Effects of manufacturing parameters on the corrosion behavior of Al–B4C nanocomposites

Abstract

The purpose of this paper is to investigate the microstructural and corrosion behaviors of Al–B4C nanocomposites fabricated by the stir casting technique. Two parameters included the stirring time and temperature have changed in the manufacturing process to affect the characteristics of nanocomposites. Both the optical microscopy (OM) and the field emission scanning electron microscopy (FESEM) were utilized for microstructural evaluations. Moreover, the X-ray diffraction (XRD) and the energy dispersive spectroscopy (EDS) methods were used to identify various phases and to study the elemental analysis of specimens, respectively. In addition, the polarization and electrochemical impedance spectroscopy (EIS) techniques were employed to peruse the corrosion properties of fabricated nanocomposites in various corrosive environments. The FESEM images showed that B4C nanoparticles were distributed uniformly in the aluminum matrix. Polarization test results demonstrated that the corrosion rate of Al–B4C nanocomposites decreased to lower than 99% compared to the aluminum alloy in 0.6 M NaCl solution; however, such a reduction was about 22–42% in 2 M NaOH solution. The EIS test results depicted that the total increase in the charge transfer resistance values for Al–B4C nanocomposites was about 23–59% with respect to the aluminum matrix in 0.1 M HCl solution. Regression analysis results displayed that for acidic solutions (such as HCl and H3BO3) the stirring temperature was more effective than the stirring time to reduce the corrosion rate.