CN104328319A - Biomedical degradable Mg-Gd-Nd-Zn-Zr alloy, and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of biomedical materials, and in particular relates to a biomedical degradable Mg-Gd-Nd-Zn-Zr alloy and a preparation method and application thereof. The alloy is composed of the following components in weight percentage: 2-7% of Gd, 0-2% of Nd, 0.1-1% of Zn, 0.1-0.5% of Zr, and the balance is Mg and unavoidable impurity elements. The preparation method of the alloy includes batching, sequentially melting Mg, Zn, Mg-Gd master alloy, Mg-Nd master alloy and Mg-Zr master alloy under protective atmosphere conditions, adding a refining solvent to refine after melting, and finally casting to obtain the biological Medical degradable Mg-Gd-Nd-Zn-Zr alloy. The obtained alloy has good biocompatibility and mechanical strength, and can be used in the preparation of vascular stent medical materials.

Description

Biomedical degradable Mg-Gd-Nd-Zn-Zr alloy and its preparation method and application

technical field

The invention belongs to the technical field of biomedical materials, and in particular relates to a biomedical degradable Mg-Gd-Nd-Zn-Zr alloy and a preparation method and application thereof.

Background technique

In recent years, the incidence of cardiovascular diseases has been increasing, and intravascular stents are one of the most effective methods for treating cardiovascular diseases. The materials currently used to make vascular stents mainly include medical polymer materials and medical metal materials. The strength of medical polymer materials is low, and the degradation products are easy to cause inflammation and swelling. Metal materials such as stainless steel, cobalt-based alloys, and titanium-based alloys are biologically inert materials that will permanently exist inside blood vessels after implantation. The long-term contact between the stent and the inner wall of the blood vessel causes damage to the blood vessel wall and intimal hyperplasia. Therefore, a new generation of medical metal materials with biodegradable properties, mainly represented by magnesium and magnesium alloys, has become a research hotspot in the field of biomedical materials.

Compared with medical polymers and non-degradable metal materials that have been put into clinical use, magnesium alloys have the following outstanding advantages: (1) good tissue compatibility, and problems such as restenosis are not easy to occur after stent implantation; It is one of the essential nutritional elements in the human body. The daily requirement of magnesium in the adult body exceeds 350mg. Excessive magnesium can be excreted through urine without toxic side effects. Therefore, the magnesium ions produced during the degradation process of the magnesium alloy stent are not only harmless to the human body, but also can meet the normal physiological needs of the human body for magnesium; (3) its resources are abundant and cheap. However, the standard electrode potential (-2.37V) of magnesium and its alloys is very low, and there is a problem that the corrosion rate is too fast. If the degradation rate is too fast, the implant material will be severely corroded before the tissue is completely healed, and its stability will be reduced, which will affect the physiological function of the body. Aiming at the problem of poor corrosion resistance of magnesium alloys, medical corrosion-resistant magnesium alloys have been developed. For example, a patent document with application number 201310275808.6 and titled "Biomedical Degradable Corrosion-Resistant Mg-Zn-Zr Alloy and Preparation Method" discloses a biomedical corrosion-resistant magnesium alloy that can be used as a human implant material. However, this alloy has the problem of low strength. The crystal structure of magnesium is hexagonal close-packed, and there are few independent slip systems at room temperature, and only the basal plane slips. Therefore, magnesium alloys have low plasticity at room temperature and are difficult to form. Alloying is an effective way to solve the above problems. Alloying can not only improve the corrosion resistance of the alloy, but also refine the grains and improve the toughness and plasticity of the alloy. However, for biomedical magnesium alloys, while improving alloy performance through alloying, it is also necessary to pay attention not to introduce alloy elements that are harmful to the human body. For example, although Al can improve the corrosion resistance of magnesium alloys, Al is not an essential trace element for the human body. On the contrary, it is neurotoxic and can easily lead to Alzheimer's disease.

Contents of the invention

In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a biomedical degradable Mg-Gd-Nd-Zn-Zr alloy.

Another object of the present invention is to provide a method for preparing the biomedical degradable Mg-Gd-Nd-Zn-Zr alloy.

Another object of the present invention is to provide the application of the above biomedical degradable Mg-Gd-Nd-Zn-Zr alloy in medical materials for vascular stents.

The object of the invention is achieved through the following technical solutions:

A biomedical degradable Mg-Gd-Nd-Zn-Zr alloy, the alloy is composed of the following components in weight percentage: Gd2～7%, Nd0～2%, Zn0.1～1%, Zr0.1～ 0.5%, the balance is Mg and unavoidable impurity elements.

The weight percent of each component of the alloy is preferably: 2.63-6.35% of Gd, 0-1.6% of Nd, 0.48-0.86% of Zn, 0.12-0.39% of Zr, and the rest is Mg.

The preparation method of the biomedical degradable Mg-Gd-Nd-Zn-Zr alloy includes the following steps:

(1) Using high-purity magnesium ingots, high-purity zinc ingots, Mg-Gd master alloys, Mg-Nd master alloys, and Mg-Zr master alloys as raw materials, according to the weight percentages and requirements of Gd, Nd and Zr in the three master alloys The weight percentage of each component in the prepared Mg-Gd-Nd-Zn-Zr alloy is prepared;

(2) Under the protection of a mixed atmosphere of nitrogen and chlorodifluoromethane (CHClF ₂ ), heat the high-purity magnesium ingot until it is completely melted, add high-purity zinc ingot when the melt temperature is 700-720°C, and add it in sequence when the temperature rises to 750°C Mg-Gd, Mg-Nd, Mg-Zr master alloys, during the addition process, the current master alloy is completely melted, and then the next one is added, and the stirring is continued to mix them evenly to obtain an alloy melt;

(3) adding a refining solvent of 0.5% to 0.8% of the total weight of raw materials to the alloy melt in step (2) and refining for 3 to 5 minutes, stopping stirring, and standing for 15 to 20 minutes;

(4) Lower the temperature of the alloy melt to 700-720°C, remove surface scum, and pour it into a mold with a preheating temperature of 240-260°C to form an alloy ingot. During the pouring process, argon is delivered to the surface of the melt, Always keep the melt in direct contact with the air, and obtain a biomedical degradable Mg-Gd-Nd-Zn-Zr alloy after cooling.

The high-purity magnesium ingots and high-purity zinc ingots described in step (1) refer to magnesium ingots and zinc ingots with a mass percentage greater than 99.99%; the Mg-Gd master alloy refers to a mass percentage of Gd that is 25% The Mg-Gd master alloy; the Mg-Nd master alloy refers to the Mg-Nd master alloy with a mass percentage of Nd of 30%; the Mg-Zr master alloy refers to a Zr percentage of 30% % Mg-Zr master alloy.

The nitrogen gas described in step (2) refers to nitrogen gas with volume percentage≧99.999%.

The refining solvent described in step (3) refers to RJ-5 refining solvent.

The preparation method of the present invention and the resulting product have the following advantages and beneficial effects:

(1) The Mg-Gd-Nd-Zn-Zr alloy of the present invention is prepared from metal elements that are harmless to the human body, which is conducive to improving the biocompatibility of the alloy, and its degradation products have no toxic effect on the human body;

(2) The Mg-Gd-Nd-Zn-Zr alloy of the present invention adopts the multi-element micro-quantization design concept, which fully utilizes the advantages of each metal element itself, and the addition of Gd, Nd and Zn all have the effects of solid solution strengthening and aging strengthening , to improve the strength of the magnesium alloy, and at the same time, the Zr element can promote nucleation during the solidification process, increase the nucleation rate, and refine the second phase;

(3) Mg-Gd-Nd-Zn-Zr alloy of the present invention has good corrosion resistance, and the raw material that smelting adopts is high-purity magnesium and high-purity master alloy, can reduce the content of impurity element to a great extent, thereby improves the magnesium alloy Corrosion resistance; the addition of Nd elements can greatly increase the electrode potential of the magnesium alloy substrate, reduce the tendency of galvanic corrosion, and significantly enhance the corrosion resistance of magnesium alloys;

(4) The preparation method of the Mg-Gd-Nd-Zn-Zr alloy of the present invention is by adopting reasonable intermediate alloy adding order, reaches the uniform distribution of second phase, reduces the burning loss in smelting process; Simultaneously this preparation method is to equipment The requirement is low, the preparation process is simple, the production cost is low, and it is easy to realize large-scale industrial production.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1

The preparation of the Mg-2.63%Gd-1.6%Nd-0.48%Zn-0.39%Zr alloy of this embodiment, the specific preparation process is:

(1) The mass percentage composition of high-purity magnesium ingot, high-purity zinc ingot, Gd as 25% Mg-Gd master alloy, Nd as 30% Mg-Nd master alloy, Zr 30% Mg-Zr master alloy as raw material, according to the weight percentages of Gd, Nd and Zr in the three master alloys, Gd2.63%, Nd1.6%, Zn0.48%, Zr0.39% by weight , and the rest are prepared for Mg;

(2) Under the protection of a mixed atmosphere of nitrogen and difluorochloromethane (CHClF ₂ ), heat the magnesium ingot until it is completely melted, add zinc ingot when the melt temperature is 700-720°C, and add Mg in sequence when the temperature rises to 750°C -Gd, Mg-Nd, Mg-Zr master alloys, the next one can only be added after the current master alloy is completely melted during the adding process, and the next one can be added by constant stirring to mix them evenly to obtain an alloy melt;

(3) adding 0.5% RJ-5 solvent of the total weight of raw materials to the alloy melt of step (2) for refining for 5 minutes, stopping stirring, and standing for 15 minutes;

(4) Lower the temperature of the alloy melt to 700-720°C, remove surface scum, and pour it into a mold with a preheating temperature of 240-260°C to form an alloy ingot. During the pouring process, argon is delivered to the surface of the melt, Keeping the melt in direct contact with air all the time, the alloy ingot is cooled to obtain the Mg-2.63%Gd-1.6%Nd-0.48%Zn-0.39%Zr alloy.

The tensile mechanical properties test at room temperature was carried out on a computer-controlled universal material testing machine (SANSCMT5105, China), with a strain rate of 2.0×10 ^-3 s ^-1 . The room temperature yield strength of the alloy was 86MPa, the tensile strength was 160MPa, and the elongation The rate is 11%. The corrosion rate of the magnesium alloy in Hank's simulated body fluid is 0.29mm/year, and it can be degraded and absorbed in the living body.

Example 2

The preparation of the Mg-4.25%Gd-1.42%Nd-0.59%Zn-0.37%Zr alloy of this embodiment, the specific preparation process is:

(1) The mass percentage composition of high-purity magnesium ingot, high-purity zinc ingot, Gd as 25% Mg-Gd master alloy, Nd as 30% Mg-Nd master alloy, Zr 30% Mg-Zr master alloy as raw material, according to the weight percentages of Gd, Nd and Zr in the three master alloys, Gd4.25%, Nd1.42%, Zn0.59%, Zr0.37% , and the rest are prepared for Mg;

(2) Under the protection of a mixed atmosphere of nitrogen and difluorochloromethane (CHClF ₂ ), heat the magnesium ingot until it is completely melted, add zinc ingot when the melt temperature is 700-720°C, and add Mg in sequence when the temperature rises to 750°C -Gd, Mg-Nd, Mg-Zr master alloys, the next one can only be added after the current master alloy is completely melted during the adding process, and the next one can be added by constant stirring to mix them evenly to obtain an alloy melt;

(3) adding 0.8% RJ-5 solvent of the total weight of raw materials to the alloy melt of step (2) to refine for 3 minutes, stop stirring, and let stand for 20 minutes;

(4) Lower the temperature of the alloy melt to 700-720°C, remove surface scum, and pour it into a mold with a preheating temperature of 240-260°C to form an alloy ingot. During the pouring process, argon is delivered to the surface of the melt, Keeping the melt in direct contact with air all the time, the alloy ingot is cooled to obtain Mg-4.25%Gd-1.42%Nd-0.59%Zn-0.37%Zr alloy.

The tensile mechanical properties test at room temperature was carried out on a computer-controlled universal material testing machine (SANSCMT5105, China), with a strain rate of 2.0×10 ^-3 s ^-1 . The room temperature yield strength of the alloy was 95MPa, the tensile strength was 190MPa, and the elongation The rate is 13%. The corrosion rate of the magnesium alloy in Hank's simulated body fluid is 0.14mm/year, and it can be degraded and absorbed in the living body.

Example 3

The preparation of the Mg-6.35%Gd-0.86%Zn-0.12%Zr alloy of this embodiment, the specific preparation process is:

(1) Using high-purity magnesium ingots, high-purity zinc ingots, Mg-Gd master alloys with a mass percentage of Gd of 25%, and Mg-Zr master alloys with a mass percentage of Zr of 30% as raw materials, according to the two intermediates The weight percentages of Gd and Zr in the alloy are Gd6.35%, Zn0.86%, Zr0.12% by weight, and the rest are Mg for material preparation;

(2) Under the protection of a mixed atmosphere of nitrogen and difluorochloromethane (CHClF ₂ ), heat the magnesium ingot until it is completely melted, add zinc ingot when the melt temperature is 700-720°C, and add Mg in turn when the temperature rises to 750°C -Gd, Mg-Zr master alloys, the next one can only be added after the current master alloy is completely melted during the adding process, and the next one can be added by constant stirring to mix them evenly to obtain an alloy melt;

(3) adding 0.8% RJ-5 solvent of the total weight of raw materials to the alloy melt of step (2) to refine for 5 minutes, stop stirring, and let stand for 20 minutes;

(4) Lower the temperature of the alloy melt to 700-720°C, remove surface scum, and pour it into a mold with a preheating temperature of 240-260°C to form an alloy ingot. During the pouring process, argon is delivered to the surface of the melt, Always keep the melt in direct contact with the air, and the alloy ingot is cooled to obtain a Mg-6.35%Gd-0.86%Zn-0.12%Zr alloy.

The tensile mechanical properties test at room temperature was carried out on a computer-controlled universal testing machine (SANSCMT5105, China), with a strain rate of 2.0×10 ^-3 s ^-1 . The room temperature yield strength of the alloy was 92MPa, the tensile strength was 210MPa, and the elongation The rate is 15%. The corrosion rate of the magnesium alloy in Hank's simulated body fluid is 0.24mm/year, and it can be degraded and absorbed in the living body.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (7)

1. A biomedical degradable Mg-Gd-Nd-Zn-Zr alloy, characterized in that: the alloy is composed of the following components in weight percentage: Gd2～7%, Nd0～2%, Zn0.1～1 %, Zr0.1～0.5%, the balance is Mg and unavoidable impurity elements. 2. A biomedical degradable Mg-Gd-Nd-Zn-Zr alloy according to claim 1, characterized in that: the weight percentage of each component of the alloy is: Gd2.63～6.35%, Nd0～ 1.6%, Zn0.48-0.86%, Zr0.12-0.39%, and the rest is Mg. 3. the preparation method of biomedical degradable Mg-Gd-Nd-Zn-Zr alloy described in claim 1 or 2, is characterized in that comprising the following steps: (1) Using high-purity magnesium ingots, high-purity zinc ingots, Mg-Gd master alloys, Mg-Nd master alloys, and Mg-Zr master alloys as raw materials, according to the weight percentages and requirements of Gd, Nd and Zr in the three master alloys The weight percentage of each component in the prepared Mg-Gd-Nd-Zn-Zr alloy is prepared; (2) Under the protection of a mixed atmosphere of nitrogen and difluorochloromethane, heat the high-purity magnesium ingot until it is completely melted, add high-purity zinc ingot when the melt temperature is 700-720°C, and add Mg-Gd, For Mg-Nd and Mg-Zr master alloys, during the addition process, the current master alloy is completely melted before adding the next one, and stirring continuously to mix them evenly to obtain an alloy melt; (3) adding a refining solvent of 0.5% to 0.8% of the total weight of raw materials to the alloy melt in step (2) and refining for 3 to 5 minutes, stopping stirring, and standing for 15 to 20 minutes; (4) Lower the temperature of the alloy melt to 700-720°C, remove surface scum, and pour it into a mold with a preheating temperature of 240-260°C to form an alloy ingot. During the pouring process, argon is delivered to the surface of the melt, Always keep the melt in direct contact with the air, and obtain a biomedical degradable Mg-Gd-Nd-Zn-Zr alloy after cooling. 4. The preparation method of the biomedical degradable Mg-Gd-Nd-Zn-Zr alloy according to claim 3, characterized in that: the high-purity magnesium ingot and the high-purity zinc ingot described in step (1) refer to a mass of 100% Magnesium ingots and zinc ingots with a content greater than 99.99%; the Mg-Gd master alloy refers to the Mg-Gd master alloy with a Gd content of 25% by mass; the Mg-Nd master alloy refers to the A Mg-Nd master alloy with a mass percentage of 30%; the Mg-Zr master alloy refers to a Mg-Zr master alloy with a Zr percentage of 30%. 5. The preparation method of biomedical degradable Mg-Gd-Nd-Zn-Zr alloy according to claim 3, characterized in that: the nitrogen gas described in step (2) refers to the volume percentage ≧99.999% nitrogen. 6. The preparation method of biomedical degradable Mg-Gd-Nd-Zn-Zr alloy according to claim 3, characterized in that: the refining solvent described in step (3) refers to RJ-5 refining solvent. 7. The application of the biomedical degradable Mg-Gd-Nd-Zn-Zr alloy described in claim 1 or 2 in medical materials for vascular stents.