Corrosion inhibition analysis on cerium induced hydrophobic surface of Al-6061/SiC/Al2O3 hybrid composites

Abstract

A new kind Al-6061/SiC/Al2O3 hybrid composite was prepared with traces amount of cerium oxide and its corrosion performance was evaluated by potentio-dynamic polarization electrochemical method. A new kind of intermetallic (γ-phase) has been observed in the microstructure with higher content of cerium oxide and Al elements. The corrosion resistance of Al-6061 alloy improved with addition of cerium oxide and this improvement could attribute to depression of the micro-galvanic couples. The corrosion rates were observed as 0.16 and 0.034 mpy corresponding to 3.5 and 2.5 wt% of NaCl corresponding to 2.5 wt% of cerium oxide. Moreover, the formation of cerium oxide and Al enrichment film over the surface of hybrid composites was also found to be main key factor for the inhibition of corrosion resistance. Another key factor that inhibits the further corrosion was observed as hydrophobicity between the aluminium liquid matrix and Al2O3/SiC reinforcement after incorporation of cerium oxide. Improvement in hydrophobicity of composites with Al2O3/SiC is due to increase in contact angle up to 100.78° after addition of 2.5 wt% cerium oxide. Micro-hardness and impact strength of the hybrid composites improved significantly after addition of traces amount of REOs from 0.5 to 2.5 wt%.