CN103736151B - Preparation method of medical porous metal material capable of replacing weight bearing bone tissue - Google Patents

Abstract

The invention provides a preparation method of a medical porous metal material capable of replacing weight bearing bone tissue, which comprises the following steps: mixing tantalum powder and ammonium bicarbonate or hydrogen peroxide, and a forming agent (one or more of stearic acid, zine stearate, paraffin and synthetic resin), compression moulding, degreasing, sintering, cooling and heat treating; wherein the compression moulding step is characterized in that a mixture is compacted in organic foams, the pressure is 50-100MPa, the degreasing step is characterized in that heating is gradually carried out at the rate of 0.3 DEG C/min-2 DEG C to the temperature of 400-800 DEG C, argon is protection atmosphere and is insulated for 300-360 minutes; the sintering step is characterized in that the degree of vacuum is 10<-4>Pa-10<-3>Pa, heating is carried out at the rate of 10-20 DEG C/min to the temperature of 1500-1800 DEG C, the insulation is carried out for 120-240 minutes, and then cooling is carried out to 200-300 DEG C, heating is carried out at the rate of 10-20 DEG C/min to 1500-1800 DEG C, insulation is carried out for 180-240 minutes, then heating is carried out at the rate of 5-10 DEG C/minutes to 2000-2200 DEG C, and then insulation is carried out for 120-360 minutes. The medical porous metal material is a medical implantation material which has the advantages of large porosity and good mechanical property, and is suitable for replacing the weight bearing bone tissue.

Description

Preparation method of medical porous metal material replacing load-bearing bone tissue

The application of the present invention is a divisional application with application number 201110296535.4, application date September 29, 2011, and the title of the invention "a preparation method of a medical porous metal material that replaces load-bearing bone tissue".

technical field

The invention relates to a preparation method of a porous medical metal implant material, in particular to a preparation method of a medical porous metal implant material which replaces the bone tissue of a load-bearing part.

Background technique

Porous medical metal implant materials have important and special uses in the treatment of bone tissue trauma and femoral tissue necrosis. Common materials of this type include porous metal stainless steel and porous metal titanium. As a porous implant material used in the treatment of bone tissue trauma and femoral tissue necrosis, its porosity should reach 30-80%, and the pores should be all connected and evenly distributed, or it should be consistent with the growth of human bone tissue as needed. , and reduce the weight of the material itself, so that it is suitable for human implantation.

The refractory metal tantalum/niobium, because of its excellent biocompatibility, its porous material is expected to replace the traditional medical metal biomaterials mentioned above. Because metal tantalum/niobium is harmless, non-toxic, and has no side effects to the human body, and with the rapid development of medicine at home and abroad, the understanding of tantalum/niobium as a human implant material has been further deepened, and people are more interested in porous metals for human implants. The demand for tantalum/niobium materials is becoming more and more urgent, and the requirements for them are also getting higher and higher. Among them, tantalum/niobium, as a porous medical implant metal, is expected to be used as a new type of bone tissue replacement material if it can have high uniformly distributed interconnected pores and physical and mechanical properties compatible with the human body.

The porous metal material used as a medical implant is basically based on the powder sintering method as the general porous metal material, especially in order to obtain a porous metal foam structure with pore connectivity and uniform distribution. The impregnation of powder slurry on organic foam, drying and sintering is mostly referred to as foam impregnation method. The mechanical properties of porous metal materials obtained by powder sintering are usually not very good. The main reason is how to arrange the support and elimination relationship of the pore-forming medium in the process, and the collapse problem during the sintering process of metal powder. However, in the known literature reports, there is no good solution and let nature go.

There are few literature reports on the production of porous tantalum/niobium by metal powder sintering method, especially there are almost no literature reports on the porous tantalum/niobium powder sintering method for the purpose of obtaining medical implant materials. Reference can be made to the publication numbers CN200510032174, titled “Porous Metal Foam with Three-Dimensional Through Holes or Partial Holes Connected to Each Other and Its Preparation Method” and CN200710152394, titled “A Novel Porous Tungsten Foam and Its Preparation Method”. However, the obtained porous metal is either used as a filter material, or used in aerospace and other high-temperature applications rather than as a medical metal implant material, and the processed porous metal is not porous tantalum/niobium.

Regarding porous tantalum, US5282861 discloses a porous tantalum material applied to cancellous bone implants, cells and tissue receptors and its preparation. This kind of porous tantalum is made of pure commercial tantalum. It uses the carbon skeleton obtained by the thermal degradation of the polyurethane precursor as the support. Pores, the porosity can be as high as 98%, and then the commercial pure tantalum is combined with the carbon skeleton by chemical vapor deposition and infiltration to form a porous metal microstructure, which is referred to as the chemical deposition method. The thickness of the tantalum layer on the surface of the porous tantalum material obtained by this method is between 40 and 60 μm; in the entire porous material, the weight of tantalum accounts for about 99%, while the weight of carbon skeleton accounts for about 1%. The literature further records that the compressive strength of the porous material is 50-70 MPa, the elastic modulus is 2.5-3.5 GPa, and the tensile strength is 63 MPa. However, when it is used as a substitute for porous tantalum for medical implant materials such as the skull, the mechanical properties of the material, such as ductility, are obviously insufficient, which will affect the subsequent processing of the porous tantalum material itself, such as molding parts. cutting etc. Also all there is such deficiency in the product that aforementioned metal powder sintering method obtains. Due to the limitation of its preparation method, the purity of the obtained finished product is not enough, and there are carbon skeleton residues, resulting in a decrease in biological safety.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a medical porous metal implant material which is excellent in strength and toughness and is suitable for replacing bone tissue in a load-bearing part.

The purpose of the present invention is achieved by the following technical means:

A method for preparing a medical porous metal material that replaces load-bearing bone tissue, characterized in that: the porous metal material is prepared by mixing tantalum powder with a pore-forming agent and a forming agent, and then undergoing compression molding, degreasing, sintering, cooling and heat treatment; The compression molding is to press the mixed powder into the organic foam, and the pressure is 50-100Mpa. The degreasing process is to gradually increase the temperature to 400-800°C at a rate of 0.3°C/min-2°C/min. Pass through to form a protective atmosphere and keep warm for 300min to 360min; the pore-forming agent is ammonium bicarbonate or hydrogen peroxide, and the forming agent is stearic acid, zinc stearate, paraffin, synthetic resin (preferably styrene-butadiene rubber or isoamyl one or more of rubber); the sintering step is that the vacuum degree is 10 ^-4 Pa ~ 10 ^-3 Pa, the temperature is raised to 1500 ~ 1800 ° C at 10 ~ 20 ° C/min, and the temperature is kept for 120 ~ 240 min. to 200-300°C, then heat up to 1500-1800°C at 10-20°C/min, keep warm for 180-240min, heat up to 2000-2200°C at 5-10°C/min, and keep warm for 120-360min; the heat treatment step is Vacuum degree is 10 ^-4 Pa ~ 10 ^-3 Pa, heat up to 800 ~ 900°C at 10 ~ 20°C/min, hold for 240 ~ 480min, then cool to 400°C at 2 ~ 5°C/min, hold for 120 ~ 300min, Then cool to room temperature with the furnace.

In the research and development process of medical porous metal materials, medical porous metal materials are required to replace load-bearing bone tissue, so that their porosity is relatively large, so that human tissues can easily grow into them, and they have good biocompatibility to fully play their role. The larger the porosity and the larger the pore diameter, the mechanical properties such as strength and toughness cannot be guaranteed; on the contrary, if the mechanical properties are good, the porosity is too small, the biocompatibility is not good, and the density is too large to cause discomfort. ; There are many preparation routes for medical porous tantalum, but the inventor creatively proposes to adopt the above steps and process to prepare medical porous tantalum implant material, which effectively prevents the easy plugging of holes and the difficult control of the dipping process by using the dipping method, and makes Inhomogeneous product quality and other issues; especially the above-mentioned heat treatment process, the inventor found in the long-term research process that the heat treatment process can fully eliminate the internal stress, make the structure of the porous tantalum material more uniform, and greatly improve the obtained quality. The toughness of the porous tantalum material; the above-mentioned sintering process makes the green body a heating element, so that the sintering is more uniform and thorough; the impurity content of the prepared porous tantalum material can be less than 0.2% after testing, and its biocompatibility Good biological safety, density up to 5.83-7.50g/cm ³ , porosity up to 55-65%, pore diameter up to 300-500μm; elastic modulus up to 4.5-6.0Gpa, elongation up to 10.5-11.7 %, the bending strength can reach 125-150Mpa, and the compressive strength can reach 72-90Mpa. Its biocompatibility and toughness are excellent, and it is close to the load-bearing bone tissue of the human body. The porous tantalum of the present invention is very suitable for medical use in place of load-bearing bone tissue. implant material.

The raw tantalum powder used in the present invention has an average particle size of less than 43 microns and an oxygen content of less than 0.1%, which is a commercially available product; the above-mentioned pore-forming agent and forming agent are also commercially available. The vacuum environment of the present invention preferably adopts a vacuum condition with a degree of vacuum ranging from 10 ^-4 Pa to 10 ^-3 Pa. The above-mentioned organic foam is preferably polyurethane foam, more preferably a pore size of 0.48-0.89 mm, a density of 0.015 g/cm ³ to 0.035 g/cm ³ , and a hardness greater than 50 ⁰ (most preferably a pore size of 0.56-0.72 mm, a density of 0.025 g/cm ³ , Hardness 50 ⁰ ~ 80 ⁰ ) in polyurethane foam.

During the research and development process, the inventor further researched and found that if the above-mentioned preparation is not well controlled, although the above-mentioned medical implant material suitable for replacing load-bearing bone tissue can be produced, the product quality stability is not ideal, and the pass rate is not high: For example, the powder is difficult to form, and the parts after pressing are prone to delamination and unevenness, and the parts after degreasing will have cracks and other technical problems.

In order to make molding easier during the powder pressing process, thereby improving the yield rate, uniformity of finished product pores, and making the preparation process more stable, the amount of the above-mentioned pore-forming agent is 15-25%, the amount of molding agent is 7-12%, and the balance It is tantalum powder, all in volume percentage (volume percentage is a unit directly calculated from the final porous tantalum material, and the solid powder in the weighing of the above-mentioned pore-forming agent and molding agent is still based on the weight of the corresponding substance. Density is calculated for its corresponding mass weighing, of course, if it is a liquid substance, then volume weighing is directly used), and it is further preferred that the pore-forming agent is hydrogen peroxide accounting for 18%, the forming agent is zinc stearate accounting for 11%, and the balance is Tantalum powder, calculated by volume percentage; the pressure in the above-mentioned pressing molding process is preferably 75-87Mpa.

In order to make the embryo body more stable during the degreasing process, reduce the prone part of the embryo body deformation and uneven pore size, so as to further improve the yield and quality stability, the above degreasing process is carried out step by step at a rate of 0.3°C/min～1°C/min Raise the temperature to 400-800°C, pass in argon gas to form a protective atmosphere and keep it warm for 330min-350min; further preferably, gradually raise the temperature to 400-800°C at a rate of 0.8°C/min, pass in argon gas to form a protective atmosphere and keep warm for 340min.

More preferably, the conditions of the above-mentioned degreasing process are: rising from room temperature to 400°C at a rate of 1-2°C/min, keeping the temperature for 300-330min, and rising from 400°C to 600-800°C at a rate of 1.5-2.5°C/min. ℃, keep warm for 180-240 minutes.

In order to make the sintering of the green body more uniform and thorough, so that the strength of the obtained porous tantalum material for medical use is higher, the above-mentioned sintering step preferably has a vacuum degree of 10 ^-4 Pa to 10 ^-3 Pa, and the temperature is raised at 12 to 15°C/min to 1500～1800°C, keep warm for 180～200min, cool with the furnace to 200～300°C, then heat up to 1500～1800°C at 16～19°C/min, keep warm for 220～240min, heat up to 2000～2000～ at 5～8°C/min 2200°C, keep warm for 250-320min; more preferably, the degree of vacuum is ^10-4 Pa- ^10-3 Pa, heat up to 1800°C at 13°C/min, keep warm for 200min, cool to 200-300°C with the furnace, and then ℃/min to 1800°C, keep warm for 230min, raise the temperature to 2000-2200°C at 7°C/min, keep warm for 300min.

In order to more fully eliminate the internal stress of the material and improve the toughness, the above heat treatment step is to make the vacuum degree 10 ^-4 Pa ~ 10 ^-3 Pa, raise the temperature to 800 ~ 900 ° C at 15 ° C / min, keep the temperature for 260 ~ 320 min, and then Cool at 3°C/min to 400°C, hold for 120min, then cool to room temperature at 18°C/min～23°C/min.

The above-mentioned cooling conditions after vacuum sintering also include: the degree of vacuum is not lower than 10 ^-3 Pa, and the temperature of the sintered porous body is lowered in stages at a cooling rate of not higher than 25°C/min and not lower than 10°C/min. Cool to 800°C, keep warm for 30min to 90min in each section, and then cool to room temperature with the furnace.

Preferably, the cooling conditions after the above-mentioned vacuum sintering are as follows: the degree of vacuum is 10 ^-4 Pa to 10 ^-3 Pa; cooling to 1500 to 1600 °C at a rate of 10 to 20 °C/min, and holding for 30 to 60 min; Cool at a rate of ℃/min to 1200-1250 ℃, hold for 60-90 minutes; cool at a rate of 10-20 ℃/min to 800 ℃, and then cool with the furnace.

The properties of metal tantalum and niobium are very similar, and the above method is also suitable for the preparation of medical porous niobium materials.

The preparation method of the porous tantalum of the present invention adopts a purely physical molding method, so that the content of impurities in the final porous tantalum material is extremely low, and the biocompatibility and biosafety are effectively improved; The optimization of process conditions leads to high yield, better pore size uniformity, more stable preparation process, good quality stability, effectively eliminates thermal stress, and makes the structure of porous tantalum material more uniform, so as to further improve the mechanical properties of porous tantalum. Properties such as strength and toughness are improved at the same time, and the preparation process of the invention leads to a high qualified rate of finished products and stable production, and the qualified rate of products can be as high as 95.5%. The porous tantalum finished product prepared by the present invention has uniform and connected pores and good biocompatibility. After testing, the impurity content can be lower than 0.2%, the density can reach 5.83-7.50g/cm ³ , and the porosity can reach 55-65%. , the pore diameter can reach 300-500μm; the elastic modulus can reach 4.5-6.0Gpa, the elongation rate can reach 10.5-11.7%, the bending strength can reach 125-150Mpa, and the compressive strength can reach 72-90Mpa, which effectively solves the problem of being an alternative load-bearing The medical porous tantalum material in the site requires both its large porosity and good mechanical properties. The porous tantalum of the present invention is very suitable for use as a medical implant material to replace the load-bearing bone tissue.

Detailed ways

The present invention is specifically described below through the examples, it is necessary to point out that the following examples are only used to further illustrate the present invention, and can not be interpreted as limiting the protection scope of the present invention, those skilled in the art can according to the above-mentioned present invention Contents Some non-essential improvements and adjustments are made to the present invention.

Example 1: Weigh zinc stearate, tantalum powder with an average particle size less than 43 microns and oxygen content less than 0.1% and hydrogen peroxide and mix evenly, wherein zinc stearate accounts for 11%, hydrogen peroxide accounts for 18%, and tantalum powder accounts for 71%. All are calculated by volume percentage. Compression molding: Add the above mixed powder into an injection molding machine and press it into a polyurethane foam (pore diameter 0.48-0.89mm, density 0.015 g/cm ³ ～0.035 g/cm ³ , hardness greater than 50 ⁰ ) at 87Mpa. Degreasing treatment: vacuum degree 10 ^-3 Pa, heating from room temperature to 400°C at a heating rate of 1.4°C/min, and holding for 311 minutes; then heating at a heating rate of 0.4°C/min from 400°C to 750°C, holding time for 350 minutes. Vacuum sintering: the vacuum degree is 10 ^-3 Pa, heat up to 1800°C at 13°C/min, hold for 200min, cool to 200-300°C with the furnace, then heat up to 1800°C at 17°C/min, hold for 230min, hold at 7°C /min Raise the temperature to 2000-2200°C and keep it warm for 300min. Cooling treatment after vacuum sintering: vacuum degree is 10 ^-4 Pa, cooling to 1500-1600°C at a rate of 10-20°C/min, holding for 30-60min, cooling to 1200-1250°C at a rate of 12-20°C/min ℃, keep warm for 60-90min, cool to 800℃ at a rate of 10-20℃/min, and then cool with the furnace. Heat treatment: Vacuum degree is 10 ^-4 Pa ~ 10 ^-3 Pa, heat up to 800 ~ 900°C at 15°C/min, hold for 260 ~ 320min, then cool to 400°C at 3°C/min, hold for 120min, then heat at 18°C /min～23℃/min to cool to room temperature, and then conventionally prepare medical porous tantalum implant materials.

According to the standards of GB/T5163-2006, GB/T5249-1985, GB/T6886-2001, etc., the inventor tested the porous material density, porosity, pore diameter and various mechanical properties of the above-mentioned porous tantalum products: the impurity content is less than 0.2 %, its pores are evenly distributed, with a density of 6.55g/cm ³ , a porosity of 60%, an average pore diameter of 350μm, an elastic modulus of 6.0Gpa, an elongation of 11.02%, a bending strength of 145MPa, and a compressive strength of 83Pa.

Embodiment 2: Weigh stearic acid and paraffin, tantalum powder with an average particle size less than 43 microns and oxygen content less than 0.1% and hydrogen peroxide and mix evenly, wherein stearic acid accounts for 9%, paraffin accounts for 3%, hydrogen peroxide accounts for 25%, tantalum Powder accounts for 63%, all in volume percentage. Compression molding: Add the above mixed powder into an injection molding machine and press it into a polyurethane foam (pore diameter 0.48-0.89mm, density 0.015 g/cm ³ ～0.035 g/cm ³ , hardness greater than 50 ⁰ ) at 75Mpa. Degreasing treatment: the vacuum degree is 10 ^-4 Pa, the temperature is raised from room temperature to 600°C at a heating rate of 0.3°C/min, and the temperature is kept for 360min. Vacuum sintering: the vacuum degree is 10 ^-4 Pa, heat up to 1500°C at 10°C/min, hold for 240min, cool to 200-300°C with the furnace, then heat up to 1500°C at 20°C/min, hold for 180min, hold at 10°C /min Raise the temperature to 2000-2200°C, keep it warm for 120min, and cool down. Heat treatment: the degree of vacuum is 10 ^-3 Pa, the temperature is raised to 800-900°C at 20°C/min, and held for 240 minutes, then cooled to 400°C at 5°C/min, held for 300 minutes, cooled to room temperature with the furnace, and then conventionally prepared for medical use Porous tantalum implant material.

According to the standards of GB/T5163-2006, GB/T5249-1985, GB/T6886-2001, etc., the inventor tested the porous material density, porosity, pore diameter and various mechanical properties of the above-mentioned porous tantalum products: the impurity content is less than 0.2 %, its pores are evenly distributed, with a density of 6.67g/cm ³ , a porosity of 55%, an average pore diameter of 300μm, an elastic modulus of 4.5Gpa, an elongation of 10.7%, a bending strength of 143MPa, and a compressive strength of 74MPa.

Embodiment 3: Take isoprene rubber, tantalum powder with an average particle size less than 43 microns and an oxygen content of less than 0.1% and ammonium bicarbonate and mix evenly, wherein isoprene rubber accounts for 7%, ammonium bicarbonate accounts for 15%, and tantalum powder accounts for 78% %, all in percent by volume. Compression molding: Add the above mixed powder into an injection molding machine and press it into a polyurethane foam (pore diameter 0.48-0.89mm, density 0.015 g/cm ³ ～0.035 g/cm ³ , hardness greater than 50 ⁰ ) at 96Mpa to form. Degreasing treatment: the degree of vacuum is 10 ^-4 Pa, the temperature is raised from room temperature to 400°C at a heating rate of 2°C/min, and the temperature is kept for 300min. Vacuum sintering: the vacuum degree is 10 ^-3 Pa, heat up to 1700°C at 20°C/min, hold for 120min, cool to 200-300°C with the furnace, then heat up to 1670°C at 10°C/min, hold for 240min, hold at 5°C /min Raise the temperature to 2000～2200℃, keep it warm for 360min, and cool down. Heat treatment: Vacuum degree is 10 ^-4 Pa, heat up to 800-900°C at 10°C/min, hold for 480min, then cool to 400°C at 2°C/min, hold for 120min, cool to room temperature with the furnace, and then make medical Porous tantalum implant material.

According to the standards of GB/T5163-2006, GB/T5249-1985, GB/T6886-2001, etc., the inventor tested the porous material density, porosity, pore diameter and various mechanical properties of the above-mentioned porous tantalum products: the impurity content is less than 0.2 %, its pores are evenly distributed, with a density of 6.13g/cm ³ , a porosity of 65%, an average pore diameter of 456μm, an elastic modulus of 5.2Gpa, an elongation of 11.0%, a bending strength of 126MPa, and a compressive strength of 88MPa.

Embodiment 4: take stearic acid, average particle diameter is less than 43 microns and oxygen content is less than 0.1% niobium powder and hydrogen peroxide mix uniformly, wherein stearic acid accounts for 8%, hydrogen peroxide accounts for 21%, niobium powder accounts for 71%, all with Volume percentage meter. Compression molding: Add the above mixed powder into an injection molding machine and press it into a polyurethane foam (pore diameter 0.48-0.89mm, density 0.015 g/cm ³ ～0.035 g/cm ³ , hardness greater than 50 ⁰ ) at 76Mpa. Degreasing treatment: the degree of vacuum is 10 ^-4 Pa, the temperature is raised from room temperature to 400°C at a heating rate of 0.8°C/min, and the temperature is kept for 340min. Vacuum sintering: the vacuum degree is 10 ^-4 Pa, heat up to 1650°C at 12°C/min, hold for 180min, cool to 200-300°C with the furnace, then heat up to 1700°C at 16°C/min, hold for 220min, hold at 8°C /min Raise the temperature to 2000～2200℃, keep it warm for 320min, and cool down. Heat treatment: Vacuum degree is 10 ^-4 Pa, heating up to 800-900°C at 13°C/min, holding for 275min, then cooling to 400°C at 4°C/min, holding for 220min, cooling to room temperature with the furnace, and then conventionally prepared medical Porous tantalum implant material.

The inventor tested the porous material density, porosity, pore diameter and various mechanical properties of the above-mentioned porous niobium finished products according to standards such as GB/T5163-2006, GB/T5249-1985, GB/T6886-2001: the impurity content is lower than 0.2 %, its pores are evenly distributed, with a density of 3.51g/cm ³ , a porosity of 59%, an average pore diameter of 344μm, an elastic modulus of 2.8Gpa, an elongation of 10.8%, a bending strength of 100MPa, and a compressive strength of 65MPa.

Embodiment 5: A kind of porous tantalum, it uses metal tantalum powder with a particle size of less than 43 μm and an oxygen content of less than 0.1%, paraffin and ammonium bicarbonate as raw materials, and then undergoes compression molding, degreasing treatment, vacuum sintering, vacuum annealing and conventional obtained after post-processing.

Among them, paraffin wax accounts for 10%, ammonium bicarbonate accounts for 23%, metal tantalum powder accounts for 67%, calculated by volume percentage;

Compression molding: Add the mixed powder of raw materials into the injection molding machine and press it into polyurethane foam (pore diameter 0.48-0.89mm, density 0.015 g/cm ³ ～0.035g/cm ³ , hardness greater than 50 ⁰ ) at 60Mpa to form;

After pressing and molding, put the mixed powder into a non-oxidizing atmosphere furnace and raise the temperature to 800°C at a certain heating rate, and the protective atmosphere is 99.999% argon for degreasing treatment. Before heating up, let pure argon gas in for at least 30 minutes to get rid of the furnace Air, temperature control process: rise from room temperature to 400°C at a rate of 1.8°C/min, keep warm for 323min, and argon gas flow rate is 0.5L/min; rise from 400°C to 800°C at a rate of 0.5°C/min, keep warm 350min, the argon flow rate is 1L/min; then turn off the power, the degreased sample is cooled with the furnace, the argon flow rate is 1L/min, and the argon gas is turned off when it cools to room temperature;

For the samples after degreasing treatment, they are placed in a high-vacuum high-temperature sintering furnace with a tungsten device and heated at a ^certain heating rate for vacuum sintering. The rate is raised from room temperature to 1500°C, kept for 200min, cooled to 200-300°C with the furnace, and the vacuum degree is 10 ^-4 Pa; then raised to 1500°C at a rate of 17°C/min, kept for 180min, and the vacuum degree is 10 ^-4 Pa～10 ^-3 Pa; rise to 2200°C at a rate of 8°C/min, hold for 320min, and the vacuum degree is 10 ^-3 Pa; after sintering, the vacuum degree is 10 ^-3 Pa, at 10～15°C/min Cool at a rate of 1600°C and hold for 30 minutes; cool at a rate of 12°C/min to 1200°C and hold for 60 minutes; cool at a rate of 10°C/min to 800°C and then cool with the furnace;

For the samples after vacuum sintering and cooling, put the corundum container in the vacuum annealing furnace and raise the temperature to ¹²⁵⁰ °C at a certain heating rate for stress relief annealing treatment. Raise from room temperature to 880°C at the rate of ℃/min, hold for 340min, and the vacuum degree is 10 ^-4 Pa to 10 ^-3 Pa; then cool to 400°C at the rate of 3°C/min, hold for 180min, and the vacuum degree is 10 ^{- 4} Pa～10 ^-3 Pa; cooling to room temperature at a rate of 22°C/min. Finally, conventional post-treatment is carried out to produce porous tantalum.

According to the standards of GB/T5163-2006, GB/T5249-1985, GB/T6886-2001, etc., the inventor tested the porous material density, porosity, pore diameter and various mechanical properties of the above-mentioned porous tantalum products: the impurity content is less than 0.2 %, its pores are evenly distributed, with a density of 6.2g/cm ³ , a porosity of 64%, an average pore diameter of 350μm, an elastic modulus of 4.8Gpa, an elongation of 11.32%, a bending strength of 138MPa, and a compressive strength of 85MPa. According to calculations, the preparation process leads to a high qualified rate of finished products and stable production, and the qualified rate of products reaches about 94.6%.

Claims (1)

1. the preparation method of the medical porous metal material of an alternative load-bearing bone tissue, it is characterized in that: be less than 43 μm, the oxygen content ta powder that is less than 0.1% with particle diameter, paraffin and ammonium bicarbonate are mixed into raw material, more repressed molding, ungrease treatment, vacuum-sintering, vacuum annealing and conventional post processing;

Wherein, paraffin accounts for 10%, ammonium bicarbonate accounts for 23%, ta powder accounts for 67%, in volumn concentration;

Compressing: raw material mixed-powder to be added in injection moulding machine under 60MPa, is pressed into molding in polyurethane foam, the aperture 0.48 ~ 0.89mm of described polyurethane foam, density 0.015 g/cm ³~ 0.035g/cm ³, hardness is greater than 50 ⁰;

Put into nonoxidizing atmosphere stove after mixed-powder is compressing and be warming up to 800 DEG C, protective atmosphere is that 99.999% argon carries out ungrease treatment, its intensification before first pass into pure argon gas at least 30min to get rid of furnace air, temperature control process: rise to 400 DEG C from room temperature with the speed of 1.8 DEG C/min, insulation 323min, argon intake 0.5L/min; 800 DEG C are risen to from 400 DEG C, insulation 350min, argon intake 1L/min with the speed of 0.5 DEG C/min; Powered-down again, the sample furnace cooling after defat, argon intake 1L/min, until close argon when being cooled to room temperature;

Be placed in intensification in fine vacuum high temperature sintering furnace for the sample after ungrease treatment with tungsten device and carry out vacuum-sintering, before heating up, the vacuum of sintering furnace at least will reach 10 ^-4pa, rises to 1500 DEG C with the speed of 12 ~ 15 DEG C/min from room temperature, and be incubated 200min, be chilled to 200 ~ 300 DEG C with stove, vacuum is 10 ^-4pa; Rise to 1500 DEG C with the speed of 17 DEG C/min again, insulation 180min, vacuum is 10 ^-4pa ~ 10 ^-3pa; Rise to 2200 DEG C with the speed of 8 DEG C/min, insulation 320min, vacuum is 10 ^-3pa; Sinter complete, vacuum is 10 ^-3pa, is cooled to 1600 DEG C with the speed of 10 ~ 15 DEG C/min, insulation 30min; 1200 DEG C are cooled to, insulation 60min with the speed of 12 DEG C/min; 800 DEG C are cooled to, then furnace cooling with the speed of 10 DEG C/min;

Be placed in vacuum annealing furnace for the cooled sample of vacuum-sintering with corundum container to be warming up to 880 DEG C and to carry out stress relief annealing process, the vacuum before heating up in annealing furnace at least will reach 10 ^-4pa, rises to 880 DEG C with the speed of 15 DEG C/min from room temperature, and insulation 340min, vacuum is 10 ^-4pa ~ 10 ^-3pa; Be cooled to 400 DEG C with the speed of 3 DEG C/min again, insulation 180min, vacuum is 10 ^-4pa ~ 10 ^-3pa; Room temperature is cooled to the speed of 22 DEG C/min.