Lubricant composition for low-friction sliding material and sliding mechanism using same

Abstract

A lubricant oil composition containing an organic molybdenum compound which contains at least either one of a nitrogen (N) atom and an oxygen (O) atom in the molecule thereof and which may optionally contain a sulfur (S) atom, wherein a sulfur content of the organic molybdenum compound is 0.5% by mass or less based on the organic molybdenum compound. The lubricant oil composition, when used as a lubricant oil for a low-friction sliding material, exhibits an extremely low friction coefficient. A sliding mechanism having excellent low-friction property and wear resistance can be provided by combining the lubricant oil composition and a sliding member having a DLC film on its sliding face.

1 . A lubricant oil composition, comprising:
 a base oil; and   an organic molybdenum compound, which comprises:
 a nitrogen (N) atom, an oxygen (O) atom, or both, and 
 optionally a sulfur (S) atom, 
 wherein a sulfur content of the organic molybdenum compound is 0.5% by mass or less based on the organic molybdenum compound. 
   
     
     
         2 . The lubricant oil composition of  claim 1 , wherein a mass ratio p/q of a nitrogen content p to a molybdenum content q in the organic molybdenum compound is 0.05 or more and 1.0 or less. 
     
     
         3 . The lubricant oil composition of  claim 1 , wherein the sulfur content is 100 ppm by mass or less based on a total weight of the lubricant oil composition. 
     
     
         4 . The lubricant oil composition of  claim 1 , wherein the organic molybdenum compound is at least one selected from the group consisting of
 (a) a reaction product of a molybdenum compound and an amine compound;   (b) a reaction product of a molybdenum compound and an organic compound, wherein the organic compound comprises:
 i) a fatty acid, a fatty acid derivative, or both, and 
 ii) an alcohol group, or both; and 
   (c) a reaction product of an acidic molybdenum compound or a salt thereof and a succinimide or carboxylic acid amide.   
     
     
         5 . The lubricant oil composition of  claim 1 , further comprising a zinc organodithiophosphate. 
     
     
         6 . The lubricant oil composition of  claim 5 , wherein the zinc organodithiophosphate comprises a hydrocarbon group comprising a secondary alkyl group. 
     
     
         7 . The lubricant oil composition of  claim 1 , wherein the lubricant oil composition has a molybdenum content of 0.02 to 0.2% by mass based on a total weight of the lubricant oil composition. 
     
     
         8 . A low-friction sliding material, comprising the lubricant oil composition of  claim 1 , wherein the low-friction sliding material is a diamond-like carbon (DLC). 
     
     
         9 . A sliding mechanism, comprising:
 the lubricant oil composition of  claim 1 ;   two sliding members with sliding faces that slidably move relative to each other, wherein the lubricant oil composition is disposed between the sliding faces; and   a diamond-like carbon (DLC) film deposited on at least one of the sliding faces.   
     
     
         10 . The sliding mechanism of  claim 9 , wherein the diamond-like carbon film comprises graphite crystals and has a graphite crystal peak in an X-ray scattering spectrum thereof. 
     
     
         11 . The sliding mechanism of  claim 10 , wherein the graphite crystals have a crystal diameter of 15 to 100 nm. 
     
     
         12 . The sliding mechanism of  claim 9 , further comprising:
 a layer between the sliding member and the diamond-like carbon film, wherein   the layer is at least one selected from the group consisting of   (a) a metal layer, which comprises at least one metal selected from the group consisting of titanium (Ti), chromium (Cr), tungsten (W) and silicon (Si),   (b) a metal nitride layer, which comprises at least one metal elected from the group consisting of titanium (Ti), chromium (Cr), tungsten (W) and silicon (Si), and   (c) a metal carbide layer, which comprises at least one metal elected from the group consisting of titanium (Ti), chromium (Cr), tungsten (W) and silicon (Si).   
     
     
         13 . The sliding mechanism of  claim 9 , wherein the diamond-like carbon film is prepared by a cathode Penning Ionization Gauge plasma CVD method in a high density plasma environment. 
     
     
         14 . The lubricant oil composition of  claim 1 , wherein the organic molybdenum compound is a sulfurized product of a molybdenum compound and an organic compound comprising:
 i) a fatty acid, a fatty acid derivative, or both, and   ii) an amino group, an alcohol group, or both.   
     
     
         15 . The lubricant oil composition of  claim 1 , wherein the organic molybdenum compound is a sulfurized product of an acidic molybdenum compound or a salt thereof and a succinimide or carboxylic acid amide.