15%SiC_p/2009Al复合材料在3.5%NaCl溶液中的腐蚀行为

Corrosion Behaviors of 15%SiC_p/2009Al Composite in 3.5%NaCl Solution

15%SiCp/2009Al复合材料是一种具有重要工程应用背景的先进复合材料。采用电化学方法研究了15%SiCp/2009Al复合材料在3.5%Na Cl溶液中的腐蚀行为,结果表明：复合材料与基体铝合金在NaCl溶液中的腐蚀电流随浸泡腐蚀时间延长均呈现周期性波动特征,相比之下,复合材料的平均腐蚀电流（ACC）更大;基体铝合金起始阶段的平均腐蚀电流相对较低,随着时间延长平均腐蚀电流逐渐增大;复合材料从始到终平均腐蚀电流都较高,浸泡40 h以后二者的平均腐蚀电流差异逐渐缩小。通过扫描电镜（SEM）以及能谱（EDS）观察分析了材料表面腐蚀形貌和成分,复合材料与基体铝合金均发生不均匀腐蚀。2009Al的腐蚀主要为富铜相同周围铝基体间的电偶腐蚀;复合材料的腐蚀主要发生在以下3种区域：富铜相周围的铝基体,SiC颗粒周围的铝基体,Mg2Si,SiC和Al2Cu混合相区域。SiC颗粒的作用在于造成基体铝合金的相成分发生变化,主要析出相Al2Cu的尺寸更细、颗粒数量更多,高活性铝基体区域更多,析出相周围电偶腐蚀加剧。

15% SiCp/2009 Al is an advanced composite with essential applications. The corrosion behavior of 15% SiCp/2009 Al composite in 3. 5% Na Cl solution was investigated using electrochemical methods. The corrosion current vs. time relationship of both the composite and 2009 Al showed periodical fluctuations with alternate decrease and increase. The composite had relatively higher average corrosion current(ACC） than 2009 Al. ACC of 2009 Al was lower than that of the composite at the beginning,and gradually increased with time. In contrast,ACC of the composite was always high throughout the test,with minor increase with time. ACC of 2009 Al was eventually close to that of the composite after 40 h corrosion test. The surface morphology and composition of samples after corrosion measurement were observed by scanning electron microscope(SEM） together with energy dispersive spectroscopy(EDS）. Both the composite and 2009 Al revealed inhomogeneous corrosion in 3. 5% Na Cl solution. Galvanic corrosion induced by rich copper phase and the Al matrix around was the main corrosion form of 2009 Al. The composite corrosion mainly occurred in the following three areas,the Al matrix around the rich copper phase,the Al matrix around the SiC particles and the multiphase mixture zone which included Mg2 Si,SiC and Al2 Cu phases. While,addition of SiC particles not only changed the phase composition of the Al matrix,but also reduced the size and enhanced the amount of Al2 Cu particles,as one of the main precipitate phases of 2009 Al. As a result,galvanic corrosion around the precipitate particles was accelerated because of the increased active Al area.