Anti-wear performance of lubricants using carbon nanoplatelets

Abstract

Provided are a lubricating engine oil and a method of improving wear protection in an engine lubricated with such lubricating oil. The method includes using as the lubricating oil a formulated oil comprising a lubricating oil base stock as a major component, an antiwear additive as a first minor component, and carbon nanoplatelets as a second minor component. The carbon nanoplatelets are dispersed in said lubricating oil base stock. Wear protection is improved as compared to wear protection achieved using a lubricating oil not containing carbon nanoplatelets as a second minor component. A synergy exists between carbon nanoplatelets and other major components of lubricants, especially with zinc dialkyldithiophosphate (ZDDP) or other phosphate antiwear additives, that helps to form a nano-composite wear resistant and low friction tribofilm both on ferrous and non-ferrous surfaces (e.g., carbon coatings, ceramic coatings, polymeric coatings, and the like) of engines/machines.

What is claimed is: 
     
         1 . A method of improving wear protection in an engine lubricated with a lubricating oil, said method comprising using as the lubricating oil a formulated oil comprising a lubricating oil base stock as a major component, an antiwear additive as a first minor component, and carbon nanoplatelets as a second minor component; wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock; and wherein wear protection is improved as compared to wear protection achieved using a lubricating oil not containing carbon nanoplatelets as a second minor component. 
     
     
         2 . The method of  claim 1  wherein the antiwear additive comprises zinc dialkyldithiophosphate (ZDDP). 
     
     
         3 . The method of  claim 1  wherein the carbon nanoplatelets comprise nanographene platelets (NGP). 
     
     
         4 . The method of  claim 3  wherein said nanographene platelets have an average thickness less than 10 nm, and a length or width less than 500 nm. 
     
     
         5 . The method of  claim 3  wherein said nanographene platelets comprise single-layer graphene. 
     
     
         6 . The method of  claim 1  wherein the engine comprises one or more components and/or surfaces that are lubricated with the lubricating oil, wherein the one or more components and/or surfaces are coated with a ferrous or non-ferrous coating, a diamond-like carbon (DLC) coating, a ceramic coating, or a polymeric coating. 
     
     
         7 . The method of  claim 1  wherein a tribofilm is formed by synergy of the nanographene platelets (NGP) and antiwear additive, thereby forming a low friction and wear resistant nano-composite tribofilm. 
     
     
         8 . The method of  claim 1  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         9 . The method of  claim 1  wherein the oil base stock is present in an amount of from 70 weight percent to 95 weight percent, the antiwear additive is present in an amount of from 0.4 weight percent to 1.2 weight percent, and the carbon nanoplatelets are present in an amount of from 0.1 weight percent to 10 weight percent, based on the total weight of the formulated oil. 
     
     
         10 . A method for improving wear protection in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil having a HTHS viscosity of less than 4.0 cP at 150° C., said formulated oil having a composition comprising a major amount of a lubricating oil base stock, a minor amount of an antiwear additive, and a minor amount of carbon nanoplatelets; wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock sufficient for the formulated oil to pass wear protection requirements of one or more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA. 
     
     
         11 . A method for improving wear protection in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil having a HTHS viscosity of less than 4.0 cP at 150° C., said formulated oil having a composition comprising a major amount of a lubricating oil base stock and a minor amount of carbon nanoplatelets; wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock sufficient for the formulated oil to pass wear protection requirements of one or more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA. 
     
     
         12 . A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component, an antiwear additive as a first minor component, and carbon nanoplatelets as a second minor component; wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock sufficient for the lubricating engine oil to exhibit improved wear protection as compared to wear protection achieved using a lubricating oil not containing carbon nanoplatelets as a second minor component. 
     
     
         13 . The lubricating engine oil of  claim 12  wherein the antiwear additive comprises zinc dialkyldithiophosphate (ZDDP), and the carbon nanoplatelets comprise nanographene platelets (NGP). 
     
     
         14 . The lubricating engine oil of  claim 13  wherein said nanographene platelets have an average thickness less than 10 nm, and a length or width less than 500 nm. 
     
     
         15 . The lubricating engine oil of  claim 13  wherein said nanographene platelets comprise single-layer graphene. 
     
     
         16 . The lubricating engine oil of  claim 12  wherein the engine comprises one or more components and/or surfaces that are lubricated with the lubricating oil, wherein the one or more components and/or surfaces are coated with a diamond-like carbon (DLC) coating. 
     
     
         17 . The lubricating engine oil of  claim 12  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         18 . The lubricating engine oil of  claim 12  wherein the oil base stock is present in an amount of from 70 weight percent to 95 weight percent, the antiwear additive is present in an amount of from 0.4 weight percent to 1.2 weight percent, and the carbon nanoplatelets are present in an amount of from 0.1 weight percent to 10 weight percent, based on the total weight of the formulated oil. 
     
     
         19 . A lubricating engine oil having a composition comprising a major amount of a lubricating oil base stock, a minor amount of an antiwear additive, and a minor amount of carbon nanoplatelets; wherein said lubricating engine oil has a HTHS viscosity of less than 4.0 cP at 150° C.; and wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock sufficient for the lubricating engine oil to pass wear protection requirements of one or more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA. 
     
     
         20 . A lubricating engine oil having a composition comprising a major amount of a lubricating oil base stock and a minor amount of carbon nanoplatelets; wherein said lubricating engine oil has a HTHS viscosity of less than 4.0 cP at 150° C.; and wherein said carbon nanoplatelets are dispersed in said lubricating oil base stock sufficient for the lubricating engine oil to pass wear protection requirements of one or more engine tests selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA.