Cavitation Corrosion Behavior of TC4 Titanium Alloy in Lithium Bromide Solution

The cavitation corrosion behaviors of TC4 alloy in both distilled water and 38% LiBr solution were investigated using an ultrasound cavitation facility at 25 ℃.The morphology of damaged surfaces was observed by scanning electron microscope (SEM).The cumulative mass loss and surface roughness were measured.The potentiodynamic polarization curves were tested under static and cavitation conditions.The results show that the cumulative mass loss of TC4 in LiBr solution increased during cavitation compared with in distilled water.Compared with static condition,the free corrosion potential shifted to the positive direction by 230 mV and the electrochemical corrosion rate was increased by one order of magnitude in cavitation condition.The morphology of damaged surfaces in LiBr solution was similar to that in distilled water.In both solutions cracks and etch pits appeared at the initial stage and then turned out to be a honeycomb appearance.The effect of mechanics was the dominant factor of mass loss under cavitation condition in LiBr solution,while the accelerating impact of electrochemical corrosion was more obvious in synergetic effect.