Fabrication, Surface Morphology and Corrosion Investigation of Al 7075-Al2O3 Matrix Composite in Sea Water and Industrial Environment

Abstract

Al 7075 matrix composites are widely used in structural and aerospace industry because of its higher hardness, wear resistance and strength to weight ratio. But properties such as low formability and poor corrosion resistance restrict its wider usage. Therefore this experiment is performed to investigate distribution of higher percentage of reinforcement in matrix and to study the corrosion behaviour of base Al 7075 alloy and Al 7075 reinforced with 10% wt and 15% wt of Al 2 O 3 fabricated by stir casting method. Metallographic study of composite was carried out using optical microscope, XRD, SEM with EDX. Density of prepared composite was determined by Archimedes principle. Corrosion study was performed in Sea water and industrial environment for three different samples, Al 7075 monolithic alloy, Al 7075 reinforced with 10% and 15% wt of Al 2 O 3 particles. Experiments were conducted using electrochemical analyzer using Tafel Polarization Technique (TPT). From the analysis of SEM images it reveals that pitting corrosion was observed in sea water environment and inter granular corrosion was observed in industrial environment. It was observed that corrosion rate of Al 7075 increases with increase in reinforcement volume and Al 7075 undergoes severe corrosion in sea water environment than Industrial environment. Tafel polarization measurement of corroded Al 7075-Al 2 O 3 (15%wt) in seawater environment and industrial environment is shown below