A study of the tribological behaviour of TiO2 nano-additive water-based lubricants

Abstract

A ball-on-disk tribometer was employed to evaluate the lubrication performance and mechanisms of innovative TiO 2 nano-additive water-based lubricants. Two experimental methods were applied to determine the optimal mass fraction of TiO 2. In the method I, lubricants were added onto the worn disk tracks at a predetermined time interval. In the method II, the disks were immersed in the lubricants continuously during the whole process of tribological tests. The results both indicate that the water-based lubricants can significantly reduce the coefficient of friction (COF). The 0.8 wt% TiO 2 lubricant demonstrates excellent tribological properties including the lowest COF and the strongest wear resistance under all lubrication conditions. The lubrication mechanisms are attributed to the rolling and mending effects of the TiO 2 nanoparticles.

Performance Evaluation and Lubrication Mechanism of Water-Based Nanolubricants Containing Nano-TiO2 in Hot Steel Rolling

“…While the difference is that the agglomeration of TiO 2 NPs induced by 8.0 wt% nano-TiO 2 lubrication may cause even deeper scratches than those produced by 4.0 wt% nano-TiO 2 lubrication, leading to higher surface roughness. This result has been proved in our previous study by using a pin-on-disk tribological test [21]. The other reason for reducing surface roughness may be ascribed to the "polishing effect" of TiO 2 NPs [29], which helps to remove the bumps or peaks embedded in steel substrate, and thus flatten the surface of rolled steel.…”

“…Glycerol is a colourless, odourless, and viscous liquid that is used to enhance the viscosity of suspensions. The detailed preparation process of the nanolubricants can be found in our previous study, and the lubricants exhibited excellent dispersibility and stability [21]. The chemical compositions of as-prepared nanolubricants in this study are outlined in Table 2.…”

“…Therefore, when the concentration of nano-TiO 2 is lower than 4.0 wt%, there are insufficient TiO 2 NPs left to form lubricating film and make rolling effect due to loss of nanolubricants when contacting the hot steel surface. When the concentration of nano-TiO 2 exceeds 4.0 wt% to a higher level of 8.0 wt%, instead, the rolling force varies at an opposite trend to present a higher value (see Figure 2) because of the agglomeration of TiO 2 NPs [20,21], which aggravates the friction between the work roll and the workpiece.…”

“…In this regard, a type of environment-friendly lubricant with excellent lubricating performance is urgently needed to substitute conventional oil-containing lubricants. In recent years, the research trend on water-based lubricants added with nanoparticles (NPs) is continuously ascending due to their excellent tribological properties and promising potential in hot steel rolling, even though the relevant reports are still scarce [8,[16][17][18][19][20][21][22][23]. For instance, Bao et al [8] carried out hot steel rolling tests at temperatures of 750-950 • C using water-based lubricants containing SiO 2 NPs, and found that the use of as-prepared lubricants with the addition of 0.5 wt% nano-SiO 2 resulted in improved surface morphology, reduced oxide scale thickness, and refined grain size, compared to that of the base lubricant.…”

Effect of cutting fluids on corrosion properties and turning surface quality of Fe-based superalloy

“…In recent years, nano-lubricant has been studied a lot. 9 H Wu et al 10 studied the tribological behavior of TiO 2 nano-additive water-based lubricants using a ball-ondisk tribometer. MK Dubey et al 11 investigated the physical properties and tribological characteristics of polytetrafluoroethylene (PTFE)-based nano-lubricants.…”