Lubricated part having partial hard coating allowing reduced amounts of antiwear additive

Abstract

A lubricated part composition containing (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and (c) an oil of lubricating viscosity. The invention further relates to the use of the composition to decrease engine wear, decrease sludge formation, filter plugging, decrease sulphur emissions and decrease phosphorus emissions.

1 . A lubricated part comprising: 
 (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof;    (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and    (c) an oil of lubricating viscosity.    
   
   
       2 . The lubricated part of  claim 1 , wherein the partial hard surface coating has an average thickness less than about 8 micrometres.  
   
   
       3 . The lubricated part of  claim 1 , wherein the partial hard surface coating contains at least one moiety selected from the group consisting of nitrides, carbides and mixtures thereof.  
   
   
       4 . The lubricated part of  claim 1 , wherein the partial hard surface coating further comprises at least one metal selected from the group consisting of Group IVb of the periodic table, Group Vb of the periodic table Group VIb of the periodic table and mixtures thereof.  
   
   
       5 . The lubricated part of  claim 4 , wherein the metal is selected from the group consisting of chromium, tungsten, vanadium and combinations thereof.  
   
   
       6 . The lubricated part of  claim 1 , wherein the substrate of the sulphonate detergent is represented by the formula (R 1 ) k -Z—SO 3 M: wherein, each R 1  is independently a hydrocarbyl group with a about 6 to about 40 carbon atoms Z is a cyclic or acyclic hydrocarbon group; M is a valence of metal ion, hydrogen, ammonium ion, or mixtures thereof; and k is 1 to about 5.  
   
   
       7 . The lubricated part of  claim 6 , wherein the substrate of the sulphonate detergent incorporates a metal ion selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof.  
   
   
       8 . The lubricated part of  claim 1 , wherein the substrate of the phenate detergent is represented by the formulae:  
     
       
         
         
             
             
         
       
     
     wherein the number of sulphur atoms in formula (VI) y, is in the range from 1 to 8; the number of (CR 10 CR 11 ) moieties y, is in the range from 0 to 8; hydrogen or hydrocarbyl groups; each R 9  are independently hydrogen or a hydrocarbyl group; w, is in the range from 0 to 3, provided at least one hydrocarbyl group is present on an oligomer; T is hydrogen or an (S) y  linkage terminating in hydrogen, an ion or a non-phenolic hydrocarbyl group; and M is a valence of metal ion or hydrogen, x is an integer and present in a sufficient number of times to form oligomers of hydrocarbyl phenol; and R 10  and R 11  are hydrogen or hydrocarbyl or mixtures thereof.  
   
   
       9 . The lubricated part of  claim 1 , wherein the substrate of the salixarate detergent is represented by a substantially linear compound comprising at least one unit of the formulae (I) or (II):  
     
       
         
         
             
             
         
       
     
     each end of the compound having a terminal group of formulae (III) or (IV):  
     
       
         
         
             
             
         
       
     
     such groups being linked by divalent bridging groups A, which may be the same or different for each linkage; wherein in formulas (I)-(IV) R 3  is hydrogen or a hydrocarbyl group; R 2  is hydroxyl or a hydrocarbyl group and j is 0, 1, or 2; R 6  is hydrogen, a hydrocarbyl group, or a hetero-substituted hydrocarbyl group; either R 4  is hydroxyl and R 5  and R 7  are independently either hydrogen, a hydrocarbyl group, or hetero-substituted hydrocarbyl group, or else R 5  and R 7  are both hydroxyl and R 4  is hydrogen, a hydrocarbyl group, or a hetero-substituted hydrocarbyl group; provided that at least one of R 4 , R 5 , R 6  and R 7  is hydrocarbyl containing at least 8 carbon atoms; and wherein the molecules on average contain at least one of unit (I) or (III) and at least one of unit (II) or (IV) and the ratio of the total number of units (I) and (III) to the total number of units of (II) and (IV) in the composition is about 0.1:1 to about 2:1.  
   
   
       10 . The lubricated part of  claim 1 , wherein the oil of lubricating viscosity is selected from the group consisting of API Group II, III, or IV oil and mixtures thereof.  
   
   
       11 . The lubricated part of  claim 1  further comprising a metal hydrocarbyl dithiophosphate represented by the formula:  
     
       
         
         
             
             
         
       
     
     wherein R 12  and R 13  are independently hydrogen, hydrocarbyl groups or mixtures thereof, provided that at least one of R 12  and R 13  is a hydrocarbyl group; M′ is a metal; and n is an integer equal to the available valence of M′.  
   
   
       12 . The lubricated part of  claim 1  further comprising a borate ester prepared by the reaction of a boron compound and at least one compound selected from epoxy compounds or equivalent, alcohols and mixtures thereof.  
   
   
       13 . The lubricated part of  claim 1  further comprising at least one other performance additives selected from the group consisting of detergents other than those of component (b) of the invention, metal deactivators, dispersants, antioxidants, antiwear agents, corrosion inhibitors, antiscuffing agents, extreme pressure agents, foam inhibitors, demulsifiers, friction modifiers other than a borate ester, viscosity modifiers, pour point depressants, fluidity modifiers and seal swelling agents.  
   
   
       14 . The lubricated part of  claim 1  comprising: 
 (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof;    (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and when present, each detergent is independently present from about 0.05 to about 20 wt % of the lubricating oil composition; and    (c) an oil of lubricating viscosity present from about 5 to about 99.8 wt % of the lubricating oil composition;    (d) a metal hydrocarbyl dithiophosphate present from about 0 to about 5 wt % of the lubricating oil composition;    (e) a borate ester present from about 0 to about 20 wt % of the lubricating oil composition; and    (f) other performance additives present from about 0 to about 30 wt % of the lubricating oil composition.    
   
   
       15 . The lubricated part of  claim 14 , wherein the lubricating oil composition has a total sulphur content below about 0.5 wt %; the total phosphorus content is below about 0.1 wt %; and the total sulphated ash content is below about 1.1 wt %.  
   
   
       16 . The lubricated part of  claim 1 , wherein the partial hard surface coating is formed by at least one technique selected from the group consisting of physical vapour deposition, chemical vapour deposition, ion beam deposition, ion beam enhanced deposition and plasma induced immersion process.  
   
   
       17 . The lubricated part of  claim 16 , wherein the technique used to form the partial hard surface coating is physical vapour deposition.  
   
   
       18 . The lubricated part of  claim 1 , wherein the part is located in the valve train, fuel injector train or mixtures thereof.  
   
   
       19 . The lubricated part of  claim 18 , wherein the part is selected from at least one of the group consisting of a rocker arm, a rocker arm pad, a cam follower, a cam lobe, a crosshead, a valve adjuster, a injector adjuster and mixtures thereof.  
   
   
       20 . A lubricated part comprising: 
 (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one chromium moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof;    (b) a salixarate salt detergent; and    (c) an oil of lubricating viscosity.    
   
   
       21 . A lubricated part comprising: 
 (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one tungsten moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof;    (b) a detergent package comprising: 
 (i) a phenate salt;  
 (ii) a sulphonate salt; and  
   (c) an oil of lubricating viscosity.    
   
   
       22 . A method for lubricating a part, wherein the lubricated part has at least one property selected from the group consisting of decreased wear, decreased filter plugging, decreased sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof; the method comprising a lubricated part comprising: 
 (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof;    (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and    (c) an oil of lubricating viscosity.