Method of producing oxide ceramic layers on barrier layer-forming metals and articles produced by the method
First Claim
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1. A method of producing oxide ceramic layers on Al, Mg, Ti, Ta, Zr, Nb, Hf, Sb, W, Mo, V, Bi or their alloys, the method comprising carrying out a plasma-chemical anodic oxidation in a substantially chloride-free electrolytic bath having less than 5×
- 10-3 mol/l chloride ions and a pH value of 2-8 and a constant bath temperature of between -30°
to +15°
C., and maintaining constant in the electrolytic bath a current density of at least 1 A/dm2 until the voltage reaches an end value;
the electrolytic bath containing phosphate ions, borate ions and fluoride ions in a quantity of up to a total of 2 mol/l, and a stabilizer selected from the group consisting of urea, hexamethylenediamine and hexamethylenetetramine, glycol and glycerin in a quantity of up to 1.5 mol/l.
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Abstract
A method of producing oxide ceramic layers on Al, Mg, Ti, Ta, Zr, Nb, Hf, Sb, W, Mo, V, Bi or their alloys by a plasma-chemical anodical oxidation in a chloride-free electrolytic bath having a pH value of 2 to 8 and a constant bath temperature of -30° to +15° C. A current density of at least 1 A/dm2 is maintained constant in the electrolytic bath until the voltage reaches a predetermined end value.
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Citations
7 Claims
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1. A method of producing oxide ceramic layers on Al, Mg, Ti, Ta, Zr, Nb, Hf, Sb, W, Mo, V, Bi or their alloys, the method comprising carrying out a plasma-chemical anodic oxidation in a substantially chloride-free electrolytic bath having less than 5×
- 10-3 mol/l chloride ions and a pH value of 2-8 and a constant bath temperature of between -30°
to +15°
C., and maintaining constant in the electrolytic bath a current density of at least 1 A/dm2 until the voltage reaches an end value;
the electrolytic bath containing phosphate ions, borate ions and fluoride ions in a quantity of up to a total of 2 mol/l, and a stabilizer selected from the group consisting of urea, hexamethylenediamine and hexamethylenetetramine, glycol and glycerin in a quantity of up to 1.5 mol/l. - View Dependent Claims (2, 3, 4)
- 10-3 mol/l chloride ions and a pH value of 2-8 and a constant bath temperature of between -30°
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5. A method of producing a wear-resistant oxide ceramic layer on aluminum or its alloys comprising carrying out a plasma-chemical anodic oxidation in a substantially chloride-free electrolytic bath containing less than 5×
- 10-3 mol/l chloride ions, and phosphate ions, borate ions and fluoride ions in a concentration of 0.01 to 0.1 mol/l and having a pH value of 10 to 12, and maintaining constant a current density of at least 5 A/dm2 until the voltage reaches an end value.
- View Dependent Claims (6, 7)
Specification