Use of nanomaterials as effective viscosity modifiers in lubricating fluids

Abstract

Nanomaterials have been used as a supplement or replacement of traditional polymer-based viscosity modifiers for lubricants and other related fluids. Compared with traditional polymer-based viscosity modifiers, nanomaterials possess better viscosity-index modification functions, i.e., more even viscosity increase across the whole temperature range. Meanwhile, a cost-effective way of making nanomaterials have been developed based on commercially available graphite materials, and the resulting nanoparticles of graphite are nanodisks (nanoplates). Furthermore, it provides a viscosity modifier which exhibits temporary shear loss, which can contribute to fuel economy, but no permanent shear loss.

1 . The method of using nanomaterials as an effective viscosity modifier for a lubricating oil, which provides better viscosity index, and with no adverse effect to the low temperature properties of the fluid, than the currently used polymer-based viscosity modifiers.  
     
     
         2 . The method of  claim 1  in which the nanomaterials are made from carbon.  
     
     
         3 . The method of  claim 1  in which the nanomaterials are carbon nanotubes.  
     
     
         4 . The method of  claim 1  in which the nanomaterials are graphite nanoparticles.  
     
     
         5 . The method of  claim 3  wherein said carbon nanotube is either single-walled, double-walled, or multi-walled, with typical aspect ratio of 100-2000.  
     
     
         6 . The method of  claim 4  wherein said graphite nanoparticles are made by ball milling commercially available bulk graphite or graphite powders or graphite foams into the desired particle size, preferably with average diameter less than 500 nanometers.  
     
     
         7 . The method of  claim 4  wherein said graphite nanoparticles are in the form of nanodisks (or nanoplates).  
     
     
         8 . The method of  claim 1  wherein said nanomaterials are used in the final lubricating formulation in the weight percentage of from 0.001% to 50%, or more preferably from 0.01% to 25%, or more preferably from 0.1% to 20%.  
     
     
         9 . The method of  claim 1  in which the said lubricating fluid can be engine oil for either gasoline or diesel engines, transmission fluid, gear oil, hydraulic fluid, shock absorber oil, or any other lubricating fluid used in a modern vehicle.