JP4067484B2 - Co-Cr-Mo type fine wire and method for producing the same, and planar body, cylindrical body, twisted wire and cable formed by processing the fine wire - Google Patents

Description

  The present invention relates to a prosthetic material for artificial bone, a porous artificial bone, a porous implant part for medical surgery, a wire and cable for bone bonding or fixation, and a bone bonding and fixation for woven or knitted fine wires. Co-Cr-Mo fine wires applied to medical implant devices, such as bands, wire meshes and guide wires for intravascular stents, and vascular embolization wires, and manufacturing methods thereof, and planar bodies processed from these fine wires, etc. In particular, the present invention relates to a technique for producing a Co—Cr—Mo fine wire excellent in biocompatibility, corrosion resistance, wear resistance, workability and flexibility.

  Conventionally, a Co—Cr—Mo alloy has been known as an alloy having excellent biocompatibility. However, since plastic working is not easy, the cast material and the forged material are limited to rigid products formed in relatively large dimensions. Therefore, it has been difficult to produce a fine wire suitable for a biological component. Moreover, since this alloy is excellent in biocompatibility, its application field is wide, and the need in the medical field was especially high. For this reason, there has been a demand for the development of a thin wire made of this alloy having strength, wear resistance and torsional resistance characteristics that match the mechanical characteristics of the bioconstituent member, and flexibility that fits the shape of the bioconstituent member. .

  In response to such a request, a technique that enables plastic working by adding Ni to the alloy has been disclosed (for example, see Patent Document 1). Specifically, it is said that an implantable medical device can be provided by manufacturing a long member made of Co—Cr—Mo containing Ni of less than 5 mass%. However, since Ni has a problem of bioallergenicity, it is desirable not to contain Ni for fine wires used in the medical field. In addition, according to the technique described in Patent Document 1, thin wires that do not contain Ni are also included, but only those containing Ni are disclosed in the embodiments in the detailed description of the invention, and contain Ni. It is uncertain whether or not fine lines that can be processed can be processed.

  In addition, in this alloy, when the Mo concentration is increased and the structure is made uniform, the wear resistance as well as the corrosion resistance is drastically improved. There was a problem. This is thought to be due to the precipitation of a hard and brittle unknown phase in addition to the γ phase and ε phase, which are relatively easy to deform plastically. During plastic processing, the processing stress suddenly increases in this unknown phase, and in some cases it becomes an unknown phase. It is thought that cracking occurs at the interface between the unknown phase and the parent phase.

  As a solution to the problem due to this unknown phase, a rapid casting of a molten alloy of Co- (26-30) mass% Cr- (6-12) mass% Mo- (0-0.3) mass% C with a water-cooled copper mold By adjusting the obtained material to a structure in which the second phase such as precipitates with high Mo concentration and intermetallic compounds are finely dispersed in grains having an average crystal grain size of 50 μm or less by a hot forging method, plastic workability is improved. An improved technique is disclosed (for example, see Patent Document 2). However, when trying to obtain a thin wire having a diameter of 300 μm from the alloy described in Patent Document 2 by the plastic working method, even if the second phase of high-concentration Mo is finely dispersed in a granular form, it is difficult to be deformed. May move inside the mother phase (first phase) and damage the inside of the mother phase, possibly causing holes and cracks inside the mother phase. Therefore, in order to finish the alloy into a thin wire shape so as not to cause this problem, it is necessary to gradually repeat the plastic working under the structure control conditions described in Patent Document 2. For this reason, the number of processes increased significantly and the problem that manufacturing cost became expensive had arisen.

  Furthermore, in the prior art, as is clear from the description of claim 13 of Patent Document 1 and the embodiment thereof, an example of creating a thin wire containing 8% by mass or more of Mo is not disclosed. There has been a demand for the development of a thin wire excellent in corrosion resistance, wear resistance and flexibility, which contains no Mo and 8% by mass or more of Mo.

  On the other hand, in the method of repeating forging as in the manufacturing method described in Patent Document 2, it is not easy to manufacture a thin wire having a circular cross section, but there is still a possibility if a foil strip is manufactured. It is also possible to produce a foil strip by a roll method using a rapid solidification means by applying the molten metal to the cooling roll side surface. However, since the foil strip is not flexible enough to fit a complex shape in a living body, a thin wire with a high degree of circularity (= minor axis / major axis) of the cross section is woven or knitted to improve flexibility. There was also a demand for the development of the belt.

JP 10-43314 A JP 2002-363675 A Japanese Examined Patent Publication No. 7-36942 Japanese Patent Application No. 2000-216090

  The present invention has been made in view of the various demands described above, and in particular, on the premise of ensuring excellent biocompatibility, which is an essential feature of Co-Cr-Mo type fine wires, particularly excellent corrosion resistance and resistance. Providing Co-Cr-Mo fine wires that exhibit wearability and workability, as well as excellent flexibility to fit the shape of living body components, a method for manufacturing the same, and planar bodies processed from these fine wires The purpose is to do.

  The present inventors examined various melt spinning methods, which are known methods for directly forming a fine wire from a Co—Cr—Mo based alloy that has been regarded as a difficult-to-work material. As a result, in the present alloy system, as a method for obtaining a thin wire having a high degree of circularity (= minor axis / major axis) in the cross section, for example, the spinning method described in Patent Document 3 and the gas described in Patent Document 4 are used. It was concluded that it would be preferable to use a medium melt spinning method. Specifically, in the production of a thin wire having a circular cross section with a circularity of 0.6 or more in the cross section, a spinning method in a rotating liquid is adopted, and the fine wire diameter is controlled by the nozzle diameter to produce a thin wire having a diameter of 300 μm or less. The knowledge that the method to obtain was suitable was acquired. In addition, a method of obtaining a fine wire having a diameter of 300 μm or less by using a melt spinning method in gas and controlling the diameter of the fine wire by a nozzle diameter is used for manufacturing a fine wire having a circular cross section having a circularity of 0.7 or more in cross section. The knowledge that it was suitable was obtained.

  Here, even when the above two manufacturing methods are used without particularly limiting the conditions relating to the diameter of the fine wire, the fine wire shape can be obtained. However, when the thickness of the fine line exceeds a certain value, it was found that the fine line is easily broken by bending deformation of 90 degrees or more, and some of the fine lines have poor ductility. As a result of examining this cause, it was found that when the thickness of the fine wire exceeds a certain value, an unknown phase other than the γ phase and the ε phase exists in the internal structure, and this causes a decrease in ductility. It was also found that the presence of this unknown phase becomes more prominent as the thin line becomes thicker. From the above point of view, it was found that by eliminating this unknown phase, a thin wire having excellent ductility and, in turn, workability was obtained.

  Further, as described above, the reason why a thin wire having a diameter of more than 300 μm is likely to break is as follows. That is, in the spinning means using a nozzle diameter exceeding 300 μm, since the cooling rate difference between the surface and the inside of the molten alloy jet is large, the flexibility is easily deteriorated due to the decrease in circularity, and at the same time, the Mo concentration Due to the non-uniformity, the deterioration of flexibility due to the promotion of the precipitation of the unknown phase is likely to occur. For this reason, it is considered that bending of 90 degrees or more is particularly difficult. Also, when the diameter of the molten alloy jet before solidification is 300 μm or less, the higher the circularity of the molten alloy jet, the more uniform the cooling from the side of the molten alloy jet is in the circumferential direction and the uniform Mo concentration As a result, it is thought that it contributes to prevention of precipitation of an unknown phase.

  Furthermore, 8 mass% or more is suitable for ensuring the compounding density | concentration of Mo, when ensuring corrosion resistance and abrasion resistance. However, it has been found that when the Mo concentration exceeds 16% by mass, bending deformation of 90 ° or more is difficult and ductility is poor even for a thin wire having a diameter of 300 μm or less. Moreover, the blending concentration of Cr is preferably 26% by mass or more in order to ensure corrosion resistance. However, it has been found that when the Cr compounding concentration exceeds 31% by mass, the fine wire is difficult to bend at 90 ° or more when the Mo compounding concentration is 8% by mass or more, resulting in a thin wire having poor ductility. In view of wear resistance and post-workability of thin wires, it has been found that C may be added at around 0.3% by mass.

The Co—Cr—Mo thin wire of the present invention is made based on the various findings shown above, including Cr: 26 to 31 mass%, Mo: 8 to 16 mass%, with the balance being Co and a diameter 300μm or less thin lines unavoidable impurities, circularity of the cross section a is (= minor axis / major axis) is 0.6 or more, phase internal organization gamma (Co group solid solution of face-centered cubic) And ε phase (co-solid solid solution of hexagonal close-packed crystal), or only both of them. Note that in such a Co—Cr—Mo thin wire, the circularity of the cross section is preferably 0.7 or more.

Next, the first method for producing a Co—Cr—Mo fine wire according to the present invention is classified as a spinning method in a rotating liquid, and a cooling formed along the inner peripheral surface of a rotating cylindrical drum. In the liquid layer, through a nozzle having a diameter of 300 μm or less, a molten alloy containing Cr: 26 to 31% by mass and Mo: 8 to 16% by mass with the balance being Co and inevitable impurities is ejected. there there is 300μm or less, roundness of cross section Ri (= minor axis / major axis) is 0.6 or more der, phase internal organization gamma (Co group solid solution of face-centered cubic) and ε-phase (hexagonal close-packed It is characterized in that a thin wire consisting of only one of them or both of them is obtained.

Moreover, the 2nd manufacturing method of the Co-Cr-Mo type | system | group fine wire of this invention is classified into the melt spinning method in gas, and includes Cr: 26-31 mass%, Mo: 8-16 mass%. The molten alloy consisting of Co and inevitable impurities is injected from a spinning nozzle having a diameter of 300 μm or less, and the injection jet is cooled and solidified in a cooling gas, so that the diameter is 300 μm or less and the cross section is circular. degrees Ri der (= minor axis / major axis) is 0.7 or more, one of the phase internal organization gamma (face-centered cubic Co-based solid solution) and ε-phase (Co base solid solution of hexagonal close-packed crystal) alone, Alternatively, it is characterized in that a thin line consisting only of both is obtained.

Furthermore, the 3rd manufacturing method of the Co-Cr-Mo type | system | group thin wire | line of this invention is classified into the melt spinning method in a gas similarly to the said 2nd manufacturing method, Cr: 26-31 mass%, Mo: A spinning nozzle having a diameter of 300 μm or less that forms a molten jet by spraying downward in a form in which the molten alloy containing 8 to 16% by mass and the balance consisting of Co and inevitable impurities is dropped, and dropping of the molten jet A gas rectifying cylinder arranged in a form surrounding the path, cooling gas introducing means for introducing a cooling gas for solidifying the molten jet into the gas rectifying cylinder, and a thin line obtained by solidifying the molten jet wherein by using a discharge means for discharging from the gas flow-guide cylinder to the outside, there is the 300μm or less in diameter state, and are circularity (= minor axis / major axis) is 0.7 or more of the cross section, the internal Weave is characterized by obtaining only one, or thin line consisting of only both of them with the γ-phase (face-centered cubic Co-based solid solution of crystal) and ε-phase (Co base solid solution of hexagonal close-packed crystal).

  In the production methods (second and third production methods) by the gas melt spinning method described above, it is desirable that the cooling gas is an oxygen-containing gas. In the third manufacturing method, the cooling gas is a first gas composed of an inert gas introduced into the gas rectifying cylinder at a first position near the spinning nozzle in the falling direction of the molten jet. A second gas component composed of an oxidizing gas introduced into the gas rectifying cylinder at a second position below the first position and a third position below the second position. It is desirable to include a third gas component having a higher cooling capacity than the first and second gas components introduced into the gas rectifying cylinder at the position. In this case, it is more desirable that the first gas component is argon or helium and the second gas component is oxygen or carbon dioxide gas. Furthermore, in order to promote cooling of the molten alloy jet, it is highly desirable to provide fourth and fifth cooling gas introduction portions below the third position.

  The above is the method for producing the Co-Cr-Mo type fine wire of the present invention, but the fine wire thus produced is woven, knitted or non-woven processed, the fine wire is woven, A tubular body formed by knitting or non-woven processing and a twisted wire or cable formed by processing the above-described thin wire are excellent in biocompatibility, corrosion resistance, wear resistance, workability and flexibility. It can be applied to implant devices.

  As described above, the Co—Cr—Mo thin wire of the present invention has excellent corrosion resistance and wear resistance by ensuring the excellent biocompatibility, which is its original characteristic, and by optimizing the amount of Mo. And processability can be ensured. In addition, excellent corrosion resistance and workability can be ensured by optimizing the Cr content. And the outstanding softness | flexibility can be ensured by optimizing the circularity of a cross section. Furthermore, it is excellent in that the internal structure is substantially composed of only one or both of the γ phase (face-centered cubic Co-based solid solution) and the ε-phase (hexagonal dense Co-based solid solution). It is possible to ensure ductility, that is, workability. By making the diameter of the thin wire 300 μm or less, it is possible to reduce the cooling rate difference between the surface and the inside of the molten alloy jet, and prevent the reduction of circularity, non-uniformity of the Mo concentration, and hence the precipitation of unknown phase. can do.

  Further, in such a Co—Cr—Mo fine wire, it is desirable that the concentration of each element is uniform. This makes it easy to obtain a structure consisting essentially of only one or both of the γ-phase and ε-phase, and a Co—Cr—Mo-based fine wire having excellent ductility and thus excellent workability can be obtained. Further, by setting the circularity to 0.7 or more, it is possible to obtain a Co—Cr—Mo type fine wire that is more flexible.

  Next, since the first method for producing the Co—Cr—Mo fine wire of the present invention is based on the spinning in a rotating liquid, the circularity of the cross section is reduced to 0. 0 based on the knowledge of the inventors described above. It can be set to 6 or more, and sufficient flexibility of the thin wire can be ensured. According to this manufacturing method, as described above, the excellent biocompatibility that is the original characteristic of the alloy is ensured, and the corrosion resistance, wear resistance, and workability are improved by optimizing the internal structure and fine wire diameter. Co-Cr-Mo-based fine wires rich in carbon can be obtained.

  In addition, since the second method for producing the Co—Cr—Mo fine wire of the present invention is based on the melt spinning method in gas, the circularity of the cross section is set to 0.7 by the knowledge of the inventors described above. As described above, higher flexibility can be ensured as compared with the first manufacturing method. In addition, regarding the biocompatibility, the corrosion resistance, the wear resistance, and the workability, excellent effects can be obtained as in the first manufacturing method.

  Furthermore, since the third method for producing the Co—Cr—Mo fine wire of the present invention is also based on the melt spinning method in gas, the circularity of the cross section can be set to 0.7 or more. High flexibility can be ensured similarly to the manufacturing method 2. Further, as to biocompatibility, corrosion resistance, wear resistance, and workability, excellent effects can be obtained as in the first and second manufacturing methods.

  Here, when the production method by the spinning in a rotating liquid is compared with the production method by a gas melt spinning method, the production method by the gas melt spinning method is more likely to obtain a finer wire with higher circularity. Explain why. That is, in the former case, the molten alloy jet enters the rotating cooling liquid layer before solidifying and is easily flattened when the molten alloy jet is bent in the traveling direction of the cooling liquid. On the other hand, in the latter case, solidification proceeds while self-correcting the circularity with the surface tension of the molten alloy jet during the air flight until the molten alloy jet that falls linearly solidifies. For this reason, it is considered that there is a difference in circularity between thin wires produced by both spinning methods.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, when manufacturing the Co—Cr—Mo type fine wire, the apparatus shown in FIG. 1 was used when the melt spinning method in gas was used. Specifically, as shown in the figure, the alloy raw material is heated and melted in a crucible having a nozzle at the tip, and the molten alloy jet ejected from the nozzle is solidified by cooling with helium gas and oxygen gas. And wound up with a winding drum. On the other hand, when utilizing the spinning in-rotating method, an ordinary apparatus as described in Patent Document 3 was used. The circularity is a value calculated from an arbitrarily selected minor axis and major axis.

<Production Example 1>
Fine wires having representative diameters of 70 μm, 100 μm, 150 μm, and 280 μm were obtained from each alloy having a blend composition of Co-29 mass% Cr- (8, 12, 16) mass% Mo by melt spinning in gas. The obtained thin wire has a circularity of 0.8 to 0.9 and can be bent and deformed by 90 ° or more, and its internal structure is within the scope of claim 1 of the present application, that is, substantially γ phase (surface It was satisfied that it consisted of only one or both of a cubic cubic Co-based solid solution) and an ε-phase (hexagonal dense Co-based solid solution).

  Here, a reflection electron beam image (hereinafter, referred to as “composition image”) of an electron microscope of a transverse section of a fine wire having a representative diameter of 100 μm of Co-29 mass% Cr-8 mass% Mo was taken. The result is shown in FIG. The resulting fine wire structure is relatively uniform and has almost no compositional irregularity, and has a minor axis of 98 μm and a major axis of 103 μm. Therefore, the circularity is 0.95, which is within the preferred range of the present invention. FIG. 3 shows the results of X-ray (Co—Kα) diffraction measurement of this fine wire. From this, it can be seen that the internal structure consists essentially of both the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal close-packed Co-based solid solution). Further, it was confirmed that the thin wire can be bent and deformed by 90 degrees or more. As described above, in the fine wire of Production Example 1, the phases other than the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal dense crystal Co-based solid solution) are X-ray (Co-Kα) diffraction. It is understood that it cannot be judged depending on.

<Production Example 2>
Representative diameters of 120 μm, 150 μm, and 180 μm from each alloy having a blending composition of Co-27 mass% Cr- (10,14) mass% Mo by a spinning in-rotating method in which the speed of the molten metal jet and the speed of the rotating drum are made equal. A thin wire of 280 μm was obtained. The obtained thin wire has a circularity of 0.6 to 0.8 and can be bent and deformed by 90 ° or more. The internal structure of the thin wire is substantially γ phase (face-centered cubic) as a result of X-ray diffraction measurement. Crystal-based Co-based solid solution) and ε phase (hexagonal close-packed Co-based solid solution). As described above, in the fine wire in Production Example 2, the phases other than the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal dense Co-based solid solution) are X-ray (Co-Kα) diffraction. It is understood that it cannot be judged depending on.

<Production Example 3>
An alloy lump was obtained by casting from an alloy having a composition of Co-29 mass% Cr-8 mass% Mo. The obtained alloy lump clearly separated into an Mo high-concentration phase (light-colored portion) and a low-concentration phase (dark-colored portion) as in the composition image shown in FIG. Further, FIG. 5 shows the results of X-ray (Co—Kα) diffraction measurement of this alloy lump. From this, it can be seen that the internal structure contains an unknown phase other than the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal dense Co-based solid solution). Moreover, it was difficult to produce a thin wire having a diameter of 300 μm from the cast material by wire drawing.

<Production Example 4>
A thin wire having a diameter of 550 μm was obtained from an alloy having a composition of Co-29 mass% Cr-8 mass% Mo by spinning in a rotating liquid. The thin wire thus obtained had a circularity of 0.3 to 0.6 and could not be bent more than 90 degrees. The internal structure contained phases other than the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal dense Co-based solid solution).

  As described above, according to the present invention, the corrosion resistance, wear resistance, and processing are ensured by optimizing the internal structure and the fine wire diameter while ensuring the excellent biocompatibility that is the original characteristic of the Co-Cr-Mo alloy. Co-Cr-Mo type fine wires rich in properties and flexibility can be obtained. Therefore, the present invention can be applied to various medical implant devices.

It is the schematic which shows the apparatus used when manufacturing a Co-Cr-Mo type | system | group thin wire | line by the melt spinning method in gas. It is a cross-sectional composition image of Co-29 mass% Cr-8 mass% Mo fine wire manufactured by the melt spinning method in gas. It is an X-ray diffraction pattern of Co-29 mass% Cr-8 mass% Mo fine wire manufactured by melt spinning in gas. It is a composition image of the cast Co-29 mass% Cr-8 mass% Mo lump. It is an X-ray-diffraction pattern of the cast Co-29 mass% Cr-8 mass% Mo lump.

Claims (12)

  Cr: 26 to 31% by mass, Mo: 8 to 16% by mass, the balance is a fine wire having a diameter of 300 μm or less composed of Co and inevitable impurities, and the circularity (= minor axis / major axis) of the cross section is 0. 6 or more, characterized in that the internal structure is composed of only one or both of γ phase (face-centered cubic Co-based solid solution) and ε phase (hexagonal close-packed Co-based solid solution). Co-Cr-Mo thin wire.   The Co-Cr-Mo type fine wire according to claim 1, wherein the circularity of the transverse section is 0.7 or more.   The cooling liquid layer formed along the inner peripheral surface of the rotating cylindrical drum contains Cr: 26 to 31 mass%, Mo: 8 to 16 mass% through a nozzle having a diameter of 300 μm or less, and the remainder is By jetting a molten alloy consisting of Co and inevitable impurities, the diameter is 300 μm or less, the circularity of the cross section (= minor axis / major axis) is 0.6 or more, and the internal structure is γ phase (surface A method for producing a Co-Cr-Mo type fine wire, characterized in that a fine wire comprising only one of or both of a centric cubic Co-based solid solution) and an ε phase (hexagonal dense Co-based solid solution) is obtained. .   A molten alloy containing Cr: 26 to 31% by mass, Mo: 8 to 16% by mass, the balance being Co and inevitable impurities is injected from a spinning nozzle having a diameter of 300 μm or less, and the injection jet is cooled in a cooling gas. By solidifying, the diameter is 300 μm or less, the circularity of the cross section (= minor axis / major axis) is 0.7 or more, and the internal structure is γ phase (Co-based solid solution of face-centered cubic crystal) and ε A method for producing a Co-Cr-Mo type fine wire, characterized in that a fine wire comprising only one of the phases (a hexagonal dense crystal Co-based solid solution) or both of them is obtained.   Spinning with a diameter of 300 μm or less forming a molten jet by jetting downward in a form of dropping a molten alloy containing Cr and 26 to 31% by mass, Mo: 8 to 16% by mass and the balance consisting of Co and inevitable impurities. A nozzle, a gas rectifying cylinder arranged in a form surrounding the molten metal drop path, cooling gas introducing means for introducing a cooling gas for solidifying the molten jet into the gas rectifying cylinder, and the molten jet By using discharge means for discharging the thin wire obtained by solidification from the gas rectifying cylinder to the outside, the diameter is 300 μm or less, and the circularity (= minor axis / major axis) of the cross section is 0.7 or more And a thin wire whose internal structure is composed of only one or both of the γ phase (face-centered cubic Co-based solid solution) and the ε phase (hexagonal dense Co-based solid solution). Co-Cr-Mo-based method for producing a fine wire to symptoms.   The method for producing a Co-Cr-Mo fine wire according to claim 4 or 5, wherein the cooling gas is an oxygen-containing gas.   The cooling gas includes a first gas component composed of an inert gas introduced into the gas rectifying cylinder at a first position near the spinning nozzle in the falling direction of the molten jet, and the first position. A second gas component made of an oxidizing gas introduced into the gas rectifying cylinder at the second lower position, and introduced into the gas rectifying cylinder at the third position below the second position. The method for producing a Co—Cr—Mo fine wire according to claim 5, further comprising a third gas component having a higher cooling capacity than the first and second gas components.   The method for producing a Co-Cr-Mo fine wire according to claim 7, wherein the first gas component is argon or helium, and the second gas component is oxygen or carbon dioxide gas.   A planar body formed by weaving, knitting, or non-woven processing the Co—Cr—Mo fine wire according to claim 1.   A cylindrical body formed by weaving, knitting or non-woven processing the Co—Cr—Mo fine wire according to claim 1. A twisted wire made of the Co-Cr-Mo fine wire according to claim 1 or 2.   A cable comprising the Co—Cr—Mo thin wire according to claim 1.

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