Effect of nano alumina content on corrosion behavior and microstructure of Za27/graphite/alumina hybrid nanocomposites

Abstract

In this study, the effect of the addition of nano-graphite and nano-alumina particles on the corrosion behavior and microstructures of ZA27 matrix hybrid nanocomposites (HNCs) was investigated. ZA27 based HNC powders were produced using mechanical milling method to obtain close homogenous distribution of the reinforcement particles in ZA27 matrix followed by hot pressing technique. Before and after corrosion tests, the microstructures of these nanocomposites were characterized using a scanning electron microscope (SEM). The corrosion behavior of hybrid nanocomposites was assessed using potentiodynamic polarization scans in 3.5% NaCl solution. The corrosion experiment results indicate that corrosion rate (85.5 mpy) of ZA27/2 vol% Al2O3-1 vol% Graphite were much higher than that of ZA27 matrix (345.5 mpy) and ZA27/1 vol% Al2O3-1 vol% Graphite nano composite (104.2 mpy). HNCs with 1%vol. nano-graphite and 2%vol. nano-alumina showed about four times higher corrosion resistance than unreinforced ZA27 matrix alloy. An increase in the corrosion rate was discussed in relation to the nano size reinforcement and porosity contents. The results showed that higher reinforcement and porosity content had an adverse effect on the corrosion behavior of hybrid nanocomposites. Keywords: Hybrid nanocomposites, Potentiodynamic polarization, ZA27 alloy