▎ 摘　　要

Fabricating high-quality graphene with simple methods has aroused considerable interests in recent years. In this paper, graphite was dispersed in esterified bio-oil as a lubricant for steel/gray cast iron friction pairs, and the shear-induced transformation from graphite to graphene was observed. The tribological behavior during this process, including the influence of the normal load and sliding velocity, was investigated. The products formed after sliding were confirmed by Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed that friction induces exfoliation, accounting for the transformation from graphite into graphene, and the frictional conditions influence the products. It was also found that high loads and low sliding velocities facilitate the formation of high-quality single-layer graphene during sliding, and high loads and low sliding velocities also contributed to obtaining excellent tribological performance for friction pairs. Friction-induced transformation demonstrates a potentially new strategy for in situ graphene preparation.