Anodizing of Ti6Al4V alloy for aeronautical applications

Abstract

The anodizing of Ti6Al4V alloy to improve adhesive bonding for aeronautical applications was investigated. Two electrolytes containing a) hydrogen peroxide (H 2 O 2 ) and sodium hydroxide (NaOH) and b) chromium trioxide (CrO 3 ) and ammonium bifloride (NH 4 F 2 ) were used. Anodizing was carried out at 10 V and 303 K for different times. Scanning electron microscopy, confocal microscopy and contact angle measurements with the sessile drop method were used to study morphology, roughness and wettability of the anodic films. The morphology of the anodic layers revealed the presence of randomly distributed pores on the surface whose diameters depend on the anodizing solution, being greater than 150 nm for the basic anodizing solution and less than 100 nm, when the anodizing is carried out in acid anodizing solution. Two key aspects that Ti6Al4V alloy surface must has to favor its adhesive bond to other materials are wettability and roughness. According to the results obtained, the anodic layers formed with acid solution for 30 min have the best wettability conditions and the greater surface roughness, compared with the anodic layers formed by other study conditions. These anodic layers will favor the application of epoxy adhesives normally used for adhesive bonding of Ti6Al4V alloy to polymeric materials.