Plasma-Chemical Method For Production Of Black Oxide-Ceramic Layers And Correspondingly Coated Object

Abstract

Plasma-chemical method for production of black oxide ceramic layers on aluminium, magnesium, titanium or alloys thereof and special materials containing these substances according to the process of anodic oxidation in aqueous electrolytes, wherein an electrolyte is used which contains iron and vanadium.

1 . Plasma-chemical method for production of black oxide ceramic layers on aluminium, magnesium, titanium or alloys thereof and special materials containing these substances according to the process of anodic oxidation in aqueous electrolytes, characterised in that an electrolyte is used which contains iron and vanadium. 
     
     
         2 . Method as claimed in  claim 1 , characterised in that the electrolyte has a pH value of 5.4 to 10.0. 
     
     
         3 . Method as claimed in  claim 1 , characterised in that the electrolyte contains 0.15 to 0.5 Mol/L citric acid or salts thereof. 
     
     
         4 . Method as claimed in  claim 1 , characterised in that the electrolyte contains 0.8 to 2.9 Mol/L of a stabiliser, in particular hexamethylene tetramine. 
     
     
         5 . Method as claimed in  claim 1 , characterised in that the electrolyte contains 0.2 to 0.9 Mol/L of a phosphate of an alkali metal, preferably a dihydrogen phosphate or pyrophosphate, in particular potassium dihydrogen phosphate or potassium pyrophosphate. 
     
     
         6 . Method as claimed in  claim 1 , characterised in that the electrolyte contains 0.04 to 0.09 Mol/L of an iron(III) salt, in particular ammonium iron(III) citrate. 
     
     
         7 . Method as claimed in  claim 1 , characterised in that the electrolyte contains 0.035 to 0.090 Mol/L of a vanadium(V) salt, in particular ammonium (mono)vanadate. 
     
     
         8 . Method as claimed in  claim 1 , characterised in that the electrolyte bath is at a temperature of 15 to 60 degrees Celsius. 
     
     
         9 . Method as claimed in  claim 1 , characterised in that the current density used is from 0.02 to 0.10 Acm-2, preferably 0.04 to 0.08 Acm-2. 
     
     
         10 . Method as claimed in  claim 9 , characterised in that a final voltage below 1000 V, preferably 300 to 650 V, is achieved. 
     
     
         11 . Method as claimed in  claim 1 , characterised in that the oxide ceramic layers have a layer thickness in the range of 5 μm to 100 μm. 
     
     
         12 . Method as claimed in  claim 1 , characterised in that the oxide ceramic layers produced consist of oxides, in particular spinels, of aluminium, iron and vanadium. 
     
     
         13 . Method as claimed in  claim 1 , characterised in that jet black oxide ceramic layers with a colour characteristic of L* being less than or equal to 30 are produced. 
     
     
         14 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 1 . 
     
     
         15 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 2 . 
     
     
         16 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 3 . 
     
     
         17 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 4 . 
     
     
         18 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 6 . 
     
     
         19 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 7 . 
     
     
         20 . Object with an oxide ceramic layer, in particular an oxide layer of aluminium, iron and vanadium, which can be obtained by a method as claimed in  claim 10 .