Titanium anodisation designed for surface colouration - Systemisation of parametric interaction using response surface methodology

This work statistically examines the influence of operating parameters on the thin oxide layer developed during titaniumanodisation and the complexity of parameter interactions on the surface colouration. The optimal parametric combinations for obtaining desired oxide thickness and interference colours are investigated. A three parametric Doehlert experimental designwas employed for the purpose. Reliable regressionmodelswere developed for oxide thickness (Tmeas), and colour specification viz., lightness (L*) and hue angle (h) with determination coefficients of 0.970, 0.988 and 0.998, respectively. The three chosen parameters namely operating voltage (V), electrolyte concentration (C), and operating temperature (T) were found to have significant interactions during anodisationwhich are analysed through a response surface. The oxide thicknesswas found to be influenced by all three parameters. It was additionally found to have multiple optimal parametric combinations for a desirable outcome because of the interactions; the lightness was found to be significantly affected by the interactions of electrolyte concentration and operating temperature; the expected periodicity in hue angle, as reported in literature, persisted amidst parameter interactions with mild variations to the trend. Furthermore, interdependencies were found among the developed regression models. (C) 2017 Elsevier Ltd. All rights reserved.