Effect of MoO3 ceramic oxide reinforcement particulates on the microstructure and corrosion behaviour of Al alloy composites processed by P/M route

Abstract

The corrosion behaviour of Al-MoO3 powder metallurgy processed composites was investigated in this paper. The weight percentage of the molybdenum trioxide was varied as 5, 10 and 15 % to obtain the test samples. The effect of the reinforcement weight percent on the corrosion behaviour was investigated through the Tafel extrapolation method. Furthermore, the effect of corrosion medium temperature i.e. 3.5 % sodium chloride solution on the corrosion behaviour was also studied. The corrosion rates of the composites obtained as a result of polarization experiment through Tafel extrapolation method were checked for its validation. The comparative analysis was undergone with weight loss and solution analysis tests. The corrosion rates derived from the potentiodynamic polarization technique test disclosed that, at both room and elevated temperature of the NaCl solution, the corrosion resistance of the composites improved with the addition of MoO3. This finding was also substantiated by the observance of less surface degradation in the SEM images of the composites incorporated with more MoO3 content. The temperature-induced corrosion behaviour was investigated by immersing in corrosion medium at 27 °C and 80 °C and the elevation of corrosion rate in high-temperature corrosion medium was confirmed. Based on the above results, Al alloys reinforced with MoO3 will be a suitable candidate for heat transfer applications where high erosion-corrosion is encountered in addition to mechanical damage.