TiO2-SiO2 Nanoparticle-Stabilized Soybean Oil-in-Water Emulsions: Dispersion Stability, Rolling Lubrication Performance, and Surface Self-Cleaning Effects

Vegetable oil-in-water emulsions are common cold rolling lubricants. However, maintaining the required dispersion for polar oil droplets for consistent lubrication and proper surface self-cleaning after rolling remains a practical challenge. In this study, titanium silicate TiO2-SiO2 nanoparticle (NP)-stabilized soybean oil emulsions are produced and NPs functions as dispersant, lubrication enhancer, and detergent agent to clean up oil residue are explored. Cold rolling of SS316 strips reveals a threshold of NPs wt%, at which stably dispersed oil droplets improve tribology and lower the rolling parameters relative to without or at high wt% of NPs. Cleaner as-rolled strips are also obtained with NPs. Favorable results are attributed to the formation of NP-coating layers on oil droplets which enhances dispersion, optimizes plate-out while keeping adequate wetting, and provides a three-body abrasive rolling as opposed to two-body adhesion without NPs. A model of sliding-rolling lubrication in cold rolling is also discussed.