The Electrochemical and Microstructure Effects of TiB2 and SiC Addition to AA5052/Al2O3 Surface Composite Coatings in 0.5 M H2SO4 Solution

In this work, Al2O3, SiC, and TiB2 ceramic coatings with different formulations were produced on the surface of AA5052 matrix by gas tungsten arc welding (GTAW). The corrosion behavior of the composites and the base metal (BM) was evaluated in a solution of 0.5 M H2SO4 with electrochemical techniques such as open circuit potential (OCP) monitoring, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The morphology of the cladded surfaces was monitored by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Based on the PDP and EIS results, BM had the lowest corrosion rate in the 0.5 M H2SO4 solution. All composite coatings shifted to higher corrosion rate values than that of BM, indicating that AA5052 composites had lower corrosion resistance compared to the BM. SEM images of the corroded surface of BM exhibit minimum pitting corrosion in sulfuric acid media. According to electrochemical studies, AA5052/Al2O3 + SiC + TiB2 composite had the lowest corrosion resistance due to the formation of micro-galvanic sites on the aluminum matrix surface. However, the AA5052/Al2O3 + TiB2 composite showed the best corrosion performance compared to other composites. In general, by adding SiC and TiB2 ceramics to Al2O3 and fabricating binary composites, the corrosion resistance of AA5052/Al2O3 composite is improved. Although the corrosion resistance of AA5052 composites is lower than the BM, their higher surface hardness makes their use justified in applications where high mechanical properties are required if the environment is not too aggressive.