Application of Taguchi Method to Study Morphological Evolution of TiO2 Nanotubes Obtained Via Anodization Process

The growth of titanium dioxide nanotubes (TiO2) via anodization process depends on the controlling parameters such as applied potential, anodization time, and electrolyte composition. In the present work, the Taguchi method was applied to evaluate statistically the influence of the anodization parameters on the morphology of anodized TiO2 films. Mixture of ethylene-glycol and glycerol was used as an electrolyte and the settings of the experimental design were parameterized on the basis of four important anodization factors consisting of chemical pretreatment, amount of fluoride, water content and applied potential. Samples were characterized by XRD and FEG-SEM. Based on 4 variables at 3 different settings, full factorial plan requires 34 = 81 tests. In this work the experiment was designed on the basis of an L9 (34) orthogonal array (4 variables, 3 levels, 9 tests). The optimum conditions were found on the basis of smaller-is-better and larger-is-better analyses. The signal-to-noise ratio was employed to find optimal process parameters levels and to analyze the influence of these parameters on the tubular length, internal and external diameters and formation of nanograss on the film surface. Hence, it is clearly shown that the performance of TiO2 nanotubes can be evaluated by the Taguchi method.二氧化钛纳米管（titanium dioxide nanotubes, TiO₂）的阳极氧化生长过程受工艺控制参数影响，涵盖外加电压、阳极氧化时间与电解液组分。本研究采用田口方法（Taguchi method），从统计学视角定量分析阳极氧化参数对阳极氧化TiO₂薄膜形貌的调控作用。实验以乙二醇与甘油的混合液作为电解液，实验设计的参数设置基于四大关键阳极氧化因子确立，分别为化学预处理步骤、氟化物添加量、含水量与外加电压。采用X射线衍射（XRD）与场发射扫描电子显微镜（FEG-SEM）对制备的样品进行表征。当存在4个变量且各变量设置3个水平时，全因子实验方案需开展3⁴=81组测试。本研究采用L9(3⁴)正交表设计实验，共包含4个变量、3个水平，总计9组测试。基于望小特性与望大特性分析确定最优工艺条件。采用信噪比法筛选最优工艺参数水平，并解析这些参数对纳米管长度、内外管径以及薄膜表面纳米草状结构形成的影响。综上，田口方法可有效用于评估二氧化钛纳米管的制备性能。