Eco-Friendly Water-Based Nanolubricants for Industrial-Scale Hot Steel Rolling

Abstract

Eco-friendly and low-cost water-based nanolubricants containing rutile TiO2 nanoparticles (NPs) were developed for accelerating their applications in industrial-scale hot steel rolling. The lubrication performance of developed nanolubricants was evaluated in a 2-high Hille 100 experimental rolling mill at a rolling temperature of 850 °C in comparison to that of pure water. The results indicate that the use of nanolubricant enables one to decrease the rolling force, reduce the surface roughness and the oxide scale thickness, and enhance the surface hardness. In particular, the nanolubricant consisting of 4 wt % TiO2, 10 wt % glycerol, 0.2 wt % sodium dodecyl benzene sulfonate (SDBS) and 1 wt % Snailcool exhibits the best lubrication performance by lowering the rolling force, surface roughness and oxide scale thickness by up to 8.1%, 53.7% and 50%, respectively. The surface hardness is increased by 4.4%. The corresponding lubrication mechanisms are attributed to its superior wettability and thermal conductivity associated with the synergistic effect of rolling, mending and laminae forming that are contributed by TiO2 NPs.

A Comprehensive Review of Water-Based Nanolubricants

“…In their recent studies, they prepared industrial-scale water-based nanolubricants using coarse TiO 2 NPs of 300 nm, with the aid of 0.1-0.2 wt.% of sodium dodecyl benzene sulfonate (SDBS) and 1 wt.% Snailcool by mechanical stirring only. The as-prepared lubricants could be stably dispersed for 24 h [24]. Sun et al [49][50][51][52] also prepared 0.1-5.0 wt.% TiO 2 water-based nanolubricants by adding 20-90 nm TiO 2 particles and different additives, including sodium hexametaphosphate (SHMP) and SDBS which exhibited good stability for 7 days.…”

“…Photography of nanofluid sedimentation using a camera over a time period is the simplest method to monitor the nanofluid stability and sedimentation coefficient [166,184]. Comparing the photos is widely used in nanofluid research, and many examples were mentioned for water-based nanoadditives such as TiO 2 [15,24,29,51]. The stability analysis using sedimentation is usually conducted immediately after the dispersion of NPs in the base lubricant, and the disturbance or movement should be avoided to ensure its reliability.…”

“…The stability analysis using sedimentation is usually conducted immediately after the dispersion of NPs in the base lubricant, and the disturbance or movement should be avoided to ensure its reliability. Wu et al [24] carried out the sedimentation experiment to compare the precipitation of TiO 2 NPs in different as-prepared water-based nanolubricants, as shown in Figure 9. They found that all the lubricants remained stable without apparent particle sedimentation at the bottom within 120 min as long as the dispersants such as sodium dodecyl benzene sulfonate and Snailcool were added into water.…”

“…All these disadvantages have greatly restricted the application and popularisation of waterbased nanolubricants in industrial-scale hot steel rolling. Accordingly, relatively coarse TiO 2 NPs (~300 nm in diameter) were adopted to replace the expensive nanosized particles in water-based lubrication formula [24]. Novel dispersant (SDBS with a linear structure) and extreme pressure agent (Snailcool) were added to compensate the degradation of of 62 lubrication performance caused by coarsened TiO 2 NPs.…”

“…Over the past decade, water-based nanolubricants have been emerging as promising eco-friendly lubricants by dispersing nanoadditives into water [12][13][14][15][16][17][18][19][20][21][22][23], which integrates superb cooling capacity of water with excellent lubricity contributed by the nanoadditives. The use of water-based nanolubricants not only provides protection against friction and wear between the tool and the workpiece, but also improves overall quality of the product, demonstrating a great potential in engineering applications, such as metal forming [24][25][26][27][28][29]. Despite an increasing number of experimental studies on various nanomaterials as nanoadditives in water, several aspects including dispersion stability, tribological behaviour, and lubrication mechanism have not yet been fully understood.…”