Synthesis of GO-Fe 3 O 4 -based ferrofluid and its lubrication performances

As a thin material with a lamellar structure, graphene oxide (GO) may extend the already superior tribological properties of ferrofluids. For this purpose, magnetic Fe 3 O 4 nanoparticles were fabricated on the GO surface with different compositions by the co-precipitation method. Then, the GO-Fe 3 O 4 nanohybrids coated with a surfactant were dispersed in paraffin oil to achieve stable ferrofluids. The tribological results demonstrated that compared with paraffin oil, friction coefficient reduced by 19.4% and 25.8–35.5% when lubricated with ferrofluids containing 0.5 wt% of Fe 3 O 4 nanoparticle and GO-Fe 3 O 4 nanohybrids, respectively. The results also indicated that nanohybrids with the higher content of GO exhibited better lubrication behaviors. It can be concluded that the introduction of GO helps to further promote the lubricity of traditional Fe 3 O 4 -based ferrofluids. The excellent tribological behaviors of GO-Fe 3 O 4 -based ferrofluids were ascribed to the triboflim and the synergistic effects of GO and Fe 3 O 4 .