Effect of ball milling on bulk MoS2 and the development of Al–MoS2 nanocomposites by powder metallurgy route

Abstract

Abstract The present study provides an in-depth investigation of the exfoliation of molybdenum disulfide (MoS2) using high-energy ball milling and the subsequent development of aluminum‒molybdenum disulfide (Al–MoS2) nanocomposites via a powder metallurgy (PM) route. X-ray diffraction confirmed that the commercially available bulk MoS2 did not develop new phases after intense ball milling for up to 30 h. The effects of ball milling on the thermal stability and morphological changes in MoS2 powder have also been reported. The milling action caused a shift in the band gap of MoS2, from 1.2 to 1.44 eV due to quantum confinement phenomena confirmed by UV–visible absorption spectroscopy. The impacts of ball milling on the specific surface area and mean pore diameter of MoS2 were determined by the Brunauer–Emmett–Teller surface area analysis technique. Additionally, the investigation through Fourier transform infrared spectroscopy verifies the presence of functional groups, such as hydroxyl (O–H), alkane (C–H), and ether (C–O), on the MoS2 surface. The milling resulted in a significant reduction in particle size from an initial mean size of 1.2 µm–480 nm. Field emission scanning electron microscopy micrographs of the exfoliated MoS2 revealed a thin, cracked, and flake-like morphology. High-resolution transmission electron microscopy images revealed that the high-energy ball milling resulted in few-layered MoS2 nanoplatelets after 30 h of ball milling. Subsequently, the investigation extended its focus to the development of Al–MoS2 nanocomposites using the PM route, incorporating MoS2 into the Al matrix at different weight percentages (1, 2, 3, and 5 wt.%). Al-5 wt.% MoS2 nanocomposite showed the highest relative density of 93.09 %, the maximum hardness of 743.6 MPa, and the best wear performance among all the Al–MoS2 nanocomposites. The hardness of Al-5 wt.% MoS2 nanocomposite was 109.11 % higher than that of the pure Al sample developed similarly. A maximum compressive strength (σ max) of 494.67 MPa was observed in Al-5 wt.% MoS2 nanocomposite, which was 1.84 times the value of σ max obtained from sintered pure Al sample.