Micro‐electrochemical investigation of the passive behavior of thin anodic titanium oxide films on TiAlV6‐4

Abstract

The present work describes the passive film behavior of thin anodic oxide films on polycrystalline TiAlV6‐4. Firstly, the influence of the microstructure was addressed. Therefore, the crystallographic grain orientations of the substrate were determined by EBSD and selected grains were investigated with an electrochemical micro‐capillary cell. The barrier‐like oxide films were produced by local anodization in an acetate buffered electrolyte (pH 5.9) and investigated by electrochemical impedance spectroscopy and optical reflectometry. Second, the chemical composition of the native oxide film was determined by XPS, and the results related with the micro‐electrochemical experiments. The work shows a strong effect of the basal orientation on the electrochemical behavior. During anodic oxidation, strong electron transfer reactions occur at this orientation, while the enhanced conductivity of the oxide film is also proved by electrochemical impedance spectroscopy. Moreover, a non‐highfield conformal oxide growth and crystallization was observed on the basal plane. These effects, especially the electron conductivity, is related to the incorporation of alloying elements in the passive film.

Effect of plasma electrolytic oxidation on the hot salt corrosion fatigue behavior of the TC17 titanium alloy

“…Titanium alloy has become the main material of choice for the manufacture of aero-engine compressors due to its high specific strength, wide operating temperature range, good high-temperature mechanical properties, and excellent corrosion resistance. [1,2] However, for carrier-borne aircraft and aircraft in-service on islands and reefs, due to the large amount of salt spray in the atmospheric environment, sodium chloride (NaCl) particles in the atmosphere enter the engine inlet with the air stream. Consequently, this salt will inevitably attach to engine-compressor parts in-service.…”