Influence of Specific Ball-Milling Energy on Mechanical and Corrosion Properties of Zn–0.2 Graphene Nanoplatelet Composites

Abstract

The specific amount of ball-milling energy (SBME) plays a significant role in achieving a homogenous dispersion of graphene nanoplatelets (GNPs) in metal matrix composites (MMCs). The dispersion of GNPs in the metal matrices, induced by SBME, can be adjusted to improve the mechanical and corrosion properties of the MMCs. Herein, high-energy ball milling is utilized to disperse 0.2 wt% of GNPs into zinc (Zn) powders using different SBMEs. Ball-milled powder mixtures (BMPMs) obtained at different SBMEs are cold-compacted at 500 MPa and sintered at 420 °C. The morphology of the BMPMs and the microstructure of the Zn–0.2GNP composites (Zn-based MMCs [ZMCs]) are evaluated utilizing X-ray diffraction and scanning electron microscopy. Compression and electrochemical testing are performed on ZMCs to analyze the mechanical and corrosion properties. Results indicated that the GNPs are uniformly dispersed in the Zn powders at the optimal SBME of 32.82 kJ g⁻¹. The microhardness, compressive yield strength, ultimate compressive strength, compressive strain, and reduced elastic modulus of the ZMC fabricated at 32.82 kJ g⁻¹ SBME are 68.7 HV, 123, 247 MPa, 22.9%, and 89.04 GPa, respectively, improvements of 66%, ≈160, ≈201, ≈51, and ≈26% compared to the reference sample ball milled at 0.91 kJ g⁻¹ SBME. The corrosion rate of the ZMCs declined with increasing SBMEs.