Anticorrosive coatings, processes and uses thereof

Abstract

The invention provides novel methods for anticorrosive protection of iron or steel surfaces, such as on embedded iron or steel reinforcement components in composite materials and on steel surfaces of piles and vessels. The unique siderite coating formed during a carbonation curing possesses excellent anticorrosive properties and is suitable for improving the overall service life of coated objects.

1 . A process for forming an anticorrosive coating on a metal surface, comprising contacting the metal surface with an aqueous atmosphere of CO 2  and water vapor at a temperature and for a time period sufficient to form an anticorrosive coating on the metal surface. 
     
     
         2 . The process of  claim 1 , wherein the metal surface is a surface of a metal selected from iron and steel. 
     
     
         3 . The process of  claim 2 , wherein the metal surface is that of an object selected from bars, wires, cables, shards, filaments, tubings, pipes, containers, vessels and equipment. 
     
     
         4 . The process of  claim 1 , wherein the aqueous atmosphere of CO 2  and water vapor is characterized by a pH value between about 3.5 to about 14. 
     
     
         5 . The process of  claim 1 , wherein the anticorrosive coating comprises metal carbonate. 
     
     
         6 . The process of  claim 5 , wherein the anticorrosive coating consists essentially of iron carbonate. 
     
     
         7 . The process of  claim 1 , wherein the anticorrosive coating has a thickness in the range from about 1 μm to about 50 μm. 
     
     
         8 . The process of  claim 1 , wherein the anticorrosive coating has a surface coverage of 90% or greater. 
     
     
         9 . The process of  claim 1 , wherein the anticorrosive coating has a porosity of about 2.5×10 −2  or less. 
     
     
         10 . A process for passivating iron or steel reinforcement wires or bars for corrosion resistance, comprising contacting the iron or steel reinforcement wires, cables or bars with an aqueous suspension of particulate calcium silicate under an atmosphere of CO 2  and water vapor at a pH from about 3.5 to about 14 to form an anticorrosive coating of iron carbonate covering the surface of iron or steel reinforcement wires, cables or bars, wherein the step of contacting the iron or steel surface with an aqueous suspension of particulate calcium silicate is conducted
 at a temperature in the range from about 10° C. to about 150° C.,   for a time period from about 1 hour to about 150 hours,   under an atmosphere of water and CO 2  having a pressure in the range from ambient atmospheric pressure to about 150 psi above ambient and having a CO 2  concentration ranging from about 10% to about 99%, and   with the particulate calcium silicate having a median particle size in the range from about 1 μm to about 100 μm.   
     
     
         11 . The process of  claim 10 , wherein the pH value is between about 3.5 to about 14.0. 
     
     
         12 . The process of  claim 10 , wherein the temperature is in the range from about 10° C. to about 150° C. 
     
     
         13 . The process of  claim 10 , wherein the atmosphere of water and CO 2  has a pressure in the range from ambient atmospheric pressure to about 40 psi above ambient and having a CO 2  concentration ranging from about 50% to about 95%. 
     
     
         14 . The process of  claim 10 , wherein the anticorrosive coating has a thickness in the range from about 1 μm to about 50 μm. 
     
     
         15 . The process of  claim 14 , wherein the anticorrosive coating has a thickness from about 1 μm to about 30 μm. 
     
     
         16 . The process of  claim 10 , wherein the anticorrosive coating has a surface coverage of 90% or greater. 
     
     
         17 . The process of  claim 16 , wherein the anticorrosive coating has a porosity of about 2.5×10 −2  or less. 
     
     
         18 . An article prepared by a process according to  claim 1 . 
     
     
         19 . An article of manufacture having a body prepared from a composite material, the body being embedded with one or more reinforcement metal wires, cables or bars, wherein
 each of the one or more reinforcement metal wires, cables or bars is coated with an anticorrosive coating; and   the composite material comprises:
 a plurality of bonding elements, wherein each bonding element comprises: a core comprising primarily calcium silicate, a silica-rich first or inner layer, and a calcium carbonate-rich second or outer layer, and 
 filler particles comprising coarse filler particles and/or fine filler particles, wherein the plurality of bonding elements and the plurality of filler particles together form one or more bonding matrices and the bonding elements and the filler particles are substantially evenly dispersed therein and bonded together. 
   
     
     
         20 . The article of  claim 19 , wherein the anticorrosive coating has a thickness in the range from about 5 to about 50 μm. 
     
     
         21 . The article of  claim 20 , wherein the anticorrosive coating has a thickness in the range from about 10 to about 40 μm. 
     
     
         22 . The article of  claim 19 , wherein the anticorrosive coating has a surface coverage of 90% or greater. 
     
     
         23 . The article of  claim 19 , wherein the anticorrosive coating has a porosity of about 2.5×10 −3  or less. 
     
     
         24 . The article of  claim 19 , wherein the metal is selected from iron and steel. 
     
     
         25 . The article of  claim 19 , wherein the article is selected from hollow core slabs, solid slabs, railroad ties, wall panels, floor panels, roof panels, Jersey barriers, blocks, beams, columns, and aerated structures and members thereof. 
     
     
         26 . An article of manufacture comprising a metal surface coated with an anticorrosive coating comprising metal carbonate. 
     
     
         27 . The article of  claim 26 , wherein the anticorrosive coating consists essentially of metal carbonate. 
     
     
         28 . The article of  claim 26 , wherein the article is selected from metal bars, wires, shards, filaments, tubings, pipes, containers, vessels and equipment. 
     
     
         29 . The article of  claim 26 , wherein the metal is selected from iron and steel. 
     
     
         30 . The article of  claim 26 , wherein the anticorrosive coating has a thickness in the range from about 5 to about 50 μm. 
     
     
         31 . The article of  claim 26 , wherein the anticorrosive coating has a surface coverage of 95% or greater. 
     
     
         32 . The article of  claim 26 , wherein the anticorrosive coating has a porosity of about 2.5×10 −3  or less. 
     
     
         33 . The article of  claim 26 , wherein the metal is steel and the metal carbonate is iron carbonate. 
     
     
         34 . An article of manufacture having a body prepared from Portland cement, the body being embedded with one or more reinforcement metal wires, cables or bars, wherein each of the one or more reinforcement metal wires, cables or bars is coated with an anticorrosive coating comprising metal carbonate. 
     
     
         35 . The article of  claim 34 , wherein the anticorrosive coating has a thickness in the range from about 5 to about 50 μm. 
     
     
         36 . The article of  claim 35 , wherein the anticorrosive coating has a thickness in the range from about 10 to about 40 μm. 
     
     
         37 . The article of  claim 34 , wherein the anticorrosive coating has a surface coverage of 90% or greater. 
     
     
         38 . The article of  claim 34 , wherein the anticorrosive coating has a porosity of about 2.5×10 −3  or less. 
     
     
         39 . The article of  claim 34 , wherein the metal is selected from iron and steel. 
     
     
         40 . The article of  claim 34 , wherein the article is selected from hollow core slabs, solid slabs, railroad ties, wall panels, floor panels, roof panels, Jersey barriers, blocks, beams, columns, and aerated structures and members thereof.