Synthesis of Hexagonal WS₂ Nanosheets by Ball-Milling and Solid State Reaction Process and Their Tribological Properties

Hexagonal WS2 nanosheets were successfully synthesized by ball-milling and solid-state reaction using W and S powders as raw materials. The phase, morphology and structure of products were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Then a possible formation mechanism of the hexagonal WS2 nanosheets was preliminarily proposed on the basis of the experimental results. The tribological properties of hexagonal WS2 nanosheets as a lubrication additive in paraffin base oil were investigated by friction testing. The results show that the best hexagonal WS2 nanosheets were prepared at condition of 700 ℃×1 h, which had uniform thickness of 100 nm with diameter around 1-2 μm. The friction coefficient declined when the hexagonal WS2 nanosheets were added into the base oil, so the hexagonal WS2 nanosheets can improve the tribological property of the base oil.