SiCp/2024Al基复合材料的点蚀行为

采用动电位阳极极化法对17%SiCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性进行了研究.结果表明:SiC颗粒的加入并不影响SiCp/2024Al基复合材料的点蚀敏感性,但与基体相比,其耐蚀性有所下降.对极化后和长期浸泡试样的腐蚀形貌观察发现:与基体相比,SiCp/2024Al基复合材料表面上的蚀孔数量相对较多,蚀孔尺寸稍小,大小分布不均匀;最大蚀孔较深,并有严重的裂缝腐蚀;裂缝腐蚀的存在会使SiCp/2024Al基复合材料的点蚀抗力明显降低.能谱分析表明:SiCp/2024Al基复合材料的腐蚀机制为富Cu阴极相与贫Cu阳极相间的电偶腐蚀,另外,SiC与Al间也存在电偶腐蚀倾向.

Pitting behavior of SiCp/2024Al metal matrix composite

The corrosion resistance of 17% SiC_p/2024Al metal matrix composite (MMC) and 2024Al in 3.5% NaCl solution was investigated by potentiodynamic polarization. The results show that pitting susceptibility is about the same for SiC_p/2024Al MMC and its matrix alloy. The corrosion resistance for SiC_p/2024Al MMC is lower than that for the matrix. Pit morphology was observed with scanning electric microscope. After anodic polarisation in ~3.5% NaCl solution, pits on SiC_p/2024Al MMC are more numerous, a little smaller and non-uniform in size compared with that on 2024Al, and severe crevice corrosion is only found at the bottom of pit on SiC_p/2024Al MMC. The biggest pits on the long-term immersion SiC_p/2024Al MMC are slightly deeper than that on 2024Al, and crevice corrosion is only found on SiC_p/2024Al MMC. The crevice corrosion can make SiC_p/2024Al MMC possess lower pitting corrosion resistance. The corrosion mechanism of SiC_p/2024Al MMC is galvanic corrosion between the phase rich in Cu and the matrix, as well as between the SiC and the matrix.