论文部分内容阅读
利用粗糙度轮廓仪、SEM、三维视频显微镜和电化学测试技术研究了纯Ti (TA2)在LiBr溶液中的空化腐蚀过程,探讨了腐蚀与空化的协同作用.结果表明,材料受到空化冲击作用后,表面产生不均匀的塑性变形.随着空化腐蚀的进行,TA2表面塑性变形程度继续增大,晶界处位错密度的增加使晶界处应力更加集中,进而导致材料表面晶界处发生轻微的脱落,局部产生裂纹,表面粗糙度Rq呈线性增长.随后裂纹沿着晶界或向晶粒内部继续扩展,材料脱落逐渐加剧,同时材料表面钝化膜因力学作用受到破坏,露出新鲜的基体,促进了LiBr的腐蚀作用.空化与腐蚀的协同作用加速了腐蚀坑的加深与扩展,但腐蚀坑周边的材料脱落降低了材料的凹凸程度,材料表面粗糙度的增长速度减缓,直至最后进入稳定阶段.“,”The evolution of cavitation-corrosion of pure titanium TA2 in LiBr solution was investigated by roughness profiler,scanning electronic microscope (SEM) and three-dimensional video microscope,while the combined action of corrosion and cavitation was examined by electrochemical measurement technologies.Results show that there was uneven plastic deformation firstly under the action of cavitation,and as the cavitation test continued,the degree of plastic deformation and the dislocation density at grain boundaries increased,causing the concentration of stress and slight falling off of materials of grain boundaries.Cracks were generated locally,while the surface roughness value (Pq) increased linearly with time.Then cracks propagated along grain boundaries or through grains,then the falling of material increased.At the same time,the passive film on the surface was easily attacked and therewith the fresh titanium substrate was exposed,which promoted the corrosive effect of lithium bromide.The synergistic effect of mechanics and corrosion may accelerate the deepening and expending of corrosion pits,eventually the materials on the periphery of corrosion pits fell off,and thereby the degree of surface concave and convex became smaller,the growth rate of Rq decreased,at the end,the value of Rq tended to stabilize.