溫度對溴化鋰溶液中Ti-6Al-4V初期空蝕行為的影響

溫度對溴化鋰溶液中Ti-6Al-4V初期空蝕行為的影響Effect of temperature on initial cavitation corrosion for Ti-6Al-4V in lithium bromide solution

采用三維視頻顯微鏡、粗糙度輪廓儀和電化學測試研究溴化鋰溶液中不同溫度條件下Ti-6Al-4V微觀空蝕形貌、粗糙度以及電化學腐蝕行為，探討溫度對空蝕的影響機理。結(jié)果表明：溫度的影響隨空蝕時間增加不斷加強，240 min時最為顯著，之后影響減弱并趨于穩(wěn)定。溫度升高，空泡潰滅產(chǎn)生的微射流沖擊強度增大，使表面鈍化膜更易被破壞，同時腐蝕作用加速了點蝕形成，導致表面局部應力集中和更多電化學電池的產(chǎn)生，從而促進了力學和腐蝕因素，兩者的協(xié)同作用加速了空蝕破壞?？瘴g破壞程度在溫度55 ℃時達到最大值，繼續(xù)升高溫度，腐蝕因素仍被促進，但微射流對表面的沖擊強度減弱，對表面鈍化膜的破壞作用降低，由于力學因素在空蝕中占據(jù)主導地位，因此使空蝕速率得到減緩。

Three-dimensional video microscope, roughness profiler and electrochemical measurement were used to investigate the cavitation corrosion morphologies, surface roughness and electrochemical corrosion behavior of Ti-4Al-4V in LiBr solution at different temperatures. Furthermore, the influence mechanism of temperature on cavitation corrosion was discussed. The results show that the temperature effect is gradually strengthened as cavitation time increasing. It is most significant for 240 min, after that, it is reduced and tends to be stable. The rise in temperature enhances micro-jet impact strength, and the passive film on the surface is easy to be damaged. Simultaneously, the corrosion effect promotes the growth of more pits, which leads to the concentration of local stress and the formation of more electrochemical cell. As a result, the mechanical and electrochemical corrosion factors are promoted. The synergetic effect accelerates the cavitation corrosion. The damage of cavitation corrosion reaches a maximum value at 55 ℃. Afterwards, the continuous increase of temperature improves the corrosion effect. However, the attenuation of impact strength of micro-jets weakens the destruction of surface passivation film. The mechanical effect plays a dominant role in cavitation erosion, accordingly the cavitation corrosion rate is mitigated.

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