ZQAl9-4-4-2镍铝青铜在2.4%NaCl溶液中的空蚀行为

CAVITATION EROSION BEHAVIOR OF A CAST NICKEL-ALUMINUM BRONZE IN 2.4%NaCl SOLUTION

利用磁致伸缩空蚀试验机研究了ZQAl9-4-4-2镍铝青铜在2.4%NaCl溶液中的空蚀行为.结果表明:空蚀使ZQAl9-4-4-2镍铝青铜的自腐蚀电位正移约16 mV,使电化学腐蚀速率增大8倍;2.4%NaCl溶液中空蚀最大失重率是蒸馏水中的2.1倍.在腐蚀与空蚀的交互作用中,力学因素起了至关重要的作用,纯空蚀失重分量占总失重量57.3%,腐蚀因素作用相对较小.微裂纹首先在α/κ相界的α相部分形成;随着空蚀的进行,这些微裂纹在α相内合并扩展导致α相出现失重,κ相也随之剥离基体.空蚀微裂纹易于横向扩展而向深度方向受阻.试样表面均匀剥落,未出现大的海绵状的空蚀坑.ZQAl9-4-4-2镍铝青铜较好的加工硬化能力,是其具有良好的抗空蚀性能的关键所在.

The cavitation erosion （CE） behavior of ZQA19-4-4-2 nickel-aluminium bronze in 2. 4% NaCl solution was investigated by using a magnetostrictive - induced cavitation facility. The micrographs of damaged surfaces were observed by scanning electron microscope （SEM）. The role of corrosion was analyzed by using polarization curve. The results showed that cavitation shifted the free corrosion potential in positive direction by about 16mV,and increased the corrosion rate by 8 times. The maximum value of the cumulative mass loss in 2. 4% NaCl was about 2. 1 times to that in distilled water. It was confirmed that the erosion played an important role in the synergistic effect under cavitation erosion condition and pure erosion took up 57.3% of the total mass loss ,and only a small fraction of the damage arose from electrochemical corrosion. SEM observation of eroded specimen indicated that the cavitation microcracks initiated in the α phase adjacent to the κ phase. They propagated and connected with each other in α phases, resuited in the removal of α phases and detachment of the κ phase from the matrix in the following test period followed. The microcracks tended to ening rate of the ZQA19-4-4-2 nickel- aluminium bronze was attributed to its good cavitation erosion resistance.