KR102150326B1 - Method for surface treatment of biocompatible affinity metal material - Google Patents

Abstract

A method of surface treatment of a biological tissue-friendly metal material has been disclosed so that it can be firmly fixed to a bone in a short time when placed in a human body.
The disclosed method includes the steps of making the surface of the metal material uneven through a low voltage anodization process on the metal material; Heat-treating the uneven-treated metal material in a high-temperature inert gas atmosphere; And forming hydroxyapatite on the surface of the metallic material through circulating calcification treatment in which the heat-treated metallic material is repeatedly deposited in the biomaterial.

Description

Method for surface treatment of biocompatible affinity metal material

The present invention relates to a method for surface treatment of a biological tissue-friendly metal material, and more particularly, to a method for surface treatment of a biological tissue-friendly metal material so that it can be firmly fixed to a bone in a short time when placed in a human body.

Today, when bones in the human body are damaged, such as tooth defects and hip joint damage, implant surgery is performed to replace them with metal biomaterials. In this regard, it is important that the implant is stable and accurately bonded to the living tissue. For example, a dental implant is a structure made of a biocompatible material that semi-permanently replaces a missing tooth, and must be firmly placed in the bones of the human body. That is, when implanted into a living body, a material having very excellent biocompatibility with respect to a living body should be selected, and a material having no biochemical side effects with the existing living tissue should be selected.

Currently, some ceramics and polymer materials are used in the dental treatment field, but the most widely used metal as an artificial tooth root material is titanium or titanium alloy, which has excellent mechanical properties, corrosion resistance, and biocompatibility. On the other hand, when the titanium alloy is embedded in a living body, a new fibrous soft tissue is formed over a long period of time over its surface layer, and thus it takes a long time to fix the implant material.

In view of this, technologies are being developed to improve the affinity with bone and to reliably fix the artificial tooth root in a short time by performing a surface treatment on a metal implant material. In other words, technology to fix the bone firmly by making the surface of the material uneven and penetrating the bone component into the inside of the uneven with the anchor effect, and the technology to promote bone formation by coating the surface with a material having strong adhesion to the bone were developed. Has become. In particular, studies have been disclosed to increase biocompatibility and shorten the osseointegration period by coating the surface of a metallic material with hydroxyapatite through various methods.

Korean Patent Application Publication No. 10-2011-0058000

The present invention was invented in view of the above points, and a method for surface treatment of a biological tissue-friendly metal material having an improved structure to have excellent bonding strength with human bones by optimizing the process of unevenness and hydroxyapatite formation of metal materials Its purpose is to provide.

In order to achieve the above object, a method for surface treatment of a biological tissue-friendly metallic material according to the present invention includes the steps of: making the surface of the metallic material uneven through a low voltage anodizing process on the metallic material; Heat-treating the uneven-treated metal material in a high-temperature inert gas atmosphere; And forming hydroxyapatite on the surface of the metallic material through circulating calcification treatment in which the heat-treated metallic material is repeatedly deposited in the biomaterial.

Here, the metallic material may be made of at least one material selected from the group consisting of chromium, nickel, magnesium, stainless steel, tantalum, titanium, titanium alloy, nickel-titanium (Nitinol) alloy, and cobalt-chromium alloy.

In addition, the metallic material may be made of a Ti ₆ Al ₄ V ELI alloy material, and the surface roughness may have a surface roughness of 0.1 to 0.25 μm.

In addition, the step of unevenly making the surface of the metallic material includes: accommodating the metallic material in an aqueous electrolyte solution in which ammonium fluoride and water are added to ethylene glycol; After forming a metal oxide layer on the surface of the metal material, including applying a DC power of 20 to 60 Volts for 1 to 4 hours, irregularities having a nanotube structure having a predetermined diameter may be formed. The content of H ₂ O (water) in the aqueous electrolyte solution may be 2 to 8 vol%. And the DC power supply can have a current density of 10 ~ 30mA / cm ² .

In addition, the heat treatment step of the uneven-treated metal material may be performed by heat treatment at a high temperature of 600° C. or higher in an argon (Ar) gas atmosphere, thereby stabilizing the structure of the anodized metal material and removing impurities.

Here, the biomaterials include a first sodium phosphate aqueous solution and a saturated calcium hydroxide aqueous solution, and the circulating calcification treatment is a method of alternately depositing the metallic material in a first sodium phosphate aqueous solution and a saturated calcium hydroxide aqueous solution. Ca-P) can be precipitated to increase bioactivity.

In the method for surface treatment of a biological tissue-friendly metallic material according to the present invention, hydroxyapatite is formed in the uneven portion through circulating calcification in order to improve the surface irregularities and bioactivity of the metallic material. Here, by optimizing the roughness of the metallic material, it is possible to form nanotube-shaped irregularities of uniform distribution when anodizing is performed on the specimen.

In addition, by optimizing the range of the DC voltage applied during the anodization, the holding time of the electrolysis, the components of the electrolyte and the amount of water added, the diameter and growth length of the nanotubes can be controlled, so that the uneven shape can be optimized.

In addition, the anodized metal material is crystallized by heat treatment at a high temperature in an inert gas atmosphere, so that the growth and proliferation rate of cells can be improved when embedded in the human body.

In addition, by circulating calcification treatment, hydroxyapatite having a more dense structure in the form of grains and clusters in the uneven portion can be deposited, thereby expanding the contact area, thereby improving the bonding strength with the bones of the human body when grafted to the human body. have.

1 is a schematic diagram showing an anodization system for a low voltage anodization process.
Figure 2 is a schematic diagram showing a TiO ₂ nanotube formation step.
3 is a SEM photograph of a nanotube after anodization of titanium in an ethylene glycol + 0.2wt% NH ₄ F + 2 vol% H ₂ O solution under a constant voltage of 60 V under a constant voltage of 60 V for 1 hour.
Figure 4 is a SEM photograph of a nanotube observation after anodizing titanium for 1 hour by varying the composition of NH ₄ F in an Ethylene glycol + NH ₄ F + 2 vol% H ₂ O solution under a 60V constant voltage condition.
5 is a SEM photograph of a nanotube after anodizing for 1 hour by varying the H ₂ O composition of ethylene glycol + 0.2wt% NH ₄ F + H ₂ O solution under 60V constant voltage condition of titanium.
6 and 7 are graphs showing changes in nanotube length and diameter according to the content of water.
8 and 9 are photographs showing a result of observing a change in the shape of a nanotube according to a voltage change.
10 is a SEM photograph showing the result of observing the change in the shape of the nanotube according to the change in current density.
11 is a graph showing the trend of the current density changing with the anodization time.
12 is a photograph of the surface and cross-section of a nanotube formed by anodizing in an electrolyte solution of ethylene glycol + 0.2wt% NH ₄ F + 2 vol% H ₂ O for a predetermined time.
13 and 14 are graphs showing changes in nanotube diameter and length according to the effect of time.
15 is a diagram of a phase change according to temperature and pressure of titanium dioxide.
16 is data obtained by analyzing XRD peaks by performing a small-angle scattering XRD test to investigate the crystallization of nanotubes before and after heat treatment.
17 shows a titanium specimen with nanotubes at 80° C. 0.5M Na ₂ HPO ₄ A diagram showing a method of circulating immersion in an aqueous solution and a saturated aqueous solution of 100℃ Ca(OH) _{2 for} 1 minute each.
18 is a SEM photograph of the surface of a specimen subjected to precipitation for 5 days in a biofuel solution (SBF) according to conditions.
19 is a circulating calcification treatment (CPT) treatment for 30 times each 1 minute in order to find out the HAp precipitation pattern according to the immersion time in the SBF solution, and then the immersion time in the SBF solution was 1 day, 3 days, 5 Photograph of observing the surface by SEM of the specimen inducing HAp precipitation by different days
20 is a graph showing the XRD diffraction patterns of specimens immersed in SBF solution after performing PT or CPT after heat treatment.

Hereinafter, a method for treating a surface of a biological tissue-friendly metallic material according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The method for surface treatment of a biological tissue-friendly metallic material according to an embodiment of the present invention consists of three steps.

The first step is a step of making the surface of the metal material uneven through a low voltage anodization process on the metal material, and the second step is a step of heat-treating the uneven-treated metal material in a high-temperature inert gas atmosphere. Step 3 is a step of forming hydroxyapatite on the surface of the heat-treated metal material.

Here, as the metal material, chromium, nickel, magnesium, stainless steel, tantalum, titanium, titanium alloy, nickel-titanium (Nitinol) alloy, cobalt-chromium alloy, and the like may be used. In the embodiment of the present invention, Ti6Al4V ELI (Extra Low Interstitials) alloy was used as the metal material. This Ti ₆ Al ₄ V ELI alloy has very similar properties when compared to Ti ₆ Al ₄ V, but as shown in Table 1, the composition table of the Ti ₆ Al ₄ V ELI alloy shows oxygen and nitrogen. , It is a low impurity alloy with low levels of carbon and iron. Therefore, since it has high strength, toughness and excellent corrosion resistance, it is mainly used as a metal material for living body used in human body such as surgical instruments or orthopedic artificial joints.

(wt %) Al V C Fe O N H Ti 6.0% 4.0% <0.03% <0.1% <0.10% <0.01% <0.003% Bal.

Metal surface Irregularities Step (Step 1)

1. Preparation of metal specimens

In this example, a Ti ₆ Al ₄ V ELI alloy plate having a thickness of 1 mm was cut into a size of 30 x 25 mm and used as a metal material for anodization.To make the surface of this metal material uniform, it was cleaned through the following cleaning process. Thus, an experimental specimen was prepared.

First, they were sequentially polished with #220 to #1000 silicon carbide (SiC) abrasive paper, ultrasonically cleaned in acetone and alcohol solution for 5 minutes each, and then washed again with deionized water. After that, in order to remove the surface oxide film, it is immersed in an aqueous solution containing hydrogen fluoride and nitric acid (HF + HNO ₃ + H ₂ O) for 10 seconds, followed by washing in the order of acetone, ethanol and distilled water, and finally prepare a specimen. .

2. Low voltage anodization process

The low voltage anodization process for the prepared metallic material may be performed in the anodization system as shown in FIG. 1. This anodization system may include a water bath 10, a power supply 11, a cooler 17 and a stirrer 19. The water tank 10 accommodates an aqueous electrolyte solution. The power supply 11 supplies DC power and has an anode and a cathode. The metal material specimen 13 may be electrically connected to the anode of the power source 11, and the platinum mesh net 15 may be electrically connected to the cathode. Here, the metallic material specimen 13 and the platinum mesh mesh 15 are positioned in the aqueous electrolyte solution to face each other with a predetermined distance apart. In this embodiment, a Ti ₆ Al ₄ V ELI alloy plate was used as the metallic material specimen 13, and the experiment was conducted in a state in which the metallic material specimen 13 and the platinum mesh net 15 were separated by 20 mm. The cooler 17 suppresses an increase in the temperature of the aqueous electrolyte solution.

In this embodiment, after the metal oxide layer is formed on the surface of the metal material specimen 13 using the above-described anodization system, irregularities having a nanotube structure having a predetermined diameter are formed. Here, as an aqueous electrolyte solution, ammonium fluoride (NH ₄ F) and water (H ₂ O) were added to ethylene glycol and used. That is, 0.2wt% NH ₄ F and 2vol% H ₂ O were added in ethylene glycol to experiment. In addition, through the power supply 11, a DC power of 20 to 60 Volts was applied for a predetermined period of time, and anodization was performed under the condition of a current density of 20 mA/cm ² .

Accordingly, a TiO ₂ layer is formed on the Ti ₆ Al ₄ V ELI alloy plate, and irregularities of a nanotube structure are formed. The mechanism of forming TiO ₂ nanotubes will be described with reference to FIG. 2. 2 is a schematic diagram showing a step of forming TiO ₂ nanotubes.

Local dissolution of the oxide layer formed on the titanium surface by the fluorine ions contained in the electrolyte results in the creation of small pores, resulting in a decrease in the local thickness of the coating layer, increasing the electric field strength at the bottom of the pores again, resulting in a new oxide layer. The nanotube layer is formed through a process that induces formation.

When the metal is anodized, a porous oxide grows with a characteristic behavior of several stages. That is, after a uniform oxide layer is formed on the metal surface at the initial stage of anodization, small pores are formed at the oxide/electrolyte interface, and pores are formed as they become wider. With the formation of pores, the dissolution of the oxide is accelerated. The chemical reaction formula for the formation of TiO ₂ nanotubes by anodic oxidation is shown in [Chemical Formula 1]. During the anodization of titanium metal, Ti ^{4 +} ions react with O ² ions contained in water to form an anodized film (refer to Equation (1)), and F-ions in the electrolyte have strong solubility generated by the reaction [ TiF ₆ ] ² complexes and H ⁺ ions increase simultaneously, increasing the chemical dissolution rate at the bottom of the pores, resulting in a porous structure (refer to Equation (2)). Therefore, Reaction Equation (1) can be considered to correspond to Fig. 2(a) as an oxide layer is formed, and Reaction Equation (2) can be considered to correspond to Fig. 2(b) as a process in which pores are formed.

Here, the effects of changes in surface state, electrolyte composition, voltage, current, and time on the growth behavior of the TiO ₂ nanotube array are as follows.

2.1 Effect of Titanium Roughness on the Shape of TiO ₂ Nanotubes

3 shows titanium in ethylene glycol + 0.2wt% NH ₄ F + 2vol% H ₂ O solution under 60V constant voltage conditions (a) raw material (average roughness 0.25㎛), (b) #220, (c) ) This is a photograph of observation of the upper part of the nanotube with HR FE-SEM after anodizing for 1 hour with different surface polishing conditions under the conditions of #600, (d) #800, (e) #1000. Until surface polishing with #1000 sandpaper, the partially uneven surface condition remains intact, and the height of TiO ₂ nanotubes is also uneven, but the roughness gradually improves, and the TiO ₂ has an almost uniform height when it reaches #1000. It shows the creation of nanotubes. In view of this, the surface roughness of the metallic material can be set to 0.1 to 0.25 µm.

2.2 Effect of composition ratio of electrolyte on TiO ₂ nanotube shape

FIG. 4 shows the composition of NH ₄ F in a solution of ethylene glycol + NH ₄ F + 2 vol% H ₂ O in titanium under 60V constant voltage conditions as (a) 0.2 wt %, (b) 0.4 wt %, and (c) 0.6 wt %. After anodizing for 1 hour, the upper part of the nanotube was observed with HR FE-SEM.

In (a), anodized with a composition of 0.2wt% NH ₄ F, the large diameter nanotubes are 130 nm, the small diameter nanotubes are about 111 nm, and the average diameter is 122.1 nm. Looking at (b) anodized with a composition of 0.4wt% NH ₄ F, the large diameter nanotubes are 131.4 nm, the small diameter nanotubes are about 120.9 nm, and the average diameter is 129.1 nm. Looking at (c) anodized with a composition of 0.6wt% NH ₄ F, the large diameter nanotube is 128 nm, the small diameter nanotube is about 109.7 nm, and the average diameter is 119.4 nm. The nanotubes were able to observe that small nanotubes were surrounded by large nanotubes. In the composition of 0.4 wt% or more, the reaction occurred more rapidly than the composition of 0.2 wt%, and it was confirmed that the surface layer having small pores shown in (a) disappeared. Therefore, the increase in the composition of NH ₄ F does not have a significant effect on the shape of the nanotube, but the increase of F ions in the initial reaction with the increase in the composition makes the decomposition of the nanotube layer more active than the formation of the nanotube layer (b), As shown in (c), it seems that the shape of the partially collapsed nanotubes was observed.

2.3 H in electrolyte ₂ O content is TiO ₂ Nano tube Effect on shape

Figure 5 shows the composition of H ₂ O in a solution of ethylene glycol + 0.2wt% NH ₄ F + H ₂ O in titanium under a constant voltage of 60V (a) 0 vol%, (b) 2 vol%, (c) 4 vol%, ( d) 6 vol% and (e) 8 vol%, after anodizing for 1 hour, the nanotubes were observed with a scanning electron microscope (HR FE-SEM).

The diameter and length of the nanotubes according to the water content are as shown in [Table 2].

Water content [vol%] 0 2 4 6 8 Diameter [nm] 68.26 70.65 85.27 89.04 92.61 Length [μm] 1.78 8.77 16.73 27.5 46.5

Looking at Table 2, it can be seen that the length of the nanotube increases from about 1.8 μm to about 46.5 μm under the same conditions as the water content increases.

6 and 7 are graphs showing changes in nanotube length and diameter according to water content. Referring to the drawings, it can be seen that the length and diameter of the nanotubes linearly increase as time increases.

The formation process of TiO ₂ nanotubes in titanium alloys usually occurs at the bottom of the pores. Although oxygen (O) atoms exist inside the ethylene glycol (C ₂ H ₆ O ₂ ) electrolyte, they are double bonded with carbon (C) atoms. It will not be able to smoothly supply oxygen from However, since O ₂ ions are supplied from OH ions generated from H ₂ O, it is relatively smooth and seems to form a good atmosphere for forming oxides. In addition, this influence affects the occurrence of projections on the tube wall in the formation of TiO ₂ nanotubes. As can be seen in Fig. 5(e), the shape of the protrusion of the tube wall can be observed. This is because when a certain amount of water is added to the electrolyte, a difference occurs in which the thickness of the oxide is thicker and thinner in the process of periodically repetitive strong dissolution and oxide formation, so protrusions are generated on the tube wall.

2.4 Effect of applied voltage and current on TiO ₂ nanotube shape

8 and 9 are photographs showing a result of observing a change in the shape of a nanotube according to a voltage change. The voltage was changed from 20V to 60V, and the anodic oxidation time proceeded for 1 hour. Referring to FIG. 8, it was observed that an oxide film was formed at a voltage of 50 V or less, and the color changed due to an interference effect due to a difference in refraction between incident light and reflected light according to the thickness of the oxide film on the surface. On the other hand, as shown in Fig. 9, no nanotubes were formed at a voltage of 50V or less.

On the other hand, it can be seen that as the voltage increases, the oxide film on the surface of titanium becomes thicker, so that the corners visible on the surface become blunt, and furthermore, as irregularities are formed, nanotubes are formed at 60V. That is, in order for nanotubes to be formed, when a certain voltage causing insulation breakdown is reached, oxide layer breakdown sites appear, and it can be seen that nanotubes are formed over the entire surface over time.

10 is a result of observing a change in the shape of a nanotube according to a change in current density, and is a photograph of observing a nanotube formed for 1 hour with a constant current density. The current density was varied from 10 to 30 mA/cm ² and the nanotube shape was observed. The chemical dissolution rate of the oxide layer is strongly influenced by H ⁺ ions supplied from water. Since the supply of ions varies depending on the current density, it was confirmed that the supply of ions was not smoothly performed below a certain current density, and thus nanotubes were not formed as shown in FIG. 10(a). On the other hand, in FIGS. 10(b) and 10(c), sufficient current was supplied to facilitate the supply of ions, so that nanotubes were formed. 11 is a graph showing a trend of current density that changes with anodization time. Section Ⅰ shows a behavior in which the current rapidly decreases as it reaches the applied voltage, and when the supplied current is constant and the voltage increases, the resistance increases according to Ohm's Law. This is the oxide layer when considering the dielectric properties of the oxide film. It can be seen that it is formed at the interface between this electrolyte and the metal. In the Ⅱ section, a breakdown site is randomly generated in the oxide film formed in the previous section. Pore is formed locally under the influence of F ^- ions in the electrolyte, and the current slightly increases due to the increase in surface area. This is the section in which the speed at which is reduced is noticeably reduced. In section III, the current density is stabilized, and the tube structure is formed by repetition of the dissolution action in the pores formed in the previous step and the formation of the oxide layer. Therefore, it seems that there is no significant change in the formation of nanotubes because the current density becomes constant as time goes into the stable section even if it increases above a certain current density.

2.5 Influence of electrolysis holding time (influence of growth time)

FIG. 12 is a photograph of a surface and a cross-sectional view of a nanotube formed by anodizing an electrolytic solution of ethylene glycol + 0.2wt% NH ₄ F + 2 vol% H ₂ O for a predetermined time. That is, each of FIGS. 12(a) to 12(f) shows the results of anodizing treatment for 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, and 16 hours.

Time [Hr] 0.5 One 2 4 8 16 Diameter [nm] 0 109.1 113.7 113.4 129.7 155.8 Length [μm] 0 13.2 18.89 25.6 56.9 114.9

The above results can be seen that the length of the nanotube increases from about 13 μm to about 114 μm as time increases.

13 and 14 are graphs showing changes in diameter and length of nanotubes according to the effect of time, respectively. Referring to FIG. 13, the length of the nanotube tends to increase linearly with increasing time, and referring to FIG. 14, it is confirmed that the nanotube diameter increases as time increases, then decreases again at a certain time, and then increases again. I can. This seems to be a phenomenon that occurs in the process of repeating the formation and destruction of nanotubes. However, when the length of the nanotube was 56.9㎛ or more, the nanotube layer was peeled off due to the stress generated when the nanotube was formed while the surface was dried. In view of this point, it is preferable to set the electrolysis holding time within 1 to 4 hours.

Structural stabilization heat treatment process of metallic materials (2nd step)

This is a process of heat-treating the uneven-treated metal material in a high-temperature inert gas atmosphere.

In this embodiment, the nanotube titanium dioxide (TiO ₂ ) layer is heat-treated in a rutile structure for effective growth of hydroxyapatite (hereinafter, referred to as'HAp') to promote structural stabilization and precipitation of HAp.

15 is a diagram of a phase change according to temperature and pressure of titanium dioxide. In consideration of FIG. 15, in order to heat treatment in a rutile structure, heat treatment at a high temperature of 600° C. or higher in an argon (Ar) gas atmosphere as an inert gas may be performed to stabilize the structure of the anodized metallic material and remove impurities. Specifically, put a metal specimen in a horizontal electric furnace, and make ultra-high purity Ar gas (99.999%) flow at 500ml/min, raise it to 650℃ at a heating rate of 10℃/min in an inert atmosphere, and then keep it at that temperature for 2 hours. Heat treatment can be performed.

The effect of the heat treatment process for structural stabilization and impurity removal of TiO ₂ after anodization is as follows.

FIG. 16 is data obtained by analyzing the XRD peak by performing a small angle scattering XRD (Small Angle X-ray Scattering Diffraction) test under the conditions of an acceleration voltage of 40 kW and a tube current of 30 mA using X-ray to investigate the crystallization of nanotubes before and after heat treatment. to be. First, only titanium metal peaks were observed in the specimen in which TiO ₂ nanotubes were formed on the titanium substrate by anodization. This means that the formed nanotubes are in an amorphous state. In the amorphous crystal structure, the XRD peak did not appear, but the Ti peak was also detected due to the thin oxide film thickness and the porous structure. On the other hand, in the specimens subjected to crystallization treatment on the titanium substrate with nanotubes in an argon atmosphere at 650°C for 2 hours, the diffraction angle 2Θ = 25° surface index 101, which is the main peak, in addition to the Ti peak, anatase phase was detected, and the diffraction angle 2Θ = The 37° plane index (004) and the diffraction angle 2Θ = 47° plane index (200) were also detected. At the diffraction angle 2Θ = 36° plane index 101, a rutile phase peak was detected. Therefore, TiO ₂ rutile (101) acts as the nucleus of HAp crystal growth, and the anatase structure has a negative charge value in SBF solution, so it absorbs Ca ions and Ca ions absorb PO43 ^- ions for the formation of HAp crystals. Accordingly, it seems that the growth of hydroxyapatite is promoted.

After the formation of the nanotubes, there is a problem that the nanotube layer falls off due to a peeling phenomenon that occurs during drying. In order to find the conditions to prevent this, the experiment was performed by varying the temperature of the nanotube formation process, the drying method in the washing process after formation, and the presence or absence of heat treatment as variables. In this experiment, the hardness and interfacial bonding strength of the nanotubes formed on the sample surface were measured using the pencil hardness measurement method of ASTM D 3363 in order to measure the change in hardness and bonding strength. For the measurement, three horizontal and vertical scribing tests were performed on the surface of the specimen to confirm the presence or absence of peeling of the surface layer. As a result, the effect of the test temperature and the presence or absence of heat treatment was not observed, but it can be observed that the hardness at which the surface peels off at a high drying temperature decreases.

Cyclic calcification treatment (third stage)

This is a step of forming hydroxyapatite (HAp) on the surface of the metallic material through circulating calcification treatment in which the heat-treated metallic material is repeatedly deposited in the biomaterial. The bio-eluent solution may include a first sodium phosphate (Na ₂ HPO ₄ ) aqueous solution and a calcium hydroxide (Ca(OH) ₂ ) saturated aqueous solution. The circulating calcification treatment can be repeated 10 or more times by alternately circulating metallic materials in a sodium phosphate (Na ₂ HPO ₄ ) aqueous solution and a saturated calcium hydroxide (Ca(OH) ₂ ) aqueous solution. It can be repeated once to 30 times.

A calcium phosphate layer was coated on the surface of the titanium alloy for the purpose of bioactivity. In order to increase the coating area, a nanotube TiO ₂ layer was formed on the surface of the titanium alloy by anodizing treatment to have a larger surface area. The thus-treated specimen was immersed in a 0.5 M Na ₂ HPO ₄ aqueous solution at 80° C. for 1 hour and a saturated aqueous solution of Ca(OH) ₂ at 100° C. for 30 minutes to perform precalcification treatment (PT). Cyclic calcification treatment (CPT) is a method in which the metallic material is alternately immersed in Na ₂ HPO ₄ aqueous solution and saturated Ca(OH) ₂ aqueous solution, and calcium phosphate (Ca-P) can be precipitated to increase bioactivity.

In order to investigate the change according to the immersion method, as shown in Fig. 17, the titanium specimen with nanotubes was circulated 10 times in an 80°C 0.5M Na ₂ HPO ₄ aqueous solution and 100°C Ca(OH) ₂ saturated aqueous solution for 1 minute each. , Cyclic Precalcification Treatment (CPT) was performed by repeated deposition of 30 times each, and PT and CPT results were compared and analyzed.

18 is a SEM photograph of the surface of a specimen subjected to precipitation for 5 days in a biofuel solution (SBF) according to conditions.

18(a) is a photograph of the raw material Ti ₆ Al ₄ V ELI itself. In this case, hydroxyapatite (Hap) finely precipitates on the surface of the specimen.

18(b) is a photograph of a sample subjected to anodization treatment (TiO ₂ nanotube layer is formed). In this case, the shape of the HAp formed on the amorphous nanotubes produced by the anodization treatment is similar, but it can be seen that the precipitation proceeds to a relatively thicker thickness.

18(c) is a photograph of a sample subjected to anodization treatment and heat treatment. In this case, it is a somewhat flat plate, showing a different crystal shape than before.

Fig. 18(d) is a photograph of a sample subjected to anodization treatment, heat treatment, and electrocalcification treatment (before immersion of SBF solution). In Fig. 18(d), the electrocalcification treatment means that the immersion time was performed for 1 hour and 30 minutes in a 0.5M NaH ₂ PO ₄ aqueous solution (80°C) and a saturated Ca(OH) ₂ aqueous solution (100°C), respectively. In this case, it could be observed that CaPO ₄ precipitated in a saturated aqueous solution of Ca(OH) ₂ was precipitated in the form of needles.

FIG. 18(e) is a photograph of a sample subjected to anodization treatment, heat treatment, and preliminary treatment (after immersion of SBF solution), and FIG. 18(f) is a photograph of a sample subjected to anodization treatment, heat treatment, and circulation calcification treatment. As described above, a flower-bud-shaped cluster was observed on the surface of the specimen that induced the precipitation of HAp by immersion in SBF solution and preliminary treatment.

In addition, each of FIGS. 18(d') and 18(e') shows the magnification of FIGS. 18(d) and 18(e) from 5,000 times to 50,000 times. In this case, spherical clusters were observed.

As a result of observing the surface according to whether or not nanotubes are formed or not, it was confirmed that the precipitation form of HAp varies depending on the formation of nanotubes and heat treatment. As a result, it can be seen that the preliminary treatment accelerates the precipitation of HAp by generating a layer capable of inducing the precipitation of HAp, and this effect is further increased when the circulating calcification treatment is performed. As such, the more even the HAp precipitation pattern is, the higher the bioactivity.

19 is a circulating calcification treatment (CPT) treatment for 30 times each 1 minute in order to find out the HAp precipitation pattern according to the immersion time in the SBF solution, and then the immersion time in the SBF solution was 1 day, 3 days, 5 This is a photograph of observation of the surface by SEM of the specimen in which HAp precipitation was induced by different days. Each of FIGS. 19(a)(b)(c) is 2,000 times, and each of FIGS. 19(a')(b')(c') is 5,000 times.

Referring to FIGS. 19(a) and 19(a'), in the case of a specimen that was precipitated for 1 day after CPT treatment, crystals in the shape of a flower bud are mixed on a ribbon. 19(b) and 19(b'), spherical precipitates were observed on the surface of the specimen, which was precipitated for 3 days after CPT treatment, although the size was small. 19(c) and 19(c'), a spherical HAp crystal uniformly precipitated could be observed on the surface of the specimen, which was precipitated for 5 days after the CPT treatment.

In SBF solution, HAp crystals precipitated on the TiO ₂ nanotube layer according to the immersion time, and the crystal shape changed. In the specimen that was immersed for 5 days after 30 cycles of calcification treatment, the specimen was uniformly spherical in shape. It was confirmed that HAp crystals were precipitated.

The chemical composition of the prepared specimen will be described with reference to [Table 4]. [Table 4] is a table summarizing the chemical composition of calcium (Ca) and phosphorus (P) in each specimen obtained from EDS measurement of the prepared specimen.

group Ca ( wt% ) P ( wt% ) One 0.27 0.8 2 0.76 1.08 3 2.83 1.75 4 5.95 2.66 5 25.11 11.61 6 21.56 10.75

Group 1 is a specimen in which a Ti ₆ Al ₄ V sheet, which is a raw material, is directly immersed in SBF solution, and Group 2 is a specimen immersed in SBF solution after only anodizing. Groups 3 and 4 were specimens subjected to precalcification treatment (PT) after heat treatment, and then immersed in SBF solution and precipitated for 3 and 5 days, respectively. Groups 5 and 6 are specimens subjected to cyclic precalcification treatment (CPT) 10 times and 30 times, respectively, and immersed in SBF solution to precipitate for 5 days after heat treatment.

Comparing PT (groups 3, 4) and CPT (groups 5, 6), it was found that the thickness of HAp was formed thicker in the case of circulating deposition than in the general deposition method, and a thicker and uniform coating film was formed as the deposition time increased. I can.

In the case of specimens immersed in SBF without preliminary treatment (Groups 1 and 2), precipitation of HAp from the surface layer is insignificant, and from this fact, it is possible to form a calcium phosphate layer on the oxide film layer by preliminary treatment. It can be seen that it greatly contributes to the improvement of activity. The HAp precipitation pattern of the preliminized specimens after heat treatment was more accelerated than that of the preliminized specimens without heat treatment.This was determined by a rutile structure similar to the HAp crystal structure deformed by heat treatment rather than the unstable TiO ₂ amorphous structure. It appears to have promoted crystal growth by acting as a nucleus.

20 shows the XRD diffraction patterns of specimens immersed in SBF solution after performing PT or CPT after heat treatment. Here, FIG. 20(a) is a case of immersion in SBF solution for 3 days after PT treatment, and FIG. 20(b) is a case of immersion in SBF solution for 5 days after PT treatment, and FIG. 20(c) is CPT 10 times, FIG. Is a specimen immersed in SBF solution for 5 days after 30 CPT times.

In all of the specimens, a peak of Ti and a peak of TiO ₂ corresponding to the base metal were observed. The Ti and TiO ₂ peaks are peaks due to the porous nanotube oxide film formed by the base metal and anodization treatment, respectively. As shown, the intensity of the HAp peaks was different for each specimen, and the peak of HAp was observed the largest in the case of the CPT-treated specimen. However, the peak of HAp was not observed in the PT-treated specimen. This indicates that in the case of the PT-treated specimen, a small amount of elements were detected in the EDS analysis, but the amount of precipitated HAp was too small, so the peak was not observed in the XRD analysis. .

The above-described embodiments are merely exemplary, and various modifications and other equivalent embodiments are possible from those of ordinary skill in the art to which the present invention pertains. Therefore, the true technical scope of the present invention should be determined by the technical spirit of the invention described in the claims.

10: water tank 11: power supply source
13: Psalm 15: Platinum mesh net
17: cooler 19: stirrer

Claims (7)

In the method for surface treatment of a biological tissue-friendly metallic material,
Making the surface of the metal material uneven through an anodizing process on the metal material;
Heat-treating the uneven-treated metal material in a high-temperature inert gas atmosphere;
Forming hydroxyapatite on the surface of the metallic material through circulating calcification treatment in which the heat-treated metallic material is repeatedly deposited in a biomaterial,
The biomaterials include a first aqueous sodium phosphate solution and a saturated aqueous calcium hydroxide solution,
The circulation calcification treatment,
The first sodium phosphate aqueous solution and the calcium hydroxide saturated aqueous solution are alternately circulating and immersed in the metallic material 10 to 30 times to increase bioactivity by depositing calcium phosphate (Ca-P). and,
The step of making the surface of the metallic material uneven,
A surface polishing step of polishing the surface of the metallic material with a polishing paper;
And an anodizing process of forming irregularities of a nanotube structure through an anodic oxidation process on the surface of the surface-polished metallic material,
The anodization process,
Accommodating the surface-polished metallic material in an aqueous electrolyte solution in which ammonium fluoride and water are added to ethylene glycol, and receiving the surface-polished metallic material in an aqueous electrolyte solution having a water content of 2 to 8 vol%;
A method for surface treatment of a biological tissue-friendly metallic material comprising the step of applying a DC power having a voltage of 20 to 60 Volts and a current density of 10 to 30 mA/cm ² for 1 to 4 hours. The method of claim 1,
The metal material,
Biological tissue-friendly metal, characterized in that it is made of at least one material selected from the group consisting of chromium, nickel, magnesium, stainless steel, tantalum, titanium, titanium alloy, nickel-titanium (Nitinol) alloy, and cobalt-chromium alloy The method of surface treatment of the material. The method of claim 2,
The metal material,
A method for surface treatment of a biological tissue-friendly metal material, characterized in that it is made of a Ti ₆ Al ₄ V ELI alloy material. The method according to any one of claims 1 to 3,
The step of making the surface of the metallic material uneven,
A surface polishing step of polishing the surface of the metallic material with a polishing paper to have a surface roughness of 0.1 to 0.25 µm;
A washing step of ultrasonically washing the surface-polished metal material, washing it with deionized water, immersing it in an aqueous solution containing hydrogen fluoride and nitric acid, and washing the surface-polished metal material in the order of acetone, ethanol, and distilled water;
And an anodizing process of forming irregularities of a nanotube structure through the anodizing process of the cleaned metal material after the surface polishing. delete The method of claim 1,
The step of heat treatment of the uneven-treated metal material,
A method for surface treatment of a biological tissue-friendly metal material, characterized in that by heat treatment at a high temperature of 600° C. or higher in an argon (Ar) gas atmosphere, structural stabilization of the anodized metal material and removal of impurities. delete

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