纯钛表面不同厚度微弧氧化膜的形貌及相结构分析

Effects of Film Thickness on the Phase Composition and Microstructure Properties of Micro-arc Oxidation Coating

本研究采用微弧氧化(micro-arc oxidation,MAO)技术,并通过控制微弧氧化处理时间,在经过抛光和清洗的商业纯钛表面分别获得5、10和20μm的TiO2及相关钛氧化物陶瓷膜层。利用扫描电镜(scanning electron microscopy,SEM)分析表征膜层厚度及表面形貌,X线衍射(X-ray diffraction,XRD)分析表征膜层晶相组成。结果表明:5μm厚的MAO膜,表面呈多孔状,较为平整,孔径较小。XRD谱线中除了突出的钛基体衍射峰外,只出现了锐钛矿的衍射峰。膜厚为10μm时,表面形貌与5μm相似,但孔径大小分布更为均匀,在2μm左右。XRD谱线中钛峰强度下降,出现了金红石型TiO2的衍射峰,但仍以锐钛矿型TiO2占主导地位。膜厚为20μm时,表面孔径进一步增大,达到4～6μm,同时可见陶瓷层表面有的地方出现了破损和裂纹。XRD谱线中钛峰弱小,金红石和锐钛矿型TiO2的衍射峰仍然分别存在,但所占比例发生变化,同时还出现了Ca(Ti2P3O12)2、CaTi O3的衍射峰。除此之外,不同膜层厚度的表面粗糙度也有较大差异。膜层厚度的改变能够显著影响MAO陶瓷层的特性,通过改变厚度,我们能够在纯钛表面获得不同组分、结构和化学特性的陶瓷膜。

In this study,we obtained the TiO2 films with different thickness by micro-arc oxidation（MAO） on commercially available pure titanium.By altering the duration time,we got the films 5 μm,10 μm,and 20 μm in thickness,respectively.XRD and SEM were employed to characterize the phase,composition and microstructure of the films.The MAO film,which was about 5 μm thick, was porous and even with the pore size about 1 μm.No other crystalline phase except anatase was detected by XRD.The film,which was 10 μm thick,was similar to the former.The pores were well separated and homogeneously distributed over the surface. The XRD pattern indicated that the film was composed of anatase and a minor amount of rutile,whereas the pore size of 20 μm film was about 4-6 μm and was bigger than the others.Furthermore,the small cracks were easy to observe.XRD pattern showed that the Ti peak was significantly reduced and new Ca,P,O containing compound was formed in addition to rutile and anatase with the film thickness increasing.There were significant differences in regard to surface roughness of the three groups.These findings suggest that the film thickness has an intense effect on the quality of the MAO coating.By changing the film thickness,we can extensively change the composition,structure and chemical properties of the surface layer on titanium.