Wet on Wet Method and Chrome-Free Acidic Solution for the Corrosion Control Treatment of Steel Surfaces

Abstract

A process for anticorrosion treatment of bare metal surfaces comprising steel surfaces, comprising contacting the bare metal surfaces with an acidic aqueous solution of a fluoro complex of at least one element M selected from the group B, Si, Ti, Zr and Hf, at least one further component selected from among: a buffer system for the pH range from 2.5 to 5.5, nitrate ions, copper ions, silver ions, vanadium or vanadate ions, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, aromatic carboxylic acids with at least two groups containing donor atoms, or derivatives of such carboxylic acids, and silica particles with an average particle size of below 1 μm; and contains no more than 1 mg/l of an organic polymer with allylamine or vinylamine monomers; then rinsing the metal surfaces with water and thereafter coating them with a cathodically depositable electro-dipcoating.

What is claimed is: 
     
         1 . A process for anticorrosion treatment of bright metal surfaces, which are at least in part steel surfaces, comprising steps of:
 1) contacting metal surfaces that are not yet coated with an anticorrosion coating, said surfaces comprising at least one steel surface, with an acidic aqueous solution of a fluoro complex of at least one element M selected from the group consisting of B, Si, Ti, Zr and Hf; wherein:   a) the aqueous solution comprises no more than 1 mg/l of an organic polymer with allylamine or vinylamine monomers;   b) the aqueous solution comprises a buffer system for the pH range from 2.5 to 5.5;   c) the aqueous solution comprises at least one component selected from the group consisting of: nitrate ions, copper ions, silver ions, vanadium ions, vanadate ions, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, aromatic carboxylic acids having at least two groups containing donor atoms, derivatives of said carboxylic acids, and silica particles having an average particle size of less than 1 μm;   2) rinsing the metal surfaces after step 1); and   3) coating the metal surfaces with a cathodically depositable electro-dipcoating.   
     
     
         2 . The process according to  claim 1 , wherein after contacting step 1) and before being coated with the cathodically depositable electro-dipcoating, the metal surface is not dried. 
     
     
         3 . The process according to  claim 1 , wherein the aqueous solution comprises no more than 1 mg/l of organic polymer. 
     
     
         4 . The process according to  claim 1 , wherein the element M is selected from the group consisting of Si, Ti, Zr and Hf, the aqueous solution contains on average at least 1 fluorine ion per ion of the element M and the fluoro complex is present in an amount such that concentration of the element M is from 1 to 5000 mg/l. 
     
     
         5 . The process according to  claim 1 , wherein the aqueous solution comprises 0.1 to 300 mg/l copper ions and/or silver ions. 
     
     
         6 . The process according to  claim 1 , wherein component c) comprises at least one component selected from the group consisting of hydroxycarboxylic acids, aminocarboxylic acids, nitrocarboxylic acids, carboxylic acids with at least two carboxyl groups, and derivatives of said acids. 
     
     
         7 . The process according to  claim 1 , wherein the aqueous solution comprises 10 to 1000 mg/l of silicon in the form of silica particles with an average particle size of less than 1 μm. 
     
     
         8 . The process according to  claim 1 , wherein the aqueous solution further comprises additional organic polymers that do not contain allylamine or vinylamine monomers, in an amount of less than 2000 mg/l, said polymers having thickening and/or dispersing properties and/or anticorrosion activity. 
     
     
         9 . A process for anticorrosion treatment of bright metal surfaces, which are at least in part steel surfaces, comprising:
 1) contacting metal surfaces that are not yet coated with an anticorrosion coating, said metal surfaces comprising at least one steel surface, with an acidic aqueous solution of a fluoro complex of at least one element M selected from the group consisting of B, Si, Ti, Zr and Hf; wherein:   a) the aqueous solution comprises no more than 1 mg/l of organic polymer;   b) the aqueous solution comprises 10 to 1000 mg/l of silicon in the form of silica particles with an average particle size of less than 1 μm;   c) the aqueous solution comprises at least one component selected from the group consisting of: nitrate ions, copper ions, silver ions, vanadium ions, vanadate ions, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, a buffer system for the pH range from 2.5 to 5.5, aromatic carboxylic acids having at least two groups containing donor atoms, and derivatives of said carboxylic acids;   2) rinsing the metal surfaces after step 1); and   3) coating the metal surfaces with a cathodically depositable electro-dipcoating.   
     
     
         10 . The process according to  claim 9 , wherein after having been brought into contact with the aqueous solution and before being coated with the cathodically depositable electro-dipcoating, the metal surface is not dried. 
     
     
         11 . The process according to  claim 9 , wherein the aqueous solution comprises 0.1 to 300 mg/l copper ions and/or silver ions. 
     
     
         12 . The process according to  claim 11 , wherein the aqueous solution contains a buffer system for the pH range from 2.5 to 5.5. 
     
     
         13 . The process according to  claim 9 , wherein the element M is selected from the group consisting of Si, Ti, Zr and Hf and the aqueous solution contains on average at least 1 fluorine ion per ion of the element M. 
     
     
         14 . The process according to  claim 9 , wherein c) comprises the buffer system for the pH range from 2.5 to 5.5; and one or more components selected from: copper ions, silver ions, tin ions, bismuth ions, aromatic carboxylic acids with at least two groups containing donor atoms, and derivatives of said carboxylic acids. 
     
     
         15 . The process according to  claim 14 , wherein the fluoro complex is present in a quantity such that the concentration of the element M is in a range from 1 to 5000 mg/l. 
     
     
         16 . The process according to  claim 14 , wherein the aqueous solution additionally contains 10 to 500 mg/l nitroguanidine or 0.1 to 5000 mg/l of nitrate ions. 
     
     
         17 . The process according to  claim 14 , wherein component b) comprises at least one component selected from the group consisting of hydroxycarboxylic acids, aminocarboxylic acids, nitrocarboxylic acids, carboxylic acids with at least two carboxyl groups, and derivatives of said acids. 
     
     
         18 . A process for anticorrosion treatment of bright metal surfaces, which are at least in part steel surfaces, comprising steps of:
 1) contacting metal surfaces that are not yet coated with an anticorrosion coating, said surfaces comprising at least one steel surface, with an acidic aqueous solution of a fluoro complex of at least one element M selected from the group consisting of Si, Ti, Zr and Hf; said aqueous solution having a pH value in the range from 2 to 5.5, and comprising:   a) organic polymer;   b) 10 to 1000 mg/l of silicon in the form of silica particles with an average particle size of less than 1 μm; and   c) one or more components selected from among: nitrate ions, copper ions, silver ions, vanadium ions, vanadate ions, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, buffer systems for the pH range from 2.5 to 5.5, aromatic carboxylic acids with at least two groups containing donor atoms, and derivatives of said carboxylic acids,   2) rinsing the metal surfaces after step 1); and   3) coating the metal surfaces with a cathodically depositable electro-dipcoating without intermediate drying wherein after contacting step 1) and before being coated with the cathodically depositable electro-dipcoating, the metal surface is not dried.   
     
     
         19 . The process according to  claim 18 , wherein the aqueous solution contains no more than 1 mg/l of organic polymers that contain allylamine or vinylamine monomers. 
     
     
         20 . The process according to  claim 19 , wherein component a) comprises organic polymers, which do not contain allylamine or vinylamine monomers; an amount of less than 2000 mg/l and component c) comprises the buffer system for the pH range from 2.5 to 5.5. 
     
     
         21 . The process according to  claim 20 , wherein the aqueous solution contains a quantity of fluoro complex such that the concentration of the element M is in a range from 5 to 1000 mg/l; and in the fluoro complex, there are six fluorine ions per ion of the element M and the aqueous solution also contains 1 to 1000 mg/l of fluoride ions which are not attached to the element M. 
     
     
         22 . The process according to  claim 20 , wherein the aqueous solution additionally contains 10 to 500 mg/l nitroguanidine or 0.1 to 5000 mg/l of nitrate ions. 
     
     
         23 . The process according to  claim 20 , wherein the aqueous solution comprises from 0.1 to 300 mg/l of copper and/or silver ions and 50 to 500 mg/l of silicon in the form of silica particles with an average particle size of below 1 μm.