Synergistic erosion-corrosion behavior of commercially pure titanium at various impingement angles

The characteristics of commercially pure titanium (CP-Ti) in erosion and erosion-corrosion conditions have been studied. The erosion-corrosion tests were carried out using a slurry impingement rig in a 3.5% NaCl solution containing 60 g/l SiO2 particles with average size of 250-500 μm at a jet velocity of 4 m/s under impingement angles of 20-90°. The pure erosion tests were also performed by applying a potential of −1 V versus open circuit potential. The corrosion behavior of CP-Ti alloy in both stagnant and the erosion-corrosion conditions were studied using polarization technique and the synergy values were calculated. Erosion and erosion-corrosion mechanisms were determined using scanning electron microscopy. The results showed that the maximum erosion and erosion-corrosion rates occurred at an impingement angle of 40°. The impact of particles during the erosion-corrosion increased the corrosion rate to a maximum of about 2300 times compared with the stagnant condition. The results also showed positive synergisms at all impingement angles with the rates significantly higher than the pure erosion rates. It was found that about 75-90% of the removal rate in erosion-corrosion was related to the effect of corrosion on erosion.