Wear and corrosion behavior of multi-walled carbon nanotubes (MWCNTs) reinforced Al-15Mg2Si in-situ composites

Abstract

In this study, Al-15Mg2Si and Al-15Mg2Si-MWCNT composites were produced by a combination of semi powder metallurgy and stir casting processes and microstructure, wear and corrosion properties were investigated. MWCNTs were selected as the ideal reinforcement in this study since they possess high specific modulus and high specific strength. The first step of the production of MWCNT-containing composites was to prepare Al-MWCNT samples by a vacuum distillation setup, followed by sintering under argon gas atmosphere. Then, the prepared Al-MWCNT ingots were added to Al-15Mg2Si melt and mixed by mechanical stirring. Microstructural characterizations were carried out by x-ray diffraction (XRD), optical and scanning electron microscopies (SEM). Wear tests were conducted by reciprocating apparatus under different applied loads. Corrosion behaviors were characterized by immersion and potentiodynamic polarization tests. The results showed that large and irregular primary Mg2Si phases were formed in both composites with surrounding Chinese-script like eutectic Mg2Si phases. The volume fraction of primary Mg2Si phase in the Al-15Mg2Si composite increased after MWCNT addition. The Al-15Mg2Si-MWCNT composite exhibited significantly higher wear resistance than the Al-15Mg2Si composite. Both immersion and potentiodynamic polarization tests revealed that the corrosion resistance of Al-15Mg2Si composite deteriorated by MWCNT addition.