Coatings and Methods for Corrosion Detection and/or Reduction

Abstract

Coatings and methods are provided. An embodiment of the coating includes microcapsules that contain at least one of a corrosion inhibitor, a film-forming compound, and an indicator. The microcapsules are dispersed in a coating vehicle. A shell of each microcapsule breaks down in the presence of an alkaline condition, resulting from corrosion.

1 . A coating comprising:
 a coating vehicle; and   microcapsules dispersed in the coating vehicle, said microcapsules comprising shells encapsulating at least an indicator for indicating the presence of corrosion;   said microcapsule shells formed of a material that breaks down in the presence of an alkaline condition naturally occurring in the presence of corrosion, thereby releasing at least the indicator.   
     
     
         2 . The coating of  claim 1 , wherein the indicator changes its color in response to the alkaline condition resulting from the corrosion. 
     
     
         3 . The coating of  claim 1 , wherein the microcapsules further encapsulate a corrosion inhibitor. 
     
     
         4 . The coating of  claim 1 , wherein the microcapsules encapsulating at least the indicator are first microcapsules, with further second microcapsules encapsulating a corrosion inhibitor. 
     
     
         5 . The coating of  claim 1 , wherein the coating vehicle is selected from the group consisting of clear paint, clear varnish, opaque varnish, opaque paint, water, solvents, and aqueous gel. 
     
     
         6 . A coating comprising:
 a coating vehicle; and   microcapsules dispersed in the coating vehicle, said microcapsules comprising shells encapsulating a corrosion inhibitor or a film-forming compound or both;   said microcapsule shells formed of a material that breaks down in the presence of an alkaline condition naturally occurring in the presence of corrosion.   
     
     
         7 . The coating of  claim 6 , wherein the microcapsules further encapsulate an indicator. 
     
     
         8 . A coating comprising:
 a coating vehicle; and   first microcapsules dispersed in the coating vehicle, each first microcapsule comprising a first shell encapsulating a first encapsulant;   said first shells formed of a material that breaks down to release the first encapsulant when exposed to alkaline conditions naturally occurring in the presence of corrosion; and   said first encapsulant comprising at least one material selected from the group consisting of corrosion indicators, corrosion inhibitors, and film-forming compounds.   
     
     
         9 . The coating of  claim 8  further comprises:
 second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second shell encapsulating a second encapsulant;   said second shells breaking down to release the second encapsulant when exposed to alkaline conditions naturally occurring in the presence of corrosion; and   said first encapsulant comprising a corrosion indicator and said second encapsulant comprising a corrosion inhibitor or a film-forming compound.   
     
     
         10 . The coating of  claim 8  further comprises:
 second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second shell encapsulating a second encapsulant;   said second shells breaking down to release the second encapsulant when exposed to alkaline conditions naturally occurring in the presence of corrosion; and   said second encapsulant having a different composition than the first encapsulant, said second encapsulant including at least one material selected from the group consisting of corrosion indicators, corrosion inhibitors, and film-forming compounds.   
     
     
         11 . The coating of  claim 8  further comprises:
 second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second shell encapsulating a second encapsulant;   said second shells breaking down to release the second encapsulant when exposed to alkaline conditions naturally occurring in the presence of corrosion; and   said first and second shells formed of the same material.   
     
     
         12 . The method of  claim 8 , wherein said shells breakdown at pH values of about 8 or above. 
     
     
         13 . The coating of  claim 1 , wherein the indicator fluoresces in the presence of an alkaline condition resulting from the corrosion. 
     
     
         14 . The coating of  claim 1 , wherein the microcapsules further encapsulate a film forming compound.