Search

An Rtec ball-on-disk tribometer was used to investigate the tribological performance of the synthesised water-based nanolubricants containing hBN/TiO2 nanocomposite at room temperature. The water-based nanolubricants with different concentrations were prepared by adding glycerol and sodium dodecyl benzene sulfonate (SDBS) under ultrasonication. These as-prepared nanolubricants demonstrated exceptional dispersion stability for 7 days without distinct sedimentation. The results indicate that the water-based nanolubricants with an overall concentration of 1.0 wt% at different ratios (hBN: TiO2 = (1:0), (0.7:0.3), (0.5:0.5), (0.3:0.7), (0:1)) can effectively reduce the coefficient of friction (COF) and the wear of the ball and disk. In particular, the water-based nanolubricant containing 0.5 wt% hBN and 0.5 wt% TiO2 exhibited the best tribological performance, leading to a significant reduction in COF up to 70%, and decreased the wear area of the ball and disk by up to 79.57% and 60.40%, respectively, compared to those obtained using distilled water. The lubrication mechanisms were mainly attributed to the formation of a protective film, and the mending, polishing, rolling, and synergistic effects of the hBN nanosheets and TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Water‐based nanolubricants are playing increasingly important roles in hot steel rolling over the past decade regarding environmental protection, energy saving, and product quality improvement. The contact friction between the work roll and the workpiece under water‐based nanolubrication, however, has been scarcely investigated. In this study, water‐based lubricants containing 0–4.0 wt% TiO2 nanoparticles are employed in hot rolling of a mild steel under different rolling conditions. The Taguchi method is used for the orthogonal design of the hot‐rolling tests to sequence the key factors that affect the rolling force in terms of importance. The as‐synthesized water‐based nanolubricants indicate excellent dispersion stability after standing for 24 h, which can be readily restored to the original state via manual shaking. The coefficient of friction (COF) during the steady‐state hot steel rolling is inversely calculated using a flow stress model developed from hot compression testing. A novel COF model for hot rolling of the steel is thus proposed through multiple linear regression. It is found that the result of linear regression agreed well with that of inverse calculation, indicating that the proposed COF model is applicable. Finally, the lubrication mechanism is examined through a boundary lubrication regime determined from a modified lubricant film thickness model. [ABSTRACT FROM AUTHOR]