Study of the influence of roughness on the gonioapparency of anodized titanium

The visual impact of a product plays a key role in the consumer-perceived quality of the product. Coatings are a good solution to improve the quality of a product by either changing its appearance or add a new property, such as corrosion protection. Anodized titanium exhibits a wide range of colors, and in some cases gonioapparency, that is color changes depending on the observation and/or the illumination directions. It also offers other properties such as corrosion protection or photocatalysis. With the development of goniospectrophotometers, the colors of gonioapparent anodized titanium can be characterized but the parameters influencing the color or its gonioapparency remain unclear. The present study focuses on the influence of the roughness on the color of anodized titanium samples through measurements and optical modeling. Colors have been characterized through BRDF measurements but future comparisons between measured and perceived colors are planned. A specific device dedicated to these perception tests has been designed and is presented in the present paper.