297铝锂合金进行了微弧氧化。利用SEM、XRD、EDS、辉光放电表征技术及电化学测试技术，分析了TiO₂纳米粒子对微弧氧化膜结构、力学性能及耐蚀性的影响。结果表明：添加TiO₂纳米粒子后，微弧氧化膜层变得平坦致密。随着TiO₂纳米粒子添加量的提高，膜层表面放电通道的孔径逐渐减小，数量逐渐增多。TiO₂纳米粒子会抑制熔融Al₂O₃与电解液中$ {\rm{SiO}}_{\rm{3}}^{{\rm{2 ^- }}}$的接触，所以膜层中Si元素的含量随TiO₂纳米粒子添加量的增加而逐渐下降(原子数分数从初始的10.27%下降到了3.10%)。显微硬度测试结果表明，TiO₂纳米粒子的引入增加了膜层的致密度及平整度，所以膜层的硬度得到了提升(添加1 g/L TiO₂纳米粒子后硬度提高了15%)。电化学测试结果显示，当微弧氧化的其它条件相同时，TiO₂纳米粒子的适量添加会提升膜层的耐蚀性，但过量添加时，由于膜层放电通道数量的增多等原因，其耐蚀性下降。

Effects of Nano-TiO2 Particles on Structure and Properties of Micro-arc Oxidation Film on Al-Li Alloy

To improve the corrosion resistance and mechanical properties of micro-arc oxidation film, 2297 Al-Li alloy was treated by micro-arc oxidation after adding TiO₂ nanoparticles into electrolyte. The effects of TiO₂ nanoparticles on the microstructure, mechanical properties and corrosion resistance of micro-arc oxidation film were studied by means of SEM, XRD, EDS, glow discharge and electrochemical test techniques. Results show that micro-arc oxidation film becomes flat and dense after addition of TiO₂ nanoparticles. With the increase of the amount of TiO₂ nanoparticles, pore size of discharge channel decreases and the number of discharge channel increases. TiO₂ nanoparticles can inhibit the contact of molten Al₂O₃ with $ {\rm{SiO}}_{\rm{3}}^{{\rm{2^- }}}$ in the electrolyte and therefore, the content of Si element in the film decreases (from initial 10.27 at.% to 3.10 at.%) as increasing TiO₂ nanoparticles additive amount. Results of micro-hardness test show that the hardness of the film is improved because the introduction of TiO₂ nanoparticles increases the compactness of the film. Micro-hardness increases by 15% after adding TiO₂ nanoparticles by 1 g/L. The appropriate addition of TiO₂ nanoparticles can improve the corrosion resistance of the film under the same micro-arc oxidation conditions, but the excessive addition will lead to the decrease of the corrosion resistance of the film due to the increase of the number of discharge channels.