Aqueous surface conditioner and surface conditioning method for phospating treatment

Abstract

An aqueous surface conditioner for use in a phosphating treatment is provided which contains crystals having an average diameter of 5 μm or less in an amount of at least 0.1 g/L. The crystals are selected to have a two-dimensional epitaxy that matches within 3% of misfit with the crystal lattice of one phosphate coating selected from among (1) hopeite/Zn 3 (PO 4 ) 2 .4H 2 O) and/or phosphophyllite (Zn 2 Fe(PO 4 ) 2 .4H 2 O), (2) scholzite (CaZn 2 (PO 4 ) 2 .2H 2 O) and (3) hureaulite (Mn 5 (PO 4 ) 2 [PO 3 (OH] 2 .4H 2 O).

What is claimed is:  
     
         1 . An aqueous surface conditioner for use in a phosphating treatment comprising crystals having an average diameter of 5 μm or less in an amount of at least 0.1 g/L, said crystals having a two-dimensional epitaxy that matches within 3% of misfit with the crystal lattice of a phosphate coating comprising one or more species selected from the group consisting of hopeite (Zn 3 (PO 4 ) 2 .4H 2 O), phosphophyllite (Zn 2 Fe(PO 4 ) 2 .4H 2 O), scholzite (CaZn 2 (PO 4 ) 2 .2H 2 O), and hureaulite (Mn 5 (PO 4 ) 2 [PO 3 (OH)] 2 .4H 2 O).  
     
     
         2 . The aqueous surface conditioner for use in a phosphating treatment according to  claim 1 , wherein the phosphate coating is comprised mainly of hopeite, phosphophyllite or a mixture of hopeite and phosphophyllite and the crystals are selected from the group consisting of magnesium hydrogenphosphate (MgHPO 4 .3H 2 O), zirconium oxide (ZrO 2 ), zinc oxalate (Zn(COO) 2 ), cobalt oxalate (Co(COO) 2 ), iron orthosilicate (Fe 2 SiO 4 ), iron metasilicate (FeSiO 3 ), and magnesium borate (Mg 3 (BO 3 ) 2 ) and mixtures thereof.  
     
     
         3 . The aqueous surface conditioner for use in a phosphating treatment according to  claim 1 , wherein the phosphate coating is comprised mainly of scholzite and the crystals are selected from the group consisting of anhydrous cobalt phosphate (CO 3 (PO 4 ) 2 ), anhydrous zinc phosphate (γ-Zn 3 (PO 4 ) 2 ), anhydrous zinc magnesium phosphate (Zn 2 Mg(PO 4 ) 2 ), anhydrous zinc cobalt phosphate (γ-Zn 2 Co(PO 4 ) 2 ), anhydrous zinc iron phosphate (γ-Zn 2 Fe(PO 4 ) 2 ) and mixtures thereof.  
     
     
         4 . The aqueous surface conditioner for use in a phosphating treatment according to  claim 1 , wherein the phosphate coating is comprised mainly of hureaulite, and the crystals are one or more types selected from the group consisting of calcium orthosilicate (Ca 2 SiO 4 .H 2 O), calcium metaphosphate (Ca 3 (PO 3 ) 6 . 10H 2 O), manganese(II) metaphosphate (Mn 3 (PO 3 ) 6 .10H 2 O) and mixtures thereof.  
     
     
         5 . A method for conditioning a surface of a metal material, comprising contacting the surface of the metal material with the aqueous surface conditioner according to any of  claims 1  to  4  prior to subjecting the surface of the metal material to phosphating treatment.