Inorganic phosphate corrosion resistant coatings

Abstract

This disclosure relates to compositions for protecting a metallic surface susceptible to corrosion, the composition comprising a first component comprising an aqueous mixture of an acid-phosphate of chemical formula A m (H 2 PO 4 ) m .nH 2 O, where A is hydrogen ion, ammonium cation, metal cation, or mixtures thereof; where m=1-3, and n=0-6; the first component solution adjusted to a pH of about 2 to about 5, the first component having a particle size distribution between 0.04 to 60 micron; and a second component, configured for combination and at least partial reaction with the first component to provide a phosphate ceramic, the second component comprising an aqueous solution or suspension of an alkaline oxide or alkaline hydroxide represented by B 2m O m , B(OH) 2m , or mixtures thereof, where B is an element of valency 2m (m=1, 1.5, or 2) the second component solution adjusted to a pH of between 9-14.

1 . A phosphate ceramic precursor composition comprising:
 a first component comprising an aqueous mixture of an acid-phosphate of chemical formula A m (H 2 PO 4 ) m .nH 2 O, where A is hydrogen ion, ammonium cation, metal cation, or mixtures thereof; where m=1-3, and n=0-6; the first component solution adjusted to a pH of about 2 to about 5, the first component having a particle size distribution between 0.04 to 60 micron; and   a second component, configured for combination and at least partial reaction with the first component to provide a phosphate ceramic, the second component comprising an aqueous mixture of an alkaline oxide or alkaline hydroxide represented by B 2m O m , B(OH) 2m , or mixtures thereof, where B is an element of valency 2m (m=1, 1.5, or 2) the second component solution adjusted to a pH of between 9-14.   
     
     
         2 . The phosphate ceramic precursor composition of  claim 1 , wherein about 50 percent of the particle size distribution of the first component is particles having a particle size less than 50 microns, less than 40 microns, less than 30 microns, or less than 20 microns. 
     
     
         3 . The phosphate ceramic precursor composition of  claim 1  wherein about 90 percent of the particle size distribution of the first component is particles having a particle size less than 50 microns, less than 40 microns, or less than 30 microns. 
     
     
         4 . The phosphate ceramic precursor composition of  claim 1 , wherein the first component average particle size is about 20 microns to about 30 microns. 
     
     
         5 . The phosphate ceramic precursor composition of  claim 1 , wherein the first component comprises at least one of mono potassium phosphate and mono calcium phosphate, water, and optionally about 2 to about 10 wt % phosphoric acid, and wherein the second component is at least one of magnesium oxide, calcium oxide, magnesium hydroxide, and calcium hydroxide, and water. 
     
     
         6 . (canceled) 
     
     
         7 . The phosphate ceramic precursor composition of  claim 5 , further comprising at least one of a mineral silicate, wollastonite, talc, amorphous magnesium silicate, amorphous calcium silicate, diatomaceous earth, silicon dioxide, amorphous silicon dioxide, a rheology modifier/suspending agent, the rheology modifier/suspending agent is at least one of guar gum, diutan gum, welan gum, and xanthan gum present in an amount of 0.15-15 weight percent. 
     
     
         8 . The phosphate ceramic precursor composition of a  claim 5 , wherein either of the first component or the second component is present in an amount of at least about 60 wt % to about 80 wt %. 
     
     
         9 . (canceled) 
     
     
         10 . A method of providing corrosion protection to a metal surface, the method comprising:
 contacting a metal surface with a first component and a second component, in any order or in combination;   wherein the first component comprises an aqueous mixture of an acid-phosphate of chemical formula A m (H 2 PO 4 ) m .nH 2 O, where A is hydrogen ion, ammonium cation, metal cation, or mixtures thereof; where m=1-3, and n=0-6; the first component solution adjusted to a pH of about 2 to about 5, the first component having a particle size distribution between 0.04 to 60 micron; and   wherein the second component comprises an aqueous mixture of an alkaline oxide or alkaline hydroxide represented by B 2m O m , B(OH) 2m , or mixtures thereof, where B is an element of valency 2m (m=1, 1.5, or 2) the second component solution adjusted to a pH of between 9-14; and   providing corrosion protection to the metal surface.   
     
     
         11 . The method of  claim 10 , wherein about 50 percent of the particle size distribution of the first component is particles having a particle size less than 50 microns, less than 40 microns, less than 30 microns, or less than 20 microns. 
     
     
         12 . The method of  claim 10  wherein about 90 percent of the particle size distribution of the first component is particles having a particle size less than 50 microns, less than 40 microns, or less than 30 microns. 
     
     
         13 . The method of  claim 10  wherein the first component average particle size is about 20 microns to about 30 microns. 
     
     
         14 . The method of  claim 10 , wherein the first component comprises a dihydrogen phosphate salt of formula M m (H 2 PO 4 ) m  and its hydrates, or mixtures thereof; where M sodium, potassium, magnesium, calcium, aluminum, or mixtures thereof, and m is 1-3. 
     
     
         15 . The method of  claim 10 , wherein the first component comprises water, at least one of mono potassium phosphate and mono calcium phosphate, and optionally, about 2 to about 10 wt % phosphoric acid, and wherein the second component is at least one of magnesium oxide, calcium oxide, magnesium hydroxide, and calcium hydroxide, and water. 
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 10 , wherein the second component further comprises wollastonite, talc, Class C fly ash, Class F fly ash, kaolin clay, kaolinite, meta kaolin, mullite, calcium aluminate minerals, calcium silicate minerals, aluminum silicate minerals, calcium aluminum silicate minerals, or mixtures thereof, in a weight ratio of between 1:0.05 to 1: 6 of the second component. 
     
     
         18 . The method of  claim 10 , wherein the first component or the second component is present in an amount of at least about 60 wt % to about 80 wt %. 
     
     
         19 . (canceled) 
     
     
         20 . A product coated by the method of  claim 10 . 
     
     
         21 . An inorganic phosphate compound of the general formula:
 i) B s (A 3−m PO 4 ) s ; wherein A has a valency of m=1 or 2; and B has a valency of s=1, or 2;   ii) B s (A (2/m) PO 4 ) s ; wherein A has a valency of m=1 or 2; B has a valency of s=1, or 2;   iii)  (2/m) A 3 B m (PO 4 ) 2 ; wherein A has a valency of m=1 or 2; B has a valency of 3; or   iv) B(AOPO 4 ) s ; wherein A has a valency of 4 and s=1 or 2; and B has a valency of 1, or 2;    wherein the inorganic phosphate i-iv has less than 0.000001 to 10 percent of unreacted, crystalline inorganic acid phosphate of an average particle size greater than about 60 microns.   
     
     
         22 . The inorganic phosphate compound of  claim 21 , wherein the compound is at least one of the following: MgKPO 4 ; Mg(ZnPO 4 ) 2  Mg(K 2 PO 4 ) 2 ; Mg 2 KPO 4 ; Mg(ZnPO 4 ) 2 ; Mg(K 2 PO 4 ) 2 ; Al 2 Mg 3 (PO 4 ) 2 ; Mg(ZrOPO 4 ) 2 ; Mg[Zr(OH) 2 PO 4 ) 2 ] 2 ; and calcium/magnesium phosphate. 
     
     
         23 . The inorganic phosphate ceramic of  claim 21 , wherein less than 0.000001 to 10 percent of the unreacted, crystalline inorganic acid phosphate is of an average particle size distribution greater than about 50 microns, less than 40 microns, or less than 30 microns. 
     
     
         24 . The inorganic phosphate compound of  claim 21 , wherein the inorganic phosphate has a density less than 1.8 g/cm 3 . 
     
     
         25 . The inorganic phosphate compound of  claim 21 , wherein the inorganic phosphate has a density less than 1.5 g/cm3.