Effect of Grain Size and Initial Surface Condition on Glossiness and Whiteness of the Pickled Titanium Surface

摘要

Titanium has been applied to roofs and walls of buildings due to its high corrosion resistance and dull finishes to reduce dazzling are demanded to the application. The dissolution of product surfaces by the nitric-hydrofluoric acid solutions is known as the way to improve the surface finish for reducing dazzling. The authors have investigated the effects of the grain size and initial surface conditions on the glossiness and the whiteness of the dissolved titanium surface. Consequently with decreasing grain sizes the unevenness of the surfaces becomes fine and the glossiness decreases because the unevenness with the same size as that of grains is formed. The effects of the initial surface conditions on the glossiness are different according to the grain sizes. In the case of coarse grains the glossiness remains constant because the unevenness of the dissolved surfaces is nearly equal to initial one. But in the case of fine grains fine unevenness by dissolving plays a dominant role in glossiness. The whiteness increases sharply by short dipping in the mixed acid regardless of initial surface conditions.