α-Zirconium phosphate nanoplatelets as lubricant additives

Abstract

 α-ZrP nanoplatelets have been successfully devel-oped and are found to be suitable as lubricant additives in mineraloil and water. Friction and viscosity reductions were success-fully observed. Investigation and analysis resulted in two possible mechanisms:

(1)  α-ZrP nanoplatelets-induced viscosity modifica-tion;

(2) van der Waals interaction of lubricant molecules onthe surface. It is the unique 2D nanostructure that promoted thealignment of α--ZrP nanoplatelets in the lubricants. These nanopar-ticles provide sites for intermolecular interaction and subsequentreduction in fluid drag, as well as more efficient lubrication.
Theutilization of 2D nanostructures as lubricant additives is a novelsolution in lubrication. More fundamental research in nano-fluidand nano-lubrication is promising in improving the efficiency andlifetime of industrial machinery.

α-ZrP nanoplatelets as lubricant additive and viscosity modifier


1. Dry friction results with α-ZrP additives (top red curve), graphite additives(bottom green curve), and without any additives (middle black curve).


2.
(a) Stribeck curves of mineral oil (top black plot), and with addition of 0.5 wt% (middle red plot) and 0.1 wt% (bottom green plot) α-ZrP nanoplatelets additives.

(b) Stribeck curves of DI water (top black plot), and with addition of 0.002 wt% (middle red plot) and 0.0004 wt% (bottom green plot) α-ZrP nanoplatelets additives.


Interaction between lubricant molecules and the solidsurface of α-ZrP nanoplatelet

1.
(a) Variation of viscosity with shear rate in mineral oil (top black plot), and with addition of 0.5 wt% (middle red plot) and 0.1 wt% (bottom green plot) α-ZrPnanoplatelets additives.

(b) Variation of viscosity with shear rate in DI water (top black plot), and with addition of 0.002 wt% (middle red plot) and 0.0004 wt% (bottom greenplot) α-ZrP nanoplatelets additives.

(c) At a constant shear rate (10,000 s−1), reduction in viscosity of mineral oil (top black plot) in the presence of α-ZrP nanoplatelets withconcentrations of 0.5 wt% (middle red plot) and 0.1 wt% (bottom green plot).

(d) At a constant shear rate (10,000 s−1), reduction in viscosity of DI water (top black plot) in thepresence of α-ZrP nanoplatelets with concentrations of 0.002 wt% (middle red plot) and 0.0004 wt% (bottom green plot).



2.
(a) Comparison of infrared spectra of α-ZrP nanoplatelets (top red curve), mineral oil (bottom black curve), and mineral oil containing 0.5 wt% α-ZrP nanoplatelets(middle green curve).

(b) Comparison of Raman spectra between α-ZrP nanoplatelets (top red curve) and mineral oil containing 0.5 wt% α-ZrP nanoplatelets (bottom greencurve). 


Mechanisms of lubrication

(a) Schematics showing ordered alignment of α-ZrP nanoplatelets in the lubricants (the left), interaction between lubricant molecules and α-ZrP solid surface (themiddle), and formation of dipole-dipole complex (the right).

(b) Hydrodynamic lift in HL regime.

(c) Schematic explanation of lubricating enhancement in ML regime.