Mojtaba Esmailzadeh

In this study, the effects of SiC and TiB2 reinforcement particles on the corrosion behaviors of the surface composites of an Al5052 substrate produced with a gas tungsten arc welding (GTAW) technique were investigated. The electrochemical behaviors of the base metal (BM) and surface composites were evaluated by open-circuit potential monitoring, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in two solutions: 0.5 M H2SO4 and 3.5% NaCl. The results of PDP and EIS showed that by adding reinforcement particles on the surface, the corrosion resistance decreased in both environments relative to BM. Among Al5052-based surface composites, the AA5052/SiC + TiB2 composite in 3.5% NaCl solution and AA5052/TiB2 in H2SO4 solution showed the lowest corrosion resistance due to the formation of microgalvanic couples in the Al matrix. The corrosion resistance of Al5052-based surface composites in 3.5% NaCl solution was much better than that in 0.5 M H2SO4. Furthermore, scanning electron microscopy (SEM) analysis confirmed the PDP and EIS results. The SEM image of the corroded surface of AA5052/TiB2 exhibited severe pitting corrosion in both solutions relative to the other composites. In contrast, the AA5052/SiC composite showed a relatively lower corrosion rate in both 3.5% NaCl and 0.5 M H2SO4. Hardness tests provided evidence for improved mechanical properties of the composites in comparison with the BM. In particular, composites containing TiB2 showed the highest hardness, followed by AA5052/SiC + TiB2 composites.