WO2013115831A1 - Des surfaces d'oxyde de titane sans nickel et des procédés de fabrication et d'utilisation correspondants - Google Patents

Des surfaces d'oxyde de titane sans nickel et des procédés de fabrication et d'utilisation correspondants Download PDF

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WO2013115831A1
WO2013115831A1 PCT/US2012/032186 US2012032186W WO2013115831A1 WO 2013115831 A1 WO2013115831 A1 WO 2013115831A1 US 2012032186 W US2012032186 W US 2012032186W WO 2013115831 A1 WO2013115831 A1 WO 2013115831A1
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nickel
μιη
nitinol
nitrogen
layer
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PCT/US2012/032186
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English (en)
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Guna S. SELVADURAY
Edin BAZOCHAHARBAKHSH
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San Jose State University Research Foundation
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/28—Materials for coating prostheses
    • A61L27/30—Inorganic materials
    • A61L27/306—Other specific inorganic materials not covered by A61L27/303 - A61L27/32
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/02—Inorganic materials
    • A61L27/04—Metals or alloys
    • A61L27/06—Titanium or titanium alloys
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/02—Inorganic materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/08—Materials for coatings
    • A61L29/10—Inorganic materials
    • A61L29/106—Inorganic materials other than carbon
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/14—Materials characterised by their function or physical properties, e.g. lubricating compositions
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/02—Inorganic materials
    • A61L31/022—Metals or alloys
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/08—Materials for coatings
    • A61L31/082—Inorganic materials
    • A61L31/088—Other specific inorganic materials not covered by A61L31/084 or A61L31/086
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/34—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in more than one step
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
    • C23C8/58—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions more than one element being applied in more than one step
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/60—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes
    • C23C8/78—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes more than one element being applied in more than one step
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2420/00—Materials or methods for coatings medical devices
    • A61L2420/02—Methods for coating medical devices

Definitions

  • This invention generally relates to metallurgy, and biomedical implants, devices and prostheses.
  • the invention provides compositions, or products of manufacture, comprising a titanium dioxide surface layer that is free, or substantially free, of nickel.
  • the invention also provides methods of making and using these compositions or products of manufacture.
  • the compositions or products of manufacture of the invention are biomedical implants, devices or prostheses.
  • Nitinol is a metallic alloy comprised primarily of nickel and titanium. It is used extensively in the biomedical industry, especially for the manufacture of various implantable devices such as stents. It is widely recognized as being biocompatible because of the titanium dioxide layer that forms on the surface of the alloy. This is known commonly as the "native oxide" layer and tends to be relatively thin. In many instances the titanium dioxide layer is also grown intentionally in order to obtain a thicker layer than the native oxide layer. Because the titanium dioxide layer is formed on a surface that contains approximately equal concentrations of nickel and titanium, the titanium dioxide layer thus grown tends to have some nickel in it, both as metallic nickel as well as nickel oxide. For biomedical purposes the presence of nickel in the titanium dioxide layer is not desirable because the nickel content can leach out into the human body, possibly resulting in allergic reactions.
  • the invention provides methods for making, fabricating or forming a titanium dioxide (T1O 2 ) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection), comprising:
  • a nitrogen-containing solid, gel or paste (a) providing a nitinol (a nickel titanium) surface and a nitrogen-containing solid, gel or paste (a solid, gel or paste comprising a nitrogen, or a solid, gel or paste comprising a source of nitrogen), a nitrogen-containing liquid (a liquid comprising a nitrogen, or a liquid comprising a source of nitrogen), a nitrogen-containing gas (a gas comprising a nitrogen, or a gas comprising a source of nitrogen), or a combination thereof;
  • the nitriding step comprises conditions of at least about 350°C, 375°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C or more, or at about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 650°C, 1000°C, 1050°C, 1200°C, 1250°C or 1300°C or more, or a temperature of between about 350°C to 1300°C, or a temperature of between about 400°C to 1200°C, for at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120 or 130 or more minutes (min), or between about 5 and 130 minutes, or between about 10 and 120 and
  • the thickness of the titanium nitride (TiN) layer on the nitinol surface is more than about 0.1 ⁇ , 0.2 ⁇ , 0.3 ⁇ , 0.4 ⁇ , 0.5 ⁇ , 0.6 ⁇ , 0.7 ⁇ , 0.8 ⁇ , 0.9 ⁇ , 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ or 6 ⁇ ,
  • TiN layer is substantially free of any form of nickel, elemental nickel, or nickel nitride (N13N2), or optionally completely free within the limits of detection of nickel, elemental nickel, or nickel nitride (N13N2); and
  • oxidizing e.g., substantially oxidizing, or completely oxidizing- within limits of detection
  • the titanium nitride (TiN) layer to form a titanium dioxide (T1O 2 ) layer on the nitinol (nickel titanium) that is substantially nickel-free (or completely nickel-free, within the limits of detection)
  • the oxidizing step comprises, or is, a thermal oxidizing, and optionally the thermal oxidizing step comprises conditions between about 675°C and 700°C, or between about 650°C and 750°C, or between about 600°C and 800°C, or between about 500°C and 1000°C, or at about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 650°C, 1000°C, 1050°C, 1200°C, 1250°C or 1300°C or more, or at a temperature of about 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C or more, or at about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 650°C or 1000°C or more,
  • the oxidizing step comprising conditions wherein the step is for (is carried out for) at least about at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 or more minutes (min), or between about 1 min and 3 hours, or between about 30 and 60 min, or between about 20 and 80 min, or between about 10 and 90 min., or between 0.5 and 2 hours (hr).
  • the thickness of the nitride layer on the nitinol surface is more than about 0.01 ⁇ , 0.05 ⁇ , 0.1 ⁇ , 0.2 ⁇ , 0.3 ⁇ , 0.4 ⁇ , 0.5 ⁇ , 0.6 ⁇ , 0.7 ⁇ , 0.8 ⁇ , 0.9 ⁇ , 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ , 6 ⁇ , 7 ⁇ , 8 ⁇ , 9 ⁇ or 10 ⁇ or more; or the nitride layer on the nitinol surface is between about 0.5 ⁇ to about 10 ⁇ ; or the nitride layer on the nitinol surface is between about 1.0 ⁇ to about 7.0 ⁇ ; or is about 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ , 6 ⁇ , 7 ⁇ , 8 ⁇ , 9 ⁇ , 10 ⁇ , 20 ⁇ , 30 ⁇ , 40 ⁇ , 50 ⁇ , 60 ⁇ or 70 ⁇ or
  • the nitrogen-containing gas comprises an ammonia, a pure ammonia, a deoxygenated ammonia, a nitrogen, or a pure nitrogen, or a combination thereof.
  • the nitriding step comprises reacting the nitinol surface with a nitrogen and a hydrogen, or a nitrogen and an ammonia, or a nitrogen and a hydrogen followed by a nitrogen and an ammonia nitriding step,
  • the hydrogen is at a concentration of about 1%, 2%, 3%, 4%, 5% or 6%, or the hydrogen is at a concentration of between about 1% to about 10% hydrogen,
  • the nitriding step comprises reaction conditions of between about 800°C to about 1000°C, for between about 10 to about 30 minutes (min).
  • methods of the invention further comprise: nitriding with nitrogen and an ammonia, wherein the ammonia is at a concentration of about 1%, 2%, 3%, 4%, 5% or 6% ammonia, and optionally the reaction conditions comprise between about 500 to about 675°C for between about 0 to 30 minutes (min), or about 5, 10, 15, 20, 15 or 30 min, or at least about 5, 10, 15, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55 or 60 or more minutes (min).
  • the titanium dioxide (T1O 2 ) layer on the nitinol (nickel titanium) is completely nickel-free within the limits of detection by an X-ray
  • XPS photoelectron spectroscopy
  • the invention provides methods for making, fabricating or forming a titanium nitride (TiN) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection), comprising:
  • a nitrogen-containing solid, gel or paste (a) providing a nitinol (a nickel titanium) surface and a nitrogen-containing solid, gel or paste (a solid, gel or paste comprising a nitrogen, or a solid, gel or paste comprising a source of nitrogen), a nitrogen-containing liquid (a liquid comprising a nitrogen, or a liquid comprising a source of nitrogen), a nitrogen-containing gas (a gas comprising a nitrogen, or a gas comprising a source of nitrogen), or a combination thereof;
  • the nitriding step comprises conditions of at least about 350°C, 375°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C or more, or at about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 650°C, 1000°C, 1050°C, 1200°C, 1250°C or 1300°C or more, or a temperature of between about 350°C to 1300°C, or a temperature of between about 400°C to 1200°C, for at least about 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, or 40 or more minutes (min),
  • the nitriding step comprises conditions of at least about 350°C, 375°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C or more, or at about 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 650°C, 1000°C, 1050°C, 1200°C, 1250°C or 1300°C or more, for at least about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120 or 130 or more minutes (min), or between about 5 and 130 minutes, or between about 10 and 120 minutes,
  • the thickness of the titanium nitride (TiN) layer on the nitinol surface is more than about 0.1 ⁇ , 0.2 ⁇ , 0.3 ⁇ , 0.4 ⁇ , 0.5 ⁇ , 0.6 ⁇ , 0.7 ⁇ , 0.8 ⁇ , 0.9 ⁇ , 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ or 6 ⁇ , and the titanium nitride (TiN) layer is substantially free of any form of nickel, elemental nickel, or nickel nitride ( 3N2), or optionally completely free within the limits of detection of nickel, elemental nickel, or nickel nitride ( 3N2).
  • the thickness of the nitride layer on the nitinol surface is more than about 0.5 ⁇ , 0.6 ⁇ , 0.7 ⁇ , 0.8 ⁇ , 0.9 ⁇ , 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ or 6 ⁇ ; or the nitride layer on the nitinol surface is between about 0.5 ⁇ to about 10 ⁇ ; or the nitride layer on the nitinol surface is between about 1.0 ⁇ to about 7.0 ⁇ ; or is about 1.0 ⁇ , 2 ⁇ , 3 ⁇ , 4 ⁇ , 5 ⁇ , 6 ⁇ , 7 ⁇ , 8 ⁇ , 9 ⁇ , or 10 ⁇ or more.
  • the nitrogen-containing gas comprises an ammonia, a nitrogen, or a pure nitrogen, or a combination thereof.
  • the nitriding step comprises reacting the nitinol surface with a nitrogen and a hydrogen, or a nitrogen and an ammonia, or a nitrogen and a hydrogen followed by a nitrogen and an ammonia nitriding step,
  • the hydrogen is at a concentration of about 1%, 2%, 3%, 4%, 5% or 6%, or the hydrogen is at a concentration of between about 1% to about 10% hydrogen,
  • the nitriding step comprises reaction conditions of between about 800°C to about 1000°C, for between about 10 to about 30 minutes (min).
  • methods of the invention further comprise: nitriding with nitrogen and an ammonia, wherein the ammonia is at a concentration of about 1%, 2%, 3%, 4%, 5% or 6% ammonia, and optionally the reaction conditions comprise between about 500 to about 675°C for between about 0 to 30 minutes (min), or about 5, 10, 15, 20, 15 or 30 min.
  • the titanium dioxide (T1O 2 ) layer on the nitinol (nickel titanium) is completely nickel-free within the limits of detection by an X-ray photoelectron spectroscopy (XPS), or an equivalent surface analysis technique.
  • XPS X-ray photoelectron spectroscopy
  • the invention provides products of manufacture comprising a titanium nitride (TiN) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection),
  • the invention provides products of manufacture comprising a titanium dioxide (T1O 2 ) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection),
  • titanium dioxide (T1O 2 ) layer on the nitinol (nickel titanium) is completely nickel-free within the limits of detection by an X-ray
  • XPS photoelectron spectroscopy
  • the invention provides products of manufacture comprising a titanium dioxide (T1O 2 ) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection) made by any method of the invention.
  • a titanium dioxide (T1O 2 ) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection) made by any method of the invention.
  • titanium dioxide (T1O 2 ) layer on the nitinol (nickel titanium) is completely nickel-free within the limits of detection by an X-ray
  • XPS photoelectron spectroscopy
  • the invention provides products of manufacture comprising a titanium nitride (TiN) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free (or completely nickel-free, within the limits of detection) made by any method of the invention.
  • TiN titanium nitride
  • a nickel titanium nickel titanium
  • titanium nitride (TiN) layer on the nitinol (nickel titanium) is completely nickel-free within the limits of detection by an X-ray photoelectron spectroscopy (XPS), or an equivalent surface analysis technique.
  • XPS X-ray photoelectron spectroscopy
  • products of manufacture of the invention comprise, or are a, or are part of, or are contained within: a device, or an industrial device or a machine, or an instrument, or a calibrating or measuring device, or a non-medical device, a medical device, an orthopedic device, a biomedical device, a probe, a needle, a catheter, a tube, an implant, a dental implant, a cochlear implant, a prosthesis, an artificial joint, a pin, a mesh, a post, a stent, a staple, a brace, a plate, a filter, a vena cava filter, a catheter or an artificial organ.
  • products of manufacture of the invention comprise, or are a, or are part of, or are contained within: a non-medical device, a neuro-stimulator electrode, a stent-type device, a pacemaker type device, a drug delivery device outlet and/or a tube, a fluid transport part and/or a connection tube, an inlet/outlet tube for body fluid or blood transport, an artificial valve, an artificial heart, artificial liver, and/or a functional or structural component of an artificial organ.
  • the invention provides kits or packages comprising a product of manufacture of the invention, wherein optionally the kit comprises instructions on practicing a method of the invention, or optionally the kit comprises one more components or ingredients to practice a method of the invention.
  • Figure 1 schematically illustrates exemplary conditions and processes of the invention, as described in detail in Example 1, below.
  • Figure 2 graphically illustrates a temperature profile along a tube furnace at 500°C to 1100°C for exemplary nitriding and oxidation processes of the invention, as described in detail in Example 1 , below.
  • Figure 3 schematically illustrates a diagram of the transverse section of an exemplary tube, or "tube furnace”, with fittings made of TEFLONTM on both ends, a thermocouple in the middle, and a nitinol specimen inside, for practicing exemplary nitriding and oxidation processes of the invention, as described in detail in Example 1, below.
  • Figure 4 schematically illustrates a diagram of a schematic of a nitinol specimen on a quartz boat in the tube furnace of Figure 3, as described in detail in Example 1, below.
  • Figure 5 illustrates an image of a nitinol specimen on the quartz boat in the tube furnace of Figure 3, as described in detail in Example 1, below.
  • Figure 6 schematically illustrates an exemplary tube furnace and gas delivery system set up for gas nitriding with pure N 2 or 96% N2 + 4% H 2 , followed by oxidation, as described in detail in Example 1, below.
  • Figure 7 schematically illustrates an exemplary gas delivery system to an exemplary tube furnace and ammonia gas disposal system, where the gas delivery system set up for gas nitriding with a 95% 2 + 5% NH 3 mix, as described in detail in Example 1, below.
  • Figure 8 schematically illustrates measurement of the ion etch rate using an
  • Atomic Force Microscope also showing that ion etching of the surface of a nitinol specimen was artificially blocked with silicon, and the step height can be measured by AFM, as described in detail in Example 1, below.
  • Figure 9 graphically illustrates the energy-dispersive X-ray spectroscopy spectrum of a mechanically polished nitinol specimen, as measured by Energy Dispersive
  • EDS Spectrometer
  • Figure 10 graphically illustrates an X-ray diffraction pattern from the
  • Figure 1 1 graphically illustrates the results of an X-ray photoelectron
  • Figure 12 illustrates scanning electron microscope images from Fig. 12(a) mechanically polished and Fig. 12(b) mechanically polished and chemically etched nitinol specimens, as described in detail in Example 1, below.
  • Figure 13 graphically illustrates an energy-dispersive X-ray spectroscopy spectrum from a chemically etched nitinol, as described in detail in Example 1 , below.
  • Figure 14 graphically illustrates X-ray diffraction results from a nitinol specimen nitrided at 800°C for 30 min, as described in detail in Example 1, below.
  • Figure 15 graphically illustrates an elemental depth profile of nitinol specimens nitrided in 96% N 2 + 4% H 2 at Fig. 15(a): 800°C for 30 min, Fig. 15 (b) 900°C for 30 min, and Fig. 15(c) 1000°C for 30 min, as described in detail in Example 1, below.
  • Figure 16 graphically illustrates an X-ray photoelectron spectroscopy survey scan of nitinol specimens nitrided in 96% N 2 + 4% H 2 at: Fig. 16(a) 800°C for 30 min, Fig. 16(b) 900°C for 20 min, Fig. 16(c) 900°C for 30 min, Fig. 16(d) 1000°C for 10 min, Fig. 16(e) 1000°C for 20 min, and Fig. 16(f) 1000°C for 30 min, as described in detail in Example 1, below.
  • Figure 17 graphically illustrates high resolution XPS spectra for Ni2p from: Fig.
  • Figure 18 (including Fig. 18(a), Fig. 18(b), Fig. 18(c), Fig. 18(d), Fig. 18(e) and Fig. 18(f)) illustrates scanning electron microscope images from the transverse section of nitinol specimens nitrided in 96% N 2 + 4% H 2 , as described in detail in Example 1, below.
  • Figure 19 graphically illustrates nitride layer thickness on the surface of the nitinol as a function of nitriding temperature; in Figure 19 the thickness of the nitride layer on the surface increased dramatically with nitriding temperature, as described in detail in Example 1, below.
  • Figure 20 graphically illustrates nitride layer thickness on the surface of the nitinol as a function of nitriding time; in Figure 20, the nitride layer thickness at 1000°C was not statistically different for nitinol specimens nitrided for 10, 20, and 30 min, as described in detail in Example 1 , below.
  • FIG. 21 graphically illustrates the results of X-ray Spectroscopy (EDS) images showing that chemical etching increased the concentration of oxygen on the nitinol specimen: 13.39% oxygen was detected by EDS, as described in detail in Example 1, below.
  • EDS X-ray Spectroscopy
  • Figure 22 illustrates a Scanning Electron Microscope (SEM) image from the transverse section of a nitinol specimen nitrided in 95% 2 + 5% H 3 at 500°C for 5 min, as described in detail in Example 1, below.
  • SEM Scanning Electron Microscope
  • Figure 23 graphically illustrates X-ray diffraction results from an oxidized nitinol in air at 700°C for 60 min.
  • Figure 24 graphically illustrates X-ray photoelectron spectroscopy depth profile of a nitinol specimen oxidized at 675°C for 30 min;
  • Fig. 24A is a full graph, and
  • Fig. 24B is an expanded view of a section of the graph of Fig. 24A, as described in detail in Example 1, below.
  • Figure 25 illustrates a nickel high resolution XPS scan results for a nitinol specimen oxidized at 675°C for 30 min, as described in detail in Example 1, below.
  • Figure 26 illustrates X-ray photoelectron spectroscopy depth profile of the specimen oxidized in air at 700°C for 60 min, as described in detail in Example 1, below.
  • Fig. 27 illustrates a nickel high resolution XPS scan results for the specimen oxidized at 675°C for 30 min, as described in detail in Example 1, below.
  • Figure 28 illustrates X-ray diffraction results from N-1000-20-O-700-30, a specimen nitrided at 1000°C for 20 min, followed by oxidation at 700°C for 30 min (a N- 1000-20-O-700-30 specimen), as described in detail in Example 1, below.
  • Figure 29 graphically illustrates X-ray photoelectron spectroscopy depth profile of a -1000-20-O-700-30 specimen, as described in detail in Example 1, below.
  • Figure 30 graphically illustrates X-ray photoelectron spectroscopy depth profile of a A-675-5-O-675-30 specimen, as described in detail in Example 1, below.
  • Figure 31, or Figure B-l illustrates an image of the topography of the surface of a nitrided specimen ion etched for 200 s.
  • Figure 32 illustrates an image of a transverse section and the measured step height from 12 points on the surface of a nitrided specimen, ion etched for 200 s.
  • Figure 33 illustrates an image of the topography of the surface of the nitrided specimen, ion etched for 700 s.
  • Figure 34 illustrates an image of a transverse section and the measured step height from 12 points on the surface of nitrided specimen, ion etched for 700 s.
  • Figure 35 illustrates an image of the topography of the surface of the nitrided specimen, ion etched for 1 100 s.
  • Figure 36 illustrates an image of a transverse section and the measured step height from 12 points on the surface of nitrided specimen, ion etched for 1100 s.
  • Figure 37 illustrates an X-ray photoelectron spectroscopy depth profile of a mechanically polished specimen, washed with DI water and air dried.
  • Figure 38 illustrates an X-ray photoelectron spectroscopy high resolution scans of the mechanically polished specimen, washed with DI water and air dried.
  • Figure 39 illustrates an X-ray photoelectron spectroscopy depth profile of the mechanically polished specimen, washed with deaerated DI water and argon dried.
  • Figure 40, or Figure C-4 illustrates an X-ray photoelectron spectroscopy high resolution scans of the mechanically polished specimen, washed with deaerated DI water and argon dried.
  • Figure 41 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% N 2 + 4% H 2 at 800°C for 30 min.
  • Figure 42 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 800°C for 30 min.
  • Figure 43 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% N 2 + 4% H 2 at 900°C for 20 min.
  • Figure 44 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 900°C for 20 min.
  • Figure 45 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% N 2 + 4% H 2 at 900°C for 30 min.
  • Figure 46 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 900°C for 30 min.
  • Figure 47 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% N 2 + 4% H 2 at 1000°C for 10 min.
  • Figure 48 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 1000°C for 10 min.
  • Figure 49 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% N 2 + 4% H 2 at 1000°C for 20 min.
  • Figure 50 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 1000°C for 20 min.
  • Figure 51 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% N 2 + 4% H 2 at 1000°C for 20 min.
  • Figure 52 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 95%> N 2 + 5%> NH 3 at 500°C for 5 min.
  • Figure 53 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 95% N 2 + 5% NH 3 at 500°C for 5 min.
  • Figure 54 or Figure C-19, illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 95% N 2 + 5% H 3 at 675°C for 5 min.
  • Figure 55 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 95% N 2 + 5% NH 3 at 675°C for 5 min.
  • Figure 56, or Figure C-21 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen oxidized in air at 675°C for 30 min.
  • Figure 57 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen oxidized in air at 675°C for 30 min.
  • Figure 58 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen oxidized in air at 700°C for 60 min.
  • Figure 59 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen oxidized in air at 675°C for 30 min.
  • Figure 60 illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 95% 2 + 5% NH 3 at 675°C for 5 min and oxidized in air at 675°C for 30 min.
  • Figure 61 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 95% 2 + 5% NH 3 at 675°C for 5 min and oxidized in air at 675°C for 30 min.
  • Figure 62 or Figure C-27, illustrates an X-ray photoelectron spectroscopy depth profile of the specimen nitrided in 96% 2 + 4% H2 at 1000°C for 20 min and oxidized in air at 700°C for 60 min.
  • Figure 63 illustrates an X-ray photoelectron spectroscopy high resolution scans of the specimen nitrided in 96% 2 + 4% H2 at 1000°C for 20 min and oxidized in air at 700°C for 60 min.
  • the invention provides compositions or products of manufacture comprising a nitinol (also called nickel titanium) having a titanium dioxide (T1O2) (also known as titanium(IV) oxide or titania) surface layer that is free, or substantially free, of a nickel (Ni), e.g., free or substantially free of Ni in either the elemental or oxide forms.
  • a nitinol also called nickel titanium
  • TiO2 titanium dioxide
  • Ti nickel
  • the invention also provides methods of making and using these compositions or products of manufacture.
  • the compositions or products of manufacture of the invention include (or are) biomedical devices, implants or prostheses, e.g., such as artificial joints, pins, stents, vena cava filters, catheters, and the like.
  • XPS photoelectron spectroscopy
  • the nickel does not form a nitride because "nickel nitride" is thermodynamically unstable.
  • the titanium nitride layer is then subsequently oxidized (e.g., completely (within limits of detection), or substantially) to convert it to titanium dioxide, which is then free of nickel.
  • Nitinol specimens were first nitrided to confirm the formation of the titanium nitride. These were also analyzed by X-ray photoelectron spectroscopy (XPS) and confirmed to be nickel-free, within the limits of detection of XPS. In separate experiments Nitinol specimens were oxidized, to confirm our capability to oxidize the Nitinol. XPS analysis of the titanium dioxide that was found showed the presence of nickel. In the third phase we first nitride nitinol specimens, and upon completion of the nitridation, i.e., formation of the titanium nitride layer, we oxidized these layers. XPS analysis of the titanium dioxide layer formed by oxidizing the titanium nitride showed that these titanium dioxide layers were nickel-free.
  • XPS X-ray photoelectron spectroscopy
  • nickel nitride is not a stable compound at room temperature and at higher temperatures as well, and that, therefore, we will be able to nitride a nickel-titanium surface and engage only the titanium in the reaction, thus forming a titanium nitride layer that is free of nickel.
  • Nitinol specimens were nitrided in nitrogen + 4% hydrogen at 800 - 1000°C for 10 - 30 min and further nitrided in nitrogen + 5% ammonia at 500 - 675°C for 0 - 30 min.
  • the thickness and chemical composition, specifically the nickel content of the surface layer were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively.
  • SEM scanning electron microscopy
  • XPS X-ray photoelectron spectroscopy
  • Titanium nitride the dominant phase on the surface of the nitrided specimens, was nickel free.
  • the nitrided Nitinol specimens were then oxidized at 675°C and 700°C for 30 and 60 min, respectively.
  • the chemical composition and elemental depth profile showed that oxidizing Nitinol specimens with a 0.4 ⁇ thick nitride layer on the surface did not provide a nickel- free oxide layer on the surface of the Nitinol. However, oxidizing the Nitinol specimens with a surface nitride layer that was thicker than 6 ⁇ resulted in a nickel-free oxide layer.
  • kits comprising compositions for practicing the methods of the invention, including instructions for use thereof.
  • the invention provides kits comprising a composition, a product of manufacture, or any combination for practicing a method of the invention; wherein optionally the kit further comprises instructions for practicing a method of the invention, e.g., methods for making, fabricating or forming a titanium dioxide (Ti0 2 ) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free.
  • EXAMPLE 1 Methods for making a titanium dioxide (TiO? layer on a nitinol surface that is substantially nickel-free
  • This example demonstrates exemplary compositions and methods of the invention, including methods for making, fabricating or forming a titanium dioxide (T1O2) layer on a nitinol (a nickel titanium) surface that is substantially nickel-free.
  • T1O2 titanium dioxide
  • a nickel titanium nickel titanium
  • TiN formation from the titanium on the surface of Nitinol and nitrogen is spontaneous.
  • Nickel nitride is not stable and there is no driving force for nickel to diffuse toward the surface. Therefore, the surface of the nitrided Nitinol will be nickel depleted TiN.
  • T1O2 is thermodynamically more stable than TiN, TiN will oxidize when in contact with oxygen, and form T1O2.
  • the surface of the Nitinol will be nickel-free. Since TiN is being used as the precursor and oxidized right after formation, the mechanical properties and issues associated with brittleness of TiN are not of concern.
  • the golden color of specimens was considered as initial evidence for the presence of TiN on the surface.
  • the surface properties were studied using Glancing Incidence X-ray Diffraction (GI-XRD) and X-ray Photoelectron Spectroscopy (XPS).
  • the thickness of the nitride layer was measured from Scanning Electron Microscopy (SEM) images of transverse sections of specimens.
  • SEM Scanning Electron Microscopy
  • Nitriding was followed by oxidation under two conditions, namely nitriding in 96% N 2 + 4% H 2 at 1000°C for 20 min followed by oxidation in air at 700°C for 60 min and nitriding in 95% N 2 + 5% NH 3 at 675°C for 5 min followed by oxidation in air at 675°C for 30 min.
  • Analytical methods namely XPS, XRD (X-ray Diffraction (XRD)), and SEM were used to analyze the nickel concentration, elemental depth profiles, the nitride and oxide layer thickness, and oxidation state of the elements on the surface.
  • Nitinol sheet with a composition of 50.8% (at.%) Ni and 49.2% (at.%) Ti was obtained from Nitinol
  • the nitriding and oxidation processes were performed in a Lindberg 55035 tube furnace with a Mullite tube of inner diameter of 1 inch.
  • the temperature profile along the tube furnace was measured with an R-type thermocouple in the temperature range of 500 - 1100°C in 100°C increments. As shown in Figure 2, the temperature at the two ends of the tube was approximately 400°C lower than at the center of the tube.
  • Figure 2 illustrates a temperature profile along the tube furnace at 500°C to 1100°C.
  • the temperature was similar to the nominal temperature from the temperature controller. Because the thermocouple connected to the temperature controller was in the middle of the tube, there was no difference between the actual temperature in the middle of the tube and the temperature displayed by the temperature controller.
  • FIG 3 is a schematic diagram of the transverse section of the tube with fittings made of TEFLONTM on both ends, a thermocouple in the middle, and a nitinol specimen inside.
  • the specimen was seated on a quartz boat in the middle of the tube.
  • a schematic and an image of the specimen on a quartz boat in the tube are shown in Figure 4 and 5.
  • Figures 3, 4, 5 illustrate: a schematic of the tube with fittings and thermocouple; a schematic of a nitinol specimen on a quartz boat in the tube furnace; and, an image of a nitinol specimen on the quartz boat in the tube furnace, respectively.
  • Oxidation was performed in dry air. Air was flowed into the tube furnace by an Elite 802 aquarium pump. The flow rates of argon, air, a 96% 2 + 4% H2 mix and a 95% 2 + 5% NH 3 mix were nominally one L (liter) per min. All processes with ammonia were performed under a laboratory fume hood, with a 1 ⁇ 4 inch Teflon tube used for gas delivery. All connections, valves and fittings were made of stainless steel 316 for the ammonia experiments.
  • FIG. 6 is a schematic of the gas delivery system, to the tube furnace, for nitriding with pure nitrogen, 96% 2 + 4% H2 and oxidation with air.
  • Figure 6 illustrates a schematic of tube furnace and gas delivery system set up for gas nitriding with pure 2 or 96% 2 + 4% H2, followed by oxidation.
  • FIG. 7 is a schematic diagram of the gas delivery system to the tube furnace and ammonia gas disposal.
  • Figure 7 illustrates a schematic diagram of the tube furnace and the gas delivery system set up for gas nitriding with a 95% 2 + 5% NH 3 mix.
  • Nitinol specimens were heated to 1000°C or 1 100°C for a dwell time of 60 min.
  • a mixture of 96% 2 + 4% H 2 was flowed through the tube furnace at 1 L per min during the high temperature dwell time.
  • Grade 4.8 gas mix of 95% N 2 + 4% H 2 (99.998%) purity) was purchased from Praxair Inc. (San Jose, CA).
  • argon gas was flowed through the tube furnace.
  • the heating ramp rate was 50°C/min.
  • Gas nitriding was performed at 800°C, 900°C, and 1000°C for dwell times of 10, 20, and 30 min, followed by furnace cooling of the specimens.
  • Grade 4.8 gas mix of 95% N 2 + 5% NH 3 (99.998% purity) was purchased from Praxair Inc.
  • the heating ramp rate was 50°C per min and after nitriding the specimens were furnace-cooled to room temperature. During heating and cooling argon gas was flowed through the tube furnace. The gas flow rate for the 95% N 2 + 5% NH3 and the argon was 1 L per min.
  • Argon gas was passed through the moisture and oxygen traps. Due to concerns with corrosion by ammonia, 95% 2 + 5% NH 3 was not passed through the oxygen and/or moisture trap. Because there was no previous study performed on surface nitriding of Nitinol with ammonia, the experimental design was based on observations during a trial run which was performed at 400°C for 60 min. The experimental design and values for each parameter are represented in Table 4.
  • Nitriding followed by oxidation was done under two conditions, namely, (a) nitride in 96% N2 + 4% 3 ⁇ 4 at 1000°C for 20 min, then oxidize with air at 700°C for 60 min (N-1000-20-O-700-60) and (b) nitride in 95% N 2 + 5% NH 3 at 675°C for 5 min, then oxidize with air at 675°C for 30 min (A-675-5-O-675-30).
  • the experimental design and values for each parameter are shown in Table 5.
  • the surfaces of the untreated, oxidized, nitrided and nitrided and oxidized specimens were characterized by XRD, SEM, Energy-dispersive X-ray Spectroscopy (EDS) and XPS.
  • the specimens characterized with XRD were:
  • the thickness of the nitride layers was measured from the elemental depth profiles based on the distance from the surface to where the nitrogen concentration drops to one half of its maximum concentration value.
  • the ion etch rate of the nitride layer was also measured using
  • Nanotechnology model Nano-I AFM (San Jose, CA). The ion etch rate was measured at
  • the ion etch rate as shown in Appendix B, below, was determined to be 0.91 nm/s for 3kV argon ion etching, with a standard deviation of 0.12 nm/s.
  • Figure 8 illustrates measurement of the ion etch rate using an Atomic Force Microscope (AFM).
  • AFM Atomic Force Microscope
  • the surface characterization techniques employed were XPS, SEM, GI-XRD and AFM. Overall, the surface oxidation of the nitrided Nitinol with a thick nitride layer was found to be capable of forming a nickel- free T1O2 layer on the surface. However, when Nitinol specimens with a thin nitride layer were oxidized, some nickel was found on the surface/atmosphere interface. Untreated Specimens
  • the surface composition of the mechanically polished specimen, washed and dried specimen and chemically etched specimen are presented in this section. This analysis was done to determine the chemical composition of the Nitinol used, and the potential effect of sample preparation technique on the surface of the Nitinol samples, prior to nitriding and/or oxidation.
  • the composition of a mechanically polished specimen was measured by Energy Dispersive Spectrometer (EDS). As shown in Figure 9, the composition of the Nitinol specimen was 50.81% Ni and 49.19% (at.%) Ti; Fig. 9 illustrates the energy-dispersive X-ray spectroscopy spectrum from the mechanically polished Nitinol after the polishing. As shown in Figure 10, Nitinol was the only phase detected by XRD (X-ray Diffraction); Fig. 10 illustrates the X-ray diffraction pattern from the mechanically polished Nitinol.
  • EDS Energy Dispersive Spectrometer
  • the Nitinol specimens were thermally nitrided in a tube furnace. Three different atmospheres, pure nitrogen, nitrogen/hydrogen mixture, and nitrogen/ammonia mixture were used. The presence of a golden color was the first indicator of the presence of nitride on the surface of the Nitinol. After visual inspection, the assumed presence of the TiN was confirmed with XPS and/or GIXRD. Using these characterization methods, the chemical state, elemental depth profile, and crystal structure of the surfaces were studied. The thickness of the TiN layers on the surfaces was measured from the SEM images of the transverse sections of specimens.
  • Nitriding in 96% N 2 + 4% H 2 was performed at 700°C for 60 min and 800°C to 1000°C for 10 to 30 min. Nitriding at 700°C for 60 min did not result in the formation of a nitride layer on the surface. The color of the specimen remained dark blue. However, at temperatures above 800°C the surface color of the specimens changed to golden, indicating the presence of TiN.
  • Figure 14 illustrates X-ray diffraction results from the specimen nitrided at 800°C for 30 min.
  • Figure 15(a) and (b) a layer with a Ti/Ni ratio of 2 was detected at a depth of 1.2 and 2.75 ⁇ from the surface of the specimens nitrided at 800°C for 30 min and at 900°C for 30 min, under the TiN layer.
  • the presence of a N1T12 layer under the TiN layer after the gas nitriding has been reported elsewhere as well [37, 39].
  • Figure 15 shows the elemental depth profile of specimens nitrided in 96% N 2 + 4% H 2 at (a) 800°C for 30 min, (b) 900°C for 30 min and (c) 1000°C for 30 min.
  • the nitride layer on the surface was very thick, and the depth profile was not able to reach the N1T12 zone, as a result of which the thickness of the nitride layer could not be estimated from the XPS depth profile.
  • the TiN layer thickness on the specimen nitrided at 1000°C for 30 min was found to be greater than 2.75 ⁇ .
  • Nickel was not detected in the TiN layer.
  • the nickel depletion on the outermost surface was confirmed by XPS survey spectra for the surface of all 6 nitrided specimens. There was no peak in the range of 800 to 900 eV of binding energy, indicating the presence of nickel and/or its compounds.
  • the nickel concentration increases only at distances, from the surface, where the nitrogen concentration starts to decrease. For example, for the specimen nitrided at 900°C for 30 min, the nitrogen concentration starts to drop at approximately 1 ⁇ from the surface and in this region the nickel concentration starts to rise. This indicates that the nitriding process formed a nickel-free TiN layer on the surface.
  • Oxygen and carbon were detected on the surface. These were most probably adsorbed on the surface during the post-nitriding handling. An increase in the oxygen concentration was observed at a distance from the surface where the nickel concentration starts increasing. The reasons for this were not explored further.
  • Figure 16 illustrates X-ray photoelectron spectroscopy survey scan of specimens nitrided in 96% N 2 + 4% H 2 at (a) 800°C for 30 min, (b) 900°C for 20 min, (c) 900°C for 30 min, (d) 1000°C for 10 min, (e) 1000°C for 20 min, and (f) 1000°C for 30 min.
  • NiO oxide form
  • Figure 17 illustrates high resolution XPS spectra for Ni2p from (a) specimen nitrided at 800°C for 30 min and (b) specimen nitrided at 900°C for 30 min.
  • the thickness of the nitride layer was determined from XPS depth profiles. Measured values for the nitride layer thickness are represented in Table 6. The nitride layers on the surfaces of specimens nitrided at 1000°C for 20 and 30 min (N- 1000-20 and N- 1000-30) were very thick, and the elemental depth profile could not reach the end of the nitride layer. Based on the measurements taken, the TiN layer thicknesses were determined to be greater than 2.75 ⁇ for specimens nitrided at 1000°C for 20 and 30 min.
  • the thickness of the nitride layer was also measured from SEM images of cross- sections. Measured values of the TiN layer thickness are listed in Table 6. As shown in Figure 18, there was some electron charging on the TiN layer, due to the low electrical conductivity of TiN. At low nitride layer thicknesses the measured values for the thickness of the nitride layer by SEM was relatively close to the values measured from the XPS, but for specimen nitrided at 1000°C for 10 min it was not the case. Figure 18 illustrates scanning electron microscope images from the transverse section of specimens nitrided in 96% N 2 + 4% H 2 .
  • Nitriding in 96% N 2 + 4% H 2 at temperatures above 800°C resulted in the formation of nickel-free TiN layers on the surfaces of the Nitinol specimens.
  • the nickel concentration was zero in the nitride layer and started to increase at depth where the nitrogen concentration started to decrease.
  • X-ray diffraction and XPS results showed a iTi2 zone under the nitride layer after nitriding.
  • the TiN layer thicknesses were measured from the SEM images of the transverse section of specimens. They varied from 0.7 ⁇ for the specimen nitrided at 800°C for 30 min to 6.3 ⁇ for the specimen nitrided at 1000°C for 30 min.
  • Nitriding temperature was found to be more effective in determining the nitride layer thickness, as compared to nitriding time.
  • the thickness of the nitride layer on the surface increased dramatically with nitriding temperature, from less than 1 ⁇ at 800°C to 6.2 ⁇ at 1000°C. This is due to the fact that diffusion of nitrogen into the surface is faster at higher temperatures.
  • the nitriding time did not affect the nitride layer thickness.
  • the nitride layer thickness at 1000°C was not statistically different for specimens nitrided for 10, 20, and 30 min.
  • Figure 19 illustrates nitride layer thickness on the surface of the nitinol as a function of nitriding temperature.
  • Figure 20 illustrates Nitride layer thickness on the surface of the Nitinol as a function of nitriding time.
  • Nitinol specimens were nitrided in 95% N2 + 5% NH 3 at 450°C for 60 min and at 500°C and 675°C for 5 and 30 min. At the nitriding temperature of 450°C there were no signs of nitriding occurring. The surface was oxidized, as there was no golden color on the surface and it was black. At nitriding temperatures of 500°C and 675°C the surface color turned to golden. The presence of TiN on the surface was confirmed by XPS analysis. As shown in Figure 21 (a) and (b), the surface of both specimens, nitrided at 500°C and 675°C for 5 min was nickel-free TiN. X-ray photoelectron spectroscopy depth profiles also detected a nickel-rich zone under the nitride layer, with a nickel
  • FIG. 21 illustrates X-ray photoelectron spectroscopy depth profile of specimens nitrided in 95% 2 + 5% NH 3 at (a) 500°C for 5 min and (b) 675°C for 5 min.
  • Figure 22 illustrates a Scanning electron microscope image from the transverse section of specimen nitrided in 95% 2 + 5% NH 3 at 500°C for 5 min.
  • nitriding in 96% 2 + 4% H2 in the temperature range of 800°C to 1000°C and in 95% N 2 + 5% NH 3 in the temperature range of 500°C to 675°C resulted in the formation of nickel-free TiN layers on the surface of the Nitinol specimens.
  • the nitride layer's crystal structure, chemical composition and thickness were studied by XRD, XPS and SEM.
  • the Nickel concentration was zero in the nitride layer and started to increase at depths where the nitrogen concentration started to decrease. For example, this distance for the specimen nitrided in a 96% N2 + 4% H2 mix at 900°C for 30 min was 1 ⁇ .
  • a nickel-rich zone with a nickel concentration of 60 to 70% (at.%) was observed under the nitride layer, after nitriding with 95% N2 + 5% NH 3 .
  • X-ray diffraction and x- ray photoelectron spectroscopy results showed a NiTi 2 zone under the nitride layer after nitriding with the 96% N2 + 4% H2.
  • Both nitriding processes were sensitive to the presence of oxygen as an impurity in the gases and/or as native oxide on the surface after specimen preparation. Based on the results two nitriding conditions were selected for nitriding the Nitinol specimens before oxidation.
  • the XPS depth profile was not able to reach the Nitinol bulk after 3,000 s of 3 kV ion etching, so it was not possible to estimate the thickness of the oxide layer. Based on 0.91 nm/s of ion etch rate, the T1O2 layer thickness was higher than 2.75 ⁇ .
  • Figure 23 illustrates X-ray diffraction results from the oxidized Nitinol in air at
  • Figure 24 illustrates X-ray photoelectron spectroscopy depth profile of specimen oxidized at 675°C for 30 min.
  • Figure 25 illustrates Nickel high resolution XPS scan results for specimen oxidized at 675°C for 30 min.
  • Nickel was also detected on the outmost surface of the specimen oxidized in air at 700°C for 60 min. As shown in Figures 26 and 27, for the specimen oxidized at 700°C for 60 min the nickel concentration dropped to zero at a distance greater than 1.8 ⁇ from the surface, compared to 0.5 ⁇ for the specimen oxidized at 675°C for 30 min.
  • Figure 26 illustrates X-ray photoelectron spectroscopy depth profile of specimen oxidized in air at 700°C for 60 min.
  • Figure 27 illustrates Nickel high resolution XPS scan results for specimen oxidized at 675°C for 30 min.
  • X-ray photoelectron spectroscopy analysis detected nickel on the surface/atmosphere interface for specimens oxidized in air at 700°C for 60 min and 675°C for 30 min. Therefore, oxidation did not result in the formation of a nickel- free oxide layer on the surface.
  • oxidation of TiN is a spontaneous reaction.
  • Surface nitriding followed by oxidation was performed on Nitinol specimens under two conditions. The first condition was nitriding in 96% 2 + 4% 3 ⁇ 4 at 1000°C for 20 min and then oxidizing in air at 700°C for 60 min ( -1000-20-O-700-60). The second condition was nitriding in 95% N 2 + 5% NH 3 at 675°C for 5 min and then oxidizing in air at 675°C for 30 min (A- 675-10-O-675-30).
  • the values of the parameters for the nitriding and oxidation process were selected based on the findings from earlier nitriding experiments, the thickness of the nitride layer with undetectable amounts of nickel on the surface, and the Nitinol specimen's color change from gold to black, an indication of the completion of the oxidation of the nitride layer.
  • Nitriding in the 96% N2 + 4% H2 atmosphere formed a 6.43 ⁇ thick TiN layer with undetectable amounts of nickel on the surface. Oxidation of this TiN layer resulted in the formation of a T1O2 layer with undetectable amounts of nickel on the surface. Also, no nitrogen was detected in the oxide layer, indicating that oxidation of the nitride layer was complete.
  • Figure 30 graphically illustrates X-ray photoelectron spectroscopy depth profile of A-675-5-0-675- 30.
  • Nitrided specimens were oxidized in air at 675°C for 30 min and 700°C for 60 min.
  • the surface oxidation of the nitrided Nitinol with a 6.4 ⁇ thick TiN layer with undetectable nickel was found to be capable of forming a T1O2 layer in which nickel was undetectable.
  • some nickel was found on the surface/atmosphere interface. It was most probably caused by an outward diffusion of nickel, due to the thermodynamic activity difference of nickel present in the nickel-rich zone and the nickel-depleted zone. Also, presence of oxygen on the surface and the thermodynamic stability of NiO was a driving force for nickel to diffuse toward the surface.
  • Nitinol specimens were surface nitrided in three different atmospheres, pure N 2 , a 96% N 2 + 4% H 2 mix, and a 95% N 2 + 5% NH 3 mix.
  • Surface nitriding of Nitinol in pure nitrogen and in a nitrogen/hydrogen gas mix has been reported by other researchers [30, 35, 36], and these two atmospheres were selected based on previous work.
  • Ammonia is also a source of nitrogen. Although there was no report for the surface nitriding of Nitinol in a nitrogen/ammonia gas mixture, it was selected to nitride the Nitinol based on ammonia being a source of atomic nitrogen.
  • nitriding in pure nitrogen did not result in the formation of a TiN layer on the surface. It was most likely due to the lack of atomic nitrogen in the atmosphere. Pure nitrogen is in the form of N 2 . Breaking the N-N bond is required to provide atomic nitrogen for the nitriding reaction. The observation that the Nitinol specimen was not nitrided was probably due to insufficient energy to break the N-N bonds. Although nitriding of the Nitinol in pure nitrogen was reported in other research at 800 - 1000°C for 5 - 30 min [35, 36], in this work, nitriding with pure nitrogen was unsuccessful for reasons that need further exploration.
  • Nitinol Another technique to nitride Nitinol, adopted from previous works, was nitriding in a 90% N 2 + 10% H 2 gas mix. After nitriding at 800°C for 300 s TiN was detected on the surface of the nitinol [30]. In this work specimens were nitrided in a 96% N 2 +5% H 2 mix. The gas with a lower percentage of hydrogen was selected due to safety concerns and availability. Based on XRD and XPS analysis, after nitriding of Nitinol in 96% N 2 +5% H 2 , TiN was formed on the surface of the Nitinol. The effect of the presence of 4% H 2 in the nitrogen on the formation of atomic nitrogen was not investigated in this research.
  • nitriding temperatures below 800°C nitriding was not observed, probably due to the lack of energy to break N-N bonds and provide atomic nitrogen at the surface of the Nitinol.
  • the nitride layer thickness increased dramatically from 0.75 - 6 ⁇ with an increase in nitriding temperature from 800 - 1000°C. It was most likely due to the fact that the increase in the nitriding temperature can accelerate the diffusion of nitrogen into the surface and titanium from the bulk toward the surface. Also, at higher nitriding temperatures more atomic nitrogen is available due to more energy available to break the N-N bonds. No nickel was detected in the TiN layer on the surface, and the nickel concentration began to rise when the nitrogen concentration began to drop. Based on thermodynamic data this was predictable.
  • Nickel does not form a nitride, due to the positive standard Gibbs free energy of formation; the surface will therefore be predominantly TiN.
  • the presence of a nickel-free TiN layer has been reported in previous research on the nitriding of the Nitinol [30, 35-41].
  • the third atmosphere selected to nitride the Nitinol was 95% 2 + 5% NH 3 , with ammonia as the source of atomic nitrogen. There was no previous study performed on the nitriding of Nitinol in ammonia, so the nitriding conditions were selected based on the observations from the experiments in this investigation.
  • nitriding was capable of forming a TiN layer on the surface of the Nitinol with no nickel being detected.
  • Two nitriding conditions were selected for nitriding prior to oxidation. They were nitriding in 96% N2 + 4% 3 ⁇ 4 at 1000°C for 20 min and nitriding in 95% N 2 + 5% NH 3 at 675°C for 5 min.
  • Nitinol specimens were oxidized in air at 675°C for 30 min and 700°C for 60 min.
  • nickel diffuses into the oxide layer toward the outermost surface due to the thermodynamic activity difference of nickel in the nickel-rich zone and the nickel in the nickel-free oxide layer.
  • Nitriding and oxidation processes were performed on the Nitinol specimens under two conditions:
  • the values of the parameters for the nitriding and oxidation process were based on observations from the nitrided specimens, which had a relatively thick and uniform nitride layer on the surface with no detectable nickel. Also, the completion of the oxidation of the nitrided layer was another factor for the selection of the oxidation parameters.
  • the first nitriding and oxidation process which was nitriding in a 96% N2 + 4% H 2 mix at 1000°C for 20 min followed by oxidation in air at 700°C for 60 min, resulted in a T1O2 layer on the surface with no detectable nickel.
  • the TiN layer was very thick, and nickel was not able to diffuse through the TiN and/or T1O2 layer, and a T1O2 layer with undetectable amounts of nickel was observed on the surface of this specimen.
  • thermocouple was placed right on the top of the specimens, but small variations in the temperature due to the accuracy of the thermocouple ( ⁇ 1°C) and temperature difference between the surface of the specimen and the tip of the thermocouple could be a source of error.
  • Errors in the XPS, SEM, and XRD analysis could also be sources of error. Since TiN's electrical conductivity is low, charging was observed during the SEM analysis. The charging potentially can decrease the accuracy of the TiN layer thickness measurements from the SEM images.
  • the invention provides products of manufacture, e.g., implants, devices, having good biocompatibility, corrosion resistance, and unique mechanical properties such as superelasticity and shape memory, and also having a surface layer lacking nickel; untreated Nitinol contains 50% nickel, a toxic material, which can cause severe allergic reactions in the human body. Nickel can leach out from the surface of Nitinol into the human body, and nickel ion release from Nitinol has been reported repeatedly.
  • nitriding followed by thermal oxidation is capable of forming an oxide layer on the surface with undetectable amounts of nickel.
  • Nitriding in 96% N 2 + 4% H 2 at 1000°C for 20 min followed by oxidation in air at 700°C for 60 min formed a Ti0 2 layer on the surface, and no nickel was detected in the Ti0 2 layer.
  • the nitride layer should also be thick enough to prevent the nickel atoms from outward diffusion due to the thermodynamic activity difference.
  • the nitriding process was very sensitive to the presence of oxygen, and small amounts of oxygen as an impurity in nitrogen sources, or other gases, can cause surface oxidation instead of nitriding.
  • TiN was the predominant phase on the surface of nitrided specimens. • The TiN layer thickness, on the surface of specimens which were nitrided in 96% N 2 + 4% H 2 at 800°C to 1000°C, was strongly affected by nitriding temperature and increased dramatically at higher temperatures. However, nitriding time was not as effective as nitriding temperature in affecting the thickness of the nitride layer.
  • Nickel was present on the outmost surface of the specimens oxidized in air at 675°C for 30 min and 700°C for 60 min.
  • NiTiCu orthodontic archwires by nitrogen diffusion treatment J APPL BIOMATER BIOM, 2, 151-155(2004).
  • the ion etch rate was measured at 12 points for three different ion etching times

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Abstract

Selon des modes de présentation alternatifs, la présente invention porte sur des compositions ou des produits fabriqués comprenant une couche de surface d'oxyde de titane qui est dépourvue, ou substantiellement dépourvue, de nickel. Selon des modes de réalisations alternatifs, l'invention concerne également des procédés de fabrication et d'utilisation desdites compositions ou desdits produits fabriqués. Selon des modes de réalisation alternatifs, les compositions ou les produits fabriqués, décrits par la présente invention, représentent des dispositifs biomédicaux ou des implants ou des prothèses.
PCT/US2012/032186 2012-01-31 2012-04-04 Des surfaces d'oxyde de titane sans nickel et des procédés de fabrication et d'utilisation correspondants WO2013115831A1 (fr)

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CN103990178A (zh) * 2014-06-07 2014-08-20 赵全明 氮化钛涂层人工关节的制备工艺
WO2015035165A1 (fr) * 2013-09-06 2015-03-12 Ormco Corporation Appareils orthodontiques et procédés de fabrication et d'utilisation
EP3299039A4 (fr) * 2015-05-22 2019-01-23 Lifetech Scientific (Shenzhen) Co., Ltd. Préforme d'instrument médical implantable, instrument médical implantable et procédé de préparation associé

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015035165A1 (fr) * 2013-09-06 2015-03-12 Ormco Corporation Appareils orthodontiques et procédés de fabrication et d'utilisation
CN105517504A (zh) * 2013-09-06 2016-04-20 奥姆科公司 正畸矫治器以及制造和使用该正畸矫治器的方法
KR20160051771A (ko) * 2013-09-06 2016-05-11 오름코 코포레이션 치아교정 기구와, 이의 제조 및 사용 방법
US10463453B2 (en) 2013-09-06 2019-11-05 Ormco Corporation Orthodontic appliances and methods of making and using same
CN105517504B (zh) * 2013-09-06 2020-08-04 奥姆科公司 正畸矫治器以及制造和使用该正畸矫治器的方法
KR102211376B1 (ko) 2013-09-06 2021-02-02 오름코 코포레이션 치아교정 기구와, 이의 제조 및 사용 방법
US10945817B1 (en) 2013-09-06 2021-03-16 Ormco Corporation Orthodontic appliances and methods of making and using same
US11992385B1 (en) 2013-09-06 2024-05-28 Ormco Corporation Orthodontic archwire stop and methods of making and using same
CN103990178A (zh) * 2014-06-07 2014-08-20 赵全明 氮化钛涂层人工关节的制备工艺
EP3299039A4 (fr) * 2015-05-22 2019-01-23 Lifetech Scientific (Shenzhen) Co., Ltd. Préforme d'instrument médical implantable, instrument médical implantable et procédé de préparation associé

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