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US5211663A
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Passivation methods for metallic medical implants
Assignee: Smith and Nephew Inc
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Filing: 1991-06-24
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Granted: 1993-05-18
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Expires: 2011-06-24
Abstract
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.
Inventors
- 👤 Paul Kovacs
- 👤 James A. Davidson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:50
CPC Classifications
A; A61; A61L; A61L27/00; A61L27/02; A61L27/04; C; C23; C23C; C23C22/00; C23C22/05; C25; C25D; C25D11/00; C25D11/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
112 words
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.
Claim 2
Dependent Claim
112 words
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.
Claim 3
Dependent Claim
30 words
The implant according to claim 1 wherein the metallic implant is fabricated from a material selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum and their alloys.
Claim 4
Dependent Claim
27 words
The implant according to claim 1 wherein the metal ion of the water soluble metal salt is selected from the group consisting of the alkali metal ions.
Claim 5
Dependent Claim
26 words
The implant according to claim 1 wherein the oxyanion is selected from the group consisting of the sulfate, phosphate, monohydrogen phosphate, di-hydrogen phosphate, and borate oxyanions.
Claim 6
Dependent Claim
54 words
The metallic implant of claim 1 wherein a. the step of immersing comprises immersing in an about 0.15 equivalents per liter aqueous solution of sodium sulfate; and b. the step of maintaining the passivating solution containing the implant comprises maintaining the passivating slution to a temperature of about 37° C. for about 24 hours.
Claim 7
Dependent Claim
28 words
The implant of claim 1 wherein the metallic implant is fabricated from a material selected from the group consisting of 316L stainless steel, cobalt-chrome-molybdenum steel and Ti--6Al--4V alloy.
Claim 8
Dependent Claim
20 words
The implant of claim 1 wherein the metallic implant is fabricated from a metal alloy selected from the stainless steels.
Claim 9
Dependent Claim
140 words
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: 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.
Claim 10
Dependent Claim
140 words
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: 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.
Claim 11
Dependent Claim
30 words
The implant according to claim 8 wherein the metallic implant is fabricated from a material selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum and their alloys.
Claim 12
Dependent Claim
21 words
The implant according to claim 8 wherein the water soluble metal is selected from the group consisting of the alkali metals.
Claim 13
Dependent Claim
26 words
The implant according to claim 8 wherein the oxyanion is selected from the group consisting of the sulfate, phosphate, monohydrogen phosphate, di-hydrogen phosphate, and borate oxyanions.
Claim 14
Dependent Claim
57 words
The metallic implant according to claim 8 wherein a. the step of immersing comprises immersing the mechanically coupled cathode rod and metallic implant in an about 0.15 equivalents per liter aqueous solution of sodium sulfate; and b. the step of maintaining the passivating solution comprises heating to a temperature of about 37° C. for about 16 hours.
Claim 15
Dependent Claim
28 words
The implant of claim 8 wherein the metallic implant is fabricated from a material selected from the group consisting of 316L stainless steel, cobalt-chrome-molybdenum steel and Ti--6Al--4V alloy.
Claim 16
Dependent Claim
20 words
The implant of claim 8 wherein the metallic implant is fabricated from a metal alloy selected from the stainless steels.
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