Inorganic phosphate corrosion resistant coatings

Abstract

This disclosure relates to phosphate coatings that inhibit corrosion of metals, specifically coatings comprising acidic phosphate and alkaline metal oxide/hydroxide components. In one particular embodiment, phosphate-based coating formulations that reduce or eliminate corrosion of steel and other metals are disclosed. In other embodiments, methods for coating steel surfaces with acidic phosphate and alkaline metal oxide/hydroxide components to reduce or eliminate corrosion of the metal surfaces are disclosed.

1 . A method for preventing or reducing corrosion of a corrodible metal surface, the method comprising contacting the corrodible metal surface with a mixture of an acidic phosphate component and a basic component comprising at least one of a metal oxide, a basic metal hydroxide, or basic mineral. 
     
     
         2 . The method of  claim 1 , wherein the acidic phosphate component is phosphoric acid, alkali metal dihydrogen phosphate MH 2 PO 4 , alkali earth dihydrogen phosphate M(H 2 PO 4 ) 2  or its hydrate, transition metal trihydrogen phosphate MH 3 (PO 4 ) 2  or its hydrate, or mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the acidic phosphate component is mono potassium phosphate or its hydrate. 
     
     
         4 . The method of  claim 1 , wherein the basic component is at least one of magnesium oxide, barium oxide, zinc oxide, calcium oxide, copper oxide, iron oxide, and hydroxides thereof, or magnesium brine containing an effective amount of magnesium hydroxide. 
     
     
         5 . The method of  claim 1 , wherein the basic component is at least one of magnesium oxide and magnesium hydroxide. 
     
     
         6 . The method of  claim 1 , wherein the acidic phosphate component is mono potassium phosphate or its hydrate, and the basic component is magnesium brine having a pH of about 9 to about 11, wherein the magnesium brine contains an effective amount of magnesium hydroxide. 
     
     
         7 . The method of  claim 1 , wherein the mixture of acidic phosphate component and basic component forms at least one of magnesium potassium phosphate, magnesium sodium phosphate, magnesium hydrogen phosphate, copper hydrogen phosphate, zinc hydrogen phosphate, or iron hydrogen phosphate. 
     
     
         8 . The method of  claim 1 , wherein the surface is steel or aluminum. 
     
     
         9 . The method of  claim 1 , further comprising painting the contacted corrodible surface with a magnesium-glass-phosphate paste and providing a hard ceramic, glossy coating. 
     
     
         10 . The method of  claim 1 , wherein the contacting is with a slurry, paste, spray, or vapor thereof, independently, of the acidic phosphate component or the at least one basic component. 
     
     
         11 . The method of  claim 1 , wherein the acidic phosphate component is alkali metal dihydrogen phosphate MH 2 PO 4 , alkali earth dihydrogen phosphate M(H 2 PO 4 ) 2  or its hydrate, transition metal trihydrogen phosphate MH 3 (PO 4 ) 2  or its hydrate, or mixtures thereof, and wherein the basic component is at least one of magnesium oxide, barium oxide, zinc oxide, calcium oxide, copper oxide, and hydroxides thereof, or magnesium brine containing an effective amount of magnesium hydroxide, further comprising wollastonite (CaSiO 3 ) or crushed or highly soluble glass. 
     
     
         12 . The method of  claim 1 , wherein the acidic phosphate component is mono potassium phosphate or its hydrate, and wherein the basic component is magnesium brine having a pH of about 9 to about 11, wherein the magnesium brine contains an effective amount of magnesium hydroxide, further comprising wollastonite (CaSiO 3 ) or crushed or highly soluble glass. 
     
     
         11 . The method of  claim 1 , wherein the acidic phosphate component is alkali metal dihydrogen phosphate MH 2 PO 4 , alkali earth dihydrogen phosphate M(H 2 PO 4 ) 2  or its hydrate, transition metal trihydrogen phosphate MH 3 (PO 4 ) 2  or its hydrate, or mixtures thereof, and wherein the basic component is at least one of magnesium oxide, barium oxide, zinc oxide, calcium oxide, copper oxide, and hydroxides thereof, or magnesium brine containing an effective amount of magnesium hydroxide, further comprising wollastonite (CaSiO 3 ) or crushed or highly soluble glass. 
     
     
         12 . The method of  claim 1 , wherein the acidic phosphate component is mono potassium phosphate or its hydrate, and wherein the basic component is magnesium brine having a pH of about 9 to about 11, wherein the magnesium brine contains an effective amount of magnesium hydroxide, further comprising wollastonite (CaSiO 3 ) or crushed or highly soluble glass. 
     
     
         13 . The method of  claim 1 , wherein the acidic phosphate component is mono potassium phosphate or its hydrate, and wherein the basic component is magnesium brine having a pH of about 9 to about 11, wherein the magnesium brine contains an effective amount of magnesium hydroxide, further comprising wollastonite (CaSiO 3 ) or crushed or highly soluble glass. The corrosion-inhibiting coating of  claim 12 , wherein the total amount of hematite used is greater than the amount of magnetite or wustite. 
     
     
         14 . A method comprising
 contacting a corrodible surface with coating consisting essentially of a mixture of magnetite or wustite, and hematite; with a solution of phosphoric acid or magnesium dihydrogen phosphate, wherein the corrodible surface is essentially without a primer layer; and   providing a corrosion-inhibiting coating, the coating comprising iron hydrogen phosphate.   
     
     
         15 . A method of providing corrosion inhibition comprising:
 providing a combination of at least one of the following:
 (i) magnesium oxide (MgO) and mono potassium phosphate (KH 2 PO 4 ); 
 (ii) magnesium oxide (MgO) and phosphoric acid solution (H 3 PO 4  solution); 
 (iii) magnesium oxide (MgO) and magnesium dihydrogen phosphate; 
 (iv) ferric oxide (Fe 2 O 3 ) and phosphoric acid (H 3 PO 4 ); 
 (v) magnesium brine containing an effective amount of magnesium hydroxide and mono potassium phosphate (KH 2 PO 4 ); 
 (vi) magnesium brine containing an effective amount of magnesium hydroxide and phosphoric acid (H 3 PO 4 ); or 
 (vii) magnesium brine containing an effective amount of magnesium hydroxide and magnesium dihydrogen phosphate; and 
   contacting the surface of a corrodible metal with at least one of the combinations (i)-(vii).   
     
     
         16 . The method of  claim 15 , wherein the combination is presented as a slurry, paste, spray, or vapor. 
     
     
         17 . An article comprising a corrosion-inhibiting coating formed by the combination of an acidic phosphate with a basic metal oxide or basic metal hydroxide. 
     
     
         18 . The article of  claim 17 , wherein the coating is at least one of magnesium potassium phosphate, magnesium sodium phosphate, magnesium hydrogen phosphate, barium hydrogen phosphate, copper hydrogen phosphate, zinc hydrogen phosphate, or iron hydrogen phosphate. 
     
     
         19 . The article of  claim 17 , wherein polyphosphates are present at the interface of the article surface and the corrosion-inhibiting coating. 
     
     
         20 . The article of  claim 17 , wherein magnesium chromates are present at the interface of the article surface and the corrosion-inhibiting coating. 
     
     
         21 . The article of  claim 17 , having a coating comprising a berlinite phase (AlPO 4 ) detectable by x-ray diffraction. 
     
     
         22 - 25 . (canceled) 
     
     
         26 . A method comprising
 contacting a metal surface, at least a portion of the metal surface being corroded, with a composition comprising a mixture of an acidic phosphate component and a basic component of at least one of metal oxide, metal hydroxide, or basic mineral;   bonding at least a portion of the composition to the corroded metal surface and the metal surface; wherein at least a portion of the composition and a portion of the previously corroded surface is removable and/or dislodges from the metal surface   removing at least a portion of both the corroded metal surface and the composition; and   forming a thin, corrosion protection layer on the surface, wherein the thin, corrosion protection layer is at least one of magnesium potassium phosphate, magnesium sodium phosphate, magnesium hydrogen phosphate, barium hydrogen phosphate, copper hydrogen phosphate, zinc hydrogen phosphate, or iron hydrogen phosphate.