KR20060101715A - Production method of ti-base alloy with low elastic modulus and excellent bio-compatibility - Google Patents

Abstract

The present invention is based on the total alloy weight, 10-30 at% of niobium (Nb), an alloy element having excellent biocompatibility without cytotoxicity, 0.1-2 at% of silicon (Si), oxygen (O) and other Provides a titanium-based alloy material consisting of a residual amount of titanium (Ti) remaining in the invasive element within 0.5 at% range,

Since it does not contain any alloying elements pointed to cytotoxicity, it is excellent in biocompatibility, and can be used as a more stable biomaterial, and it is possible to have an elastic modulus close to the elastic modulus of bone, thereby making it possible to use titanium for conventional biomaterials. Low elastic modulus titanium-based alloy material with excellent biocompatibility that can maximize the possibility of use as implant for next-generation biomaterials by preventing adverse effects such as bone osteoporosis or reoperation caused by stress shielding phenomenon by using alloy It is about.

Biomaterial, low modulus, biocompatibility, titanium alloy

Description

Production method of Ti-base alloy with low elastic modulus and excellent bio-compatibility

1 is a photograph showing stress shielding phenomena exhibited by high modulus implants and low modulus implants, respectively.

2 is a table for determining the cytotoxicity of known metals,

3 is a microstructure photograph of the alloy of the present invention,

Figure 4 is a graph showing the X-ray diffraction analysis of the alloy of the present invention.

Table 1 is a table comparing the mechanical properties of the titanium alloy having a low modulus of elasticity and the conventional titanium alloy according to the prior patent registration No. 303612.

Table 2 is a table showing the mechanical properties of the titanium alloy of the present invention and the conventional alloy and the alloy according to the prior patent.

Table 3 is a comparison table of the elastic modulus of the titanium alloy of the present invention and the conventional biomedical titanium alloy developed in various countries.

The present invention relates to a titanium-based alloy material suitable for artificial biomaterials such as artificial bones, artificial joints, artificial teeth, etc., which can repair bones, joints, teeth, etc., which have lost function, and include titanium (Ni), niobium (Nb), The present invention relates to a low elastic modulus titanium-based alloy material having excellent biocompatibility, excellent mechanical properties and corrosion resistance, and a low modulus of elasticity formed by complex addition of silicon (Si).

As the life span of human beings is significantly extended with the development of scientific and technological civilization, researches to understand life phenomena such as medicine and biotechnology are rapidly developing, and degenerative due to the causes of stress and obesity, which can be called modern diseases. Artificial bones, artificial joints, and artificial teeth ( hereinafter referred to collectively as implants) are referred to as arthritis progressing or damage to body bones, joints, etc. due to various accidents, and the like . When the tissue of the human body is lost, it refers to a substitute for restoring it, which is commonly used as an artificial tooth type in dentistry, but in the present invention, it will be collectively referred to as an implant by the original meaning. Frequently, it is well known.

Therefore, the implant to be used for the bioskeletal replacement should function while harmonizing with the surrounding tissues of the living body. In other words, biomaterials must be functionally safe and nontoxic in vivo, and in order to meet these requirements, artificial biomaterials have appropriate physical properties and are free of foreign body reactions such as cytotoxicity and allergic reactions, It should be stable and good for biological tissue. Therefore, the selection of implants by superior biomaterials has a great influence on the success and prognosis of artificial teeth or joints, so the development and selection of the correct biomaterials is very important for transplantation.

As an alloy material for biotransplantation, in the past, stainless steel and cobalt alloys such as STS 316L were used as a prominent artificial joint alloy until titanium's superiority was known. Dissolved metal ions spread through the blood and cause various diseases, and a fibrous coating is formed on the surface of the implant due to a foreign body reaction phenomenon when a implant made of a non-active metal and a bioinert material is inserted into the body. It is formed and isolated from the tissue of the body, and separated from the graft site over time after the procedure is easy to fall out, and these implants are considerably stronger than human bones, so destroying the surrounding bone tissue loosening the graft site Problems such as reoperation were noted.

In order to solve this problem as the superiority of titanium was proved, pure titanium and Ti-6Al-4V materials were initially used in vivo, but the possibility that Al can cause dementia in humans and the cytotoxicity of V are known. Development of new alloys has been attempted.

Therefore, titanium alloys containing zirconium (Zr), niobium (Nb), tantalum (Ta), palladium (Pd), and indium (In) in addition to titanium are invented. It has been filed with the Korean Patent Office under the name of biocompatible titanium-based alloy with excellent suitability, and registered as a patent No. 211097.

However, Ti-20Zr-3Ta-0.2Pd-1In alloy of the patent No. 211097 has a corrosion rate of 0.29 MPA, which still lacks mechanical properties and corrosion resistance, and there is no mention of the elastic modulus of the alloy. Many of these titanium alloys, which have been completed or under development, have a higher elastic modulus than the elastic modulus of body bones.

Meanwhile, in the case of Patent Registration No. 303612, filed with the Korean Intellectual Property Office, 3 to 20% by weight of indium (In), 1 to 5% by weight of niobium (Nb), 1 to 5% by weight of tantalum (Ta), 0.1 An alloy having physical properties and modulus of elasticity as shown in Table 1, consisting of ˜0.5% of palladium (Pd) and residual amount of titanium (Ti), is proposed.

TABLE 1

 Comparison of Mechanical Properties of Alloys of Patent 303612 and Conventional Alloys alloy Furtherance Hardness (Hv) Tensile Strength (MPa) Modulus of Elasticity (E / GPa)  Patent No. 303612 Alloy Ti-17.4In-4Nb-4Ta-0.2Pd 305.5 1125 91 Ti-13.1In-4Nb-4Ta-0.2Pd 301.8 838 99 Ti-9.1In-4Nb-4Ta-0.2Pd 297 801 104.9 Ti-4.5In-4Nb-4Ta-0.2Pd 238.6 692 94.4 Conventional alloy Pure Ti 166.5 550 110 Ti-6Al-4V 358.3 1166 116

As shown in Table 1, the prior patent provides a titanium alloy containing only elements that are harmless to the human body, and its elastic modulus is similar to that of Ti-6Al-4V, which is used as a conventional alloy, and contains harmful elements to the human body. It was developed as a replacement for conventional alloys.

Here, when considering that the bone elastic modulus of the human body is 10 ~ 40GPa, the elastic modulus of the alloy according to the prior patent is 91 ~ 104.9GPa, and thus has an elastic modulus of about 2.5 to 10 times, the stress shielding phenomenon It can be seen that there is a possibility of occurrence.

To describe the problem pointed out in more detail, the artificial hip and the knee joint should be used for a long time after being implanted in human biological tissues, and the fatigue life should be long and the fatigue life should be long because the fatigue load is applied for a long time. Wear resistance between the femoral head and Acetabular cup should be excellent, and even if the implant is used for a long time, the stress shiding, which is the cause of the deterioration of bone, should be suppressed. Problems and the like are well known.

In this case, the present invention is a particularly important problem to solve the present invention is to provide a titanium alloy material having a low modulus of elasticity similar to the bone in the human body to reduce the stress shielding phenomenon.

Stress shieding of implants is caused by the difference in elastic modulus between bones with low modulus of 10-40 GPa and implants with higher modulus.

The difference in the elastic modulus of the bone and the implant will change the stress distribution in the bone that has been reshaped around the implanted implant, bearing the stress that the implant with high modulus must be transferred to the bone. As such, when the tension, compression, and bending moments of the body's bones do not work for a long period of time, the thickness and weight of the bones decrease, causing osteoporosis around the implants. It weakens and eventually leads to the problem of having to re-insert the implant.

This problem also appears in the case of the Republic of Korea Patent 303612.

1 is a photograph showing the results as described above published in the Journal of Biomechanics in 1998, when the cortical bone tissue present in the area close to the femoral region of the implant having a low modulus of elasticity (Fig. 1a) almost the density of the cortical bone tissue On the other hand, in the case of an implant having a high modulus of elasticity (FIG. 1B), it can be seen that the cortical bone tissue is largely damaged. In addition, looking at the end of the implant is also found in the case of an implant having a high modulus of elasticity (Fig. 1b) hypertrophy of the bone marrow tissue.

U. Simon et al. Also reported that implants with low and high modulus were implanted into sheep bones and compared with the results of FEM calculations, indicating that implants with low modulus exhibit uniform stress distribution. Although efforts have been made to develop alloy materials that lower the elastic modulus of implants, in the case of alloys developed by the prior art as described above, existing Ti-6Al-4V alloy elastic modulus ranges far exceed the bone elastic modulus. And it has a mechanical property, but made of only an element harmless to the human body was invented to replace the existing alloy, it is difficult to see a complete solution such as the above-mentioned stress shielding phenomenon.

Therefore, when the researchers added niobium (Nb) and silicon (Si) to a known titanium (Ti) group among the harmless elements of the human body, the researchers have an elastic material similar to that of bone in the human body and have excellent mechanical properties. Led to develop.

Therefore, an object of the present invention is to remove the harmful elements to the human body of the elements added to the titanium as an alloying material, and to have a modulus of elasticity similar to the human bone and at the same time to be added to only the elements harmless to the human body as an important problem. The purpose of the present invention is to provide a titanium-based alloy material for biomaterials having excellent stress shielding prevention and mechanical properties.

The present invention for achieving the above object,

Niobium (Nb) 10-30 at%, silicon (Si) 0.1-2 at%, oxygen (O) and other invasive elements It provides a low elastic modulus titanium-based alloy material with excellent biocompatibility remaining in the range of 0.5 at% and consisting of the remaining amount of titanium (Ti).

Niobium (Nb) adopted in the present invention was added as an element for improving the workability of the titanium alloy in a composition range of 10 to 30% relative to the total 100 at%.

Niobium (Nb) is known as a metal element having excellent biocompatibility because it not only has excellent corrosion resistance in the biomolecules with titanium (Ti) but also does not deleteriously react with corrosion products, fibrous cells, and biological fluids.

Figure 2 is a diagram of what is widely known by investigating the cytotoxicity of metal elements, Fe, Co, Bi, Ag, Sr, Mg, V, Cu, Zn, Cd, Zn, Cd, Hg and the like is more cytotoxic It is known to be strong, and Ti, Nb, Si and other alloying elements Ta, In, Zr, Sn, Cr, Au and the like which constitute the present invention are known to be cytotoxic.

In general, the titanium alloy has a fraction of the α and β phases depending on the amount of α stabilizing element and β stabilizing element. Since the β phase is more workable than the α phase, the titanium alloy of niobium (Nb) By adding it as an alloying element to expand the β-phase region, the workability of the alloy can be improved.

In particular, the β-titanium alloy has many advantages, such as heat treatment, hardenability and increase of elongation due to BCC structure, and excellent fracture toughness, as compared with α + β alloy. By adding a third β-stabilizing element to lower the β transformation, the BCC structure is maintained at a stable temperature at room temperature. As the β-stabilizing element, in the present invention, the above-described niobium (Nb), which corresponds to β-isomorphous, And silicon (Si) belonging to β-Eutectoid was added to obtain the titanium alloy of the present invention.

Here, in the case of silicon (Si), the addition of about 0.5 at% reduces the stacking defect energy of the titanium alloy to limit the cross slip, thereby significantly reducing the movement of dislocations (S. Amelinckx; The direct observation of dislocations, Academic Press, New York, (1964), 381) It is known to be very effective in improving the high temperature creep strength of titanium alloys and to have a significant effect on the microstructure and static strength.

However, such silicon (Si) is limited in the addition of the semi-α alloy, because the change in the microstructure to reduce the elongation during long-term use occurs in the present invention in view of such characteristics, in the present invention The content of silicon (Si) was limited to within 0.1 to 2 at%.

In addition, by controlling the addition amount of oxygen (O) and other invasive elements within 0.1 ~ 0.5 at% to control the phase stability.

Here, oxygen (O) has a property of enhancing emphasizing β phase and not embrittlement.

After dissolving each element alloy having such a composition ratio, the elasticity of the titanium alloy is obtained by aging heat treatment through one of the heat treatment methods selected from quenching, water cooling, air cooling, and furnace cooling from a high temperature to a low temperature within a predetermined range within a predetermined time range. A low modulus titanium alloy material having a modulus similar to the elastic modulus of bone in the human body was obtained.

The titanium alloy developed by the researchers of the present invention has a low modulus of elasticity and at the same time gives superelastic and shape memory characteristics by fine adjustment of heat treatment conditions, and can be rolled, extruded and drawn at room temperature. It will be described a method of producing a low elastic modulus titanium-based alloy material excellent in biocompatibility of the present invention to enable the production of plate, wire, mold.

The titanium-based alloy of the present invention is first quantified by dissolving each alloying component in a predetermined amount satisfying the alloy composition of the present invention as described above and dissolved in the melting furnace.

The titanium alloy composition ratio of the present invention is as follows.

Ti _a -Nb _b -Si _c -X _d

Where a, b, c, and d are all atomic percent, and the detailed alloy composition ranges are b: 10 to 30 at% and c: 0.1 to 2 at%.

In the above titanium alloy, X is in addition to titanium (Ti), niobium (Nb) and silicon (Si) in order to control phase stability as described above, oxygen (O) and other invasive elements within the range of 0.1 to 0.5 at%. It is present and forms titanium (Ti) in the remaining amount excluding niobium (Nb), silicon (Si), oxygen (O) and other invasive elements.

The alloying element thus formed is melted and treated in a melting furnace of an inert gas atmosphere having an atmosphere such as argon gas or nitrogen gas by a conventional vacuum arc melting, vacuum induction melting, vacuum skull melting method or the like.

Then, after the water-cooled heat treatment at a cooling rate of 100 ℃ / sec for 30 minutes to 2 hours in a low temperature region of -50 ℃ to 50 ℃ in a high temperature region of 700 ℃ ~ 1200 ℃, 50 ~ 500 It is obtained by aging heat treatment for 30 minutes to 2 hours in the temperature range of ℃.

Aging heat treatment is generally known to precipitate a fine equilibrium α phase on the supersaturated β phase matrix of martensite formed by quenching to improve the strength of the alloy. As determined by the strength, you will typically choose a temperature and time that will not overage.

Aging heat treatment conditions in the present invention showed that the above-mentioned temperature and time have the most appropriate strength required by the present invention.

On the other hand, in the case of water-cooled heat treatment, but 30 minutes to 2 hours in the high temperature region of 700 ~ 1200 ℃ air-cooled or in the high temperature region of 700 ~ 1200 ℃ to -50 ℃ ~ 50 ℃ low temperature region After the low temperature heat treatment at a cooling rate of 10 ° C./sec or less, a titanium alloy having the same mechanical properties according to the present invention was obtained even by aging heat treatment under the same conditions.

Table 2 shows the mechanical properties of the titanium alloy of the present invention, the conventional alloy and the alloy according to the prior patent

 Comparison of Mechanical Properties of Alloys According to the Present Invention and Conventional Alloys Alloy Furtherance Hardness (Hv) Tensile Strength (MPa) Modulus of Elasticity (E / GPa) Invention alloy Ti _a -Nb _b -Si _c -X _d 220 ~ 300 300-600 45-55 Conventional alloy Pure Ti 110-180 240-440 100-120 Ti-6Al-4V 340-400 830-1200 105-116 Patent No. 303612 Ti-In-4Nb-4Ta-0.2Pd 238.6 ~ 305.5 692-1125 91-104.9

(In of the composition of the prior patent 303612 In is within the range of 9.1 to 17.4 at%.)

As shown in Table 2, the modulus of elasticity of the titanium alloy obtained by the present invention is within the range of 45 to 55 GPa, and it has a significant low modulus when compared to other alloys, and the elastic modulus of bone is 10 to 40 GPa. A close result was obtained.

Therefore, when the low-elastic titanium-based alloy material is used as an implant in the present invention, it is biocompatible as an artificial biomaterial such as artificial bones, artificial joints, artificial teeth, etc., which can repair bones, joints, teeth, etc., in which the function of the body is lost. It is excellent, can prevent the stress shielding, etc. When compared with the existing biomaterials, hardness and tensile strength, etc. are in a similar range, it has a value as a fairly suitable new material.

In addition, Table 3 is a table comparing the mechanical properties of the low-elastic modulus titanium alloy according to the present invention and the biomedical titanium alloy currently developed and released in various parts of the world.

TABLE 3

 alloy  Microstructure  Modulus of elasticity (GPa)  Developing country The present invention (Tia-Nbb-Sic-Xd) β 45-55 Ti-6Al-7Nb α + β 114 Swiss Ti-5Al-2.5Fe α + β 112 Germany Ti-15Sn-4Nb-2Ta-0.2Pd α + β 89-103 Japan Ti-15Zr-4Nb-2Ta-0.2Pd α + β 94-99 Japan Ti-13Nb-13Zr near β 79-84 United States of America Ti-12Mo-6Zr-2Fe β 74-85 United States of America Ti-15Mo β 78 United States of America Ti-16Nb-10Hf β 81 United States of America Ti-15Mo-5Zr-3Al β 80 Japan

As shown in Table 3 above, when comparing the elastic modulus of the biomedical titanium alloy currently developed in each country and the elastic modulus of the titanium alloy developed by the present researchers, the titanium alloy produced by the present invention has an elastic modulus of bone. Results closest to.

In addition, in the case of the low-elasticity titanium alloy produced by the present invention, the shape of the low-elasticity titanium alloy can be formed through a conventional processing method such as rolling, extrusion, drawing in the form of a wire rod, a bar rod, and a plate as needed.

Therefore, the titanium-based alloy for biomaterials according to the present invention is excellent in biocompatibility using an alloying element having no cytotoxicity, and has an effect of being usable as a more stable biomaterial.

In addition, the titanium alloy according to the present invention can have an elastic modulus close to the elastic modulus of the bone, such as osteoporosis of the bone due to the stress shielding phenomenon according to the use of the conventional titanium alloy for biomaterials, re-treatment due to this By preventing the adverse effects of the can be expected to maximize the potential for use as a next-generation biomaterial implant.

Claims (2)

10-30 at% of niobium (Nb), 0.1 to 2 at% of silicon (Si), oxygen (O) and other invasive elements, which are alloy elements having excellent biocompatibility with unknown cytotoxicity based on total alloy weight Low elastic modulus titanium-based alloy material having excellent biocompatibility, which remains in the range of 0.5 at% and consists of the remaining amount of titanium (Ti). A process of dissolving an alloying element having the composition ratio of claim 1 in a melting furnace of an inert gas atmosphere by a conventional dissolving method or the like; 30 minutes to 2 hours in the high temperature range of 700 ℃ to 1200 ℃ 30 minutes to 2 hours in the low temperature region of -50 ℃ to 50 ℃ Water-cooled heat treatment at a cooling rate of 100 ℃ / sec, 30 minutes to 2 hours in the high temperature region of 700 to 1200 ℃ Heat-treatment process for selecting any one of air-cooling heat treatment, furnace cooling heat treatment at a cooling rate of 10 ° C./sec or lower from a high temperature range of 700 to 1200 ° C. to a low temperature range of -50 ° C. to 50 ° C., The method for producing a low elastic modulus titanium-based alloy material having excellent biocompatibility consisting of the heat treatment of the heat-treated alloy material for 30 minutes to 2 hours in a temperature range of 50 ~ 500 ℃.

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