TC4鈦合金在溴化鋰水溶液中的空蝕行為Cavitation Corrosion Behavior of TC4 Titanium Alloy in Lithium Bromide Solution
利用超聲波氣蝕試驗(yàn)機(jī)研究了TC4鈦合金在溫度為25 ℃蒸餾水和38%溴化鋰水溶液中的空蝕行為.利用掃描電鏡跟蹤觀察了空蝕形貌,測量了空蝕條件下的累積失重以及表面粗糙度的變化,對比了其在溴化鋰溶液中靜態(tài)和空蝕條件下的動(dòng)電位極化曲線.結(jié)果表明,在空蝕相同時(shí)間條件下,TC4在溴化鋰溶液中的累積失重量相比蒸餾水中有所升高.與靜態(tài)相比,空化使TC4的自腐蝕電位正移近230 mV,電化學(xué)腐蝕速率增加一個(gè)數(shù)量級.兩種介質(zhì)中的空蝕形貌相似,都是由初期出現(xiàn)裂紋和蝕坑發(fā)展到后期的蜂巢狀結(jié)構(gòu).在溴化鋰水溶液空蝕過程中,力學(xué)因素是造成腐蝕磨損失重的主要因素,但在交互作用中腐蝕對空蝕的促進(jìn)作用更為明顯.
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.

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