Method of using intrinsically conductive polymers with inherent lubricating properties, and a composition having an intrinsically conductive polymer, for protecting metal surfaces from galling and corrosion

Abstract

A method for protecting a metal surface from galling and corrosion includes a step of providing a protective dry film on the metal surface. The film includes a solid lubricant and a conducting polymer, the conducting polymer having lubricant properties and being capable of binding the solid lubricant to the metal surface. Threaded metal joint surfaces coated with the film are capable of resisting galling under high pressure and high torque conditions, even after several fastening and unfastening operations or over a long period of time. Protection from corrosion is also provided by the film. The method and film are economical in that only a single layer of protective compound need be applied in order to provide metal surfaces with both lubrication and protection against corrosion, and problems such as removal or leakage, which are associated with protective compounds that use oils, are avoided. Additionally, the dry film is advantageous because it does not contain heavy metals that are harmful to the environment.

1 . A method for protecting a metal surface from galling and corrosion, said method comprising the step of: 
 providing a dry film on the metal surface, the dry film comprising a binding intrinsically conductive polymer;    wherein the intrinsically conductive polymer itself has lubricant properties and is capable of binding solid lubricants to the metal surface.    
     
     
         2 . The method according to  claim 1 , wherein the dry film includes a solid lubricant.  
     
     
         3 . The method according to  claim 1 , wherein the dry film is formed by application to the metal surface of a liquid solution of the intrinsically conductive polymer.  
     
     
         4 . The method according to  claim 2 , wherein the dry film is formed by application to the metal surface of a liquid composite comprising the intrinsically conductive polymer and the solid lubricant in a solvent.  
     
     
         5 . The method according to  claim 4 , wherein the dry film is formed by drying a wet film of the liquid composite which has been applied on the metal surface with a brush.  
     
     
         6 . The method according to  claim 4 , wherein the dry film is formed by drying the liquid composite which has been applied on the metal surface by spraying.  
     
     
         7 . The method according to  claim 1 , wherein the dry film is formed by electropolymerization.  
     
     
         8 . The method according to  claim 1 , wherein the dry film is formed by electrophoretic deposition of the intrinsically conductive polymer.  
     
     
         9 . The method according to  claim 1 , wherein the dry film is formed by electrophoretic deposition of the intrinsically conductive polymer in the presence of at least one solid lubricant.  
     
     
         10 . The method according to  claim 1 , wherein the intrinsically conductive polymer is polyaniline, in a concentration in a range of about 1% to about 20% by weight of the dry film.  
     
     
         11 . The method according to  claim 1 , wherein the intrinsically conductive polymer is a ring-substituted polyaniline, a nitrogen-substituted polyaniline, or a polyaniline copolymer in a concentration in a range of about 1% to about 20% by weight of the dry film.  
     
     
         12 . The method according to  claim 2 , wherein the solid lubricant is molybdenum disulfide.  
     
     
         13 . The method according to  claim 2 , wherein the solid lubricant is graphite.  
     
     
         14 . The method according to  claim 12 , wherein the intrinsically conductive polymer is polyaniline in its emeraldine base form, in a polyaniline-to-molybdenum disulfide weight ratio of about 1:4 to about 1:2.  
     
     
         15 . The method according to  claim 14 , wherein the emeraldine and the molybdenum disulfide are dissolved in fifty parts by weight of N-methylpyrrolidone solvent.  
     
     
         16 . The method according to  claim 4 , wherein plural layers of the liquid composite are successively applied, a first layer being applied directly to the metal surface to form the dry film, and each successive layer being applied over a previous layer when the previous layer has dried.  
     
     
         17 . The method according to  claim 16 , wherein about 5 to about 20 twenty layers of the liquid composite are successively applied.  
     
     
         18 . The method according to  claim 16 , wherein the thickness of each of the layers is about 1 to about 2 micrometers.  
     
     
         19 . The method according to  claim 1 , wherein a conversion coating is provided on the metal surface before said step of providing the dry film.  
     
     
         20 . The method according to  claim 19 , wherein the conversion coating is selected from the group consisting of manganese phosphate, zinc phosphate, and oxalate.  
     
     
         21 . The method according to  claim 1 , wherein a conversion coating and the conducting polymer are co-deposited on the metal surface.  
     
     
         22 . The method according to  claim 21 , wherein the conversion coating is selected from the group consisting of manganese phosphate, zinc phosphate, and oxalate.  
     
     
         23 . A composition for protecting a metal surface from galling and corrosion, said composition comprising: 
 a binding intrinsically conductive polymer with lubricant properties; and    a solid lubricant.    
     
     
         24 . The composition according to  claim 23 , wherein said intrinsically conductive polymer is polyaniline or a chemical modification of polyaniline in any of its oxidation states, in a concentration in a range of about 1% to about 20% by weight of said composition.  
     
     
         25 . The composition according to  claim 23 , wherein said intrinsically conductive polymer is sulfonated polyaniline having any degree of sulfonation, in a concentration in a range of about 1% to about 20% by weight of said composition.  
     
     
         26 . The composition according to  claim 23 , wherein said solid lubricant is molybdenum disulfide.  
     
     
         27 . The composition according to  claim 23 , wherein said solid lubricant is graphite.  
     
     
         28 . The composition according to  claim 26 , wherein said intrinsically conductive polymer is polyaniline in its emeraldine base form, in a polyaniline-to-molybdenum disulfide weight ratio of about 1:4 to about 1:2.  
     
     
         29 . The composition according to  claim 28 , wherein the emeraldine and the molybdenum disulfide are dissolved in fifty parts by weight of N-methylpyrrolidone solvent.  
     
     
         30 . An improved metal threaded connection that is resistant to corrosion and galling, comprising: 
 a phosphatized female threaded part having a first surface provided with a dry film comprising intrinsically conductive polyaniline and molybdenum disulfide; and    a male threaded part having a second surface to be in contact with the first surface, the second surface being provided with a dry film comprising intrinsically conductive polyaniline.