Electrochemically Produced Layers for Corrosion Protection or as a Primer

Abstract

Use of a layer on an electrically conductive surface as a corrosion protection layer and/or as a primer for an organic coating, which may be obtained in a stage (a), in which a layer of at least one inorganic compound of at least one metal A having a weight per unit area of 0.01 to 10 g/m 2 is deposited electrochemically on the said surface from a solution containing the metal A in dissolved form, wherein the metal A is a different metal from the main component of the electrically conductive surface and wherein the inorganic compound contains less than 20 wt. % phosphate ions, process for producing a coating comprising at least two layers, at least one layer of an organic polymer being applied to the layer deposited in stage a); metal component comprising a coating comprising at least two layers obtainable in this manner.

1 . Use of a layer on an electrically conductive surface as a corrosion protection layer and/or as a primer for an organic coating, may be obtained in a stage (a), in which a layer of at least one inorganic compound of at least one metal A having a weight per unit area of 0.01 to 10 g/m 2  is deposited electrochemically on the said surface from a solution containing the metal A in dissolved form, wherein the metal A is a different metal from the main component of the electrically conductive surface and wherein the inorganic compound contains less than 20 wt. % phosphate ions.  
   
   
       2 . Use as claimed in  claim 1  wherein the compound deposited in stage (a) is an oxide.  
   
   
       3 . Use as claimed in one or both of claims  1  and  2  wherein the metal A is selected from Mg, Ca, Sr, Ba, Al, Si, Sn, Pb, Sb, Bi, Ti, Zr, V, Nb, Ta, Mo, W, Mn, Fe, Co, Ni, Zn, Cu.  
   
   
       4 . Use as claimed in one or more of  claims 1  to  3  wherein the inorganic compound is deposited on the electrically conductive surface at a potential relative to a standard hydrogen electrode of between ±0.1 and ±300 V or a current density of from ±0.1 to ±10000 mA per cm 2  of electrically conductive surface.  
   
   
       5 . Use as claimed in one or more of  claims 1  to  4  wherein the inorganic compound is X-ray crystalline.  
   
   
       6 . A process for producing a coating comprising at least two layers on an electrically conductive surface, characterised in that, in a stage (a), a layer of at least one inorganic compound of at least one metal A having a weight per unit area of 0.01 to 10 g/m 2  is electrochemically deposited on the electrically conductive surface from a solution containing the metal A in dissolved form, wherein the metal A is a different metal from the main component of the electrically conductive surface and wherein the inorganic compound contains less than 20 wt. % phosphate ions, and in a subsequent stage (b), at least one layer of an organic polymer is applied to the layer deposited in stage (a).  
   
   
       7 . A process as claimed in  claim 6  wherein the compound deposited in stage (a) is an oxide.  
   
   
       8 . A process as claimed in one or both of claims  6  and  7  wherein the metal A is selected from Mg, Ca, Sr, Ba, Al, Si, Sn, Pb, Sb, Bi, Ti, Zr, V, Nb, Ta, Mo, W, Mn, Fe, Co, Ni, Zn, Cu.  
   
   
       9 . A process as claimed in one or more of  claims 6  to  8  wherein the inorganic compound is deposited on the electrically conductive surface at a potential relative to a standard hydrogen electrode of between ±0.1 and ±300 V or a current density of from ±0.1 to ±10000 mA per cm 2  of electrically conductive surface.  
   
   
       10 . A process as claimed in one or more of  claims 6  to  9  wherein in substage (b) a cathodically or anodically depositable electrocoating lacquer is applied.  
   
   
       11 . A process as claimed in one or more of  claims 6  to  9  wherein the process is performed as a coil process and in substage (b) an organic polymer layer is applied by dipping or spraying or by applicator rolls.  
   
   
       12 . A process as claimed in one or more of  claims 6  to  9  wherein in substage (b) a powder coating is applied.  
   
   
       13 . A process as claimed in one or more of  claims 6  to  9  wherein in substage (b) an adhesive is applied.  
   
   
       14 . A metal component, the surface of which bears a coating comprising at least two layers, which may be obtained according to one or more of  claims 6  to  13 .  
   
   
       15 . A metal component as claimed in  claim 14  wherein the inorganic compound of at least one metal A is X-ray crystalline.