POROUS METAL MATERIAL AND PREPARATION METHOD THEREOF

Abstract

A multilevel porous metal material, where the levels are classified based on the pore size of the material. The number of classified levels are at least more than two. The pore size of the smallest level of porous metal material is less than 1 micrometer. The elasticity modulus of the smallest level of porous metal material is less than 80 GPa. The porosity is no less than 48%. The preparation method thereof is as follows. The raw material powder used to prepare porous metal material and the pore-forming agent used to prepare the smallest level of pores cavities are mixed to prepare the slurry. The slurry is uniformly filled into polymer material support to form a green body. The green body is dried and crushed to obtain mixed grains.

Claims

1. A porous metal material, comprising: a material body; wherein the material body is a multilevel porous metal material; levels of the multilevel porous metal material are classified based on a pore size of the material: the levels are classified into at least more than two levels; in the multilevel porous metal material, a pore size of a smallest level of porous metal material is less than 1 micrometer; an elasticity modulus of the smallest level of porous metal material is less than 80 GPa; a porosity is no less than 40%.

2. The porous metal material of claim 1, wherein the material body is formed by respective level of pore cavities classified based on the pore size of the material and respective level of cavity walls surrounding to form the pore cavity; the cavity wall, surrounding three-dimensional space to form an upper level of pore cavities, is formed by lower level of porous metal materials; pore cavities of different levels are interconnected with each other, and pore cavities within each level are also interconnected with each other.

3. The porous metal material of claim 1, wherein the multilevel porous metal material is classified into three levels, a first level of pore cavities have micrometer level pores, a third level of pore cavities have nanometer level pores, a pore size of a second level of pore cavities is between the pore size of the first level of pore cavities and the pore size of the third level of pore cavities.

4. The porous metal material of claim 1, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are one level larger than the smallest level of pore cavities is less than 60 GPa, and a porosity is no less than 48%.

5. The porous metal material of claim 1, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are two levels larger than the smallest level of pore cavities is less than 30 GPa, and a porosity is no less than 63%.

6. The porous metal material of claim 1, wherein the porous metal material in a same level within the material body is a continuous structure body.

7. The porous metal material of claim 6, wherein a maximum outer boundary of the continuous structure body formed by the porous metal material in the same level is equivalent to a maximum space boundary of the entire material body.

8. The porous metal material of claim 1, wherein pore cavities of the porous metal material in the same level of the multilevel porous metal material are distributed uniformly within the material body.

9. The porous metal material of claim 1, wherein the porous metal material is a medical implant regeneration material.

10. The porous metal material of claim 9, wherein the porous metal material is made of one or more items selected from the group consisting of tantalum, niobium, tantalum niobium alloy, medical titanium-based alloy medical stainless steel, and medical cobalt-based alloy.

11. A preparation method of a porous metal material, wherein the porous metal material is prepared by the following steps: (1) material preparation mixing raw material powder used to prepare the porous metal material with a pore-forming agent used to prepare a pore cavity of a smallest level of the porous metal material of a multilevel porous metal material, and preparing a slurry; filling the slurry uniformly into a polymer material support, to form a green body; drying the green body; crushing the green body to obtain mixed grains containing the raw material powder, the pore-forming agent, and the polymer material support material; (2) uniformly mixing the above obtained mixed grains with a pore-forming agent used to prepare a pore cavity of an upper level of porous metal material which is larger than the pore cavity of the smallest level of porous metal material of the multilevel porous metal material, so as to prepare a compact green body; (3) sintering the compact green body in vacuum; conducting conventional fellow-up processing on the sintered green body based on treatment processing of the raw material used to prepare the porous metal material, so as to obtain the porous metal material.

12. The preparation method of the porous metal material of claim 11, wherein before preparing the compact green body, firstly, uniformly mixing the mixed grains with a pore-forming agent used to prepare a pore cavity which is one level larger than the pore cavity of the smallest level of porous metal material of the multilevel porous metal material; uniformly pouring a mixture of the mixed grains and the pore-forming agent into the polymer material support; wherein a pore size of a pore cavity of the polymer material support is lore than a large value in a particle size of the mixed grains and a particle size of the pore-forming agent; a strut of the polymer material support is used as a pore-forming agent used to prepare a pore cavity which is two levels larger than of the smallest level of pore cavities of the multilevel porous metal material.

13. The preparation method of the porous metal material of claim 11, wherein pore cavities of the polymer material support are three-dimensionally interconnected.

14. The porous metal material of claim 2, wherein the multilevel porous metal material is classified into three levels, a first level of pore cavities have micrometer level pores, a third level of pore cavities have nanometer level pores, a pore size of a second level of pore cavities is between the pore size of the first level of pore cavities and the pore size of the third level of pore cavities.

15. The porous metal material of claim 2, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are one level larger than the smallest level of pore cavities is less than 60 GPa, and a porosity is no less than 48%.

16. The porous metal material of claim 3, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are one level larger than the, smallest level of pore cavities is less than 60 GPa, and a porosity is no less than 48%.

17. The porous metal material of claim 2, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are two levels larger than the smallest level of pore cavities is less than 30 GPa, and a porosity is no less than 63%.

18. The porous metal material of claim 3, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are two levels larger than the smallest level of pore cavities is less than 30 GPa, and a porosity is no less than 63%.

19. The porous metal material of claim 4, wherein in the multilevel porous metal material, an elasticity modulus of an upper level of porous metal material having pores that are two levels larger than the smallest level of pore cavities is less than 30 GPa, and a porosity is no less than 63%.

20. The preparation method of the porous metal material of claim 12, wherein pore cavities of the polymer material support are three-dimensionally interconnected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Hereinafter, the present invention will be further described with reference to the accompanying drawings and embodiments.

[0037] FIG. 1 is a schematic diagram of the porous material of the present invention; 1-1 is the front view, 1-2 is the left view, 1-3 is the top view;

[0038] FIG. 2 is an enlarged view of portion A in FIG. 1;

[0039] FIG. 3 is a cross-sectional view taken along B-B in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, embodiments of the present invention are described with reference to drawings. Embodiments are provided based on the technical solution of the present invention. Detailed embodiments and specific operating procedure are provided. However, the protective scope of the present invention is not only limited to the following embodiments.

[0041] As shown in FIG. 1, the figure is a porous metal material with three-dimensional interconnected pores, wherein 1 is pore cavity, and 2 is the cavity wall of the pore cavity. It can be seen from FIG. 2, cavity wall 2 of pore cavity 1 is formed by smaller pore cavities 3 (the next level of pores) and cavity wall 4 surrounding the next level of pore cavities 3. With reference FIG. 2 which is an enlarged view of cavity wall 2, and FIG. 3 which is a cross-sectional view taken along B-B, it can be seen that pore cavities 3 are three-dimensionally interconnected, and two levels of pores are also mutually three-dimensionally interconnected.

[0042] Similarly, porous material with multilevel porous structure can be formed with more than three levels.

[0043] Each level of porous material containing pore cavities 1 and pore cavities 3 within the material body is a continuous structure body.

[0044] Each level of porous material containing pore cavities 1 and pore cavities 3 thoroughly occupies the entire material body.

[0045] Respective level of pore cavities including pore cavity 1 and pore cavity 3 are uniformly distributed within the material body.

[0046] Hereinafter, embodiments of the present invention are provided in detail:

Embodiment 1

[0047] A porous metal material is provided. Metal tantalum powder is selected as the raw material of such material, including material body, wherein the material body is multilevel porous material. The multilevel porous material is classified based on the pore size of the material. The number of classified levels is three. The pore size of the first level of pore cavities is 400 m-600 m. The pore size of the second level of pore cavities is 25 m-60 m. The pore size of the third level of pore cavities is 200 mm-500 nm.

[0048] The material body of such porous material is formed by the pore cavity which is classified based on the pore size of the material and cavity wall surrounding to form the pore cavity. The cavity wall surrounding in the three-dimensional space to form the pore cavity of the previous level of porous material is formed by the next level of porous material. Pore cavities of each level of porous material respectively are interconnected with each other, and pore cavities of respective level of porous material are also interconnected with each other. Each level of porous material is a continuous structure body. The maximum outer boundary of each level of porous material is substantially equivalent to the space boundary of the entire material body. Pore cavities in the same level of porous material in each level of the multi-level porous material are distributed uniformly within the material body.

[0049] The preparation method thereof is as below:

[0050] (1) Material Preparation

[0051] Tantalum powder with the particle size of 1 m-2 m is used as raw material. Urea with the particle size of 300 nm-600 nm is used as the pore-forming agent of the smallest level of pores. Polystyrene with the particle size of 300 nm-600 nm is used as a binder. The slurry is prepared based on a volume ratio of 1:2:1:8 of tantalum powder:uea:polystyrene:distilled water.

[0052] Polyester foam with the pore size of 100 m-200 m is used. The slurry is uniformly filled into the polyester foam with the foam impregnation method, so as to form a green body. The green body is dried and crushed to obtain mixed grains with the particle size of 30 m-70 m, containing raw material, pore-forming agent, and polyester foam.

[0053] (2) After the mixed grains are uniformly mixed, ethyl cellulose with the particle size of 30 m-70 m based on a volume ratio of 1:2, the mixture is uniformly poured into three-dimensional interconnected polyester foam with a strut diameter of 500 m-700 m and a pore size of 400 m-600 m. Next, the polyester foam is disposed into a closed mold to be pressed into the compact green body.

[0054] (3) The compact green body is sintered in vacuum. The sintered green body is subjected to conventional follow-up heat treatment based on tantalum material processing, so as to obtain porous tantalum with a level number of three.

[0055] The cross-sectional direct observation method is used to test the porosity. The result is that the porosity of the first level of pores is 79%. The porosity refers to a porosity of the material which only has the first level of pore cavities. That is, during the calculation, the second and the third level of pore cavities are not taken into account (the second and the third level of pore cavities are deemed as a dense entity). The porosity of the third level of pore cavities is 64%. The porosity refers to a porosity of material which only has the third level of pore cavities. That is, during the calculation, analysis and calculation are performed on the material portion which only has the third level of pore cavities. The porosity of the second level of pores is 71%. The porosity refers to a porosity of material which only has the second level of pore cavities. That is, during the calculation, analysis and calculation are performed on the material portion which only has the second level and the third level of pore cavities. However, the third level of pore cavities are not taken into account. The material portion is deemed as a dense entity.

[0056] The nano-indentation method is used to measure the elasticity modulus of the second level of porous material and the third level of porous material. The elasticity modulus of porous tantalum with the second level of pore cavities is measured as 46 GP. The elasticity modulus of porous tantalum with the third level of pore cavities is 71 GP. Test instrument and parameters are as follows. G200 nano-indentation instrument is used. Berkovich type of pressure head made of equilateral triangle diamond is used as the pressure head. Continuous stiffness measurement technology is used. During the test, the loading is performed at a loading rate of 0.005 s.sup.1 to a predetermined maximum depth of 2000 nm. The maximum load maintains for 100 s. Next, unloading is performed at the same rate as that of loading, till 10% of the maximum load is left. The load maintains for 50 s, till the unloading is finished completely. The status maintains for 10 s to the end. The experiment temperature is 20 C., 5 spots are tested. An average value is obtained

[0057] Conventional foam impregnation method is used to prepare porous tantalum which only has the first level of pore cavities. Instronmechanics test machine is used to test compression stress-strain curve of the above porous tantalum sample at 25 C. Initial deformation shown in the stress-train curve is elastic deformation. Elasticity modulus is taken as the ratio of stress value of the elastically deformed portion to corresponding strain value. The measured elasticity modulus is 1.9 GPa.

[0058] Similarly, with the above testing method, the overall elasticity modulus of porous tantalum which has three levels of pore cavity structure is measured as 1.6 GPa.

[0059] Such porous tantalum with three levels can be used as a bone regeneration material.

[0060] Animal implant experiment is performed on porous tantalum of the present embodiment and traditional porous tantalum product prepared by chemical vapor deposition (hereinafter, referred as traditional porous tantalum in short). The procedure and analysis are as follows:

[0061] (1) Implant Material Preparation

[0062] The porous tantalum with the structure of three levels of pores prepared by the present embodiment is made into a sample with the size of 12 mm12 mm6 mm. Traditional chemical vapor deposited porous tantalum is also made into a sample with the size of 12 mm12 mm6 mm. The ultrasonic cleaning is conducted on implanting piece samples with distilled water, acetone solution, and 70% ethyl alcohol sequentially for 20 min. Again, ultrasonic cleaning is conducted with distilled water for 15 min. Then, high-pressure steam sterilization is performed.

[0063] (2) Experiment Animal Preparation

[0064] 9 healthy dogs of either gender are selected, with the weight of 10-13 kg. The dogs are randomly divided into a 4-week group, an 8-week group, and a 12-week group, with 3 dogs in each group.

[0065] (3) Operation Implant Material

[0066] Pentobarbital is selected as the anesthetic, the total amount of which is calculated based on 30 mg/Kg weight. The solution with a concentration of 1% is prepared with 0.9% normal saline. The solution is injected slowly via the ear vein to achieve anesthesia. After general anesthesia, the dog is fixed on the operation table. The skin and subcutaneous tissue on the inner side of left thighbone are cut open. The blunt separation is performed along muscle space to reach the thighbone. The periosteum is cut open, so as to expose thighbone cortex. A drilling machine is used to create a bone loss of 12 mm12 mm6 mm. One porous tantalum sample prepared by the present embodiment is disposed inside. In the same way, one traditional porous tantalum sample is implanted in the right thighbone. The periosteum is sutured. The wound is sutured layer by layer. After the operation, 1.0 g cephazolin sodium is injected intramuscularly for 3 days. After 10 days, stitches are taken out (for all 3 groups of dogs, 9 dogs in total). Their activities are not restricted.

[0067] An intravenous administration is conducted with 3 mg/kg of sodium fluorescein and 90 mg/kg of xylenol orange, so as to conduct fluorescein label.

[0068] (4) Analysis of the Testing Results

[0069] In 4, 8, and 12 weeks after the operation, the groups of dogs are executed respectively. The thighbone is taken out. After a treatment with 80% ethyl alcohol, the implant material is subject to dehydration, resin embedding, and hard tissue section. Each implanting piece is sliced into two sections, wherein one section is dyed with toluidine blue or HE.

[0070] The hard tissue section is observed under fluorescence microscope. Under the fluorescence microscope, xylenol orange emits orange light, while sodium fluorescein emits green light.

[0071] In 4 weeks after the implantation, fluorescence strip is mainly located in the host bone surface near the implanted part and is in a linear parallel distribution. In a direction from the host bone surface to the implanted part, orange fluorescence and green fluorescence occur sequentially. The difference between two kinds of implanting pieces is not obvious.

[0072] In 8 weeks after the implantation, in two kinds of implanting pieces, fluorescence strips have already contacted the surface of the implanting pieces and begun to extend into pore openings. The orange fluorescence in a piece-like and bulk-like distribution. The green fluorescence is in a linear distribution, extending into pore openings. Fluorescence extending into pore openings of the porous tantalum prepared by the present embodiment is more than that of traditional porous tantalum.

[0073] In 12 weeks after the implantation, in pore openings of implanting piece, a great amount of orange and green fluorescence can be seen. The distribution does not have a certain rule. Fluorescence strips are intertwined and overlapped with each other. Traditional porous tantalum fluorescein only deposits in pore openings near the surface of the implanted part. There is no fluorescence in deep pore openings. Deep pore openings of the porous tantalum prepared by the present embodiment have a great amount of fluorescein deposition.

[0074] Hard tissue section is dyed with toluidine blue or HE to be observed. Under the optical microscope osteoblast is orange, osteoid is amaranth, newly mineralized bone is blue, and matured bone is green.

[0075] In 4 weeks after the implantation, gaps exist between two kinds of implanting pieces and host bone. Fibrous connective tissue can be seen in gaps and has a light orange color. Bone surface is amaranth and is undifferentiated and immatures osteoid.

[0076] In 8 weeks after the implantation, gaps between two kinds of implanting pieces and host bone are reduced. The regenerated bone tissue has contacted the surface of the implanted part, and begun to grow into pore openings. In the pore openings of surface of implanting piece and the pore openings near the surface, non-mineralized osteoid can be seen. The inner side of the pore opening in the deep portion of the implanting piece includes fibrous tissue. The regenerated bone tissue and fibrosis tissue has grown into pore openings of porous tantalum implant piece prepared by the embodiment are more than those of traditional porous tantalum.

[0077] In 12 weeks after the implantation, surfaces of two kinds of implanting pieces have formed synostosis with bone tissue. Moreover, the bone tissue, inside the pore opening has differentiated, matured and mineralized. In traditional porous tantalum implanting piece, bone tissue has only grown into superficial pore openings of the implanting piece. In deep pore openings of implanting piece, only a small amount of osteoid and fibrous tissue can be seen. In the porous tantalum implant piece prepared by the embodiment, calcified and matured bone tissue can also be seen in deep pore openings of the implant piece, with blood capillaries passing therethrough.

[0078] Further, the hard tissue section is observed under a low-magnification optical microscope. The bone growing depth is measured with image processing system. Results show that the bone growth of the porous tantalum implanting piece prepared by the embodiment is 32% more than that of traditional porous tantalum.

[0079] Experimental and analysis results show that porous tantalum with the structure of three levels of pores prepared by the present embodiment is pretty suitable to be used as bone repair material. The overall elasticity modulus and the value of the elasticity modulus of the smallest level facilitate the bone tissue and cells to sense the stress stimulation, promoting the growth of the bone tissue and cells. The first level of large pore cavities makes overall elasticity modulus of the material reduced significantly, compared to the elasticity modulus of the dense material, eliminating the bone tissue stress shielding, and facilitating the growth of tissue and vessels. The second level of pore cavities is used for cells to stay. The elasticity modulus of the third level of pore cavities enables cells staying in the cavity wall of the second level of pore cavities to sense the stress, facilitating cell division, eliminating the cell stress shielding, creating conditions for cell division, facilitating cell division and growth. Thus, it is truly suitable for medical implanting bone tissue repair and regeneration material.

Embodiment 2

[0080] A porous niobium material, which is multilevel porous material, is classified based on the pore size of the material. The number of classified levels is three levels. The pore size of the first level of pores cavities is 800 m-1500 m. The pore size of the second level of pores cavities is 20 m-60 m. The pore size of the third level of pores cavities is 100 nm-350 nm.

[0081] The material body of such porous material is formed by the pore cavities which are classified based on the pore size of the material and cavity wall surrounding to form the pore cavities. The cavity wall surrounding in the three-dimensional space to for the pore cavity of the upper level of porous material is formed by the lower level of porous material. Pore cavities of different level of porous material respectively are interconnected with each other, and pore cavities within respective level of porous material are also interconnected with each other. Each level of porous material is a continuous structure. The maximum outer boundary of each level of porous material is substantially equivalent to the space boundary of the entire material body. Pore cavities in the same level of porous material are distributed uniformly within the material body.

[0082] The preparation method thereof is as below:

[0083] (1) Material Preparation

[0084] Niobium powder with the particle size of 1 m-2 m is used as the raw material. Methyl cellulose with the particle size of 200 nm-450 nm is used as the pore pore-forming agent of the smallest level of pores. Polystyrene with the particle size of 200 nm-450 nm is used as the binder. The slurry is prepared based on a volume ratio of 1:1.5:1:7.5 based on niobium powder:methyl cellulose:polystyrene:distilled water.

[0085] Polyester foam with the pore size of 100 m-200 m is used. The slurry is uniformly tilled into the polyester foam with the foam impregnation method, so as to form a green body. The green body is dried and crushed to obtain mixed grains with the particle size of 25 m-70 m, containing raw material, pore-forming agent, and polyester foam.

[0086] (2) After the mixed grains are uniformly mixed with ethyl cellulose with the particle size of 25 m-70 m based on a volume ratio of 1:2, the mixture is uniformly poured into three-dimensional interconnected polyester foam with the strut diameter of 900 m-1600 m and the pore size of 400 m-600 m. Next, the polyester foam is disposed into a closed mold to be pressed into the compact green body.

[0087] (3) The compact green body is sintered in vacuum. The sintered green body is subjected to conventional follow-up heat treatment based on niobium material processing to obtain porous niobium with a level number of three.

[0088] Based on the testing method and the preparation method of Embodiment 1. The porosity of the first level of pores of such porous niobium is tested as 78%. The elasticity modulus is 0.8 GPa. The porosity of the second level of pores is 48%. The elasticity modulus is 60 GPa. The porosity of the third level of pores is 40%. The elasticity modulus is 79 GPa. The overall elasticity modulus is 0.65 GPa.

[0089] Such porous niobium with three levels can be used as a bone regeneration material.

Embodiment 3

[0090] A porous titanium material, which is multilevel porous material, is classified based on the pore size of the material. The number of classified levels are two, wherein the pore size of the pore cavity of the small pore is 250 nm-470 nm. The pore size of the pore cavity of large pore is 130 m-360 m.

[0091] The material body of such porous material is formed by the pore cavity which is classified based on the pore size of the material and cavity wall surrounding to form the pore cavity. The cavity wall surrounding in the three-dimensional space to form the pore cavity of the upper level of porous material is formed by the lower level of porous material. Pore cavities of each level of porous material respectively are interconnected with each other, and pore cavities of respective level of porous material are also interconnected with each other.

[0092] The preparation method thereof is as below:

[0093] (1) Material Preparation

[0094] Titanium powder with the size of 1 m-3 m is used. Ammonium chloride with the particle size of 350 nm-570 nm is used as the pore pore-forming agent of the smallest level of pores. Titanium powder is uniformly mixed with ammonium chloride. Starch with the size of 350 nm-570 nm is used as the binder. The slurry is prepared based on a volume ratio of 1:1.5:1:8 of titanium powder:ammonium chloride:starch:distilled water.

[0095] The slurry is uniformly filled into the polyester foam with a strut diameter of 200 m-450 m with the foam impregnation method, so as to form a green body. The green body is dried and crushed to obtain mixed grains with the particle size of 200 m-450 m, containing titanium powder, pore-forming agent, and polyester foam.

[0096] (2) After the mixed grains are uniformly mixed with methyl cellulose with the particle size of 200 m-450 m based on a volume ratio of 1:3, the mixture is disposed into a closed mold to be pressed into the compact green body.

[0097] (3) The compact green body is sintered in vacuum. The sintered green body is subjected to follow-up processing based on the conventional processing of titanium to obtain porous titanium with the level number of two.

[0098] Based on the testing method and the preparation method of Embodiment 1, the porosity of the first level of pores of such porous titanium is tested as 63%. The elasticity modulus is 30 GPa. The porosity of the second level of pores is 40%. The elasticity modulus is 80 GPa. The overall elasticity modulus is 27 GPa.

[0099] Such porous titanium with two levels can be used as a bone implant material.

Embodiment 4

[0100] A porous material is provided. Metal 316L stainless steel alloy powder is selected as the raw material powder of the material, includes material body, wherein the material body is multilevel porous material, the multilevel porous material is classified based on the pore size of the material. The number of classified levels are three levels. The pore size of the first level of pore cavities is 200 m-400 m. The pore size of the second level of pore cavities is 40 m-80 m. The pore size of the third level of pore cavities is 300 nm-600 nm.

[0101] The material body of such porous material is formed by the pore cavity which is classified based on the pore size of the material and cavity wall surrounding to form the pore cavity. The cavity wall surrounding the three-dimensional space to form the pore cavity of the upper level of porous material is formed by the lower level of porous material. Pore cavities of different levels of porous material respectively are interconnected with each other, and pore cavities within each level of porous material are also interconnected with each other. Each level of porous material is a continuous structure body. Pore cavities in the same level of porous material in the multilevel porous material are distributed uniformly within the material body.

[0102] The preparation method thereof is as below:

[0103] (1) Material Preparation

[0104] 316L stainless steel powder with the particle size of 1 m-3 m is used as the raw material. Starch with the particle size of 400 nm-700 nm is used as the pore pore-forming agent of the smallest level of pores. Stearic acid with the particle size of 400 nm-700 nm is used as the binder. The slurry is prepared based on a volume ratio of 1:2:1:9 of 316L stainless steel powder:starch:stearic acid:distilled water.

[0105] Polyester foam with the pore size of 400 m-700 m is used. The slurry is uniformly filled into the polyester foam with the foam impregnation method, so as to form a green body. The green body is dried and crushed to obtain mixed grains with the particle size of 50 m-90 m, containing raw material, pore-forming agent, and polyester foam.

[0106] (2) The mixed grains are uniformly mixed with ammonium sulfate with the particle size of 50 m-90 m based on a volume ratio of 1:2. The mixture is uniformly poured into three-dimensional interconnected polyester foam with the strut diameter of 300 m-500 m and the pore size of 300 m-500 m. Next, the polyester foam is disposed into a closed mold to be pressed into the compact green body.

[0107] (3) The compact green body is sintered in vacuum. The sintered green body is subjected to conventional follow-up heat treatment based on the processing of 316L stainless steel material to obtain porous 316L stainless steel with three levels.

[0108] Based on the testing method and the preparation method of Embodiment 1, the porosity of the first level of pores of such porous 316L stainless steel is tested as 79%. The elasticity modulus is 26 GPa. The porosity of the second level of pores is 70%. The elasticity modulus is 54 GPa. The porosity of the third level of pores is 65%. The elasticity modulus is 75 GPa. The overall elasticity modulus is 21 GPa.

[0109] Such porous 316L stainless steel with a level number of three can be used as a bone regeneration material.

Embodiment 5

[0110] A porous material is provided. Metal alloy CoNiCrMo (F562) is selected as the raw material of the material. The material includes a material body, wherein the material body is multilevel porous material. The multilevel porous material is classified based on the pore size of the material. The number of classified levels are three levels. The pore size of the first level of pore cavities is 350 m-560 m. The pore size of the second level of pore cavities is 15 m-50 m. The pore size of the third level of pores cavitie is 1 nm-45 nm.

[0111] The material body of such porous material is formed by the pore cavities which are classified based on the pore size of the material and cavity wall surrounding to form the pore cavities. The cavity wall surrounding the three-dimensional space to form the pore cavity of the upper level of porous material is formed by the lower level of porous material. Pore cavities of different level of porous material respectively are interconnected with each other, and pore cavities within each level of porous material are also interconnected with each other. Each level of porous material is a continuous structure body. The maximum outer boundary of each level of porous material is substantially equivalent to the space boundary of the entire material body. Pore cavities in the same level of porous material in the multilevel porous material are distributed uniformly within the material body.

[0112] The preparation method thereof is as below:

[0113] (1) Material Preparation

[0114] CoNiCrMo alloy powder with the particle size of 1 m-2 m is used as raw material. Urea with the particle size of 10 nm-60 nm is used as the pore pore-forming agent of the smallest level of pores. Polystyrene with the particle size of 10 nm-60 nm is used as a binder. the slurry is prepared based on a volume ratio of 1:1.5:1:8 of CoNiCrMo alloy powder:urea:polystyrene:distilled water.

[0115] Polyester foam with a pore size of 350 m-700 m is used. The slurry is uniformly filled into the polyester foam with the foam impregnation method, so as to form a green body. The green body is dried and crushed to obtain mixed grains with the particle size of 20 m-60 m, containing raw material, pore-forming agent, and polyester foam.

[0116] (2) After mixed grains are uniformly mixed with ethyl cellulose with the particle size of 20 m-60 m based on a volume ratio of 1:2, the mixture is uniformly poured into three-dimensional interconnected polyester foam with the pore size of 200 m-400 m and a strut diameter of 450 m-650 m. Next, the polyester foam is disposed into a closed mold to be pressed into the compact green body.

[0117] (3) The compact green body is sintered in vacuum. The sintered green body is subjected to conventional follow-up heat treatment based on CoNiCrMo alloy processing, so as to obtain porous CoNiCrMo alloy with a level number of three.

[0118] Based on the testing method and the preparation method of Embodiment 1, the porosity of the first level of pores of such porous CoNiCrMo alloy is tested as 78%. The elasticity modulus is 30 GPa. The porosity of the second level of pores is 69%, The elasticity modulus is 60 GPa. The porosity of the third level of pores is 64%. The elasticity modulus is 80 GPa. The overall elasticity modulus is 25 GPa.

[0119] Such porous CoNiCrMo alloy with a level number of three can be used as a bone regeneration material.