TC4钛合金在溴化锂水溶液中的空蚀行为

Cavitation Corrosion Behavior of TC4 Titanium Alloy in Lithium Bromide Solution

利用超声波气蚀试验机研究了TC4钛合金在温度为25℃蒸馏水和38%溴化锂水溶液中的空蚀行为。利用扫描电镜跟踪观察了空蚀形貌,测量了空蚀条件下的累积失重以及表面粗糙度的变化,对比了其在溴化锂溶液中静态和空蚀条件下的动电位极化曲线。结果表明,在空蚀相同时间条件下,TC4在溴化锂溶液中的累积失重量相比蒸馏水中有所升高。与静态相比,空化使TC4的自腐蚀电位正移近230mV,电化学腐蚀速率增加一个数量级。两种介质中的空蚀形貌相似,都是由初期出现裂纹和蚀坑发展到后期的蜂巢状结构。在溴化锂水溶液空蚀过程中,力学因素是造成腐蚀磨损失重的主要因素,但在交互作用中腐蚀对空蚀的促进作用更为明显。

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.