TiO2纳米粒子对铝锂合金微弧氧化膜结构及性能的影响

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

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SiO32-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。

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 SiO32- 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.