Tribological Properties of Nano-Fe3O4 as Additive in Cold Rolling Emulsion for Steel Strip

Fe3O4 nanoparticles surface-modified with oleic acid, with an average size of 20 nm, were dispersed in a cold-rolling emulsion for steel strips. The tribological properties of the cold-rolling emulsion doped with nano-Fe3O4 nanoparticles were evaluated by using a four-ball machine. The phase composition and microstructure of nano-Fe3O4 nanoparticles were analyzed by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The worn surfaces of the steel balls were observed by using an optical microscope (OM). Besides, the lubricity of the cold-rolling emulsion doped with nano-Fe3O4 nanoparticles for steel strip was evaluated on a cold-rolling tester by using the emulsion without nano-Fe3O4 nanoparticles as a reference. Results indicated that Fe3O4 nanoparticles as an additive in a cold-rolling emulsion were able to significantly improve the friction-reducing, antiwear, and extreme pressure properties of the base stock. Meanwhile, Fe3O4 nanoparticles also showed good lubricity to the cold-rolled steel strips. Namely, the steel strips cold-rolled under the lubrication of the cold-rolling emulsion containing nano-Fe3O4 nanoparticles possessed considerably decreased after-rolling thickness and improved surface quality as well.