High-Temperature Wettable Water-Based Lubricants toward Hot Rolling Lubrication

Water-based lubricants have attractive properties compared to flammable oily lubricants but in high-temperature environments remain a tricky challenge due to the Leidenfrost effect-induced poor wettability once contacting sufficiently hot surfaces. Herein, a surfactant-modified Laponite nanoclay (LNC), as a prototype water-based lubricant with considerable lubricity, exhibits spontaneous high-temperature wettability by which the Leidenfrost point (LFP) can be improved above approximate to 350 degrees C on crude stainless steels, increasing by approximate to 140 degrees C compared to pure water. The inter-particle attractions between LNC nanoplates increase the liquid viscosity, causing viscous force of bulk water near the substrate, allowing in situ deposition of LNC layers on the hot surface to trigger three-phase contact line (TCL) pinning. As a basis, wettable lubricants are further optimized on their lubricity by intercalating zwitterionic surfactants between LNC nanoplates, thereby reducing friction coefficient to approximate to 0.1. The LNC lubricants have been demonstrated in a four-ball tribometer to simulate hot rolling lubrication, providing insights for high-temperature metal processing, and potential applications in mechanical engineering and the aerospace field. A new paradigm is developed to suppress the Leidenfrost effect of water droplets on crude stainless steel above approximate to 350 degrees C via tuning the fluid characteristics. A surfactant-modified Laponite nanoclay (LNC) water-based lubricant is fabricated, exhibiting spontaneous high-temperature wettability while preserving considerable lubricity. image