Galvanic Corrosion Performance of an Al-BN Abradable Seal Coating System in Chloride Solution

In this study, we investigated the galvanic corrosion performance of an Aluminum-Boron Nitride (Al-BN) abradable seal coating system (with a Ni5Al bond layer and a 0Cr17Ni4Cu4Nb substrate) in chloride solution by electrochemical methods. The results indicated a three-stage process occurred during the anodic dissolution of the coupled coating system, consisting of a spontaneous pitting stage I under charge transfer control with a decreasing rate, a corrosion developing stage II under mass transfer control with an increasing rate, and a final steady stage III. Precipitation of Al(OH)(3) restricts the oxygen transport process to the cathode and induces localized acidification of the occluded pores of the Al-BN layer, which was the mechanism that could explain the changes of corrosion performance during the three immersion stages of Al-BN coating system. The study suggests that galvanic corrosion of the porous multi-layer Al-BN abradable coating system is mostly influenced by its corrosion product deposition.

Automated summary

The galvanic corrosion of the porous multi-layer Al-BN abradable coating system is mainly influenced by the deposition of its corrosion products, leading to a three-stage process in chloride solution.