TiO2-SiO2 nanoparticle-stabilised soybean oil-in-water emulsions: dispersion stability, rolling lubrication performance and surface self-cleaning effects

Vegetable oil-in-water (VO/W) 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) stabilised soybean oil emulsions are produced and NPs function as dispersant, lubrication enhancer, and detergent agent to clean up oil residue are explored. Cold rolling of SS316 reveals a threshold of NPs wt %, at which stably dispersed oil droplets improve tribology and lower the rolling parameters relative to that without or at high wt % of NPs. Cleaner as-rolled strips are also obtained with NPs. Favourable results are attributed to formation of NP-coating layers on oil droplets which enhances dispersion, optimises plate-out while keeping adequate wetting, and provides a 3-body abrasive rolling as opposed to 2-body adhesion without NPs. A model of sliding-rolling lubrication in cold rolling is also discussed.

Thermoelectric properties of Zn– and Ce–alloyed In2O3 and the effect of SiO2 nanoparticle additives

Thermoelectric materials are considered promising candidates for thermal energy conversion. This study presents the fabrication of Zn– and Ce–alloyed In2O3 with a porous structure. The electrical conductivity was improved by the alloying effect and an ultra–low thermal conductivity was observed owing to the porous structure, which concomitantly provide a distinct enhancement of ZT. However, SiO2 nanoparticle additives react with the matrix to form a third-phase impurity, which weakens the electrical conductivity and increases the thermal conductivity. A thermoelectric module was constructed for the purpose of thermal heat energy conversion. Our experimental results proved that both an enhancement in electrical conductivity and a suppression in thermal conductivity could be achieved through nano–engineering. This approach presents a feasible route to synthesize porous thermoelectric oxides, and provides insight into the effect of additives; moreover, this approach is a cost-effective method for the fabrication of thermoelectric oxides without traditional hot-pressing and spark–plasma–sintering processes.