Passivation methods for metallic medical implants
First Claim
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1. A metallic medical implant having a surface covered at least partially with a thin surface film selected from the group consisting of metal oxides and hydroxides wherein the film is produced by the process comprising:
- a. immersing the metallic implant in a passivating solution, said solution comprising an aqueous solution of a water soluble metal salt containing an oxyanion in a concentration of from about 0.05 to about 0.25 equivalents per liter; and
b. maintaining the passivating solution containing the implant to a temperature of from about 20°
C. to about 50°
C. for a time sufficient to form a thin, uniform tightly adherent coating of less than about 20 nanometers thickness.
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Abstract
Passivated implants and passivation methods that provide superior corrosion resistance and surface performance characteristics as compared to conventional nitric acid passivation are disclosed. The method uses either the spontaneous or galvanic passivation of metallic prosthetic implants in aqueous alkali salt solutions containing non-aggressive oxyanions to produce a thin and uniform passive coating on the metal implant, thereby rendering the implant more stable in the biological environment.
58 Citations
14 Claims
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1. A metallic medical implant having a surface covered at least partially with a thin surface film selected from the group consisting of metal oxides and hydroxides wherein the film is produced by the process comprising:
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a. immersing the metallic implant in a passivating solution, said solution comprising an aqueous solution of a water soluble metal salt containing an oxyanion in a concentration of from about 0.05 to about 0.25 equivalents per liter; and b. maintaining the passivating solution containing the implant to a temperature of from about 20°
C. to about 50°
C. for a time sufficient to form a thin, uniform tightly adherent coating of less than about 20 nanometers thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A metallic medical implant having a surface covered at least partially with a thin surface film selected from the group consisting of metal oxides and hydroxides wherein the thin film is produced by the process comprising:
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a. mechanically coupling the implant to a cathode rod; b. immersing the metallic implant mechanically coupled to a cathode rod in a passivating solution, the solution comprising an aqueous solution of a water soluble metal salt containing a non-aggressive oxyanion in a concentration of from about 0.05 equivalents per liter to about 0.25 equivalents per liter; and c. maintaining the passivating solution containing the metallic implant and cathode rod at a temperature of from about 20°
C. to about 50°
C. for a time sufficient to form a passive uniform tightly adherent coating of up to about 20 nanometers thickness on the implant surface. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification