Effect of TiO2 nanoparticle lubrication on precision forming

The purpose of this work is to explore the mechanism of lubricants containing TiO2 nanoparticles to improve tribological properties and the effect of nanoparticle lubrication on precision forming. Firstly, the friction coefficients, wear rates, and average surface roughness for different concentration of TiO2 nanoparticle in lubricants are obtained from friction and wear tests. It is found that when the TiO2 concentration is 0.1wt%, the surface roughness of the sample reaches the lowest, while the surface roughness is higher under the lubricant of 0.5wt% nanoparticles which is ideal for friction coefficient and wear. Then, the effect of adhesion which mainly occurs when using lubricant containing no nanoparticles on the workpiece surface roughness is analyzed, including the joint action of height reduction of the micro-convex peak and the root roughening. Mechanism of lubricants containing TiO2 nanoparticles to improve tribological properties is presented, in which the wear and morphology evolution of workpiece surface are influenced by the coupling of tip adhesion and nanoparticle smoothing. Meanwhile the addition of nanoparticles can inhibit the adhesive wear of the tip, the effect of which is enhanced with the increase of TiO2 particle concentration. This explains why the surface roughness is higher and the friction coefficient and wear are minimal when the content of TiO2 nanoparticle is 0.5wt%. Finally, the effect of TiO2 nanoparticle lubrication on precision forming, including the metal flow, the forming load, and the error tolerance, is discussed. This work will help to further promote the development of precision forming technology.