The Intelligent Lubrication of Porous Prussian Blue Nanocontainers

Abstract Prussian blue analogs (PBAs) are demonstrated to possess promising application in the field of mechanical transmission lubrication. In this paper, porous CoFe-PB nanocontainers (PBN) loaded with sodium hydroxide solution (CoFe-PBN-SH) were synthesized via the coprecipitation method. It was confirmed that the stored sodium hydroxide solution could be released under the coupled action of frictional force and electric current and migrated to the friction interface, leading to improved friction reduction and wear resistance. Tribological results revealed that the wear resistance of all composite lubricants was superior to that of the base lubricant. The composite lubricant 1 wt % CoFe-PBN was characterized by a wear volume reduction of 56.36%, along with a stable coefficient of friction (COF). Following the adsorption of the sodium hydroxide medium, corrosion was induced on the friction interface accompanied by an increased wear volume, while a decreased COF was maintained. It was demonstrated by the current-carrying friction that the wear volume of the composite lubricant was reduced by 45.4% compared with the base lubricant, and a remarkable enhancement in corrosion mitigation was observed. That is because the real contact area was reduced by their cubic morphology via rolling friction. In the electrically controlled intelligent lubrication system, the applied electric field induces directional alignment of particles and their adsorption on the friction interface, isolating the metal matrix from corrosive substances and suppressing interfacial corrosion. Under frictional sliding, the synergistic effect of mechanical force and an electric field triggers the release of sodium hydroxide encapsulated in nanocontainers, which improves lubricating properties and reduces the coefficient of friction.