Effects of hard anodizing on mechanical and electrochemical characteristics of aluminum alloys under tribocorrosion condition

Abstract

In this research, the effects of hard anodizing on the mechanical and electrochemical characteristics of aluminum alloys under tribocorrosion conditions was investigated. Compared with dry conditions, friction coefficient of aluminum alloys under tribocorrosion conditions increased, whereas that of hard anodized specimens decreased. This was attributed to corrosive ions in the solution corroding the transfer film of the counter-body and tribofilm of the hard anodized specimen. In potentiodynamic polarization experiments under tribocorrosion conditions, the aluminum alloys exhibited high current density with applied load. However, at potentials above –0.05 V, current density decreased and was reversed. This is believed to be due to the corrosive ions preferentially reacting with the generated wear debris, thereby reducing the oxidation reaction with wear track. However, the current density of the hard anodized specimens increased with load and potential. In addition, the increasing rate in the wear width and depth was significant under tribocorrosion conditions (Width: 42.65 %, Depth: 32.63 %). This is due to the cavitation and fluid impact generated during friction/wear accelerating the cracking and damage of the hard anodizing film with the brittleness and porousity. However, the tribocorrosion resistance of the hard anodized aluminum alloy was improved by more than 97 %.