NaCl溶液质量分数和空蚀时间对被腐蚀铝青铜空蚀的影响

Influences of mass fraction of NaCl solution and cavitation time on cavitation erosion of corroded aluminum bronzes

将铝青铜试样分别置于0.3%、3%和6%(质量分数)的NaCl溶液中腐蚀72 h,然后利用超声空蚀装置对腐蚀后的铝青铜试样进行超声空蚀实验。借助金相显微镜、扫描电子显微镜和激光共聚焦显微镜观察试样的表面形貌,测量试样的表面粗糙度、累积质量损失、自腐蚀电位和自腐蚀电流密度。结果表明:试样在6%NaCl溶液中腐蚀后,其表面出现明显的材料剥落现象。在空蚀60 min条件下,试样的表面粗糙度和累积质量损失随着NaCl溶液质量分数增加呈总体上升趋势。自腐蚀电流密度证明空蚀后的试样的耐腐蚀性更强。经6%NaCl溶液腐蚀的试样在空蚀后期的空蚀速率有下降趋势。随着NaCl溶液质量分数的增加,被腐蚀试样的空蚀加剧;当NaCl溶液质量分数达到6%时,由于Cu2O氧化膜的存在,材料的去除速率降低,材料的累积质量损失率与溶液的质量分数之间不存在正相关关系。累积质量损失随着空蚀时间的延长不断增加;同时,试样表面出现硬化层,截面硬度沿深度方向逐渐下降。

The aluminum bronze samples were corroded by 0.3%,3%and 6%NaCl solution for 72 h,and then the ultrasonic cavitation experiments were carried out on corroded aluminum bronze samples using ultrasonic cavitation device.The surface morphology of the samples was observed by means of metallographic microscope,scanning electron microscope and confocal laser microscope.The surface roughness,accumulated mass loss,self-corrosion potential and self-corrosion current density of the samples were measured.The results show that after corrosion in 6%NaCl solution,the surface of the sample has obvious material-peeling phenomenon.After cavitation erosion for 60 min,the surface roughness and accumulated mass loss of the samples increase with the increase of NaCl solution mass fraction.The corrosion current density proves that the corrosion resistance of the sample after cavitation erosion is stronger.For the samples corroded by 6%NaCl solution,the cavitation erosion rate tends to decrease in the later stage of cavitation erosion.The cavitation erosion of corroded samples is intensified with the increase of NaCl solution mass fraction.When the NaCl solution mass fraction reaches a certain value,the removal rate of the material decreases due to the presence of Cu2O oxide film,and there is no positive correlation between the cumulative mass loss rate of the material and the NaCl solution mass fraction.The accumulated mass loss increases with the prolonging of cavitation impact.Meanwhile,a hardened layer appears on the surface of the sample,and the cross-section hardness decreases gradually along the depth direction.