KR102095813B1 - Method for manufacturing biodegradable metal alloy - Google Patents

Abstract

Provided is a method for manufacturing biodegradable metal alloy, which includes the following steps of: melting 0.1 to 0.5 wt% of calcium, 0.3 to 2 wt% of a metal element X having an HCP structure, and the remaining amount of magnesium; firstly extruding alloy obtained after the step of melting; heat-treating the obtained alloy after the step of firstly extruding; secondarily extruding the alloy obtained after the step of heat-treating; and rigid plasticity-processing the alloy obtained after the step of secondarily extruding. The metal element X does not form a separate precipitation phase after the step of heat-treating.

Description

Method for manufacturing biodegradable metal alloy}

The present invention relates to a method for manufacturing a biodegradable metal alloy, and more specifically, a biomaterial that improves both elongation and toughness as well as corrosion and strength by combining heat treatment and multi-stage extrusion processes and a swaging process to reduce diameter. It is to provide a method for manufacturing a biodegradable metal alloy that can produce a decomposable metal alloy.

Recently, a technique using a metal that decomposes in vivo as an implant and a stent material used for medical treatment has been studied.

The biodegradable metal must have high mechanical properties to withstand the torsional stress generated in the screw or the load generated in the bone bone when placed in the human body. Among them, the toughness characteristic represents the amount of energy that can absorb the load that may occur in a torsional stress or bone fracture occurring in a screw, and in general, to improve the toughness characteristic, the yield point and elongation must be improved. In order to realize this, the biodegradable metal is required to refine the structure of the metal alloy and control the internal residual stress by performing additional processes such as rapid cooling, plastic working, and heat treatment. In addition, metal alloys used as biodegradable metals must be properly designed with added elements and alloy compositions. Here, the change in the alloy composition is generally performed by adjusting the amount of added elements, and the mechanical strength is improved as the amount of added elements contained in the alloy increases.

However, when the amount of added elements increases, an intermetallic compound or a secondary phase is formed in the metal constituting the implant, thereby forming a micro galvanic circuit that increases the corrosion rate. Accordingly, the rate of corrosion of the biodegradable metal is increased. In addition, it is possible to increase or decrease the decomposition rate of the biodegradable metal alloy by suppressing or increasing galvanic corrosion depending on the type of the added element of the biodegradable metal. Therefore, a biodegradable metal material having only good mechanical properties and a high biodegradation rate is difficult to apply to an implant.

To this end, Republic of Korea Patent Publication No. 10-2014-0099431 is a biodegradable implant containing magnesium, the magnesium is manganese (Mn) as an impurity; Contains one selected from the group consisting of iron (Fe), nickel (Ni), and a mixture of iron (Fe) and nickel (Ni), and the content of the impurities exceeds 0 parts by weight and 1 part by weight based on 100 parts by weight of the magnesium. The biodegradable implant characterized in that it is less than, and is selected from the group consisting of iron (Fe), nickel (Ni), a mixture of iron (Fe) and nickel (Ni) / manganese (Mn) = 0 and 5 or less, and Disclosed is a method for manufacturing the same.

However, an alloy having a level capable of processing only sufficient mechanical properties to a desired level while slowing the corrosion rate has not yet been disclosed.

Therefore, the problem to be solved by the present invention is to provide a method for manufacturing a biodegradable metal alloy based on a new composition with enhanced corrosion and mechanical properties.

In order to solve the above problems, the present invention is 0.1 to 0.5% by weight of calcium; HCP structure, metal element X 0.3 or more and 2% by weight; And melting the remaining amount of magnesium. First extruding the alloy obtained after the melting step; Heat-treating the obtained alloy after the first extruding step; Extruding a second alloy after the heat treatment; And stiffening the alloy obtained after the second extrusion step, wherein the metal element X does not form a separate precipitation phase after the heat treatment step, and X is Zn.

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In one embodiment of the present invention, the prepared biodegradable metal alloy has a maximum tensile strength of 350MPa or more, an elongation of 10% or more, or a maximum tensile strength of 240MPa or more, an elongation of 23% or more, and hydrogen generation in a biomimetic solution It provides a method for producing a biodegradable metal alloy, characterized in that the rate is 0.015ml / cm ² / hr or less.

In one embodiment of the present invention, the first extrusion temperature T1 is higher than the second extrusion temperature T2, and the ratio of the first extrusion temperature and the second extrusion temperature T1 / T2 is 1.0 <T1 / T2 <1.3.

In one embodiment of the present invention, the first extrusion step proceeds to a heating temperature: 280 ~ 380 degrees, extrusion ratio: 5 ~ 15: 1.

In one embodiment of the present invention, the second extrusion step proceeds to a heating temperature: 260-350 degrees, an extrusion ratio: 20-50: 1.

In one embodiment of the present invention, the sintering process is carried out in a swaging process, the diameter change rate proceeds from 0% to 62%.

According to the present invention, after the addition of calcium and an element of HCP structure having a high solubility in magnesium to magnesium, through multi-stage extrusion and heat treatment therebetween, it suppresses the formation of a precipitation phase that affects the corrosion rate. As a result, it is possible to improve only the mechanical strength of the alloy without affecting the corrosive properties in vivo through rigid plastic processing such as swaging. Therefore, it improves the mechanical properties (strength, elongation) of the alloy without affecting the corrosiveness, thereby increasing the toughness characteristics, and when used as a biodegradable implant, it improves the resistance to torsion due to torsion and the supporting load capacity at the bone fracture site and simultaneously corrodes. The properties can be improved.

1 is a step view of a biodegradable alloy manufacturing method according to an embodiment of the present invention.
Figure 2 is a result of analyzing the strength and elongation of the alloy (same as the conditions in Figure 1) prepared in each composition range (X-axis) according to an embodiment of the present invention.
Figure 3 is a graph analyzing the mechanical properties according to the alloy composition, Figure 4 is a table summarizing this.
5 is a graph analyzing the corrosion characteristics of a biodegradable alloy prepared in accordance with an embodiment of the present invention in a biomimetic solution (PBS solution: Phosphate-Buffered Saline), and FIG. 6 is a table summarizing the quantitative values .
7 is a first embodiment of the alloy composition of Example 3 according to the method according to an embodiment of the present invention after extrusion (370 ℃), heat treatment (400 ℃, 24 hours) precipitation phase (Ca ₂ Mg ₆ Zn) ₃ ) It is a picture explaining the effect of removing the image.
8 and 9 are the mechanical strength and table of the alloy according to the rate of change of diameter, and FIGS. 10 and 11 are graphs and tables of the corrosion rate.
12 is a result of analyzing the surface defects of the alloy according to the pressure temperature condition.

Hereinafter, a preferred embodiment of the intracellular delivery microfluidic platform based on inertia according to the present invention will be described in detail based on the accompanying drawings. For reference, the terms and words used in the present specification and claims should not be interpreted as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. In addition, the configuration shown in the embodiments and drawings described in this specification is only one of the most preferred embodiments of the present invention, and does not represent all of the technical spirit of the present invention, and thus can replace them at the time of application. It should be understood that there may be equivalents and variations.

In order to solve the above-mentioned problems, the present invention develops an alloy body of a level that does not affect the corrosion rate despite mechanical processing through the heat treatment and extrusion process together with the composition of the alloy, followed by rigid plastic processing (for example, sway It provides a method of manufacturing an alloy that can improve only mechanical strength through gong).

1 is a step view of a biodegradable alloy manufacturing method according to an embodiment of the present invention.

Referring to Figure 1, the method of manufacturing a biodegradable alloy according to an embodiment of the present invention begins with the step of melting a metal element X having calcium and HCP (Hexagonal Close Packing) structure in magnesium. In an embodiment of the present invention, the number attached to the components of Ca and X excluding magnesium means weight% in the entire alloy. For example, 5Ca1Zn represents an alloy consisting of 5% by weight of calcium, 1% by weight of zinc, and the remaining amount of magnesium in the total alloy.

In one embodiment of the present invention, the calcium and metal element X are each composed of 0.1 to 0.5% by weight, 0.3 to 2% by weight, and the metal element X is Zn.

Subsequently, the molten alloy is first extruded, and the temperature in the first extrusion step is lower than the following heat treatment temperature, but is higher than the second extrusion proceeding thereafter.

In the present invention, in particular, the precipitated phase composed of Mg, Ca, and Zn formed in the first extrusion is resolved through heat treatment, and then extruded again, and as a result, an alloy that is not affected by corrosion in the solution in vivo even in mechanical processing. It can be obtained in the second extrusion step.

In one embodiment of the present invention, the first extrusion is performed at 280 to 380 ° C, and an extrusion ratio: 5 to 15: 1.

Thereafter, the heat treatment is performed. The heat treatment is performed at a temperature higher than that of the first extrusion, that is, in the range of 390 to 500 ° C for 12 to 48 hours. According to the heat treatment, all of the precipitation phases such as Ca ₂ Mg ₆ Zn ₃ are removed to form an alloy in which both Ca and X are dissolved.

Thereafter, the second extrusion proceeds, and the heating temperature of the second extrusion proceeds at 260 to 350 ° C. and an extrusion ratio: 20 to 50: 1.

In one embodiment of the present invention, since the second extrusion is in a state in which all of the precipitation phases affecting the corrosion rate in vivo of the alloy are removed through the preceding heat treatment, the mechanical strength of the alloy proceeds at a stronger extrusion ratio than the first extrusion. It improves, and the temperature proceeds to a temperature relatively lower than the first temperature. The reason is to remove the surface defect (Surface defect) generated during extrusion, which will be described in more detail in FIG.

In one embodiment of the present invention, the temperature of the first extrusion step T1 is preferably higher than the temperature T2 of the second extrusion step, and the ratio of the first extrusion temperature and the second extrusion temperature T1 / T2 is 1.0 <T1 / T2 < 1.3 is preferred. That is, when the temperature of T1 is higher than the above temperature range, that is, when the temperature of T2 is low, a precipitated phase of Ca and Zn that has been employed after heat treatment may be formed. Conversely, when the T2 temperature is equal to or higher than T1, the alloy surface defect is Can occur. This is explained in more detail through FIG. 12.

Subsequently, after the second extrusion, severe plastic deformation is performed. Through this, the alloy formed through the extrusion-heat treatment-extrusion process has a constant corrosion rate in vivo and mechanical strength is improved regardless of the processing degree. .

The alloy produced by the above-described method can be used in vivo, such as an implant, and the maximum tensile strength is 350 MPa or more, the elongation is 10% or more, or the maximum tensile strength is 240 MPa or more, and the elongation is 23% or more. The hydrogen generation rate of has a characteristic of 0.015ml / cm ² / hr or less, and in particular, in the final processing step, the mechanical strength can be strengthened according to the rate of change in diameter (ie, the degree of compression) due to processing without affecting the corrosion at all. have.

Hereinafter, the configuration and effects of the present invention will be described in more detail through experimental examples.

Selection of composition range

Mechanical properties

In the present invention, a tensile strength of 240MPa, an elongation of at least 23%, should be a biodegradable metal alloy, recognized that it is applicable to actual implant products, and selected a composition based on this value.

Figure 2 is a result of analyzing the strength and elongation of the alloy (same as the conditions in Figure 1) prepared in each composition range (X-axis) according to an embodiment of the present invention.

Referring to FIG. 2, it can be seen that when the metal element X is zinc (Zn), only the result of entering the red box satisfies both the strength and elongation conditions. This means that zinc is preferably 0.3 to 2% by weight of the alloy composition, and calcium is preferably 0.1 to 0.5% by weight.

Figure 3 is a graph analyzing the mechanical properties according to the alloy composition, Figure 4 is a table summarizing this.

3 and 4, it can be seen that the mechanical strength increases as zinc increases, but the elongation decreases (see Comparative Examples 1, 2, 4, 5, and Example 1). It can be seen that this increases (see Examples 3, 4 and 5).

That is, it can be seen from the above results that the composition that satisfies the criteria of mechanical strength of tensile strength 240 MPa and elongation of 23% is 0.3 to 2% by weight of zinc and 0.1 to 0.5% by weight of calcium.

Corrosion characteristic analysis

5 is a graph analyzing the corrosion characteristics of a biodegradable alloy prepared in accordance with an embodiment of the present invention in a biomimetic solution (PBS solution: Phosphate-Buffered Saline), and FIG. 6 is a table summarizing the quantitative values . 5, blue is 48 hours, yellow is 168 hours is the result of immersing the alloy in a biomimetic solution.

Referring to FIG. 5, the hydrogen generation rate (proportional to the corrosion rate) in the biomimetic fluid was set to 0015 ml / cm ² / hr or less as a preferred criterion, and the corrosion rate increased as calcium increased (Examples 3 and 4). , 5), Zinc has no specific effect on the corrosion rate, except for the result of Example 9 for 168 hours.

In conclusion, considering the mechanical properties of the alloy and corrosion characteristics in vivo, it can be concluded that zinc is preferably 0.3 to 2% by weight and 0.1 to 0.5% by weight of calcium in magnesium.

However, the present invention does not produce an alloy having a high mechanical strength and a low corrosion rate in vivo through the selection of the above-described composition range, but through the extrusion-heat treatment-extrusion of Ca ₂ Mg ₆ Zn ₃ phase in the middle of the process. By removing, it is possible to manufacture an alloy that can enhance mechanical strength without affecting the corrosion rate.

Removal of precipitation phase due to heat treatment

7 is a first embodiment of the alloy composition of Example 3 disclosed in the drawing according to the method according to an embodiment of the present invention after extrusion (370 ℃), heat treatment (400 ℃, 24 hours) precipitation phase in the case (Ca) _{2 This} is a picture explaining the removal effect of Mg ₆ Zn ₃ ) phase.

The left side of FIG. 7 is a photo after heat treatment before the right side heat treatment.

Referring to Figure 7, it can be seen that the precipitation phase (including Ca, Zn) is effectively removed according to the heat treatment. Particularly, in the present invention, the Ca and Zn precipitation phases formed in the temperature range of the first extrusion step are completely dissolved in Ca and Zn through heat treatment at a temperature higher than the temperature of the first extrusion step, whereby a separate precipitation phase is followed. It is not formed in.

Mechanical strength and corrosion rate according to the rate of change in diameter after sintering

After the second extrusion, processing was performed to reduce the diameter by a swaging process by stiffness processing, and mechanical properties and corrosion rates of alloys according to various diameter change rates were measured.

8 and 9 are the mechanical strength and table of the alloy according to the rate of change of diameter, and FIGS. 10 and 11 are graphs and tables of the corrosion rate.

8 and 9, the alloy undergoing the extrusion-heat treatment-extrusion process has mechanical strength as the diameter change is reduced to 62% as the Ca and Zn components are sufficiently employed to form a separate precipitation phase. It can be seen that is sufficiently increased.

On the other hand, referring to FIGS. 10 and 11, the alloy subjected to extrusion-heat treatment-extrusion according to the present invention is virtually unaffected by the corrosion rate in vivo despite extreme diameter changes according to swaging. The rate of change in diameter of the swaging process according to an embodiment of the present invention is preferably 31% to 62%, and if it is less than the above range, the shape of the material changes due to a low mechanical strength and a high rate of change when exceeding the above range.

Alloy analysis according to extrusion temperature

12 is a photograph analyzing the alloy surface according to the extrusion temperature, when the alloy of the above-described composition range is treated with the first extrusion-heat treatment-second extrusion.

In Figure 12, the left picture is the surface picture of the alloy material after the first extrusion, and the right picture is the surface picture of the alloy material after the second extrusion.

Referring to FIG. 12, it can be seen that alloy bonding occurs when the temperature of the first extrusion step (first extrusion temperature, T1) is lower than the temperature of the second extrusion step (second extrusion temperature, T2). Therefore, it is preferable that T1 / T2 exceeds 1, whereas when the T1 / T2 ratio exceeds 1.32, it can be seen that binding occurs somewhat in the right picture.

That is, when T1 / T2 is 1 or less, it can be confirmed that surface defects occur immediately after the first extrusion step, and it can also be seen that surface defects occur after the second extrusion step from when T1 / T2 is 1.32.

Claims (7)

Biodegradable metal alloy manufacturing method,
0.1 to 0.5% by weight of calcium; HCP structure, metal element X 0.3 or more and 2% by weight; And melting the remaining amount of magnesium.
First extruding the alloy obtained after the melting step;
Heat-treating the obtained alloy after the first extruding step;
Extruding a second alloy after the heat treatment; And
After the second extrusion step comprises the step of stiffening the alloy obtained,
The metal element X does not form a separate precipitation phase after the heat treatment, the X is zinc, the first extrusion temperature T1 is higher than the second extrusion temperature T2, and the ratio of the first extrusion temperature and the second extrusion temperature is T1 / T2 is a method for producing a biodegradable metal alloy, characterized in that 1.0 <T1 / T2 <1.3. delete According to claim 1,
The biodegradable metal alloy prepared above has a maximum tensile strength of 350 MPa or more, an elongation of 10% or more, or a maximum tensile strength of 240 MPa or more, and an elongation of 23% or more, and the rate of hydrogen generation in the biomimetic solution is 0.015 ml / cm ² / Method of manufacturing a biodegradable metal alloy, characterized in that less than hr. delete According to claim 1,
The first extrusion step is a biodegradable metal alloy manufacturing method characterized in that the heating temperature: 300 ~ 380 ℃, extrusion ratio: 5 ~ 15: 1. The method of claim 5,
The second extrusion step is a biodegradable metal alloy manufacturing method characterized in that the heating temperature: 260 ~ 350 ℃, extrusion ratio: 20 ~ 50: 1. According to claim 1,
The method of manufacturing the biodegradable metal alloy is characterized in that the sintering process proceeds to a diameter change rate of 31% to 62% by a swaging process.

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