Corrosion Behaviour of Aluminium Matrix Composite Reinforced with Boron Carbide in 3.5% NaCl

Abstract

The corrosion behavior of Aluminium matrix composite reinforced with micro-size boron carbide was investigated in a 3.5% NaCl solution. The sample was prepared using the stir casting technique with compositions of 2, 4, 6, 8 and 10 wt% of B₄C particles. Potentiodynamic polarisation methods were used to derive the electrochemical parameters while hardness analysis methods were used to derive the mechanical properties. A field emission scanning electron microscope (SEM) was employed to investigate the particle boron carbide distribution on the matrix and surface morphology of the metal surface before and after the corrosion test. The X-ray diffraction (XRD) analysis was used to investigate the received powders and matrix samples for phase recognition and the presence of reinforcement particles (B₄C) in the composite samples. The findings demonstrated that in a 3.5% NaCl solution, the aluminium matrix composite corrosion rate was inferior to that of the base alloy. At the same time, the corrosion rates of the composite increased with the increase in the composition of B₄C in matrix aluminium. Passive layer breakdown due to agglomeration of boron carbide particles caused the increased corrosion rate. Hardness analysis has shown that the value of hardness was improved with the increase in the composition of B₄C in the aluminium matrix.