WO2016082682A1 - 管腔支架与其预制件、管腔支架与其预制件的制备方法 - Google Patents

管腔支架与其预制件、管腔支架与其预制件的制备方法 Download PDF

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Publication number
WO2016082682A1
WO2016082682A1 PCT/CN2015/094488 CN2015094488W WO2016082682A1 WO 2016082682 A1 WO2016082682 A1 WO 2016082682A1 CN 2015094488 W CN2015094488 W CN 2015094488W WO 2016082682 A1 WO2016082682 A1 WO 2016082682A1
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Prior art keywords
lumen
stent
lumen stent
preform
iron
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PCT/CN2015/094488
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English (en)
French (fr)
Inventor
张德元
陈贤淼
林文娇
刘香东
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先健科技(深圳)有限公司
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Application filed by 先健科技(深圳)有限公司 filed Critical 先健科技(深圳)有限公司
Priority to US15/526,509 priority Critical patent/US11389308B2/en
Priority to EP15863271.1A priority patent/EP3225215B1/en
Publication of WO2016082682A1 publication Critical patent/WO2016082682A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous 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
    • A61L27/02—Inorganic materials
    • A61L27/04—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
    • A61L31/02—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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C23C8/02—Pretreatment of the material to be coated
    • 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
    • C23C8/08—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 only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2240/00—Manufacturing or designing of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2240/001—Designing or manufacturing processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
    • B21C1/003—Drawing materials of special alloys so far as the composition of the alloy requires or permits special drawing methods or sequences
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
    • B21C1/16—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes
    • B21C1/22—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes specially adapted for making tubular articles
    • B21C1/24—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes specially adapted for making tubular articles by means of mandrels

Definitions

  • the present invention relates to the field of interventional medical devices, and more particularly to a lumen stent and a lumen stent preform, and respective methods of preparation.
  • implanted medical devices are typically made from metals and their alloys, ceramics, polymers, and related composite materials.
  • metal-based implanted medical devices are particularly popular for their superior mechanical properties, such as high strength and high toughness.
  • Iron is an important element in the human body and participates in many biochemical processes, such as the transport of oxygen.
  • Corrosive pure iron stents made by laser engraving and similar in shape to clinically used metal stents were implanted into the descending aorta of 16 New Zealand rabbits. The results of this animal experiment showed that there was no thrombotic complication within 6-18 months, and no adverse events occurred.
  • Pathological examination confirmed that there was no inflammatory reaction in the local vascular wall, and there was no obvious proliferation of smooth muscle cells. It is preliminarily indicating that the degradable iron stent is safe and reliable. Has a good application prospects. However, the study found that the corrosion rate of pure iron stents in the in vivo environment is slow.
  • nitriding methods include gas nitriding, salt bath nitriding, and ion nitriding.
  • gas nitriding and salt bath nitriding have no special requirements on the microstructure and original hardness of the scaffold raw materials, but the modification process of gas nitriding is too long, the production efficiency is very low, and it is difficult to use in scale in actual production.
  • Salt bath nitriding needs a lot of drama The toxic cyanide molten salt is nitrided, and the risk of clinical application is extremely high for high-risk third-class implanted medical device products such as absorbable vascular stents.
  • the compound layer on the surface of the sample after gas nitriding and salt bath nitriding treatment is usually very thick ( ⁇ 0.01mm), which is not conducive to thin-walled (wall thickness ⁇ 0.12mm) medical devices with complex hollow design or Subsequent polishing of the components and design of the fine structure.
  • Ion nitriding has high nitriding efficiency. It uses nitrogen and hydrogen as processing gases, and does not introduce any other toxic substances.
  • the compound layer on the surface after nitriding (commonly known as white bright layer, compound layer of nitrogen) is usually thin and discontinuous.
  • the radial strength is at least 50 kPa and the over-plasticity (ie, plasticity) is at least 20%. It is therefore necessary to provide a lumen stent preform that is not only advantageous for nitriding, but also that the lumen stent prepared after nitriding can meet the requirements of radial strength and plasticity.
  • the technical problem to be solved by the present invention is to provide a lumen stent preform and a lumen stent, and a corresponding preparation method, in view of the defects of the prior art.
  • the present invention provides a lumen stent preform
  • the lumen stent preform is pure iron or iron alloy
  • the total impurity element content of the pure iron is ⁇ 0.5 wt.%
  • all alloying elements of the iron alloy The content is ⁇ 3wt.%
  • the iron alloy does not contain a strong nitride forming element
  • the hardness of the cavity bracket preform is 160 ⁇ 25 0HV0.05/10
  • the microstructure is grain size grade ⁇ 9 or cold working Post-deformation organization.
  • the lumen stent preform of the present invention has a hardness of 200 to 250 HV 0.05 /10, and the microstructure is a deformed structure after cold working.
  • the carbon content of all the impurity elements of the pure iron is ⁇ 0.022%; the carbon content of all the alloying elements of the iron alloy is ⁇ 0.45 ⁇ .%.
  • the outer diameter of the lumen stent preform is 1.2 to 4.2 mm;
  • the thickness is 0.08 ⁇ 0.24mm.
  • the present invention provides a lumen stent preform, the lumen stent preform is a ferroalloy, and the iron alloy contains at least one strong nitride forming element, and the total alloying element content of the iron alloy is ⁇ 3wt .
  • the total content of the strong nitride forming element is ⁇ 0.05 wt.%; the microstructure of the lumen stent preform is a grain size grade ⁇ 9 or a deformed structure after cold working.
  • the strong nitride forming element includes Ti, Cr, Al, Zr,
  • At least one of Nb, V, B, W, Mo is at least one of Nb, V, B, W, Mo.
  • the carbon content of all the alloying elements of the iron alloy is ⁇ 0.45 / ⁇ .
  • the outer diameter of the lumen stent preform is 1.2 to 4.2 mm; and the wall thickness is 0.08 to 0.24 mm.
  • the present invention provides a method of preparing a lumen stent preform comprising drawing the blank into the above-described lumen stent preform.
  • the billet is pure iron having a total impurity element content of ⁇ 0.5% ⁇ %; or the total alloying element content is ⁇ 3 ⁇ .%, and An iron alloy containing a strong nitride forming element; or an iron alloy having a total alloying element content of ⁇ 3 ⁇ .% and a total content of strong nitride forming elements of ⁇ 0.05%.
  • the carbon content of all the impurity elements of the pure iron is ⁇ 0.022%; and the carbon content of all the alloying elements of the iron alloy is ⁇ 0.45 wt. ⁇ 3 ⁇ 4.
  • the method of preparing further comprises processing the blank into a fully annealed or incompletely annealed tissue prior to drawing the blank.
  • the drawing the drawing pass includes at least one core rod drawing and one empty drawing.
  • the drawing coefficient of the cored rod drawing is 1.2
  • the drawing coefficient of the cored rod drawing is 1.5
  • the air is drawn to pull or slightly greater than a factor of about 1.
  • the annealing pass is supplemented by the annealing pass before the core rod is drawn. It is 400 ⁇ 650 °C.
  • annealing temperature is 400 ⁇ 650 °C
  • the present invention provides a method for preparing a lumen stent, comprising: drawing a blank into the above-mentioned lumen stent preform, wherein the blank is pure iron having an impurity element content of ⁇ 0.5 ⁇ .%, or All iron alloys with alloying element content ⁇ 3 ⁇ .% and no strong nitride forming elements, or iron alloys with total alloying element content ⁇ 3 ⁇ .% and total content of strong nitride forming elements ⁇ 0.05wt.% .
  • the preparation method further comprises: forming the lumen stent preform into an initial stent, and heating the initial stent to 320 to 560 ° C, at 10 Under the bias of ⁇ 500Pa and 500 ⁇ 700V, nitriding the initial support ion for 15 ⁇ 180 minutes.
  • the preparation method further includes forming the lumen stent preform into an initial stent, and after the initial stent is heated to 320 to 420 ° C, iontophoresis of the initial stent at a pressure of 50 to 500 Pa and a bias of 500 to 700 V. Nitrogen 30 to 180 minutes.
  • the nitrogen-hydrogen flow ratio of the gas source in the ion nitriding is 1:1 to 1:3.
  • the preparation method further comprises performing polishing after ion nitriding to obtain the lumen stent.
  • the present invention provides a lumen stent, which is prepared by the above method for preparing a lumen stent, having a hardness of 250 to 350 HV0.05/10, and a microstructure of a grain size of ⁇ 9. Grade or deformation structure after cold working.
  • the hardness of the lumen stent preform is 200 ⁇ 250HV0.05/10, and the microstructure is the deformed tissue after cold working
  • the hardness of the lumen stent is 300 ⁇ 350HV0.05/10
  • the microstructure is the deformed structure after cold working.
  • the radial strength of the lumen stent is 80-260 kPa, and the over-expansion plasticity is 2
  • the radial strength of the lumen stent is 80-260 kPa, and the over-expansion plasticity is 2
  • the in vitro immersion corrosion rate of the lumen stent is 0.25 to 1.5 times faster than the in vitro immersion corrosion rate of the initial stent.
  • the in vitro immersion corrosion rate of the lumen stent is 1 to 1.5 times faster than the in vitro immersion corrosion rate of the initial stent.
  • the metal coverage of the lumen stent is 11 to 16% or 7 to 11%.
  • the lumen stent comprises a solid solution and an iron-nitrogen compound; or the lumen stent comprises a solid solution, an iron-nitrogen compound, and a strong nitride forming element and a nitrogen compound.
  • the lumen stent includes a first layered structure and a second layered structure in order from the surface inward; wherein the first layered structure comprises a solid solution and an iron-nitrogen compound
  • the second layered structure includes a solid solution; or the first layered structure includes a solid solution, an iron-nitrogen compound, and a strong nitride forming element and a nitrogen compound, and the second layered structure includes a solid solution.
  • the lumen stent includes a first layered structure, a second layered structure, and a third layered structure in order from the surface inward; wherein the first layered structure Including solid solution and iron nitriding
  • the second layered structure comprises a solid solution
  • the third layered structure is a core layer; or the first layered structure comprises a solid solution, an iron-nitrogen compound, and a strong nitride forming element and a nitrogen composition.
  • the compound, the second layered structure comprises a solid solution
  • the third layered structure is a core layer.
  • the technical solution adopted by the present invention to solve the technical problem thereof is: using a hardness of 160 ⁇ 250HV0.05/10
  • the microstructure is an iron-based lumen support preform with a grain size grade ⁇ 9 or a deformed structure after cold working; or a microstructure with a grain size of ⁇ 9 or a deformed structure after cold working, strong A ferrite-forming element of a ferroalloy lumen stent preform, the above two stent preforms are suitable for ion nitriding, and the applicable temperature range in the ion nitriding process is large; The radial strength and plasticity meet the requirements of the lumen support products, so that the ion nitriding process can be applied to the commercial preparation of the lumen stent.
  • FIG. 1 is a flow chart of a method of preparing a lumen stent according to an embodiment of the present invention
  • 2a-2c are schematic diagrams showing the composition of a lumen stent according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional metallographic view of a 160HV HV0.05/10 hardness OD 1.6 mm pure iron pipe;
  • FIG. 3 is a longitudinal section metallographic view corresponding to the pure iron pipe of FIG. 2;
  • FIG. 4 is a cross-sectional metallographic view of an OD4.2 mm pure iron pipe having a hardness of 160 HV 0.05/10;
  • FIG. 5 is a longitudinal section metallographic view corresponding to the pure iron pipe of FIG. 4;
  • FIG. 6 shows a cross-sectional metallographic view of a lumen stent preform having a cold deformed tissue with an OD of 1.6 mm
  • FIG. 7 shows a lumen with cold deformed tissue having an OD of 1.6 mm.
  • FIG. 8 shows a longitudinal section of a lumen stent preform having a cold deformed tissue with an OD of 1.6 mm under scanning electron microscopy.
  • the present invention provides a vascularized catheter stent preform and a preparation method thereof, and a method for preparing a lumen stent satisfying the mechanical performance requirements of a conventional lumen stent and a lumen obtained by the preparation method using the preform support.
  • the mechanical properties of the coronary stent are in the range of OD (outer diameter) of 2.0 to 5.0 mm, and the radial strength of the coronary stent is required to be not less than 80 kPa and the overexpansion plasticity is not less than 20%;
  • the stent has a radial strength of not less than 50 kPa and a degree of overexpansion of not less than 20% in the range of OD of 5.0 to 14.0 mm.
  • 20% of overexpansion plasticity refers to the clinical expansion of the lumen stent to a maximum diameter of 20% beyond the nominal diameter of the stent, and the stent rod does not split or break.
  • a method 100 for preparing a lumen stent of the present invention includes: Step 101: drawing a pure iron or iron alloy blank to obtain a lumen stent preform; Step 102, forming a lumen stent preform into an initial Stent; Step 103, ion nitriding the initial stent to obtain a lumen stent.
  • the lumen stents described above include, but are not limited to, vascular stents, esophageal stents, and tracheal stents.
  • the billet is pure iron or an iron alloy (or iron-based alloy); wherein, all the impurity element content of the pure iron is ⁇ 0.5 ⁇ .%; the total alloying element content of the iron alloy is ⁇ 3wt.%. .
  • the carbon content in all the impurity elements of the pure iron may be less than or equal to 0.022%, or the carbon content in all the alloying elements of the iron alloy is ⁇ 0.45 wt.%.
  • the ferroalloy includes an iron alloy containing a strong nitride forming element and an iron alloy containing no strong nitride forming element, and all of the alloying elements of the iron alloy containing a strong nitride forming element may contain one or more strong nitride forming elements, strong nitride
  • the total content of the forming elements is ⁇ 0.05 ⁇ 1. ⁇ 3 ⁇ 4, and the above strong nitride forming elements include, but are not limited to, Ti, Cr, Al, Zr, Nb, V, B.
  • Pulling means that at the recrystallization temperature of the tube blank material, for example, at normal temperature, an external force is applied to the front end of the drawn pipe, and the pipe is pulled out from the die hole smaller than the pipe diameter to obtain a smaller diameter pipe.
  • the control of the microstructure and hardness of the lumen stent preform is achieved by drawing a thin-walled tubular blank (hereinafter referred to as a tube blank) to produce a lumen stent preform.
  • a tube blank a thin-walled tubular blank
  • the drawing process parameters that are planned during the drawing process such as the number of drawing passes and/or the drawing factor. Etc., choose the right mold, no longer here. An enumeration.
  • the step of treating the blank into an incompletely annealed structure, or a fully annealed state may be included prior to drawing.
  • the billet can be completely annealed at an annealing temperature of 570 to 700 ° C for 0.5 to 2 hours, so that the billet is completely annealed; the billet is at a lower annealing temperature (eg, 400 to 550 ° C).
  • Incomplete heat treatment such as 0.5 ⁇ lh
  • incompletely annealed structure can be obtained.
  • Fully annealed and incompletely annealed structures can be drawn using the same or similar drawing process (eg, the same drawing factor and drawing pass).
  • the hardness of pure iron can be selected as 90HV0.05/10, and the hardness of ferroalloy can be selected from 10 0-150HV0.05/10; the microstructure is equiaxed crystal , grain size ⁇ 4; corresponding optional size range is wall thickness 0.16 ⁇ 3mm, outer diameter 3.5 ⁇ 20mm. If the billet is incompletely annealed, the hardness of the billet is higher than that of the fully annealed structure of the corresponding component. For example, the hardness of pure iron is generally greater than 90 HV0.005/10, which may be 100 or 120 HV0.05/10.
  • the hardness of the ferroalloy is at least 110HV0.05 /10; the microstructure is deformed; the corresponding blank size range is 0.13 ⁇ 3mm and the outer diameter is 2.3 ⁇ 20mm. It is to be understood that the billet characteristics recited herein are by way of example only, and are not limiting of the invention, and one of ordinary skill in the art, in accordance with the teachings of the present invention, may select any suitable blanks as desired.
  • the drawn drawing pass includes at least one core rod drawing and at least one empty drawing after the core rod is drawn, and the core rod drawing may be a long core rod drawing.
  • the drawing coefficient is characterized by the length ratio of the pipe, which is also called the elongation coefficient. It should be understood that for the solid piece, the volume before and after drawing is not changed, so the cross-sectional area ratio is inversely proportional to the length ratio.
  • the core rod and the tube blank are adhered together, and the mold release is required to separate the core rod from the tube blank.
  • Demolding involves extruding the blank to plastically deform the tube blank.
  • the core rod has a relatively high hardness and will not deform and will separate from the blank. Since the billet undergoes plastic deformation after being pulled by the core rod, the surface state and the outer diameter of the billet are changed, and at least one empty pulling is required to sizing (precisely fixing the outer diameter dimension) and eliminating the deformation trace of the surface of the pipe after demolding. .
  • the drawing coefficient used in the air pulling process is about 1.0, or slightly more than 1.0, for example, 1.01 to 1.05, and the outer diameter of the tube blank is made smaller by air pulling, and the wall thickness is increased.
  • the empty drawing is the last pass in the drawing process, that is, after the end of the empty drawing, the entire drawing process ends; when the blank is composed of a strong nitride forming element
  • the ferroalloy crucible can also be annealed after empty drawing, and the billet is completely or incompletely annealed. The annealing temperature and the crucible are related to the material.
  • annealing temperature 570 to 700 ° C for 0.5 to 2 hours.
  • Annealing in the lower annealing temperature (such as 400 ⁇ 550 °C), the insulation treatment of short turns (such as 0.5 ⁇ lh) can be performed to achieve incomplete annealing.
  • a long core rod drawing of 3 to 5 passes and an empty pull of the last pass may be used, and 0 to 5 annealing passes may be supplemented during the drawing pass.
  • no annealing pass is required in the drawing process; if a lumen stent preform having a hardness of less than 250HV0.05/10 is obtained, the drawing process Several annealing passes can be added.
  • the annealing of the annealing depends on the hardness of the pipe in the middle drawing. When the hardness of the pipe in the middle pass is between 200-240HV0.05/10, the annealing pass can be considered, and the annealing temperature can be considered. Choose from 400 ⁇ 650 °C.
  • the outer diameter (OD) of the lumen stent preform obtained by drawing is 1.2 to 4.2 mm, and the wall thickness is 0.08 to 0.24 mm; and the mechanical properties, the hardness is 160 to 250 HV 0.05/10 (in The Vickers hardness value measured by the test force of 0.05 kg force for 10 s); the microstructure or microstructure, the grain size of the cavity bracket preform is ⁇ 9 or has a deformed structure after cold working (may be referred to as Cold deformed tissue).
  • the hardness of the lumen support preform is 200 ⁇ 250HV0.05/10, and the microstructure is a deformed structure after cold working;
  • the material of the lumen support preform is the same as the material of the blank, for example, when The billet is a ferroalloy crucible containing a strong nitride forming element, and the tubular stent preform obtained by drawing is also maintained as an iron alloy containing a strong nitride forming element.
  • the hardness (Vickers hardness) is carried out according to the test method in GB/T 4340.1-2009, using a load of 50gf, holding pressure for 10s, according to the diagonal length of the indentation, the Vickers hardness value of the material is obtained.
  • the high hardness causes the plasticity of the cold work hardening sacrificial material, which in turn causes the flexibility and fracture resistance of the prepared lumen support to decrease as the degree of cold work hardening increases; and the higher the hardness of the lumen support preform The greater the likelihood of recovery and annealing during subsequent nitriding, the greater the extent.
  • the tube stent preform prepared with hardness of 160 ⁇ 250HV0.05/10 in the invention combined with the microstructure grain size grade ⁇ 9 or the deformed structure after cold working is not only beneficial to the implementation of the subsequent nitriding process.
  • the present invention also provides a lumen stent preform made of an iron alloy containing a strong nitride forming element, which is more easily combined with nitrogen to form a compound, in combination with a microstructure grain size rating thereof. ⁇ 9 or with deformed structure after cold working, which is also conducive to the implementation of the subsequent nitriding process, and can take into account the requirements of the radial support (hardness) and plasticity of the lumen support, which will be described in detail later.
  • the microstructure can be tested in the following manner, for example, by first taking a sample to be tested, such as a lumen stent preform or a lumen stent, and curing the sample using a resin casting to embed the sample in the resin. Sandpaper sanding and velvet polishing cloth polishing remove scratches on the cross section of the resin sample. Then use 3 to 4% nitric acid to erode approximately 5 to 40 s. The metallographic structure of the sample was observed using a high power microscope of 500 times or more. If the metallographic structure is found to be equiaxed, the grain size of the material is evaluated according to the straight line intercept method in GB/T 6394-2002. If the metallographic phase is deformed, no grain size calculation is required.
  • a sample to be tested such as a lumen stent preform or a lumen stent
  • Sandpaper sanding and velvet polishing cloth polishing remove scratches on the cross section of the resin sample. Then use 3 to 4% nitric acid
  • Step 102 The lumen stent preform prepared in step 101 is made into an initial stent.
  • the lumen stent preform can be cut according to the preset stent pattern and subsequently cleaned to make the initial stent.
  • Step 103 performing ion nitriding on the initial stent prepared in step 102 to obtain a lumen stent.
  • it can be 320 to 560° under the conditions of a bias voltage of 500 to 700 V, a total pressure of 10 to 500 Pa, and a nitrogen-hydrogen flow rate of the gas source of 1:1 to 1:5 (also referred to as Ion nitriding of 15 to 18 Omins was performed for the above initial scaffold for nitriding temperature).
  • a bias voltage of 500 to 700 V a total pressure of 10 to 500 Pa
  • a nitrogen-hydrogen flow rate of the gas source of 1:1 to 1:5 (also referred to as Ion nitriding of 15 to 18 Omins was performed for the above initial scaffold for nitriding temperature).
  • Ion nitriding also referred to as Ion nitriding of 15 to 18 Omins was performed for the above initial scaffold for nitriding temperature.
  • those skilled in the art will also be able to select
  • the hardness of the lumen stent prepared above is 250 ⁇ 350HV0.05/10; the microstructure remains unchanged compared with the lumen stent preform, and the grain size is still ⁇ 9 or maintains the initial Cold deformed tissue; the radial strength of the lumen stent is 1.1 to 2 times the radial strength of the initial stent; the in vitro corrosion rate is 0.25 to 1.5 times faster than the lumen stent preform, and the overexpansion plasticity is at least 20%, usually up to 30-50%, meeting the requirement of conventional tube stent overexpansion of at least 20%.
  • the radial strength is at least 80 kPa, usually up to 80 to 260 kPa, which satisfies the coronary artery.
  • the radial strength of the bracket is required to be at least 80 kPa; for a peripheral bracket with a wall thickness of 90 to 200 ⁇ m, a metal coverage of 7 to 11%, and an OD of 5.0 to 14 mm, the radial strength is at least 50 kPa, usually up to 85 -130 kPa, meeting the requirements of the conventional peripheral support radial strength of at least 50 kPa.
  • the luminal stent obtained by nitriding the lumen stent preform provided by the present invention is in accordance with the usual
  • the mechanical properties of the stent are regulated. It should be understood that the parameters recited herein are for illustrative purposes only and are not limiting of the invention. Any method for preparing a lumen stent preform and a lumen stent based on the teachings of the present invention, both of which are employed Within the scope of protection of the invention.
  • the internal structure of the lumen stent provided by the present invention can be adjusted according to actual intended use requirements, and specifically, the nitriding depth can be controlled by controlling the nitriding time and the nitriding temperature, thereby preparing the lumen stent with different internal structures.
  • . 2a to 2c are shown as an example, showing a schematic structural view of the inside of a lumen stent.
  • the square in the figure indicates the cross section of a component of the lumen stent.
  • the square shape is only an example, and may of course be a circular shape or other cutting shape;
  • the arrows indicate the direction of ion nitriding and penetrate inwardly from the surface. Referring to Fig.
  • the composition inside the lumen stent is a single uniform structure 1
  • the structure 1 includes a solid solution and an iron-nitrogen compound, and the iron-nitrogen compound is dispersed in the solid solution
  • the solid solution is a nitrogen-containing iron solid solution
  • the iron-nitrogen compound includes It is not limited to Fe 4 N, Fe 2 — 3 N.
  • the lumen support preform is a ferroalloy crucible containing a strong nitride forming element
  • the single uniform structure 1 includes a solid solution, an iron-nitrogen compound, and a strong nitride forming element and a nitrogen compound, an iron-nitrogen compound, and a strong nitride.
  • the compound forming the element and the nitrogen is dispersed in the solid solution
  • the iron-nitrogen compound includes, but is not limited to, Fe 4 N, Fe 2 - 3 N.
  • the component structure inside the lumen stent includes the first layered structure 1 and the second layered structure 2, in order from the surface of the lumen stent inwardly, that is, in the direction of penetration indicated by the arrow, wherein
  • the layered structure 1 comprises a solid solution and an iron-nitrogen compound, and the iron-nitrogen compound is dispersed in the solid solution;
  • the second layered structure 2 comprises a solid solution layer, and the solid solution is a nitrogen-containing iron solid solution.
  • the lumen stent preform is a ferroalloy crucible containing a strong nitride forming element
  • the difference is that the first layered structure 1 includes a solid solution, an iron-nitrogen compound, and a compound of a strong nitride forming element and nitrogen, an iron-nitrogen compound. And a compound having a strong nitride forming element and nitrogen is dispersed in the solid solution.
  • the composition of the interior of the lumen stent includes, in order, the first layered structure 1, the second layered structure 2, and the third The layered structure 3, wherein the first layered structure 1 comprises a solid solution and an iron-nitrogen compound, the iron-nitrogen compound is dispersed in the solid solution; the second layered structure 2 comprises a solid solution; the third layered structure 3 is an iron core layer, and the solid solution is The nitrogen-containing iron solid solution is the original iron-based material in the iron core layer 3.
  • the lumen stent preform is a ferroalloy crucible containing a strong nitride forming element
  • the difference is that the first layered structure 1 includes a solid solution, an iron-nitrogen compound, and a compound of a strong nitride forming element and nitrogen, an iron-nitrogen compound. And the combination of strong nitride forming elements and nitrogen The matter is dispersed in the solid solution.
  • FIGS. 2b and 2c are only schematic structures.
  • the one-component structure is gradually changed to form an adjacent another component structure, for example, FIG. 2c.
  • the solid solution layer 2 in the middle gradually becomes the iron core layer 3.
  • Figure 2c forms the composition of the composition in Figure 2b.
  • FIG. 2a The component structure in FIG. 2a is formed, that is, the component structure inside the lumen stent is a single structure, and the whole is a solid solution, and the iron-nitrogen compound is dispersed in the solid solution.
  • a compound layer on the outermost surface of the lumen stent which is also called a white bright layer (not shown in the above figure), and the components of the white bright layer are all iron-nitrogen compounds.
  • the white bright layer is removed using the polishing process referred to in step 103 or any other suitable manner to obtain the final lumen stent.
  • the lumen stent preform provided by the present invention is not only suitable for surface alloying modification treatment by ion nitriding, but also can be in a large temperature range (320 to 560 ° C). Ion nitriding is carried out to make the ion nitriding process suitable for commercial large-scale preparation of lumen stents.
  • Pure iron or iron alloy generally begins to recover at about 400 ° C, and recrystallization annealing occurs at around 500 ° C.
  • High temperature ion nitriding such as temperatures above 500 ° C, may result in recovery or recrystallization annealing of pure iron or iron alloys.
  • the recovery means that the heat treatment temperature is not high, because the atom diffusion ability is not large, but the defects such as internal vacancies and interstitial atoms are greatly reduced by the movement and the composite disappears, but the dislocations introduced by the cold deformation remain, and the deformation of the metal is obvious. Microscopic tissue does not change significantly. Rejuvenation increases the plasticity of the material and slightly reduces its strength and hardness.
  • Recrystallization means that when the annealing temperature is high enough and the crucible is long enough, in the microstructure of the cold-worked deformed metal or alloy, new unstrained grains are produced, and the new grains continue to grow until the original cold working deformation The process of completely disappearing, the properties of metals or alloys also undergo a significant change. Recrystallization significantly increases the plasticity of the material, while significantly reducing the strength and hardness of the material.
  • the nitriding temperature has a great influence on the material properties of the lumen stent. If nitriding is selected at a temperature below 400 ° C in order to avoid the effects of recovery and/or recrystallization, Infiltrated nitrogen ions are difficult Overcoming the diffusion energy barrier cannot effectively spread inside the material, which will reduce the nitriding effect. That is to say, it is difficult to balance the nitriding effect and avoid the effects of recovery and/or recrystallization only by lowering the nitriding temperature.
  • the present invention also provides a lumen preform that is not only suitable for low temperature nitriding to minimize the effects of recovery and/or recrystallization, but also to ensure efficient diffusion of nitrogen ions within the material during nitriding.
  • the hardness of the lumen stent preform prepared in step 101 is 200 to 25 0 HV 0.05/10, and the microstructure is a deformed structure after cold working.
  • the lumen stent preform is made into an initial stent and ion nitriding is performed, wherein the pressure can be 320 to 420 under the conditions of a bias voltage of 500 to 700 V, a total pressure of 50 to 500 Pa, and a nitrogen to hydrogen ratio of 1:1 to 1:3.
  • the above initial stent is subjected to ion nitriding at 30 to 180 mins, and a lumen stent having a hardness of 300 to 350 HV 0.05/10 can be obtained, and the microstructure remains still deformed after cold working.
  • the radial strength of the lumen stent is 1.1 to 2 times the radial strength of the initial stent; the in vitro corrosion rate is 1 to 1.5 times faster than the lumen stent preform, and the overexpansion plasticity is at least 20%, usually up to 30- 40%; and for wall thickness in the range of 40 ⁇ 150 microns, metal coverage is 11 ⁇ 16%, OD is 2 ⁇ 5.0mm coronary stent, radial strength is at least 80kPa, usually up to 110 ⁇ 260kPa, satisfying
  • the conventional radial stent has a radial strength of at least 80 kPa; for a peripheral stent having a wall thickness of 90 to 200 ⁇ m, a metal coverage of 7 to 11 ⁇ 3 ⁇ 4, and an OD of 6 to 14 mm, the radial strength is at least 50 kPa, usually Up to 85 kPa, even higher, up to 130 kPa, meeting the requirements of conventional peripheral support radial strength of at least 50 kPa.
  • the lumen stent produced in this embodiment satisfies the mechanical performance requirements of conventional lumen stents. It should be understood that the parameters recited herein are for illustrative purposes only, and the parameters that can be achieved for different sizes of lumen stents are not the same, and thus are not limiting of the invention, any catheter stent preforms obtained based on the teachings of the present invention. And the method of preparing the lumen stent and both of them are within the scope of the present invention.
  • the microstructure of the lumen support preform includes a cold deformed structure, and a large amount of vacancy defects, broken grain boundaries, and cold deformation energy are stored inside the material, which facilitates the first penetration of nitrogen atoms into the grain boundary, and then Diffusion into the crystal, and the deformed structure and the fine-grained material have more grain boundaries with respect to the coarse equiaxed grains, providing more channels for the infiltration of nitrogen atoms.
  • the deformed energy storage of the material introduced by cold working can help the nitrogen atom overcome the diffusion energy barrier and diffuse into the interior of the material even at lower nitriding temperatures.
  • the tube holder preform can be used for low temperature ion nitriding at 320 ⁇ 420°, and the material strength and hardness caused by vacancies and dislocations after cold working are saved, and the corrosion rate is improved, and the ion nitriding zone is used.
  • the strength and hardness of the rise and the increase of the corrosion rate are superimposed, so that the hardness of the lumen stent is in vitro.
  • Both the corrosion rate and the plasticity meet the requirements. That is, the use of the lumen stent preform can overcome the influence of excessive temperature during the high temperature ion nitriding process on the plasticity and strength of the lumen stent.
  • the radial strength of the lumen stent can be uniformly applied to the stent by the compression module to compress the stent to produce uniform deformation.
  • the radial (outer diameter) of the bracket 10% deformation.
  • the radial pressure applied is the radial strength of the bracket.
  • a pure iron pipe preform can be used to design a laser-engraved initial support according to a preset pattern.
  • the nominal diameter of the bracket is 3.0 mm and the length is 18 mm. After coarse polishing, it is placed in a plasma vacuum nitriding furnace for nitriding. , then fine polishing to the predetermined finished size.
  • the stent was expanded by a balloon to a nominal diameter of 3.0 mm ⁇ for radial strength testing and in vitro immersion corrosion rate testing.
  • the plasticity test of the lumen stent was carried out as follows. For example, an OD3.0xl8mm (OD 3.0mm, tube length 18mm) stent is used to expand the nominal diameter of the balloon catheter with a matching 3.0x18mm balloon catheter (usually labeled on the balloon catheter, typically 8atm)
  • the lower jaw, the inner diameter of the bracket is 3.0mm, which is the nominal diameter of the bracket.
  • Different sizes of preforms made of preforms of different specifications are used with different nominal diameter balloon catheters or with different expansion pressures.
  • the stents are gradually expanded from small to large, and the stent fracture is observed. The stent is expanded without breaking.
  • the maximum expansion diameter D (mm) is calculated by lOOx (D-3 .0) /D% to characterize the overexpansion of the material.
  • the in vitro immersion corrosion test of the lumen stent is as follows: The polished stent is expanded to a nominal diameter with a balloon catheter, and the initial weighing is performed with a balance of one millionth precision, which is recorded as M0, accurate to O. .OOlmg, the immersion corrosive medium is 0.9 ⁇ 3 ⁇ 4NaCl salt solution, the ratio of the surface area of the sample to the volume of the immersion corrosive medium is 0.05 cm ml (corresponding to the wall thickness of 50 ⁇ m described in the example, 3.0 ⁇ 18 mm bracket soaked with a rod width of 90 ⁇ m) In 15 ml medium, the opening was placed in a 37 ° C water bath shaker for 2 h.
  • the corroded stent is ultrasonically cleaned with 3 ⁇ 5% tartaric acid solution for 3 ⁇ 5mins until the corrosion product is completely removed, neutralized by 2% sodium hydroxide aqueous solution for 10mins, deionized water for 5mins, and finally anhydrous ethanol dehydrated for 10mins. After the ethanol is completely volatilized, it is weighed with a one-million-precision balance, which is recorded as Ml, accurate to 0.001 mg. Assumed If the corrosion is constant, the result of in vitro immersion corrosion weight loss is expressed as mm/y, and the formula is (1 0-2- ⁇ ) / (pSt). ⁇ is substituted into the numerical value in mg, and t is converted into adult y.
  • S is substituted into the numerical calculation in units of cm 2
  • This embodiment provides a method of preparing a lumen stent using pure iron tubing.
  • step 101 the preform of the lumen support is drawn into an ultra-thin wall.
  • Figure 2 and Figure 3 show the cross-section metallographic and longitudinal section of the pure iron pipe with a hardness of 160 HV0.05 /10 and an OD of 1.6 mm after drawing;
  • Figure 4 and Figure 5 show the drawing respectively.
  • the drawing of the high-precision pipe can be carried out using a long mandrel drawing process, and the drawing pass to be used depends on the hardness and plasticity of the billet.
  • a pure iron pipe blank having a fully annealed structure of 6x0.5 (outer diameter of 6 mm, wall thickness of 0.5 mm) is used (all impurity element content ⁇ 0.5 wt.%, wherein carbon content ⁇ 0.022%)
  • the hardness of the pure iron tube embryo is about 90 HV0.05/10, and the metallographic structure of the fully annealed structure is equiaxed crystal, and the grain size grade is ⁇ 4.
  • the drawing passes are in turn: 1 using an outer mold of 5 mm and a core rod of 4.4 mm for long core rod drawing; 2 using an outer mold of 4.4 mm and a mandrel of 4.0 mm for long core rod drawing;
  • the annealing pass is used, for example, the semi-small crucible can be annealed at 650 ° C after the completion of the pass;
  • 3 the long core bar is drawn by using the outer mold 3.5 mm and the mandrel 3.19 mm;
  • Long core rod drawing is carried out with outer mold 2.3mm and mandrel 2.02mm;
  • 5 long core rod drawing is carried out with outer mold 1.83mm and core rod 1.60mm; after the drawing pass, it can be supplemented with annealing pass, for example
  • the semi-small crucible is annealed at 510 ° C; 6 is taken by an outer mold of 1.62 mm to obtain a stent preform having a microstructure close to a fully
  • the drawing coefficient (which may also be referred to as an elongation coefficient) of all the drawing passes cannot exceed 2.0, and in the present embodiment, the elongation coefficient may be selected to be about 1.5.
  • the metal material has a certain elastic aftereffect, for example, after drawing through the outer mold of 1.62 mm, the outer diameter will have a certain rebound, and the measured outer diameter is 1.63 mm and the wall thickness is 0.125 mm.
  • reserve 0.03mm The polishing allowance, after mechanical polishing of 0.03mm, the composition is unchanged (all impurity element content ⁇ 0.5wt.%,
  • the carbon content is ⁇ 0.022 ⁇ 3 ⁇ 4), the outer diameter is 1.60mm, the wall thickness is 0.110 ⁇ 0.005mm, and the hardness is 160HV0.05/10.
  • the finished pure iron pipe with a grain size of 9 or above is used as a cavity bracket preform.
  • the quality of the inner wall of the pipe is obtained by controlling the mandrel.
  • the surface of the mandrel must be polished. No obvious visible machining marks are observed under a 200X stereo microscope, and the hardness reaches HRC58-64.
  • the material of the mandrel can be SKD11, SK. H-9 and other mold steel.
  • the dimensional uniformity of the pipe is obtained by strictly controlling the precision dimensions of the mandrel and the outer die, the accuracy of the outer die is ⁇ 3 ⁇ , and the precision of the mandrel is ⁇ 2 ⁇ .
  • the lumen stent preform is laser-cut to obtain a 3.0x18mm crown initial stent, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the surface metal mesh coverage is about It is 13%.
  • the laser-cut pure iron stent is polished to the finished product size (the support rod width is 90 micrometers, the stent wall thickness is 70 micrometers), and the radial strength is about 80 kPa.
  • the in vitro immersion corrosion rate is about 1.0 mm/y. About 50%.
  • step 103 the laser-cut pure iron stent is roughly polished and washed, and then charged into a glow ion furnace for ion nitriding treatment. Selecting a nitriding temperature of about 560 ° C, a nitrogen to hydrogen flow ratio of 1:3, a bias of 50 to 130 P a and a pressure of 500 V, and nitriding for 90 to 150 minutes, the entire section of the stent rod is permeated, that is, except for the outermost surface.
  • the composition of the compound is the structure shown in Fig. 2a.
  • the nitriding iron stent was embedded in resin and ground and polished.
  • the metallographic observation and hardness test results showed that the microstructure remained unchanged, that is, the grain size level was ⁇ 9, and the hardness value was increased to about 250 HV0.05/10.
  • Another sample of nitriding iron bracket was polished to the finished product size. The bracket rod width was 90 micrometers, and the wall thickness of the bracket was 70 micrometers. The radial strength of the thin-walled bracket was increased to 115 kPa, and the over-expansion plasticity was 50%. The corrosion rate was increased to 1.5 mm/y.
  • step 101 a pure iron tube embryo having 6 ⁇ 0.5 (outer diameter 6 mm, wall thickness 0.5 mm) having a completely annealed structure (all impurity element content ⁇ 0.5 wt.%, wherein carbon content ⁇ 0.022%)
  • the tube stent preform is drawn by drawing.
  • the hardness of the pure iron tube embryo is about 90 HV0.05/10, and the metallographic structure of the fully annealed structure is equiaxed crystal, and the grain size grade is ⁇ 4.
  • the drawing passes include: 1 using the outer mold 5mm and the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4mm, the core rod 4.0mm for the long core rod drawing; 3 using the outer mold 3.5mm, the core rod 3.19mm for long core rod drawing; this drawing line can be supplemented with annealing pass, for example, can be pulled
  • the semi-small crucible is annealed at 500 ° C; 4 the long core rod is drawn by using the outer mold 2.3 mm and the core rod 2.02 mm; 5 the long core rod drawing is performed by using the outer mold 1.78 mm and the core rod 1.60 mm;
  • the annealing pass can be supplemented.
  • the half-small crucible can be annealed at 400 ° C after the drawing is completed; 6 is taken by the outer mold of 1.62 mm, and the empty drawing is in the drawing. The last pass.
  • the range (drawing factor) is 1.2 to 2.0, and can be selected to be around 1.5. Since the metal material has a certain elastic aftereffect, after the outer mold of 1.62mm is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63m, and the wall thickness is 0.095mm. In order to strictly control the quality of the outer surface of the pipe, a polishing margin of 0.03mm is reserved.
  • the composition After mechanical polishing of 0.03mm, the composition is unchanged (all impurity element content ⁇ 0.5wt. ⁇ 3 ⁇ 4, of which carbon content is ⁇ 0.022%), outer diameter 1.60mm, the wall thickness is 0.080 ⁇ 0.005mm, the hardness is about 200HV0.05/10, and the finished pure iron pipe with the deformed structure after cold working is used as the bracket preform.
  • 6 shows a cross-sectional metallographic view of a lumen stent preform having a cold deformed structure with an OD of 1.6 mm
  • FIG. 7 shows a prefabricated stent with cold deformed tissue having an OD of 1.6 mm.
  • Figure 8 shows a longitudinal section of a tubular stent preform having a cold deformed tissue with an OD of 1.6 mm under scanning electron microscopy.
  • the stent preform prepared above is laser-cut to obtain an initial coronary stent of OD3.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is obtained. About 13%.
  • the laser-cut initial stent was polished to the finished product size (the holder rod width was 90 ⁇ m, the stent wall thickness was 50 ⁇ m), and the radial strength was measured to be 80 kPa, the in vitro immersion corrosion rate was 1.0 mm/y, and the overexpansion plasticity was 50%. .
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature was selected to be 480 ° C, a ratio of nitrogen to hydrogen of 1: 1 , a bias of 10 to 20 Pa and a pressure of about 600 V, and nitriding for 60 to 120 minutes.
  • the nitriding iron stent was embedded with resin and ground and polished. The results of metallographic observation and hardness test showed that the material still retained the deformed structure and the hardness value increased to about 250 HV0.05/10.
  • the pure iron blank is drawn to obtain a lumen stent preform.
  • the pure iron billet is a pure iron tube blank having a completely annealed structure of 6x0.5 (outer diameter 6mm, wall thickness 0.5mm) (all impurity element content ⁇ 0.5 ⁇ 1. ⁇ 3 ⁇ 4, wherein carbon content ⁇ 0.022 ⁇ 3 ⁇ 4), the hardness of the pure iron tube embryo is about 90 HV0.05/10, the metallographic structure of the fully annealed structure is equiaxed crystal, and the grain size grade is ⁇ 4.
  • the drawing times include: 1 long core rod drawing with ⁇ ⁇ 5 5mm and mandrel 4.4mm; 2 long core rod drawing with outer mold 4.4mm, mandrel 4.0mm; 3 outer mold 3.5mm, core Rod 3.19mm for long core rod drawing; 4 using outer mold 2.3mm, mandrel 2.02mm for long core rod drawing; 5 using outer mold 1.8mm, mandrel 1.63mm for long core rod drawing; 6 using outer mold The 1.62mm is pulled, which is the last pass in the draw.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the 1.62mm outer mold is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63mm and the wall thickness is 0.095mm. In order to strictly control the quality of the outer surface of the pipe, a polishing allowance of 0.03 mm is reserved, and after mechanical polishing of 0.03 mm, the composition is unchanged (all impurity element content ⁇ 0.5 wt. ⁇ 3 ⁇ 4,
  • the stent preform prepared by the above method is laser-cut to obtain an initial coronary stent of OD3.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is obtained. About 13%.
  • the laser-cut initial stent was polished to the finished product size (the holder rod width was 90 ⁇ m and the stent wall thickness was 50 ⁇ m).
  • the radial strength was measured to be 90 kPa, the in vitro immersion corrosion rate was 1.0 mm/y, and the overexpansion plasticity was 40%. .
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature is selected to be about 320 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of about 380-500 Pa and a pressure of about 700 V, and nitriding for 90 to 150 minutes.
  • the stent rod is perforated in cross section, that is, the material inside is the structure shown in Fig. 2a except for the compound layer on the outermost surface.
  • the nitriding lumen stent was embedded with resin and ground and polished.
  • the iron alloy blank is drawn to obtain a lumen stent preform.
  • the iron alloy billet is a 6 ⁇ 0.5 (outer diameter 6 mm, wall thickness 0.5 mm) iron alloy tube blank having a completely annealed structure, and the alloying element of the iron alloy does not contain a strong nitride forming element such as Ti, Cr, Al, Zr, Nb, V, B, W, Mo, etc., and C content is 0.3wt. ⁇ 3 ⁇ 4, Si content is 0.30wt. ⁇ 3 ⁇ 4, Mn content is 0.60wt. ⁇ 3 ⁇ 4, P content is 0.025 wt.%, S The content is 0.025 wt. ⁇ 3 ⁇ 4, the Ni content is 0.25 wt. ⁇ 3 ⁇ 4, and the Cu content is 0.25 wt. ⁇ 3 ⁇ 4, that is, the total alloying element content thereof is 1.75 wt.%.
  • the hardness of the iron alloy tube blank is 130HV0.05/10, and the alloy composition can be changed to obtain different hardness.
  • the hardness range of 100-150HV0.05/10 can be selected; the metallographic structure of the fully annealed state is equiaxed crystal , grain size grade ⁇ 4 grades.
  • the drawing pass includes: 1 using the outer mold 5mm, the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4 mm, the core rod 4.0mm for the long core rod drawing; 3 using the outer mold 3.5mm , the core rod 3.19mm for long core rod drawing; the end of the drawing pass can be supplemented with annealing pass, for example, can be annealed at 550 ° C after the drawing is completed; 4 using the outer mold 2.3mm , the core rod 2.02mm for long core rod drawing; 5 using the outer mold 1.83mm, the core rod 1.60mm for long core rod drawing; the end of the drawing pass can be supplemented with annealing pass, for example, can be drawn After completion, the semi-small crucible is annealed at 430 ° C; 6 is taken with an outer mold of 1.62 mm, and the empty pull is the last pass in the drawing.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the 1.62mm outer mold is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63mm and the wall thickness is 0.125 ⁇ 0.005mm. In order to strictly control the quality of the outer surface of the pipe, a polishing allowance of 0.03mm is reserved. After mechanical polishing of 0.03mm, the material is the same as the material of the blank, the outer diameter is 1.60mm, the wall thickness is 0.110 ⁇ 0.005mm, and the hardness is about 200HV0.05/10. A ferroalloy stent preform having a deformed structure after cold working.
  • step 102 the stent preparation prepared above is laser-cut to obtain an initial coronary stent of OD3.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is obtained. About 13%.
  • the laser-cut iron alloy initial support was polished to the finished product size (the support rod width was 90 ⁇ m and the support wall thickness was 70 ⁇ m).
  • the radial strength was 92 kPa
  • the in vitro immersion corrosion rate was 1.0 mm/y
  • the overexpansion plasticity was 50. %.
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature was selected to be 380 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of 50-130 Pa and a pressure of about 650 V, and nitriding for 60 to 120 minutes.
  • the cross section of the stent rod penetrates, that is, except for the compound layer on the outermost surface, a single dispersion layer runs through the wall thickness direction of the entire stent rod.
  • the nitriding iron alloy stent after nitriding treatment was embedded with resin and ground and polished.
  • the iron alloy blank is drawn to obtain a lumen stent preform.
  • the billet is a 6x0.5 (outer diameter 6mm, wall thickness 0.5mm) ferroalloy tube with fully annealed structure, total alloying element content ⁇ 3 ⁇ .%, wherein carbon content ⁇ 0.45wt.%, alloying elements It does not contain strong nitride forming elements such as Ti, Cr, Al, Zr, Nb, V, B, W, Mo, and the like.
  • the hardness of the iron alloy tube blank is 100-150HV0.05/10
  • the alloy composition is different, the hardness will be slightly different; the fully annealed metallographic structure is equiaxed, and the grain size is ⁇ 4.
  • the drawing pass includes: 1 using the outer mold 5mm, the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4 mm, the core rod 4.0mm for the long core rod drawing; 3 using the outer mold 3.5mm , the core rod 3.21mm for long core rod drawing; the end of the drawing pass can be supplemented with annealing pass, for example, after the drawing is completed, the semi-small crucible is annealed at 530 ° C; 4 using the outer mold 3 . 015mm is carried out, and the drawing process is hollowed out as the last pass.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the 3.015mm outer mold is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 3.03mm and the wall thickness is 0.170mm. In order to strictly control the quality of the outer surface of the pipe, a polishing allowance of 0.03mm is reserved. After mechanical polishing of 0.03mm, the material is the same as the material of the blank, the outer diameter is 3.0mm, the wall thickness is 0.155mm ⁇ 0.005mm, and the hardness is 160HV0.05/10. Finished pure iron pipe with left and right grain size grade ⁇ 9 as the prefabricated part of the bracket.
  • step 102 the stent preform prepared above is selected for laser cutting to obtain an outer circumferential initial stent of OD8.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the surface of the metal grid Coverage is about 13%.
  • the laser-cut initial support was polished to the finished product size (the support rod width was 178 ⁇ m and the support wall thickness was 120 ⁇ m).
  • the radial strength was measured to be 65 kPa, the in vitro immersion corrosion rate was 1.0 mm/y, and the overexpansion plasticity was 50%. .
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature was selected to be 560 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of 50 to 130 Pa and a bias of about 600 V, and nitriding for 90 to 150 minutes.
  • the cross section of the stent rod penetrates, that is, the compound layer except the outermost surface, and the inside of the material is the structure shown in Fig. 2a.
  • the nitriding iron stent after nitriding treatment was embedded in resin and ground.
  • the iron alloy blank is drawn to obtain a lumen stent preform.
  • the billet is a 6 ⁇ 0.5 (outer diameter 6 mm, wall thickness 0.5 mm) iron alloy billet having a completely annealed structure, and the alloying elements do not contain strong nitride forming elements such as Ti, Cr, Al, Zr, Nb, V, B, W, Mo, etc., and C is 0.4 wt.%, Si is 0.4 wt. ⁇ 3 ⁇ 4, Mn is 0.65 wt. ⁇ 3 ⁇ 4, P is 0.04 wt. ⁇ 3 ⁇ 4, S is 0.04 wt. ⁇ 3 ⁇ 4, Ni It is 0.5 wt. ⁇ 3 ⁇ 4, Cu is 0.5 wt.
  • the hardness of the iron alloy tube blank is 140HV0.005/10, and the alloy composition can be changed to obtain different hardness. For example, a hardness range of 100-150HV0.05/10 can be selected; the fully annealed metallographic structure is equiaxed crystal , grain size grade ⁇ 4 grades.
  • the drawing pass includes: 1 using the outer mold 5mm, the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4 mm, the core rod 3.96mm for the long core rod drawing; 3 using the outer mold 4.22mm Carrying out the empty pull, the empty pull is the last pass of the pull.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient may be selected to be about 1.5.
  • the metal material has a certain elastic aftereffect, for example, after drawing through the outer mold of 4.22 mm, the outer diameter will have a certain rebound, and the measured outer diameter is 4.23 mm and the wall thickness is 0.235 mm.
  • a polishing margin of 0.03mm is reserved. After mechanical polishing of 0.03mm, the material of the blank is unchanged, the outer diameter is 4.2mm, the wall thickness is 0.220 ⁇ 0.005mm, and the hardness is about 250HV0.05/10.
  • a finished iron alloy tube having a deformed structure after cold working is used as a stent preform.
  • the prepared stent preform is laser-cut to obtain an outer circumferential initial stent of OD12.0x18 mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is obtained. About 13%.
  • the laser-cut iron alloy initial support was polished to the finished product size (the support rod width was 228 ⁇ m, the support wall thickness was 160 ⁇ m), and the radial strength was measured to be 60 kPa, the in vitro immersion corrosion rate was 1.0 mm/y, and the overexpansion plasticity was 35. ⁇ 3 ⁇ 4.
  • step 103 the laser-cut initial stent is roughly polished and washed, and then charged into a glow ion furnace for nitriding treatment.
  • the nitriding temperature is selected to be about 420 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of 200 to 300 Pa and a bias of about 600 V, and nitriding for 120 to 180 minutes.
  • the stent rod cross-section penetrates, that is, the structure shown in Fig. 2a except for the compound layer on the outermost surface.
  • the nitriding iron alloy stent after nitriding treatment was embedded with resin and ground and polished.
  • step 101 the iron alloy blank is drawn to obtain a lumen stent preform.
  • a ferroalloy tube with a fully annealed structure of 6x0.5 (outer diameter 6mm, wall thickness 0.5mm) is used.
  • the composition is: C is 0.10wt. ⁇ 3 ⁇ 4, Si is 0.17wt. ⁇ 3 ⁇ 4, Mn is 0.50 wt. ⁇ 3 ⁇ 4, P is 0.03 wt. ⁇ 3 ⁇ 4, S is 0.020 wt.%, Mo is 0.45 wt. ⁇ 3 ⁇ 4, Cr is 1.0 wt.%, Cu is 0.15 wt. ⁇ 3 ⁇ 4, Ni is 0.25 wt.
  • the total alloying element content is 2.67 wt.%
  • the strong nitride forming element (Mo and Cr) content is 1.45 wt. ⁇ 3 ⁇ 4.
  • the hardness of the iron alloy tube blank is 120HV0.05/10, and the alloy composition (including strong nitride forming elements) can be changed to obtain different hardnesses. For example, a hardness range of 100-150HV0.05/10 can be selected; The metallographic structure is equiaxed, and the grain size is ⁇ 4.
  • the drawing pass includes: 1 using the outer mold 5mm, the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4 mm, the core rod 4.0mm for the long core rod drawing; After the end, the annealing pass can be supplemented. For example, it can be annealed at 600 ° C for 1 hour after the drawing is completed. 3
  • the outer core is 3.5 mm and the mandrel 3.19 mm is used for the long core rod drawing. 4
  • the outer mold is 2.3 mm.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the outer mold of 1.62mm is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63mm and the wall thickness is 0.095mm. In order to strictly control the quality of the outer surface of the pipe, a polishing margin of 0.03mm is reserved. After mechanical polishing of 0.03mm, the material is the same as the blank, the outer diameter is 1.6mm, the wall thickness is 0.080 ⁇ 0.005mm, and the hardness is about 230HV0.05/10. A finished ferroalloy tube having a deformed structure after cold working is used as a stent preform.
  • step 102 the stent preform prepared above is laser-cut to obtain an initial coronary stent of OD3.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is obtained. About 13%.
  • the laser-cut iron alloy initial support was polished to the finished product size (the support rod width was 90 ⁇ m and the support wall thickness was 50 ⁇ m).
  • the radial strength was measured to be 70 kPa, the in vitro immersion corrosion rate was 1.0 mm/y, and the overexpansion plasticity was 50. %.
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature is selected to be about 380 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of 50 to 130 Pa and a bias of about 600 V, and nitriding for about 15 to 90 minutes.
  • the stent rod cross-section penetrates, that is, the structure shown in Fig. 2a except for the compound layer on the outermost surface.
  • the nitriding iron alloy stent after nitriding treatment was embedded with resin and ground.
  • step 101 the ferroalloy blank is drawn to obtain a lumen stent preform.
  • a ferroalloy billet having a fully annealed structure of 6x0.5 (outer diameter 6mm, wall thickness 0.5mm) is used.
  • the composition is: C is 0.018w t.%, Si is 0.03wt. ⁇ 3 ⁇ 4, and Mn is 0.10wt. ⁇ 3 ⁇ 4, P is 0.037wt. ⁇ 3 ⁇ 4, S is 0.011wt. ⁇ 3 ⁇ 4, Ti is 0.30wt.%, that is, the total alloying element content is 0.496wt. ⁇ 3 ⁇ 4, and the strong nitride element Ti content is 0.30wt. 3 ⁇ 4.
  • the hardness of the iron alloy tube blank is 100HV0.05/10, and the alloy composition (including strong nitride forming elements) can be changed to obtain different hardness. For example, a hardness range of 100-150HV0.05/10 can be selected;
  • the metallographic structure is equiaxed, and the grain size is ⁇ 4.
  • the use of the drawing passes includes: 1 using the outer mold 5mm, the core rod 4.4mm for the long core rod drawing; 2 using the outer mold 4.4mm, the core rod 4.0mm for the long core rod drawing; After the end of the pass, the annealing pass can be supplemented. For example, it can be annealed at 650 ° C for 1 hour after the drawing is completed.
  • the outer core is 3.5 mm and the mandrel 3.19 mm is used for long core rod drawing.
  • the outer mold is used. 2.3mm, mandrel 2.02mm for long core rod drawing; 5 using outer mold 1.8 3mm, mandrel 1.60mm for long core rod drawing; 6 using outer mold 1.62mm for empty pulling, after the end of the empty pull It can be supplemented with an annealing pass, for example, it can be annealed at 600 ° C for 1 hour after the completion of the air pulling.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the outer mold of 1.62mm is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63mm and the wall thickness is 0.095mm. In order to strictly control the outer surface quality of the pipe, a polishing margin of 0.03mm is reserved. After mechanical polishing of 0.03mm, the material is the same as the blank, the outer diameter is 1.6mm, the wall thickness is 0.080 ⁇ 0.005mm, and the hardness is about 120HV0.05/10. Finished iron alloy tubes with a grain size class ⁇ 9 are used as bracket preforms.
  • step 102 the stent preform prepared above is laser-cut to obtain an initial coronary stent of OD3.0xl8mm size, the cutting precision is ⁇ 5 micrometers, the stent is expanded to a diameter of 3.0 mm, and the metal mesh coverage of the surface is About 13%.
  • the laser-cut iron alloy initial support was polished to the finished product size (the support rod width was 90 ⁇ m and the support wall thickness was 50 ⁇ m).
  • the radial strength was 37 kPa
  • the in vitro immersion corrosion rate was 1.0 mm/y
  • the overexpansion plasticity was 50. %.
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature is selected to be about 530 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of 200 to 300 Pa and a bias of about 700 V, and a nitriding time of about 90 to 150 minutes.
  • the stent rod cross-section penetrates, that is, the structure shown in Fig. 2a except for the compound layer on the outermost surface.
  • the nitriding iron alloy stent after nitriding treatment was embedded with resin and ground and polished.
  • step 101 the blank is drawn to obtain a lumen stent preform.
  • the number of drawing passes that can be used includes: 1 using a male mold of 5 mm and a core rod of 4.4 mm for long core rod drawing; 2 using an outer mold of 4.4 mm and a mandrel of 4.0 mm for long core rod drawing; After the end of the extraction, the annealing pass may be supplemented, for example, the semi-small crucible may be annealed at 650 ° C after the drawing is completed.
  • the elongation coefficient of all the drawing passes should not exceed 2.0, and the elongation coefficient can be selected to be about 1.5. Since the metal material has a certain elastic aftereffect, after the 1.62mm outer mold is drawn, the outer diameter will have a certain rebound. After the actual measurement, the outer diameter is 1.63mm and the wall thickness is 0.095mm. In order to strictly control the quality of the outer surface of the pipe, a polishing allowance of 0.03 mm is reserved, and after mechanical polishing of 0.03 mm, the composition is unchanged (all impurity element content ⁇ 0.5 wt. ⁇ 3 ⁇ 4,
  • the finished pure iron pipe with carbon content ⁇ 0.022 ⁇ 3 ⁇ 4), outer diameter 1.60mm, wall thickness 0.080 ⁇ 0.005mm, hardness 90HV0.05/10, and grain size class 6 is used as the bracket preform.
  • step 102 the stent preform prepared above is subjected to laser cutting to obtain an initial coronary stent of OD3.0 ⁇ l8 mm, and the cutting precision is ⁇ 5 ⁇ m.
  • the laser-cut initial stent was polished to the finished product size (the holder rod width was 90 ⁇ m and the stent wall thickness was 50 ⁇ m).
  • the radial strength was measured to be 30 kPa, the in vitro immersion corrosion rate was 0.9 mm/y, and the overexpansion plasticity was 50 ⁇ 3 ⁇ 4.
  • step 103 after the laser-cut initial stent is roughly polished and cleaned, it is loaded into a glow ion furnace for nitriding treatment.
  • the nitriding temperature is selected to be about 320 ° C, a nitrogen to hydrogen flow ratio of 1:3, a pressure of about 380-500 Pa and a pressure of about 700 V, and nitriding for 90 to 150 minutes.
  • the length of the nitriding zone is determined by the size of the medical device and its components (such as wall thickness), the depth of penetration to be controlled, and the nitriding temperature.
  • the nitriding crucible given in this embodiment is the size of the iron tube supported by the embodiment, and the cross section of the stent rod penetrates (except for the compound layer of the outermost surface, the single dispersion layer runs through the wall thickness direction of the entire stent rod) In the daytime.
  • the nitriding lumen stent after nitriding treatment was embedded with resin and ground and polished. The results of metallographic observation and hardness test showed that the material still retained the deformed structure and the hardness increased to 120HV0.05/10.
  • nitriding iron bracket was polished to The size of the product (the support rod width is 90 microns, the support wall thickness is 50 microns), the radial strength is 37 kPa, the over-expansion plasticity is maintained at 50%, and the in vitro immersion corrosion rate is still 0.9 mm/y.
  • the empty passage in the drawing is continued with the annealing pass, and the hardness is only about 90 HV0.05/10, and the grain size is 6
  • the stage lumen stent preform has a hardness that is not within the range of 160 to 250 HV 0.05/10 required for the lumen stent prepared by the present invention, and has a grain size grade of at least 9 grades as required by the present invention.
  • the modification effect of the tube stent preform by ion nitriding is not obvious.
  • the radial strength is only increased from 30 kPa to 37 kPa, and the hardness is only increased from 90 HV0.05/10 to 120 HV0.05/ 10,
  • the in vitro immersion corrosion rate and over-expansion plasticity remain unchanged, and the above radial strength cannot meet the requirements of the lumen stent.
  • the drawing process is changed, and the annealing process is not performed after the empty drawing, and the drawing process is retained.
  • the deformed structure formed in the middle can be obtained by drawing a tubular stent preform having a hardness of about 250 HV0.05/10 and having a deformed structure after cold working. After ion nitriding, the radial strength can be increased from 90 kPa to 110 kPa.
  • the hardness is increased to 300HV0.05/10, the in vitro immersion corrosion rate is doubled, the over-expansion plasticity is maintained unchanged, and still reaches 35%, which satisfies the requirements of conventional lumen support for radial strength and plasticity.
  • the present invention can draw a billet of a pure iron or an iron alloy containing no strong nitride forming element into a hardness of 160 to 250 HV 0.05/10 by a drawing process, and the microstructure is An iron-based lumen support preform having a grain size of ⁇ 9 or a deformed structure after cold working; or a strong nitride-forming element having a microstructure of grain size ⁇ 9 or a deformed structure after cold working Ferroalloy lumen bracket preforms.
  • the preform can realize ion nitriding in a large temperature range (320 ⁇ 560 °C), and the hardness of the lumen stent thus obtained is 250-350 HV0.05/10, over-expanding plasticity 20-50%, and for wall thickness in the range of 40-150 microns, metal coverage of 11 ⁇ 16% OD2 ⁇ 5.0mm coronary stent, radial strength is 80-260kPa; for wall thickness 90-200 microns range
  • the outer bracket with internal and metal coverage of 7 ⁇ 11 ⁇ 3 ⁇ 4, OD5.0 -14mm, the radial strength can reach 50-130kPa, which meets the mechanical performance requirements of conventional lumen brackets.
  • a low temperature (320 to 420 ° C) iontophoresis is prepared by a drawing process with a hardness of 200 to 250 HV 0.05 /10 and a microstructure of the denatured structure after cold working.
  • Nitrogen lumen stent preforms to reduce side effects of recovery and/or recrystallization due to excessive temperature setting during nitriding Influence, the hardness of the lumen stent thus obtained can reach 300-350
  • HV0.05/10 over-expansion plasticity is 20-40%, and for wall thickness in the range of 40-150 microns, metal coverage of 11 ⁇ 16 ⁇ 3 ⁇ 4 OD2 ⁇ 5.0mm coronary stent, radial strength is 80- 260kPa; For peripheral stents with a wall thickness of 90-200 microns, metal coverage of 7-11%, OD5.0-14mm, the radial strength can reach 85kPa, or even higher, still meet the mechanical performance requirements of conventional lumen stents. .

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Abstract

提供了利用离子渗氮技术的管腔支架预制件及其制备方法，以及使用该预制件制备管腔支架的方法和依照该方法获得的管腔支架。该预制件由纯铁或不含强氮化合物的铁合金制成，硬度为160-250HV0.05/10，显微结构为晶粒度等级≥9级或者为冷加工后的变形组织。或者，该预制件为含强氮化合物的铁合金，显微结构为晶粒度等级≥9级或者为冷加工后的变形组织。该管腔支架预制件满足常规支架对径向强度和塑性的要求，从而使离子渗氮适用于商业制备管腔支架。

Description

说明书 发明名称:管腔支架与其预制件、 管腔支架与其预制件的制备方法 技术领域
[0001] 本发明涉及介入医疗器械领域， 尤其涉及一种管腔支架和管腔支架预制件、 及 各自的制备方法。
背景技术
[0002] 当前， 植入医疗器械通常采用金属及其合金、 陶瓷、 聚合物和相关复合材料制 成。 其中， 金属材料基植入医疗器械以其优越的力学性能， 如高强度、 高韧性 等， 尤为受人青睐。
[0003] 铁作为人体内的重要元素， 参与到诸多生物化学过程中， 如氧的搬运。 Peuster M等采用激光雕刻方法制成的、 与临床使用的金属支架形状相似的易腐蚀性纯铁 支架， 植入到 16只新西兰兔的降主动脉处。 此动物实验结果表明， 在 6-18个月内 没有血栓并发症， 亦无不良事件发生， 病理检査证实局部血管壁无炎症反应， 平滑肌细胞无明显增殖， 初步说明可降解铁支架安全可靠， 具有良好的应用前 景。 但该研究同吋发现， 纯铁支架在体内环境下的腐蚀速率较慢。 另外， 有报 道称， 铁基支架的径向强度和纵向抗压强度与不锈钢支架和钴铬支架接近， 但 纯铁支架的力学性能较低。
[0004] 为提高铁基支架的力学性能， 当前研究主要集中于研制新型铁合金， 寻找新的 铁材料制备方法， 或者在纯铁材料表面制备铁合金层以及对纯铁材料进行改性 等。 我们发现， 通过对纯铁 /铁合金进行渗氮， 一方面可提高支架的强度 （用硬 度或径向强度表征） 而减少材料用量， 另一方面可加快纯铁 /铁合金的腐蚀速度 ， 从而缩短支架吸收周期。 并且， 渗氮在提高纯铁 /铁合金强度和硬度的同吋， 不会显著降低材料的塑性， 采用渗氮后铁合金制作的植入医疗器械部件能经受 使用吋的扩张变形， 不易发生断裂。
[0005] 现有渗氮方法包括气体渗氮、 盐浴渗氮和离子渗氮。 其中， 气体渗氮和盐浴渗 氮对支架原材料的显微组织和原始硬度无特殊要求， 但气体渗氮的改性处理吋 间过长， 生产效率很低， 难于在实际生产中规模使用。 盐浴渗氮需采用大量剧 毒的氰化物熔融盐进行渗氮处理， 对于高风险的第三类植入医疗器械产品 （如 可吸收血管支架） 而言， 临床应用风险极高。 同吋， 气体渗氮和盐浴渗氮处理 后的样品表面的化合物层通常很厚 （≥0.01mm) ， 不利于薄壁 （壁厚≤0.12mm) 的、 具有复杂镂空状设计的医疗器械或其部件的后续抛光及精细结构的设计。 离子渗氮的渗氮效率高， 其采用氮气和氢气作为处理气体， 不引入其它任何有 毒的物质， 渗氮后表面的化合物层 （俗称白亮层， 为氮的化合物层） 通常较薄 且不连续， 通过控制离子渗氮的工艺参数能做到处理后没有化合物层， 大大便 利了后续的抛光处理， 给后续医疗器械精细结构的设计留下了较大的余地。 但 是并非所有的铁基材料通过渗氮处理后都适用于制备管腔支架， 对于常规管腔 支架而言， 需同吋兼顾径向强度和塑性的要求， 例如， 对于冠脉支架， 通常需 要同吋满足径向强度至少为 80kPa， 过扩塑性 （即塑性） 至少为 20%， 对于外周 支架， 需要同吋满足径向强度至少为 50kPa， 过扩塑性 （即塑性） 至少为 20%。 因此有必要提供一种管腔支架预制件， 其不仅利于渗氮， 且渗氮后以之制得的 管腔支架可同吋满足径向强度和塑性的要求。
技术问题
[0007] 本发明要解决的技术问题在于， 针对现有技术的缺陷， 提供一种管腔支架预制 件和管腔支架、 以及各自的制备方法。 问题的解决方案
技术解决方案
[0008] 本发明提供了一种管腔支架预制件， 所述管腔支架预制件为纯铁或铁合金， 所 述纯铁的全部杂质元素含量≤0.5wt.%， 所述铁合金的全部合金元素含量≤3wt.% ， 且所述铁合金不含强氮化物形成元素， 所述管腔支架预制件的硬度为 160〜25 0HV0.05/10, 显微结构为晶粒度等级≥9或者为冷加工后的变形组织。
[0009] 在本发明的管腔支架预制件中， 所述管腔支架预制件的硬度为 200〜250HV0.05 /10， 显微结构为冷加工后的变形组织。
[0010] 在本发明的管腔支架预制件中， 所述纯铁的全部杂质元素中的碳含量≤0.022% ； 所述铁合金的全部合金元素的碳含量≤0.45\^.%。
[0011] 在本发明的管腔支架预制件中， 所述管腔支架预制件的外径为 1.2〜4.2mm; 壁 厚为 0.08〜0.24mm。
[0012] 本发明提供了一种管腔支架预制件， 所述管腔支架预制件为铁合金， 且所述铁 合金中含有至少一种强氮化物形成元素， 所述铁合金的全部合金元素含量≤3wt.
% , 所述强氮化物形成元素的总含量≥0.05wt.%; 所述管腔支架预制件的显微结 构为晶粒度等级≥9或者为冷加工后的变形组织。
[0013] 在本发明的管腔支架预制件中， 所述强氮化物形成元素包括 Ti、 Cr、 Al、 Zr、
Nb、 V、 B、 W、 Mo中的至少一种。
[0014] 在本发明的管腔支架预制件中， 所述铁合金的全部合金元素中碳含量≤0.45\^.
。
[0015] 在本发明的管腔支架预制件中， 所述管腔支架预制件的外径为 1.2〜4.2mm; 壁 厚为 0.08〜0.24mm。
[0016] 本发明提供了一种管腔支架预制件的制备方法， 包括将坯料拉拔成上述的管腔 支架预制件。
[0017] 在本发明的管腔支架预制件的制备方法中， 所述坯料为全部杂质元素含量≤0.5 \^.%的纯铁； 或为全部合金元素含量≤3\^.%、 且不含强氮化物形成元素的铁合 金； 或为全部合金元素含量≤3\^.%、 且强氮化物形成元素的总含量≥0.05\^.%的 铁合金。
[0018] 在本发明的管腔支架预制件的制备方法中， 所述纯铁的全部杂质元素中的碳含 量≤0.022%； 所述铁合金的全部合金元素的碳含量≤0.45wt.<¾。
[0019] 根据权利要求 10所述的管腔支架预制件的制备方法， 所述强氮化物形成元素包 括 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo中的至少一种。
[0020] 在本发明的管腔支架预制件的制备方法中， 所述制备方法还包括在拉拔所述坯 料前将所述坯料处理为完全退火态组织或不完全退火态组织。
[0021] 在本发明的管腔支架预制件的制备方法中， 所述拉拔的拉拔道次包括至少一次 带芯棒拉拔和一次空拉。
[0022] 在本发明的管腔支架预制件的制备方法中， 当所述坯料为前述纯铁或前述不含 强氮化物形成元素的铁合金吋， 所述空拉为所述拉拔中的最后一个道次； 当所 述坯料为前述含强氮化物形成元素的铁合金吋， 所述空拉之后还包括退火道次 [0023] 在本发明的管腔支架预制件的制备方法中， 所述带芯棒拉拔中的拉拔系数为 1.2
〜2.5。
[0024] 在本发明的管腔支架预制件的制备方法中， 所述带芯棒拉拔中的拉拔系数为 1.5
〜2.0。
[0025] 在本发明的管腔支架预制件的制备方法中 : 所述空拉中的拉拔系数约为 1或略 大于 1。
[0026] 在本发明的管腔支架预制件的制备方法中 : 所述带芯棒拉拔为带长芯棒拉拔。
[0027] 在本发明的管腔支架预制件的制备方法中 : 在所述坯料的再结晶温度下实施所 述拉拔道次。
[0028] 在本发明的管腔支架预制件的制备方法中 : 所述拉拔道次之间还辅以退火道次
[0029] 在本发明的管腔支架预制件的制备方法中 : 当坯料的硬度为 200〜240HV0.05/1 0吋， 在该带芯棒拉拔道次前辅以退火道次， 退火温度为 400〜650°C。
[0030] 在本发明的管腔支架预制件的制备方法中 : 当欲制得硬度小于 250HV0.05/10的 管腔支架预制件吋， 所述拉拔道次之间还辅以退火道次， 退火温度为 400〜650°C
[0031] 本发明提供了一种管腔支架的制备方法， 包括将坯料拉拔成上述的管腔支架预 制件， 所述坯料为全部杂质元素含量≤0.5\^.%的纯铁， 或为全部合金元素含量≤ 3\^.%且不含强氮化物形成元素的铁合金， 或为全部合金元素含量≤3\^.%、 且强 氮化物形成元素的总含量≥0.05wt.%的铁合金。
[0032] 在本发明的管腔支架的制备方法中， 所述制备方法还包括将所述管腔支架预制 件制成初始支架， 将所述初始支架升温至 320〜560°C后， 在 10〜500Pa气压和 500 〜700V偏压下， 对所述初始支架离子渗氮 15〜180分钟。
[0033] 在本发明的管腔支架的制备方法中， 当所述管腔支架预制件的硬度为 200〜250 HV0.05/10、 显微结构为冷加工后的变形组织吋， 所述制备方法还包括将所述管 腔支架预制件制成初始支架， 将所述初始支架升温至 320〜420°C后， 在 50〜500 Pa气压和 500〜700V偏压下， 对所述初始支架离子渗氮 30〜180分钟。 [0034] 在本发明的管腔支架的制备方法中， 所述离子渗氮中气源的氮氢流量比为 1:1 〜1:3。
[0035] 在本发明的管腔支架的制备方法中， 所述制备方法还包括在离子渗氮后进行抛 光制得所述管腔支架。
[0036] 本发明提供了一种管腔支架， 所述管腔支架采用上述的管腔支架的制备方法制 得， 硬度为 250〜350HV0.05/10， 显微结构为晶粒度等级≥9级或者为冷加工后的 变形组织。
[0037] 在本发明的管腔支架中， 当管腔支架预制件的硬度为 200〜250HV0.05/10、 显 微结构为冷加工后的变形组织吋， 所述管腔支架的硬度为 300〜350HV0.05/10， 显微结构为冷加工后的变形组织。
[0038] 在本发明的管腔支架中， 所述管腔支架的径向强度为 80-260kPa， 过扩塑性为 2
0〜50%； 或者径向强度为 50〜130kPa， 过扩塑性为 20〜50%。
[0039] 在本发明的管腔支架中， 所述管腔支架的径向强度为 80-260kPa， 过扩塑性为 2
0〜40%； 或者径向强度为 50〜130kPa， 过扩塑性为 20〜40%。
[0040] 在本发明的管腔支架中， 所述管腔支架的体外浸泡腐蚀速率比初始支架的体外 浸泡腐蚀速率加快了 0.25〜1.5倍。
[0041] 在本发明的管腔支架中， 所述管腔支架的体外浸泡腐蚀速率比初始支架的体外 浸泡腐蚀速率加快了 1〜1.5倍。
[0042] 在本发明的管腔支架中， 所述管腔支架的金属覆盖率为 11〜16%或者为 7〜11%
[0043] 在本发明的管腔支架中， 所述管腔支架包括固溶体和铁氮化合物； 或者所述管 腔支架包括固溶体、 铁氮化合物和强氮化物形成元素与氮的化合物。
[0044] 在本发明的管腔支架中， 所述管腔支架从表面向内依次包括第一层状结构和第 二层状结构； 其中， 所述第一层状结构包括固溶体和铁氮化合物， 第二层状结 构包括固溶体； 或者所述第一层状结构包括固溶体、 铁氮化合物、 以及强氮化 物形成元素与氮的化合物， 所述第二层状结构包括固溶体。
[0045] 在本发明的管腔支架中， 所述管腔支架从表面向内依次包括第一层状结构、 第 二层状结构以及第三层状结构； 其中， 所述第一层状结构包括固溶体和铁氮化 合物， 所述第二层状结构包括固溶体， 以及所述第三层状结构为铁芯层； 或者 所述第一层状结构包括固溶体、 铁氮化合物、 以及强氮化物形成元素与氮组成 的化合物， 所述第二层状结构包括固溶体， 以及所述第三层状结构为铁芯层。 发明的有益效果
有益效果
[0046] 本发明解决其技术问题所采用的技术方案是： 采用硬度为 160〜250HV0.05/10
、 显微结构为晶粒度等级≥9或者为冷加工后的变形组织的铁基管腔支架预制件 ； 或者采用显微结构为晶粒度等级≥9或者为冷加工后的变形组织的、 含强氮化 物形成元素的铁合金管腔支架预制件， 上述两种支架预制件均适合进行离子渗 氮， 且离子渗氮过程中的适用温区范围较大； 同吋由此制备获得的管腔支架的 径向强度和塑性满足管腔支架类产品的要求， 从而使离子渗氮这种工艺能适用 于在商用上制备管腔支架。
对附图的简要说明
附图说明
[0047] 下面将结合附图及实施例对本发明作进一步说明， 附图中：
[0048] 图 1是本发明实施例的管腔支架的制备方法的流程图；
[0049] 图 2a-2c为本发明的实施例的管腔支架的成分结构示意图；
[0050] 图 2为 160HV0.05/10硬度的 OD1.6mm的纯铁管材的横截面金相图；
[0051] 图 3为图 2中纯铁管材对应的纵截面金相图；
[0052] 图 4为 160HV0.05/10硬度的 OD4.2mm纯铁管材的横截面金相图；
[0053] 图 5为图 4中纯铁管材对应的纵截面金相图；
[0054] 图 6示出了 OD为 1.6mm的具有冷变形组织的管腔支架预制件的横截面金相图； [0055] 图 7示出了 OD为 1.6mm的具有冷变形组织的管腔支架预制件在扫描电镜下的横 截面形貌图；
[0056] 图 8示出了 OD为 1.6mm的具有冷变形组织的管腔支架预制件在扫描电镜下的纵 截面形貌。
实施该发明的最佳实施例 本发明的最佳实施方式
[0057] 本发明提供利于渗氮的管腔支架预制件及其制备方法， 以及使用该预制件制备 满足常规管腔支架的力学性能要求的管腔支架的方法和依该制备方法获得的管 腔支架。 该力学性能对于冠脉支架而言， 在 OD (外径长） 为 2.0〜5.0mm的范围 内， 要求该冠脉支架径向强度不低于 80kPa、 过扩塑性不低于 20%; 对于外周支 架， 在 OD为 5.0〜14.0mm的范围内， 要求该外周支架径向强度不低于 50kPa、 过 扩塑性不低于 20%。 其中， 20%的过扩塑性指的是临床上将管腔支架最大扩张到 外径超过支架名义直径 20%吋， 支架杆不发生幵裂或断裂。 为了对本发明的技术 特征、 目的和效果有更加清楚的理解， 现对照附图详细说明本发明的具体实施 方式。
[0058] 参见图 1， 本发明的管腔支架的制备方法 100包括： 步骤 101， 对纯铁或铁合金 坯料进行拉拔获得管腔支架预制件； 步骤 102， 将管腔支架预制件制成初始支架 ； 步骤 103， 对初始支架进行离子渗氮获得管腔支架。 上述管腔支架包括但不限 于血管支架、 食管支架、 以及气管支架。
[0059] 步骤 101中， 所述坯料为纯铁或铁合金 （或称为铁基合金） ； 其中， 纯铁的全 部杂质元素含量≤0.5\^.%； 铁合金的全部合金元素含量≤3wt.%。 作为本发明的 一种实施方式， 纯铁的全部杂质元素中的碳含量可以小于或等于 0.022%， 或者 铁合金的全部合金元素中碳含量≤0.45wt.%。 铁合金包括含强氮化物形成元素的 铁合金和不含强氮化物形成元素的铁合金， 含强氮化物形成元素的铁合金的全 部合金元素中可包含一种或多种强氮化物形成元素， 强氮化物形成元素的总含 量≥0.05\¥1.<¾， 上述强氮化物形成元素包括但不限于 Ti、 Cr、 Al、 Zr、 Nb、 V、 B
[0060] 拉拔是指在管坯材料的再结晶温度下， 例如常温下， 用外力作用于被拉管材的 前端， 将管材从小于管材直径的模孔中拉出， 以获得较小直径管材。 本发明中 通过对薄壁的管状坯料 （以下可称为管坯） 进行拉拔以制得管腔支架预制件， 来实现对管腔支架预制件的显微组织和硬度的控制。 实际中可在本发明的教导 下， 根据欲制得的管腔支架的径向尺寸， 并结合拉拔过程中计划采用的拉拔工 艺参数， 例如拉拔道次的数量和 /或拉拔系数等， 选择适合的模具， 此处不再一 一列举。
[0061] 在进行拉拔前可包括将坯料处理成不完全退火态组织， 或者完全退火态组织 ( 等轴晶组织） 的步骤。 一般可将坯料在 570〜700°C的退火温度下保温 0.5〜2小吋 实现完全退火， 使坯料形成完全退火态组织； 将坯料在较低的退火温度下 （如 4 00〜550°C) 进行较短吋间 （如 0.5〜lh) 的保温处理， 可得到不完全退火态组织 。 完全退火态组织和不完全退火态组织， 均可采用相同或近似的拉拔工艺 （例 如相同的拉拔系数和拉拔道次） 进行拉拔。 例如， 在具体实施中， 如果是完全 退火态组织的坯料， 其纯铁硬度可选择 90HV0.05/10左右， 铁合金硬度可选择 10 0-150HV0.05/10; 显微组织均为等轴晶， 晶粒度≥4级； 相应可选的尺寸范围为 壁厚 0.16~3mm， 外径 3.5~20mm。 如果是不完全退火态组织的坯料， 其硬度比相 应成分的完全退火态组织的坯料的硬度要高， 例如， 纯铁的硬度一般大于 90HV0 .05/10， 可以是 100或 120HV0.05/10, 甚至更高， 铁合金硬度至少大于 110HV0.05 /10； 显微组织均为变形组织； 相应可选的坯料尺寸范围为壁厚可选为 0.13~3mm ， 外径 2.3~20mm。 应当知晓， 此处列举的坯料特性仅用作举例， 并不是对本发 明的限制， 本领域的普通技术人员， 基于本发明的教导， 可根据具体需要选择 任意适合的坯料。
[0062] 拉拔的拉拔道次包括至少一次带芯棒拉拔、 以及带芯棒拉拔之后的至少一次空 拉， 带芯棒拉拔可以是长芯棒拉拔。 各带芯棒拉拔过程中的拉拔系数 μ=1.2〜2.5 ， 本发明的一实施方式中选为 1.5〜2.0， 其中， =Q0/Ql， Q0为拉拔前原始管材 的横断面积， Q1为拉拔后管材预制件的横断面积。 该拉拔系数当采用管材的长 度比进行表征吋也称之为延伸系数， 应当知晓， 对于固体件， 拉拔前后体积不 变， 因此横断面积比与长度比成反比。
[0063] 带芯棒拉拔后， 芯棒与管坯粘连在一起， 需要脱模， 使得芯棒与管坯分离。 脱 模包括挤压坯料使得管坯发生塑性变形， 芯棒相对硬度较高， 不会发生变形， 将与坯料分离。 由于坯料经带芯棒拉拔后发生了塑性变形， 其表面状态和外径 都发生了变化， 需至少一个空拉以定径 （精确固定外径尺寸） 和消除脱模后管 材表面的变形痕迹。 通常， 空拉过程中采用的拉拔系数约为 1.0， 或略大于 1.0， 例如可以是 1.01〜1.05， 通过空拉使管坯外径变小， 壁厚增大。 当坯料为前述纯 铁或前述不含强氮化物形成元素的铁合金吋， 空拉是拉拔过程中的最后一个道 次， 即空拉结束后， 该拉拔整个过程结束； 当坯料为包含强氮化物形成元素的 铁合金吋， 还可以在空拉后再退火， 将坯料完全或不完全退火， 退火温度和吋 间与材料相关， 例如， 可在 570〜700°C的退火温度下保温 0.5〜2小吋实现完全退 火； 可在较低的退火温度下 （如 400〜550°C) 进行较短吋间 （如 0.5〜lh) 的保 温处理， 实现不完全退火。
[0064] 例如， 可以采用 3〜5道次的长芯棒拉拔和最后 1道次的空拉， 还可在拉拔道次 期间辅以 0〜5次退火道次。 若需获得硬度在 250HV0.05/10或以上的管腔支架预 制件， 拉拔工序中不需要设置退火道次； 若需获得硬度小于 250HV0.05/10的管 腔支架预制件， 拉拔工序中可增加若干退火道次， 退火的吋机取决于中间拉拔 道次的管材硬度， 当中间道次的管材硬度在 200-240HV0.05/10之间吋， 可以考虑 设置退火道次， 退火温度可选择 400〜650°C。
[0065] 通过拉拔制得的管腔支架预制件的外径长 （OD) 为 1.2〜4.2mm， 壁厚为 0.08〜 0.24mm; 力学性能方面， 硬度为 160〜250HV0.05/10 (在 0.05千克力的试验力下 保持 10s测得的维氏硬度值） ； 显微结构或显微组织方面， 管腔支架预制件的晶 粒度等级≥9或者具有冷加工后的变形组织 （可简称为冷变形组织） 。 在其中的 一实施方式中， 管腔支架预制件的硬度为 200〜250HV0.05/10， 显微结构为冷加 工后的变形组织； 管腔支架预制件的材质与坯料的材质相同， 例如， 当坯料为 含强氮化物形成元素的铁合金吋， 拉拔所制得的管腔支架预制件也同样保持为 含强氮化物形成元素的铁合金。 其中， 硬度 （维氏硬度） 根据 GB/T 4340.1-2009 中测试方法进行， 采用 50gf的载荷， 保压 10s， 根据压痕对角线长度进行计算， 得出该材料的维氏硬度值。
[0066] 管腔支架预制件的硬度越高越有利于渗氮， 且渗氮可显著提高材料硬度。 然而 ， 高硬度会导致冷加工硬化牺牲材料的塑性， 进而造成所制得的管腔支架的柔 顺性和抗断裂性随着冷加工硬化的程度增大而降低； 并且硬度越高的管腔支架 预制件在后续渗氮过程中被回复和退火的可能性越大、 程度越高。 本发明中制 备的硬度介于 160〜250HV0.05/10的管腔支架预制件， 结合其显微结构晶粒度等 级≥9或者具有冷加工后的变形组织， 不仅有利于后续渗氮过程的实施， 且能同 吋兼顾管腔支架对径向强度 （硬度） 和塑性的要求。 另一方面， 本发明还制备 了材质为含强氮化物形成元素的铁合金的管腔支架预制件， 该强氮化物形成元 素更易于与氮元素结合形成化合物， 结合其显微结构晶粒度等级≥9或者具有冷 加工后的变形组织， 同样利于后续渗氮过程的实施， 且能同吋兼顾管腔支架对 径向强度 （硬度） 和塑性的要求， 后续将对此进行详细描述
[0067] 显微结构可按以下方式测试， 例如， 先截取一段待测样品， 如管腔支架预制件 或管腔支架， 使用树脂浇注固化样品使样品镶嵌于树脂中。 砂纸打磨、 丝绒抛 光布抛光去除树脂样品横截面上的划痕。 然后使用 3~4%的硝酸酒精侵蚀大致为 5 〜40s。 使用 500倍及以上的高倍显微镜观察样品的金相组织。 若发现金相组织为 等轴晶， 则根据国标 GB/T 6394-2002中的直线截点法， 对材料的晶粒度进行评估 ， 若金相为变形组织则不需进行晶粒度计算。
[0068] 步骤 102， 将步骤 101中制得的管腔支架预制件制成初始支架。 例如， 可按照预 设的支架花纹对管腔支架预制件进行切割， 随后进行清洗， 制成初始支架。
[0069] 步骤 103， 对步骤 102中制得初始支架进行离子渗氮获得管腔支架。 在本发明的 一实施方式中， 可在偏压 500〜700V、 总气压 10〜500pa、 气源的氮氢流量比 1:1 〜1:5的条件下对 320〜560° (也可称之为渗氮温度） 的上述初始支架进行 15〜18 Omins的离子渗氮。 当然， 本领域的技术人员还可选择其它合适的渗氮温度、 偏 压、 总气压、 渗氮吋间和 /或氮氢流量比。
[0070] 上述所制得的管腔支架的硬度为 250〜350HV0.05/10; 显微结构与管腔支架预 制件相比维持不变， 仍然为晶粒度等级≥9级或者维持初始的冷变形组织； 管腔 支架的径向强度为初始支架径向强度的 1.1〜2倍； 体外腐蚀速度相比管腔支架预 制件加快 0.25〜1.5倍， 过扩塑性至少为 20%， 通常可达 30-50%， 满足常规管腔 支架过扩塑性至少为 20%的要求。 且对于壁厚在 40〜150微米范围内， 金属覆盖 率为 11~16%、 OD为 2〜5.0mm的冠脉支架， 其径向强度至少为 80kPa， 通常可达 80〜260kPa， 满足冠脉支架径向强度至少为 80kPa的要求； 对于壁厚在 90〜200 微米范围内、 金属覆盖率为 7~11%、 OD为 5.0-14mm的外周支架， 径向强度至少 为 50kPa， 通常能达到 85-130kPa， 满足常规外周支架径向强度需至少为 50kPa的 要求， 综上， 采用本发明所提供的管腔支架预制件渗氮制得的管腔支架符合常 规管腔支架的力学性能要求。 应当知晓， 此处列举的参数仅用作举例说明， 并 不是对本发明的限制， 任何基于本发明的教导所获得管腔支架预制件及管腔支 架、 所采用的两者的制备方法均在本发明的保护范围之内。
[0071] 本发明提供的管腔支架的内部结构可根据实际预定使用需求进行调节， 具体可 通过控制渗氮吋间和渗氮温度等以控制渗氮深度， 从而制备不同内部结构的管 腔支架。 图 2a〜2c作为举例， 示出了管腔支架内部的成分结构示意图， 图中的方 形示意管腔支架某部件的横断面， 方形仅为示例， 当然可以为圆形或其它切割 形状； 图中的箭头示意离子渗氮方向， 从表面各处均匀向内渗透。 参见图 2a， 管 腔支架内部的成分结构为单一均匀结构 1， 该结构 1包括固溶体和铁氮化合物， 铁氮化合物弥散分布于固溶体中， 该固溶体为含氮的铁固溶体， 铁氮化合物包 括但不限于 Fe 4N、 Fe 2— 3N。 或者， 当管腔支架预制件为含强氮化物形成元素的 铁合金吋， 上述单一均匀结构 1包括固溶体、 铁氮化合物、 以及强氮化物形成元 素与氮的化合物， 铁氮化合物、 以及强氮化物形成元素与氮的化合物弥散分布 于固溶体中， 铁氮化合物包括但不限于 Fe 4N、 Fe 2— 3N。
[0072] 参见图 2b， 从管腔支架的表面向内， 即沿箭头所示的渗透方向， 管腔支架内部 的成分结构依次包括第一层状结构 1和第二层状结构 2， 其中第一层状结构 1包含 固溶体和铁氮化合物， 铁氮化合物弥散分布于固溶体中； 第二层状结构 2包含固 溶体层， 固溶体为含氮的铁固溶体。 或者， 当管腔支架预制件为含强氮化物形 成元素的铁合金吋， 不同之处在于第一层状结构 1包括固溶体、 铁氮化合物、 以 及强氮化物形成元素与氮的化合物， 铁氮化合物、 以及强氮化物形成元素与氮 的化合物弥散分布于固溶体中。
[0073] 参见图 2c， 从管腔支架的表面向内， 即沿箭头所示的渗透方向， 管腔支架内部 的成分结构依次包括第一层状结构 1、 第二层状结构 2和第三层状结构 3， 其中第 一层状结构 1包含固溶体和铁氮化合物， 铁氮化合物弥散分布于固溶体中； 第二 层状结构 2包含固溶体； 第三层状结构 3为铁芯层， 固溶体为含氮的铁固溶体， 铁芯层 3中为原始的铁基材料。 或者， 当管腔支架预制件为含强氮化物形成元素 的铁合金吋， 不同之处在于第一层状结构 1包括固溶体、 铁氮化合物、 以及强氮 化物形成元素与氮的化合物， 铁氮化合物、 以及强氮化物形成元素与氮的化合 物弥散分布于固溶体中。
[0074] 应当知晓， 上述图 2b和 2c中的各层状成分结构仅为示意结构， 实际中， 随着氮 离子的渗透， 一成分结构渐变形成相邻的另一成分结构， 例如， 图 2c中的固溶层 2渐变为铁芯层 3。 而当改变渗氮工艺参数或选择更薄壁厚的管腔支架吋， 离子 渗氮进一步深入， 铁芯层 3接近固溶体层 2的一侧逐渐形成固溶体， 当整个铁芯 层 3全部形成固溶体吋， 从图 2c形成图 2b中的成分结构。 进一步地， 对于图 2b中 的成分结构， 随着离子渗氮的继续深入， 越来越多的铁氮化合物在固溶体层 2中 形成， 当整个固溶体层 2中全部弥散有均匀的铁氮化合物吋， 形成图 2a中的成分 结构， 即管腔支架内部的成分结构为单一结构， 整体为固溶体， 铁氮化合物弥 散于该固溶体中。
[0075] 另外， 还有可能在管腔支架的最外层表面形成化合物层， 该化合物层也称之为 白亮层 （上述图中未示意） ， 该白亮层的成分全部为铁氮化合物， 可采用步骤 1 03中提及的抛光过程或其它任意适合的方式去除该白亮层以得到最终的管腔支 架。
[0076] 从以上可以看出， 本发明提供的管腔支架预制件不仅适于采用离子渗氮来进行 表面合金化改性处理， 且还可在较大的温区范围 （320〜560°C) 内实施离子渗氮 ， 从而使离子渗氮工艺适于在商用上大规模制备管腔支架。
[0077] 纯铁或铁合金一般在 400°C左右幵始出现回复， 在 500°C左右幵始出现再结晶退 火。 高温离子渗氮比如温度高于 500°C吋， 纯铁或铁合金可能存在回复或再结晶 退火。 回复是指在热处理温度不高吋，由于原子扩散能力不大， 只是晶粒内部空 位、 间隙原子等缺陷通过移动、 复合消失而大大减少， 但冷变形引入的位错仍 然保留， 变形金属的显微组织不发生明显的变化。 回复会提高材料的塑性， 略 微降低其强度和硬度。 再结晶是指当退火温度足够高、 吋间足够长吋， 在冷加 工变形金属或合金的显微组织中， 产生无应变的新晶粒， 且新晶粒会不断长大 ， 直至原来的冷加工变形组织完全消失， 金属或合金的性能也发生显著变化的 过程。 再结晶会显著提高材料的塑性， 同吋显著降低材料的强度和硬度。
[0078] 由此可以看出， 渗氮温度对管腔支架的材料特性的影响很大， 若为了避免回复 和 /或再结晶带来的影响而选择 400°C以下的温度进行渗氮， 则渗入的氮离子难以 克服扩散能垒， 无法有效地在材料内部扩散， 将降低渗氮效果。 也就是说， 仅 通过降低渗氮温度难以同吋兼顾渗氮效果和避免回复和 /或再结晶带来的影响。 本发明还提供一种管腔预制件， 不仅能适于进行低温渗氮以尽量避免回复和 /或 再结晶带来的影响， 还能确保渗氮过程中氮离子在材料内部的有效扩散。
[0079] 在本发明的一实施方式中， 步骤 101中制得的管腔支架预制件的硬度为 200〜25 0HV0.05/10, 显微结构为冷加工后的变形组织。 将该管腔支架预制件制成初始 支架并进行离子渗氮， 此处可在偏压 500〜700V、 总气压 50〜500pa、 氮氢比 1:1 〜 1 :3的条件下对 320〜420°的上述初始支架进行 30〜 180mins的离子渗氮， 可以 制得硬度为 300〜350HV0.05/10， 显微结构仍然维持冷加工后的变形组织的管腔 支架。 该管腔支架的径向强度为初始支架径向强度的 1.1〜2倍； 体外腐蚀速度相 比管腔支架预制件加快了 1〜1.5倍， 过扩塑性至少为 20%， 通常可达 30-40%; 且 对于壁厚在 40〜150微米范围内， 金属覆盖率为 11~16%、 OD为 2〜5.0mm冠脉支 架， 径向强度为至少为 80kPa， 通常可达 110〜260kPa， 满足常规冠脉支架径向 强度至少为 80kPa的要求； 对于壁厚为 90〜200微米、 金属覆盖率为 7~11<¾、 OD 为 6〜14mm的外周支架， 径向强度至少为 50kPa， 通常可达 85kPa， 甚至更高， 可达 130kPa， 满足常规外周支架径向强度至少为 50kPa的要求。 综上， 在该实施 方式中所制得的管腔支架满足常规管腔支架的力学性能要求。 应当知晓， 此处 列举的参数仅用作举例说明， 不同规格的管腔支架可达到的参数不尽相同， 因 此其并不是对本发明的限制， 任何基于本发明的教导所获得管腔支架预制件及 管腔支架、 所采用的两者的制备方法均在本发明的保护范围之内。
[0080] 该实施方式中， 管腔支架预制件的显微结构包括冷变形组织， 其材料内部储存 了大量空位缺陷、 破碎的晶界以及冷变形的能量， 利于氮原子首先渗入晶界， 再向晶内扩散， 且变形组织和细晶材料相对于粗大的等轴晶粒而言， 晶界更多 ， 为氮原子的渗入提供了更多通道。 另外， 由冷加工引入的材料变形储能可帮 助氮原子克服扩散的能垒， 即使在较低的渗氮温度下也能向材料内部扩散。 采 用该管腔支架预制件可在 320〜420°的条件下进行低温离子渗氮， 保存冷加工后 空位、 位错带来的材料强度和硬度的提高以及腐蚀速率的提升， 并与离子渗氮 带来的强度和硬度的提升及腐蚀速率的提升相叠加， 使管腔支架的硬度、 体外 腐蚀速率以及塑性均满足要求。 即采用该管腔支架预制件可以克服高温离子渗 氮过程中过高温度对管腔支架的塑性和强度的影响。
[0081] 在管腔支架的性能测试方面， 管腔支架的径向强度可通过压缩模块均匀地对支 架施加径向压力， 使支架压缩， 产生均匀变形。 定义支架径向 （外径） 发生 10% 变形吋所施加的径向压强大小为支架的径向强度。 例如， 可选用纯铁管预制件 按预设花纹设计激光雕刻成镂空的初始支架， 支架的名义直径为 3.0mm， 长度为 18mm, 再经过粗抛光后放入等离子真空渗氮炉中进行渗氮， 然后精抛光抛至预 定的成品尺寸。 采用球囊扩张该支架成品到其名义直径 3.0mm吋， 进行径向强度 测试和体外浸泡腐蚀速率测试。
[0082] 管腔支架的塑性测试按以下例子进行。 以 OD3.0xl8mm (OD为 3.0mm， 管长为 18mm) 规格的支架为例， 用配套的 3.0x18mm球囊导管扩张至球囊导管的名义直 径压力 （球囊导管上通常有标注， 一般为 8atm) 下吋， 支架内径为 3.0mm， 此为 支架的名义直径。 将不同材质的预制件制成的相同规格的支架用不同名义直径 的球囊导管或使用不同的扩张压力， 从小到大逐渐扩张支架吋， 观察支架的断 裂情况， 记录支架扩张而不发生断裂的最大扩张直径 D (mm) ， 计算 lOOx (D-3 .0) /D% , 以此表征材料的过扩塑性。 支架扩张而不发生断裂的最大扩张直径越 高， 表明其抗断裂性能越好， 塑性越高。 若支架未能扩张到 1.2倍名义直径 （相 当于 20%的过扩塑性） 就发生断裂， 则此种材料在当前的拔管工艺下， 或者此种 材料在当前的拔管工艺下再经相应的改性处理后， 塑性太低， 不能用于制作支 架。
[0083] 管腔支架的体外浸泡腐蚀测试如下： 将抛光处理后的支架用球囊导管扩幵至名 义直径， 用百万分之一精度的天平进行初始称重， 记为 M0， 精确到 O.OOlmg, 浸 泡腐蚀介质为 0.9<¾NaCl盐溶液， 样品的表面积与浸泡腐蚀介质体积的比例为 0.05 cm ml (相当于实施例中描述到的壁厚 50微米， 杆宽 90微米的 3.0x18mm支架浸 泡在 15ml介质中） ， 敞口置于 37°C水浴摇床中浸泡腐蚀 2h。 腐蚀后的支架用 3〜 5%的酒石酸溶液超声清洗 3〜5mins至腐蚀产物完全除尽后， 经 2%的氢氧化钠水 溶液中和 10mins， 去离子水清洗 5mins， 最后无水乙醇脱水 lOmins , 待乙醇完全 挥发后用百万分之一精度的天平进行称重， 记为 Ml， 精确到 0.001mg。 假定随吋 间延长， 腐蚀匀速进行， 则体外浸泡腐蚀失重结果表示为 mm/y， 计算公式为 （1 0-2-ΔΜ) /(p-S-t) , ΔΜ以 mg为单位代入数值计算， t换算成年 y为单位代入数值 计算， S以 cm 2为单位代入数值计算， p以 g/cm2为单位代入数值计算， 如材料为 纯铁， 贝 ljp=7.8g/cm2) 。
[0084] 实施例一
[0085] 本实施例提供一种利用纯铁管材制备管腔支架的方法。 步骤 101中对坯料拉拔 制得管腔支架预制件为超薄壁， 从图 2〜5的金相图中可以明显的看到， 纯铁管 的晶粒会细化， 不再是等轴晶粒。 图 2和图 3所示分别为拉拔后硬度为 160HV0.05 /10、 OD为 1.6mm的纯铁管材的横截面金相和纵截面金相； 图 4和图 5所示分别为 拉拔后硬度为 160HV0.05/10、 OD为 4.2mm的纯铁管材的横截面金相和纵截面金 相； 由图可知沿管坯的拉拔方向， 晶粒被拉长了。
[0086] 拔制高精度管材可使用长芯棒拉拔工艺， 需采用的拉拔道次取决于坯料的硬度 和塑性。 本实施例中采用具有完全退火态组织的的 6x0.5 (外径为 6mm， 壁厚为 0 .5mm) 的纯铁管坯料 （全部杂质元素含量≤0.5wt.%，其中碳含量≤0.022%) ， 该 纯铁管胚的硬度为 90HV0.05/10左右， 该完全退火态组织的金相组织为等轴晶， 晶粒度等级≥4级。
[0087] 采用的拉拔道次依次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ② 采用外模 4.4mm、 芯棒 4.0mm进行长芯棒拉拔； 该拉拔道次结束后辅以退火道次 ， 例如可在完成该拉拔道次后在 650°C下退火半小吋； ③采用外模 3.5mm、 芯棒 3. 19mm进行长芯棒拉拔； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉拔； ⑤采 用外模 1.83mm、 芯棒 1.60mm进行长芯棒拉拔； 该拉拔道次结束后可辅以退火道 次， 例如可在此次拉拔完成后在 510°C下退火半小吋;⑥采用外模 1.62mm进行空 拉， 获得显微组织接近于完全退火状态的支架预制件， 该空拉为此次拉拔中的 最后一个道次。
[0088] 为了减少拉拔缺陷的产生， 所有的拉拔道次的拉拔系数 （也可称之为延伸系数 ) 不能超过 2.0， 本实施方式中延伸系数可选择 1.5左右。 由于金属材料具有一定 的弹性后效， 例如经过 1.62mm的外模拉拔后， 外径会存在一定的回弹， 实测后 外径为 1.63mm， 壁厚为 0.125mm。 为了严格控制管材外表面质量， 预留 0.03mm 的抛光余量， 经机械抛光 0.03mm后， 得到成分不变 （全部杂质元素含量≤0.5wt. %,
其中碳含量≤0.022<¾) 、 外径 1.60mm、 壁厚 0.110±0.005mm、 硬度 160HV0.05/10
、 晶粒度等级为 9级或以上的成品纯铁管作为管腔支架预制件。 管材内壁的质量 通过控制芯棒来得到， 芯棒表面必须经过精抛， 在 200X体视显微镜下观察无明 显可见的机械加工痕迹， 且硬度达到 HRC58-64, 芯棒的材质可以为 SKD11、 SK H-9等模具钢。 管材的尺寸均匀性通过严格控制芯棒和外模的精度尺寸来获得， 外模的精度≤±3μηι,芯棒的精度≤±2μηι。
[0089] 步骤 102中， 将上述管腔支架预制件进行激光切割得到 3.0x18mm规格的冠脉初 始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆盖率 约为 13%。 将激光切割后的纯铁支架抛光至成品尺寸 （支架杆宽 90微米， 支架壁 厚 70微米） ， 测得其径向强度约为 80kPa， 体外浸泡腐蚀速率约为 1.0mm/y， 过 扩塑性约为 50%。
[0090] 步骤 103中， 将激光切割后的纯铁支架粗抛光并清洗之后， 装入辉光离子炉进 行离子渗氮处理。 选择渗氮温度为 560°C左右、 1:3的氮氢流量比、 气压 50〜130P a和 500V的偏压， 渗氮 90〜150分钟， 该支架杆整个截面渗穿， 即除最外表面的 化合物层外， 成分结构为图 2a所示结构。 将渗氮铁支架用树脂包埋并磨抛， 金相 观察和硬度测试结果表明显微结构保持不变， 即晶粒度级别≥9， 硬度值提高到 约为 250HV0.05/10。 另取渗氮铁支架样品抛光至成品尺寸， 支架杆宽 90微米， 支架壁厚为 70微米， 测得该薄壁支架的径向强度可提高到 115kPa， 过扩塑性为 5 0% , 体外浸泡腐蚀速率提高到 1.5mm/y。
[0091] 实施例二
[0092] 步骤 101中对具有完全退火态组织的 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的纯铁 管胚 （全部杂质元素含量≤0.5wt.%，其中碳含量≤0.022%) 拉拔制得管腔支架预 制件， 该纯铁管胚的硬度为 90HV0.05/10左右， 该完全退火态组织的金相组织为 等轴晶， 晶粒度等级≥4级。 拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长 芯棒拉拔； ②采用外模 4.4mm、 芯棒 4.0mm进行长芯棒拉拔； ③采用外模 3.5mm 、 芯棒 3.19mm进行长芯棒拉拔； 此次拉拔道次后可辅以退火道次， 例如可在拉 拔完成后在 500°C下退火半小吋； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉 拔； ⑤采用外模 1.78mm、 芯棒 1.60mm进行长芯棒拉拔； 此次拉拔道次后可辅以 退火道次， 例如可在拉拔完成后在 400°C下退火半小吋;⑥采用外模 1.62mm进行 空拉， 该空拉为此次拉拔中的最后一个道次。
[0093] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数
(拉拔系数） 的范围为 1.2〜2.0， 可选择 1.5左右。 由于金属材料具有一定的弹性 后效， 经过 1.62mm的外模拉拔后， 外径会存在一定的回弹， 实测后外径为 1.63m m， 壁厚为 0.095mm。 为了严格控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到成分不变 （全部杂质元素含量≤0.5wt.<¾，其中碳含量 <0.022%) 、 外径 1.60mm、 壁厚 0.080±0.005mm、 硬度 200HV0.05/10左右、 具有 冷加工后的变形组织的成品纯铁管作为支架预制件。 其中， 图 6示出了上述 OD为 1.6mm的具有冷变形组织的管腔支架预制件的横截面金相图； 图 7示出了上述 OD 为 1.6mm的具有冷变形组织的管腔支架预制件在扫描电镜下的横截面形貌图； 图 8示出了上述 OD为 1.6mm的具有冷变形组织的管腔支架预制件在扫描电镜下的 纵截面形貌。
[0094] 步骤 102中将上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的初始支架抛光至成品尺寸 （支架杆宽 90微米， 支 架壁厚 50微米） ， 测得其径向强度为 80kPa， 体外浸泡腐蚀速率为 1.0mm/y， 过 扩塑性为 50%。
[0095] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度为 480°C、 1: 1的氮氢流量比、 气压 10〜20Pa和 600V左右 的偏压， 渗氮 60〜120分钟。 该支架杆截面渗穿， 即除最外表面的化合物层外， 成分结构为图 2a所示结构。 将渗氮铁支架用树脂包埋并磨抛， 金相观察和硬度测 试结果表明材料仍然保留变形组织， 硬度值提高到 250HV0.05/10左右。 另取渗 氮铁支架样品抛光至成品尺寸 （支架杆宽 90微米， 支架壁厚 50微米） ， 测得其 径向强度提高到 90kPa左右， 过扩塑性保持在 50%， 体外浸泡腐蚀速率提高到 1.7 5mm/y。 [0096] 实施例三
[0097] 步骤 101中对纯铁坯料进行拉拔获得管腔支架预制件。 该纯铁坯料为具有完全 退火态组织的 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的纯铁管坯 （全部杂质元素含 量≤0.5\¥1.<¾，其中碳含量≤0.022<¾) ， 该纯铁管胚的硬度为 90HV0.05/10左右， 该 完全退火态组织的金相组织为等轴晶， 晶粒度等级≥4级。 拉拔道次包括： ①采用 夕卜模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用外模 4.4mm、 芯棒 4.0mm进行长 芯棒拉拔； ③采用外模 3.5mm、 芯棒 3.19mm进行长芯棒拉拔； ④采用外模 2.3mm 、 芯棒 2.02mm进行长芯棒拉拔； ⑤采用外模 1.8mm、 芯棒 1.63mm进行长芯棒拉 拔； ⑥采用外模 1.62mm进行空拉， 该空拉为此次拉拔中的最后一个道次。
[0098] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 1.62mm外模拉拔后， 外径会存在一定的回弹， 实测后外径为 1.63mm， 壁厚为 0.095mm。 为了严格控 制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到成分 不变 （全部杂质元素含量≤0.5wt.<¾,
其中碳含量≤0.022<¾) 、 外径 1.60mm、 壁厚 0.080±0.005mm、 硬度 250HV0.05/10 左右、 具有冷加工后的变形组织的成品纯铁管作为支架预制件。
[0099] 步骤 102中对上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的初始支架抛光至成品尺寸 （支架杆宽 90微米， 支 架壁厚 50微米） ， 测得其径向强度为 90kPa， 体外浸泡腐蚀速率为 1.0mm/y， 过 扩塑性为 40%。
[0100] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度为 320°C左右、 1:3的氮氢流量比、 气压 380-500Pa和 700 V左右的偏压， 渗氮 90〜150分钟。 该支架杆截面渗穿， 即除最外表面的化合物 层外， 材料内部为图 2a所示结构。 将渗氮管腔支架用树脂包埋并磨抛， 金相观察 和硬度测试结果表明材料仍然保留变形组织， 硬度提高到 300HV0.05/10。 另取 渗氮铁支架样品抛光至成品尺寸 （支架杆宽 90微米， 支架壁厚 50微米） ， 测得 其径向强度提高到 110kPa， 过扩塑性能达到 35%， 体外浸泡腐蚀速率提高到 2.0m m/y°
[0101] 实施例四
[0102] 步骤 101中对铁合金坯料进行拉拔获得管腔支架预制件。 该铁合金坯料为具有 完全退火态组织的 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的铁合金管坯， 该铁合金 的合金元素中不含强氮化物形成元素， 如 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo 等， 且 C含量为 0.3wt.<¾， Si含量为 0.30wt.<¾， Mn含量为 0.60wt.<¾， P含量为 0.025 wt.% , S含量为 0.025wt.<¾， Ni含量为 0.25wt.<¾， Cu含量为 0.25wt.<¾， 即其全部合 金元素含量为 1.75wt.%。 该铁合金管坯的硬度为 130HV0.05/10, 还可改变合金成 份以获得不同的硬度， 例如还可选择 100-150HV0.05/10的硬度范围； 完全退火态 的金相组织为等轴晶， 晶粒度等级≥4级。
[0103] 拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用外模 4.4 mm、 芯棒 4.0mm进行长芯棒拉拔； ③采用外模 3.5mm、 芯棒 3.19mm进行长芯棒 拉拔； 此次拉拔道次结束后可辅以退火道次， 例如可在拉拔完成后在 550°C下退 火半小吋； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉拔； ⑤采用外模 1.83m m、 芯棒 1.60mm进行长芯棒拉拔； 此次拉拔道次结束后可辅以退火道次， 例如 可在拉拔完成后在 430°C下退火半小吋； ⑥采用外模 1.62mm进行空拉， 空拉为此 次拉拔中的最后一个道次。
[0104] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 1.62mm外模拉拔后， 外径会存在一定的回弹， 实测后外径为 1.63mm， 壁厚为 0.125±0.005mm。 为了严 格控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到 与坯料材质相同、 外径 1.60mm、 壁厚 0.110±0.005mm、 硬度 200HV0.05/10左右、 具有冷加工后的变形组织的铁合金支架预制件。
[0105] 步骤 102中对上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的铁合金初始支架抛光至成品尺寸 （支架杆宽 90微 米， 支架壁厚 70微米） ， 测得其径向强度为 92kPa， 体外浸泡腐蚀速率为 1.0mm/ y， 过扩塑性为 50%。 [0106] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度为 380°C、 1:3的氮氢流量比、 气压 50-130Pa和 650V左右 的偏压， 渗氮 60〜120分钟。 该支架杆截面渗穿， 即除最外表面的化合物层外， 单一弥散层贯穿整个支架杆的壁厚方向。 将经过渗氮处理后的渗氮铁合金支架 用树脂包埋并磨抛， 金相观察和硬度测试结果表明材料仍然保留变形组织， 硬 度值提高到 350HV0.05/10。 另取渗氮铁合金支架样品抛光至成品尺寸 （支架杆 宽 90微米， 支架壁厚 70微米） ， 测得其径向强度显著提高到 180kPa左右， 过扩 塑性达到 40%， 体外浸泡腐蚀速率显著提高到 2.25mm/y。
[0107] 实施例五
[0108] 步骤 101中对铁合金坯料进行拉拔获得管腔支架预制件。 该坯料为具有完全退 火态组织的 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的铁合金管胚， 总的合金元素含 量≤3^.%， 其中碳含量≤0.45wt.%， 合金元素中不含强氮化物形成元素， 如 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo等。 该铁合金管坯的硬度为 100-150HV0.05/10
， 合金成份不同， 硬度会略有不同； 完全退火态的金相组织为等轴晶， 晶粒度 等级≥4级。
[0109] 拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用外模 4.4 mm、 芯棒 4.0mm进行长芯棒拉拔； ③采用外模 3.5mm、 芯棒 3.21mm进行长芯棒 拉拔； 此次拉拔道次结束后可辅以退火道次， 例如可在拉拔完成后在 530°C下退 火半小吋； ④采用外模 3.015mm进行空拉， 此次拉拔过程中空拉为最后一个道次
[0110] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 3.015mm外模拉拔后 ， 外径会存在一定的回弹， 实测后外径为 3.03mm， 壁厚为 0.170mm。 为了严格 控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到与 坯料材质相同、 外径 3.0mm， 壁厚为 0.155mm±0.005mm、 硬度 160HV0.05/10左右 、 晶粒度级别≥9级的成品纯铁管作为支架预制件。
[0111] 步骤 102中选择上述制得的支架预制件进行激光切割得到 OD8.0xl8mm规格的 外周初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格 覆盖率约为 13%。 将激光切割后的初始支架抛光至成品尺寸 （支架杆宽 178微米 ， 支架壁厚 120微米） ， 测得其径向强度为 65kPa， 体外浸泡腐蚀速率为 1.0mm/y ， 过扩塑性为 50%。
[0112] 步骤 103中， 将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进 行渗氮处理。 选择渗氮温度为 560°C、 1:3的氮氢流量比、 气压 50〜130Pa和 600V 左右的偏压， 渗氮 90〜150分钟。 该支架杆截面渗穿， 即除最外表面的化合物层 夕卜， 材料内部为图 2a所示结构。 将经过渗氮处理后的渗氮铁支架用树脂包埋并磨 抛， 金相观察和硬度测试结果表明材料晶粒度级别仍≥9级， 硬度值提高到 250H V0.05/10左右。 另取渗氮铁支架样品抛光至成品尺寸 （支架杆宽 178微米， 支架 壁厚 120微米） ， 测得其径向强度提高到 90kPa， 过扩塑性保持 50%， 体外浸泡腐 蚀速率提高到 1.5mm/y。
[0113] 实施例六
[0114] 步骤 101中对铁合金坯料进行拉拔获得管腔支架预制件。 该坯料为具有完全退 火态组织的 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的铁合金坯料， 其合金元素中不 含强氮化物形成元素， 如 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo等， 且 C为 0.4wt. % , Si为 0.4wt.<¾， Mn为 0.65wt.<¾， P为 0.04wt.<¾， S为 0.04wt.<¾， Ni为 0.5wt.<¾， Cu为 0.5wt.<¾， 即总的合金元素含量为 2.53wt.%。 该铁合金管坯的硬度为 140HV0 .05/10， 还可改变合金成份以获得不同的硬度， 例如还可选择 100-150HV0.05/10 的硬度范围； 完全退火态的金相组织为等轴晶， 晶粒度等级≥4级。
[0115] 拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用外模 4.4 mm、 芯棒 3.96mm进行长芯棒拉拔； ③采用外模 4.22mm进行空拉， 空拉为本次拉 拔的最后一个道次。
[0116] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 例如经过 4.22mm的外模拉 拔后， 外径会存在一定的回弹， 实测后外径为 4.23mm， 壁厚为 0.235mm。 为了 严格控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得 到与坯料材质不变、 外径 4.2mm、 壁厚 0.220±0.005mm、 硬度 250HV0.05/10左右 、 具有冷加工后的变形组织的成品铁合金管作为支架预制件。 [0117] 步骤 102中对上述制得的支架预制件进行激光切割得到 OD12.0x l8mm规格的外 周初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的铁合金初始支架抛光至成品尺寸 （支架杆宽 228 微米， 支架壁厚 160微米） ， 测得其径向强度为 60kPa， 体外浸泡腐蚀速率为 1.0 mm/y , 过扩塑性为 35<¾。
[0118] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度约为 420°C、 1 :3的氮氢流量比、 气压 200〜300Pa和 600V 左右的偏压， 渗氮 120〜180分钟。 该支架杆截面渗穿， 即除最外表面的化合物 层外， 内部为图 2a所示结构。 将经过渗氮处理后的渗氮铁合金支架用树脂包埋并 磨抛， 金相观察和硬度测试结果表明材料仍然保留变形组织， 硬度值提高到 350 HV0.05/10。 另取渗氮铁合金支架样品抛光至成品尺寸 （支架杆宽 228微米， 支 架壁厚 160微米） ， 测得其径向强度显著提高到 85kPa， 过扩塑性仍能达到 30<¾， 体外浸泡腐蚀速率显著提高到 2.5mm/y。
[0119] 实施例七
[0120] 步骤 101中对铁合金坯料进行拉拔获得管腔支架预制件。 采用具有完全退火态 组织、 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的铁合金管胚， 按重量百分比， 其成 分为： C为 0.10wt.<¾， Si为 0.17wt.<¾， Mn为 0.50wt.<¾， P为 0.03wt.<¾， S为 0.020wt. % , Mo为 0.45wt.<¾， Cr为 1.0wt.% , Cu为 0.15wt.<¾， Ni为 0.25wt.<¾， 即其全部合 金元素含量为 2.67wt.%， 强氮化物形成元素 （Mo和 Cr) 含量为 1.45 wt.<¾。 该铁 合金管坯的硬度为 120HV0.05/10 , 还可改变合金成份 （包括强氮化物形成元素 ) 以获得不同的硬度， 例如还可选择 100- 150HV0.05/10的硬度范围； 完全退火态 的金相组织为等轴晶， 晶粒度等级≥4级。
[0121] 拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用外模 4.4 mm、 芯棒 4.0mm进行长芯棒拉拔； 此次拉拔道次结束后可辅以退火道次， 例如 可在拉拔完成后在 600°C下退火 1小吋； ③采用外模 3.5mm、 芯棒 3.19mm进行长芯 棒拉拔； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉拔； ⑤采用外模 1.83mm 、 芯棒 1.60mm进行长芯棒拉拔； 此次拉拔道次结束后可辅以退火道次， 例如可 在拉拔完成后在 500°C下退火半小吋； ⑥采用外模 1.62mm进行空拉， 空拉为此次 拉拔的最后一个道次。
[0122] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 1.62mm的外模拉拔后 ， 外径会存在一定的回弹， 实测后外径为 1.63mm， 壁厚为 0.095mm。 为了严格 控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到材 质与坯料相同、 外径 1.6mm、 壁厚 0.080±0.005mm、 硬度 230HV0.05/10左右、 具 有冷加工后的变形组织的成品铁合金管作为支架预制件。
[0123] 步骤 102中将上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的铁合金初始支架抛光至成品尺寸 （支架杆宽 90微 米， 支架壁厚 50微米） ， 测得其径向强度为 70kPa， 体外浸泡腐蚀速率为 1.0mm/ y， 过扩塑性为 50%。
[0124] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度约为 380°C、 1:3的氮氢流量比、 气压 50〜130Pa和 600V 左右的偏压， 渗氮约 15〜90分钟。 该支架杆截面渗穿， 即除最外表面的化合物 层外， 内部为图 2a所示结构。 将经过渗氮处理后的渗氮铁合金支架用树脂包埋并 磨抛， 金相观察和硬度测试结果表明材料仍保留变形组织， 硬度值提高到 350HV 0.05/10。 另取渗氮铁支架样品抛光至成品尺寸 （支架杆宽 90微米， 支架壁厚 50 微米） ， 测得其径向强度提高到 130kPa， 过扩塑性仍能达到 40%， 体外浸泡腐蚀 速率提高到 2.25mm/y。
[0125] 实施例八
[0126] 步骤 101中对铁合金坯料进行拉拔获得管腔支架预制件。 采用具有完全退火态 组织、 6x0.5 (外径 6mm， 壁厚为 0.5mm) 的铁合金管坯， 其成分为： C为 0.018w t.% , Si为 0.03wt.<¾， Mn为 0.10wt.<¾， P为 0.037wt.<¾， S为 0.011wt.<¾， Ti为 0.30wt. %, 即全部合金元素含量为 0.496wt.<¾， 强氮化物元素 Ti含量为 0.30wt.<¾。 该铁合 金管坯的硬度为 100HV0.05/10, 还可改变合金成份 （包括强氮化物形成元素） 以获得不同的硬度， 例如还可选择 100-150HV0.05/10的硬度范围； 完全退火态的 金相组织为等轴晶， 晶粒度等级≥4级。 [0127] 采用的拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采用 外模 4.4mm、 芯棒 4.0mm进行长芯棒拉拔； 此次拉拔道次结束后可辅以退火道次 ， 例如可在拉拔完成后在 650°C下退火 1小吋； ③采用外模 3.5mm、 芯棒 3.19mm进 行长芯棒拉拔； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉拔； ⑤采用外模 1.8 3mm、 芯棒 1.60mm进行长芯棒拉拔； ⑥采用外模 1.62mm进行空拉， 此次空拉道 次结束后可辅以退火道次， 例如可在空拉完成后在 600°C下退火 1小吋。
[0128] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 1.62mm的外模拉拔后 ， 外径会存在一定的回弹， 实测后外径为 1.63mm， 壁厚为 0.095mm。 为了严格 控制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到材 质与坯料相同、 外径 1.6mm、 壁厚 0.080±0.005mm、 硬度 120HV0.05/10左右、 晶 粒度级别≥9级的成品铁合金管作为支架预制件。
[0129] 步骤 102中将上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米， 该支架扩张到 3.0mm直径吋， 表面的金属网格覆 盖率约为 13%。 将激光切割后的铁合金初始支架抛光至成品尺寸 （支架杆宽 90微 米， 支架壁厚 50微米） ， 测得其径向强度为 37kPa， 体外浸泡腐蚀速率为 1.0mm/ y， 过扩塑性为 50%。
[0130] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度约为 530°C、 1:3的氮氢流量比、 气压 200〜300Pa和 700V 左右的偏压， 渗氮约 90〜150分钟。 该支架杆截面渗穿， 即除最外表面的化合物 层外， 内部为图 2a所示结构。 将经过渗氮处理后的渗氮铁合金支架用树脂包埋并 磨抛， 金相观察和硬度测试结果表明材料晶粒度级别仍≥9级， 硬度值提高到 350 HV0.05/10。 另取渗氮铁支架样品抛光至成品尺寸 （支架杆宽 90微米， 支架壁厚 50微米） ， 测得其径向强度提高到 130kPa， 过扩塑性仍能达到 40%， 体外浸泡腐 蚀速率提高到 2.25mm/y。
[0131] 对比例
[0132] 步骤 101中对坯料进行拉拔获得管腔支架预制件。 采用具有完全退火态组织的 6 X0.5 (外径 6mm， 壁厚为 0.5mm) 的纯铁管胚 （全部杂质元素含量≤0.5wt.<¾，其 中碳含量≤0.022%) ， 该纯铁管胚的硬度为 90HV0.05/10左右， 该完全退火态组 织的金相组织为等轴晶， 晶粒度等级≥4级。
[0133] 可采用的拉拔道次包括： ①采用外模 5mm、 芯棒 4.4mm进行长芯棒拉拔； ②采 用外模 4.4mm、 芯棒 4.0mm进行长芯棒拉拔； 此次拉拔道次结束后可辅以退火道 次， 例如可在拉拔完成后在 650°C下退火半小吋。 ③采用外模 3.5mm、 芯棒 3.19m m进行长芯棒拉拔； ④采用外模 2.3mm、 芯棒 2.02mm进行长芯棒拉拔； ⑤采用外 模 1.83mm、 芯棒 1.60mm进行长芯棒拉拔； ⑥采用外模 1.62mm进行空拉， 空拉结 束后辅以退火道次， 例如可在空拉完成后在 570°C下退火 1小吋以完成整个拉拔过 程。
[0134] 为了减少拉拔缺陷的产生， 所有的拉拔道次的延伸系数不能超过 2.0， 延伸系数 可选择 1.5左右。 由于金属材料具有一定的弹性后效， 经过 1.62mm外模拉拔后， 外径会存在一定的回弹， 实测后外径为 1.63mm， 壁厚为 0.095mm。 为了严格控 制管材外表面质量， 预留 0.03mm的抛光余量， 经机械抛光 0.03mm后， 得到成分 不变 （全部杂质元素含量≤0.5wt.<¾,
其中碳含量≤0.022<¾) 、 外径 1.60mm、 壁厚 0.080±0.005mm、 硬度 90HV0.05/10 左右、 晶粒度级别为 6级的成品纯铁管作为支架预制件。
[0135] 步骤 102中对上述制得的支架预制件进行激光切割得到 OD3.0xl8mm规格的冠 脉初始支架， 切割精度 ±5微米。 将激光切割后的初始支架抛光至成品尺寸 （支 架杆宽 90微米， 支架壁厚 50微米） ， 测得其径向强度为 30kPa， 体外浸泡腐蚀速 率为 0.9mm/y， 过扩塑性为 50<¾。
[0136] 步骤 103中将激光切割后的初始支架粗抛光并清洗之后， 装入辉光离子炉进行 渗氮处理。 选择渗氮温度为 320°C左右、 1:3的氮氢流量比、 气压 380-500Pa和 700 V左右的偏压， 渗氮 90〜150分钟。 其中渗氮吋间的长短， 由医疗器械及其部件 的尺寸 （如壁厚） 、 需要控制的渗透深度以及渗氮温度共同决定。 本实施例中 给出的渗氮吋间为该实施例依托的铁管尺寸下， 支架杆截面渗穿 （除最外表面 的化合物层外， 单一弥散层贯穿整个支架杆的壁厚方向） 的吋间。 将经过渗氮 处理后的渗氮管腔支架用树脂包埋并磨抛， 金相观察和硬度测试结果表明材料 仍然保留变形组织， 硬度提高到 120HV0.05/10。 另取渗氮铁支架样品抛光至成 品尺寸 （支架杆宽 90微米， 支架壁厚 50微米） ， 测得其径向强度为 37kPa， 过扩 塑性维持 50%， 体外浸泡腐蚀速率仍为 0.9mm/y。
[0137] 在上述对比例中， 对于纯铁管坯， 拉拔中的空拉道次结束后继续辅以退火道次 ， 制得硬度仅为 90HV0.05/10左右、 晶粒度级别为 6级的管腔支架预制件， 硬度 未在本发明所制备的管腔支架要求的 160〜250HV0.05/10范围内， 且晶粒度等级 小于本发明所要求的至少为 9级。 该管腔支架预制件通过离子渗氮获得的改性效 果不明显， 例如， 经过离子渗氮后， 径向强度仅从 30kPa增加到 37kPa， 硬度仅 从 90HV0.05/10提高到 120HV0.05/10， 体外浸泡腐蚀速率和过扩塑性维持不变， 上述径向强度无法满足管腔支架的要求。
[0138] 以本发明的实施例三为例与该对比例进行对比， 实施例三中采用相同的纯铁管 坯， 改变拉拔工艺， 在空拉后不再进行退火处理， 保留拉拔过程中形成的变形 组织， 由此可通过拉拔制得硬度 250HV0.05/10左右、 具有冷加工后的变形组织 的管腔支架预制件， 经过离子渗氮后， 径向强度可从 90kPa增加到 110kPa， 硬度 提高到 300HV0.05/10, 体外浸泡腐蚀速率增加一倍， 过扩塑性维持不变， 仍可 达 35%， 满足常规管腔支架对径向强度和塑性的要求。
[0139] 通过以上可以看出， 本发明通过拉拔工艺可将材质为纯铁或不含强氮化物形成 元素的铁合金的坯料拉拔成硬度为 160〜250HV0.05/10、 显微结构为晶粒度等级 ≥9或者为冷加工后的变形组织的铁基管腔支架预制件； 或者制得显微结构为晶 粒度等级≥9或者为冷加工后的变形组织的、 含强氮化物形成元素的铁合金管腔 支架预制件。 该预制件可实现在较大的温区范围 （320〜560°C) 内实施离子渗氮 ， 同吋由此制得的管腔支架的硬度为 250-350 HV0.05/10, 过扩塑性为 20-50%， 且对于壁厚在 40-150微米范围内， 金属覆盖率 11~16%的 OD2〜5.0mm冠脉支架， 径向强度为 80-260kPa; 对于壁厚 90-200微米范围内、 金属覆盖率 7~11<¾、 OD5.0 -14mm的外周支架， 径向强度能达到 50-130kPa， 满足常规管腔支架的力学性能 要求。
[0140] 在本发明的一些具体实施方式中， 通过拉拔工艺制备了硬度为 200〜250HV0.05 /10、 显微结构为冷加工后变性组织的适于低温 （320〜420°C) 离子渗氮的管腔 支架预制件， 减少渗氮过程中因温度设置过高带来的回复和 /或再结晶的副作用 影响， 由此制得的管腔支架的硬度可达到 300-350
HV0.05/10、 过扩塑性为 20-40%， 且对于壁厚在 40-150微米范围内， 金属覆盖率 11~16<¾的 OD2〜5.0mm冠脉支架， 径向强度为 80-260kPa; 对于壁厚 90-200微米 范围内、 金属覆盖率 7~11%、 OD5.0-14mm的外周支架， 径向强度能达到 85kPa， 甚至更高， 仍然满足常规管腔支架的力学性能要求。
应当知晓， 以上数据为本发明中的具体实施例中的数值， 上述数值随具体产品 的规格不同而调整， 因此其仅用作举例， 并不是对本发明的限制， 本领域的普 通技术人员， 基于本发明的教导所制得的管腔支架预制件及管腔支架、 以及所 采用的上述两者的制备方法， 均在本发明的保护范围之内。

Claims

权利要求书
一种管腔支架预制件， 其特征在于， 所述管腔支架预制件为纯铁或铁 合金， 所述纯铁的全部杂质元素含量≤0.5\^.%， 所述铁合金的全部合 金元素含量≤3wt.%， 且所述铁合金不含强氮化物形成元素， 所述管 腔支架预制件的硬度为 160〜250HV0.05/10， 显微结构为晶粒度等级 ≥9或者为冷加工后的变形组织。
根据权利要求 1所述的管腔支架预制件， 其特征在于， 所述管腔支架 预制件的硬度为 200〜250HV0.05/10， 显微结构为冷加工后的变形组 织。
根据权利要求 1所述的管腔支架预制件， 其特征在于， 所述纯铁的全 部杂质元素中的碳含量≤0.022%； 所述铁合金的全部合金元素的碳含 量≤0.45\¥1.<¾。
根据权利要求 1所述的管腔支架预制件， 其特征在于， 所述管腔支架 预制件的外径为 1.2〜4.2mm; 壁厚为 0.08〜0.24mm。
一种管腔支架预制件， 其特征在于， 所述管腔支架预制件为铁合金， 且所述铁合金中含有至少一种强氮化物形成元素， 所述铁合金的全部 合金元素含量≤3wt.%， 所述强氮化物形成元素的总含量≥0.05wt.% ; 所述管腔支架预制件的显微结构为晶粒度等级≥9或者为冷加工后的 变形组织。
根据权利要求 5所述的管腔支架预制件， 其特征在于， 所述强氮化物 形成元素包括 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo中的至少一种。 根据权利要求 5所述的管腔支架预制件， 其特征在于， 所述铁合金的 全部合金元素中碳含量≤0.45\^.%。
根据权利要求 5所述的管腔支架预制件， 其特征在于， 所述管腔支架 预制件的外径为 1.2〜4.2mm; 壁厚为 0.08〜0.24mm。
一种管腔支架预制件的制备方法， 其特征在于， 包括将坯料拉拔成如 权利要求 1-8任一项所述的管腔支架预制件。
根据权利要求 9所述的管腔支架预制件的制备方法， 其特征在于， 所 述坯料为全部杂质元素含量≤0.5\^.%的纯铁； 或为全部合金元素含量 ≤3wt.%、 且不含强氮化物形成元素的铁合金； 或为全部合金元素含 量≤3\^.%、 且强氮化物形成元素的总含量≥0.05\^.%的铁合金。
[权利要求 11] 根据权利要求 10所述的管腔支架预制件的制备方法， 其特征在于， 所 述纯铁的全部杂质元素中的碳含量≤0.022%； 所述铁合金的全部合金 元素的碳含量≤0.45wt.<¾。
[权利要求 12] 根据权利要求 10所述的管腔支架预制件的制备方法， 所述强氮化物形 成元素包括 Ti、 Cr、 Al、 Zr、 Nb、 V、 B、 W、 Mo中的至少一种。
[权利要求 13] 根据权利要求 9所述的管腔支架预制件的制备方法， 其特征在于， 所 述制备方法还包括在拉拔所述坯料前将所述坯料处理为完全退火态组 织或不完全退火态组织。
[权利要求 14] 根据权利要求 9所述的管腔支架预制件的制备方法， 其特征在于， 所 述拉拔的拉拔道次包括至少一次带芯棒拉拔和一次空拉。
[权利要求 15] 根据权利要求 9所述的管腔支架预制件的制备方法， 其特征在于， 当 所述坯料为前述纯铁或前述不含强氮化物形成元素的铁合金吋， 所述 空拉为所述拉拔中的最后一个道次； 当所述坯料为前述含强氮化物形 成元素的铁合金吋， 所述空拉之后还包括退火道次。
[权利要求 16] 根据权利要求 14所述的管腔支架预制件的制备方法， 其特征在于， 所 述带芯棒拉拔中的拉拔系数为 1.2〜2.5。
[权利要求 17] 根据权利要求 14所述的管腔支架预制件的制备方法， 其特征在于， 所 述带芯棒拉拔中的拉拔系数为 1.5〜2.0。
[权利要求 18] 根据权利要求 14所述的管腔支架预制件的制备方法， 其特征在于， 所 述空拉中的拉拔系数约为 1或略大于 1。
[权利要求 19] 根据权利要求 14所述的管腔支架预制件的制备方法， 其特征在于， 所 述带芯棒拉拔为带长芯棒拉拔。
[权利要求 20] 根据权利要求 14所述的管腔支架预制件的制备方法， 其特征在于， 在 所述坯料的再结晶温度下实施所述拉拔道次。
[权利要求 21] 根据权利要求 15所述的管腔支架预制件的制备方法， 其特征在于， 所 述拉拔道次之间还辅以退火道次。
根据权利要求 20所述的管腔支架预制件的制备方法， 其特征在于， 当 坯料的硬度为 200〜240HV0.05/10吋， 在该带芯棒拉拔道次前辅以退 火道次， 退火温度为 400〜650°C。
根据权利要求 20所述的管腔支架预制件的制备方法， 其特征在于， 当 欲制得硬度小于 250HV0.05/10的管腔支架预制件吋， 所述拉拔道次之 间还辅以退火道次， 退火温度为 400〜650°C。
一种管腔支架的制备方法， 其特征在于， 包括将坯料拉拔成如权利要 求 1-8任一项所述的管腔支架预制件， 所述坯料为全部杂质元素含量≤ 0.5wt 纯铁， 或为全部合金元素含量≤3\^.%且不含强氮化物形成 元素的铁合金， 或为全部合金元素含量≤3\^.%、 且强氮化物形成元 素的总含量≥0.05wt.<¾的铁合金。 根据权利要求 24所述的管腔支架的制备方法， 其特征在于， 所述制备 方法还包括将所述管腔支架预制件制成初始支架， 将所述初始支架升 温至 320〜560°C后， 在 10〜500Pa气压和 500〜700V偏压下， 对所述 初始支架离子渗氮 15〜180分钟。
根据权利要求 24所述的管腔支架的制备方法， 其特征在于， 当所述管 腔支架预制件的硬度为 200〜250HV0.05/10、 显微结构为冷加工后的 变形组织吋， 所述制备方法还包括将所述管腔支架预制件制成初始支 架， 将所述初始支架升温至 320〜420°C后， 在 50〜500Pa气压和 500〜 700V偏压下， 对所述初始支架离子渗氮 30〜180分钟。
根据权利要求 25或 26所述的管腔支架的制备方法， 其特征在于， 所述 离子渗氮中气源的氮氢流量比为 1:1〜1:3。
根据权利要求 25或 26所述的管腔支架的制备方法， 其特征在于， 所述 制备方法还包括在离子渗氮后进行抛光制得所述管腔支架。
一种管腔支架， 其特征在于， 所述管腔支架的硬度为 250〜350HV0.0 5/10， 显微结构为晶粒度等级≥9级或者为冷加工后的变形组织。 根据权利要求 29所述的管腔支架， 其特征在于， 硬度为 300〜350HV0 .05/10， 显微结构为冷加工后的变形组织的所述管腔支架由硬度为 200 〜250HV0.05/10、 显微结构为冷加工后的变形组织的管腔支架预制件 制成。
根据权利要求 29所述的管腔支架， 其特征在于， 所述管腔支架由硬度 为 160〜250HV0.05/10、 显微结构为晶粒度等级≥9或者为冷加工后的 变形组织的管腔支架预制件制成。
根据权利要求 29或 31所述的管腔支架， 其特征在于， 所述管腔支架的 径向强度为 80-260kPa， 过扩塑性为 20〜50%； 或者径向强度为 50〜1 30kPa, 过扩塑性为 20〜50%。
根据权利要求 30所述的管腔支架， 其特征在于， 所述管腔支架的径向 强度为 80-260kPa， 过扩塑性为 20〜40%； 或者径向强度为 50〜130kP a， 过扩塑性为 20〜40%。
根据权利要求 29或 31所述的管腔支架， 其特征在于， 所述管腔支架的 体外浸泡腐蚀速率比初始支架的体外浸泡腐蚀速率加快了 0.25〜1.5倍 根据权利要求 30所述的管腔支架， 其特征在于， 所述管腔支架的体外 浸泡腐蚀速率比初始支架的体外浸泡腐蚀速率加快了 1〜1.5倍。
根据权利要求 29或 30或 31所述的管腔支架， 其特征在于， 所述管腔支 架的金属覆盖率为 11〜16%或者为 7〜11%。
根据权利要求 29或 30或 31所述的管腔支架， 其特征在于， 所述管腔支 架包括固溶体和铁氮化合物； 或者所述管腔支架包括固溶体、 铁氮化 合物和强氮化物形成元素与氮的化合物。
根据权利要求 29或 30或 31所述的管腔支架， 其特征在于， 所述管腔支 架从表面向内依次包括第一层状结构和第二层状结构； 其中， 所述第 一层状结构包括固溶体和铁氮化合物， 第二层状结构包括固溶体； 或 者所述第一层状结构包括固溶体、 铁氮化合物、 以及强氮化物形成元 素与氮的化合物， 所述第二层状结构包括固溶体。 [权利要求 39] 根据权利要求 29或 30或 31所述的管腔支架， 其特征在于， 所述管腔支 架从表面向内依次包括第一层状结构、 第二层状结构以及第三层状结 构； 其中， 所述第一层状结构包括固溶体和铁氮化合物， 所述第二层 状结构包括固溶体， 以及所述第三层状结构为铁芯层； 或者所述第一 层状结构包括固溶体、 铁氮化合物、 以及强氮化物形成元素与氮组成 的化合物， 所述第二层状结构包括固溶体， 以及所述第三层状结构为 铁芯层。
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