Electrochemical assessment of erosion-corrosion of commercially pure titanium and a titanium alloy in slurry impingement

The economic and effective operation of machinery and plant involved in fluids handling is increasingly dependent on the utilization of materials that combine high corrosion resistance and good wear resistance. This paper focuses on erosion-corrosion where mechanical wear is due to impacting solid particles entrained in a liquid flow. The characteristics of commercially pure (CP) titanium (grade 2) and titanium alloy (Ti 5111) in erosion-corrosion conditions are assessed. There is much literature available on the corrosion behaviour of titanium and titanium alloys but little has been reported on corrosion in wear environments. The erosion-corrosion characteristics of each material at 18 and 50degreesC were assessed using an impinging jet apparatus. The tests were performed in a 3.5% NaCl saline solution. Experiments were conducted to determine the mass loss by combined erosion-corrosion processes before independently determining the electrochemical corrosion mass loss and the mechanical mass loss. It has been shown that under erosion corrosion conditions titanium and its alloys exhibit active corrosion behaviour, in contrast to passive behaviour when the tenacious oxide film remains intact in static conditions. The synergistic effect between erosion and corrosion is significant and is dependent on the material.