Porous Material and Preparation Method Thereof

Abstract

A porous material and preparation method thereof is provided. The material includes a material body. The body consists of pore cavities classified according to pore size of material and cavity walls surrounding to form the pore cavities. The lower-level pore cavities are arranged on the cavity walls of the upper-level pore cavities framed by surrounding a three-dimensional space. All the pore cavities are interconnected. The preparation method is: mixing raw powders with pore-forming agent for the smallest-level pore cavities of porous material to formulate slurry; uniformly filling the slurry into polymer material support to form green body and get dried and smashed to obtain mixed grains; uniformly mixing the mixed grains with pore-forming agent for upper-level pore cavities greater than the smallest-level pore cavities of porous material to make compact green body; performing vacuum sintering; performing the conventional follow-up treatment according to the raw materials process of porous material.

Claims

1. A porous material, comprising: a material body, wherein the material body is composed of pore cavities classified according to a pore size of the material; and cavity walls surrounding to form the pore cavities; wherein the cavity walls of upper-level pore cavities are arranged with lower-level pore cavities, the upper-level pore cavities are formed by surrounding a three-dimensional space; the pore cavities of a same level at all levels are connected to each other, and the pore cavities among different levels are connected with each other.

2. The porous material according to claim 1, wherein each level of the porous material is a continuous structure body in the material body.

3. The porous material according to claim 2, wherein a maximum outer boundary of each level of the porous material is equivalent to a space boundary of the entire material body.

4. The porous material according to any of claim 1, wherein each level of the porous material in the material body has its own physicochemical properties.

5. The porous material according claim 1, wherein a lower-level of the porous material constitutes the cavity wall of the upper-level pore cavity.

6. The porous material according to claim 1, wherein the cavity wall of the upper-level pore is formed by a plurality of lower-level of multilevel porous materials.

7. The porous material according to claim 1, wherein the cavity wall of the upper-level pore is formed by a composite of all levels of the lower-level porous material.

8. The porous material according to claim 1, wherein the pores of each level are uniformly distributed in the material body.

9. The porous material according to claim 1, wherein pore sizes of the pore cavities of a same level are highly concentrated in a specific size range.

10. The porous material according to claim 9, wherein pore cavities in a particular size range of the same level accounts for more than 80% of all the pore cavities of the level.

11. The porous material according to claims 1, wherein the porous material is a porous metal material, a porous non-metal material or a composite material made of the porous metal material and the porous non-metal material.

12. The porous material according to claim 11, wherein the porous metal material is one or more selected from the group consisting of tantalum, niobium, titanium, titanium alloy, stainless steel, cobalt based alloy, nickel, nickel alloy, magnesium and magnesium alloy.

13. The porous material according to claim 11, wherein the porous non-metal material is one or more selected from the group consisting of ceramic materials, high siliceous silicate materials, aluminosilicate materials, diatomaceous earth materials, pure carbonaceous materials, corundum and diamond.

14. A method for preparing a porous material, comprising the following steps: mixing raw material powder with a pore-forming agent for preparing smallest-level pore cavities of the porous material and formulating a slurry, wherein the slurry is uniformly filled into a polymer material support to form a green body and is dried and smashed to obtain mixed grains containing the raw material, the pore-forming agent and a material of the polymer material support; uniformly mixing the mixed grains above with a pore-forming agent for preparing, upper-level pore cavities which are larger than the smallest-level pore cavities of the porous material to make a compact green body; performing vacuum sintering to the compact green body, wherein the sintered green body is subjected to a conventional follow-up treatment according to a raw material process of the porous material to obtain the porous material; wherein the porous material comprises a material body, wherein the material body is composed of pore cavities classified according to a. pore size of the material; and cavity walls surrounding to form the pore cavities; wherein the cavity walls of upper-level pore cavities are arranged with lower-level pore cavities, the upper-level pore cavities are formed by surrounding a three-dimensional space are arranged with lower-level pore cavities: the pore cavities of a same level at all levels are connected to each other, and the pore cavities among different levels are connected with each other.

15. The method for preparing the porous material according to claim 14, comprising the following substeps before making the compact green body: uniformly mixing the mixed grains with a pore-forming agent used for making a level of pore cavities to obtain a mixture, wherein the level of pore cavities is one level higher than the smallest-level of the porous material; uniformly pouring the mixture into the polymer material support, the polymer material support has a pore size that is bigger than a particle size of the mixed grains and a particle size of the pore-forming agent, an strut of the polymer material support is used as a pore-forming agent for making a level of pore cavities, wherein the level of pore cavities is two levels higher than the smallest-level of the porous material.

16. The method for preparing the porous material according to claim 14, wherein pores of the polymer material support is three-dimensionally interconnected.

17. The porous material according to claim 2, wherein pore sizes of the pore cavities of_a same level are highly concentrated in a specific size range.

18. The porous material according to claim 3, wherein pore sizes of the pore cavities of_a same level are highly concentrated in a specific size range.

19. The porous material according to claim 4, wherein pore sizes of the pore cavities of_a same level are highly concentrated in a specific size range.

20. The porous material according to claim 5, wherein pore sizes of the pore cavities of_a same level, are highly concentrated in a specific size range.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0039] The present invention will be further described with reference to the accompanying drawings and embodiments.

[0040] FIG. 1 is a schematic view of the porous material of the present invention, (a) is a front view, (b) is a left view, (c) is a plan view;

[0041] FIG. 2 is a partial enlarged view of A in FIG. 1;

[0042] FIG. 3 is a B-B sectional view of FIG. 2;

DETAILED DESCRIPTION OF THE INVENTION

[0043] Specific embodiments of the present invention are described below with reference to the accompanying drawings. The embodiments are given based on the technical solutions of the present invention, and the specific implementation manners and specific operation procedures are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0044] FIG. 1 shows a three-dimensionally interconnected porous material, wherein, 1 is the pore cavity and 2 is the cavity wall. It can be seen from FIG. 2 that the cavity wall 2 of the cavity 1 is formed by the smaller pore cavities 3 (the next level pores) and the cavity wall 4 surrounding the pore cavity 3. Combining the enlarged view of the cavity wall 2 in FIG. 2 with the B-B sectional view in FIG. 3, it can be seen that the pore cavity 3 is three-dimensionally interconnected, and the pores at two levels are also three-dimensionally interconnected.

[0045] Similarly, the porous material with more than three levels of multilevel pore structure can be formed.

[0046] The porous material of each level containing pore cavity 1 and pore cavity 3 in the material body is a continuous structure body.

[0047] The maximum boundary of each level of porous material containing pore cavities 1, and pore cavities 3 is equivalent to the space boundary of the entire material body.

[0048] The porous material of each level containing pore cavities 1 and pore cavities 3 in the material body has its own physicochemical properties.

[0049] Pore cavities 1, pore cavities 3 and the pores at all levels are uniformly distributed in the material body.

[0050] In the figure, the number of pore cavities 1 and pore cavities 3 accounts for 100% of the total number of pore cavities in this level.

[0051] The porous material may be made of metal or non-metal, or a composite material made ref metal and non-metal.

[0052] The embodiments of the present invention are given below in detail.

Embodiment 1

[0053] The porous material of the present embodiment is porous tantalum and has three-level pores, wherein the cavity walls of the first-level pore cavities, which are uniformly distributed and interconnected, are provided with the uniformly distributed and interconnected second-level pore cavities, the cavity walls of the second-level pore cavities are provided with uniformly distributed and interconnected third-level pore cavities; and the pore cavities at different levels are also connected with each other, forming a three-dimensional interconnection. The porous material of each level is a continuous structure body, the maximum boundary of the porous material of each level equivalent to the space boundary of the material body.

[0054] The preparation method is as follow.

[0055] (1) The preparation of materials.

[0056] Use tantalum powder with particle size of 1-10 m as raw material and starch with particle size of 300 nm-700 nm as a pore-forming agent for the smallest-level pore cavities of porous material, use stearic acid with particle size of 300 nm-700 nm as a binder, and formulate a slurry by tantalum powder, starch, stearic acid and distilled water in a volume ratio of 3:1:1:10.

[0057] Use a polyester foam having a pore size of 500-800 m, and uniformly fill the slurry therein by a foam dipping method to form a green body and get dried, and then get smashed to obtain the mixed grains with particle size of 40-80 m containing raw materials, a pore-forming agent and a polyester foam.

[0058] (2) Uniformly mix the mixed grains with ethyl cellulose having a particle size of 40-80 m in a volume ratio of 3:1, then uniformly pour into a three-dimensional interconnected polyester foam having a strut diameter of 200-400 m and a pore diameter of 340-440 m. Then put the polyester foam into a closed mould to press into a compact green body.

[0059] (3) Perform vacuum sintering to the compact green body; perform the conventional follow-up heating treatment to sintered green body according to the tantalum material process to obtain the three-level porous tantalum.

[0060] Using the section direct observation method to respectively prepare planes in the three-dimensional direction of the sample and observe the pores through an electron microscope. Image was digitally processed and the average of the three surfaces was taken. The observation results showed that: the pore size of the first-level pore cavities was 150 m360 m, the pore size of the third-level pore cavities was 200 nm600 nm, and the pore size of the second-level pore cavities was 3070 m. Wherein, in the first-level pore cavities, pore size of 27030 m account for 87%, in the second-level pore cavities, pore size of 5010 m account for 85%, in the third-level pore cavities, pore size of 45060 nm account for 82%. Respectively comparing the total pore area of each level with the total area of the sample, the porosity of the first-level pore cavities was 64%, the porosity of the second-level pore cavities was 10%, the porosity of the third-level pore cavities was 6%.

[0061] According to GBT/7314-2005 Metallic materials-Compression testing at ambient temperature, the material of this embodiment has a compressive strength of 36 MPa and an elastic modulus of 1.15 GPa, which is very close to the elastic modulus of human cancellous bone.

[0062] In the porous tantalum, the porous material of each level has its own structure and properties, for example, the porous material of each level has a unique pore size, compressive strength, elastic modulus, etc. Thereby each level can satisfy different functional requirements, it can be used as biological regeneration material. The size of the first-level pore cavities is used to satisfy the growing needs of blood vessels and other tissues; the pore cavities of second-level are used for inhabited of variety of cells; the pore cavities of third-level are used for satisfying the needs of adhesion and differentiation of cells. Particularly, the multilevel pore structure thereof makes elastic modulus of the cavity wall different horn that of the raw material itself, but to reduce the elastic modulus of the cavity walls. The existence of the third-level pore cavities enable the cells to inhabit on the cavity walls of the second-level pore cavities to truly sense the stress when the material is stressed to promote the cell division, thereby creating a fundamental condition for cell division and avoiding stress shielding. Besides, the connectivity of the pore cavities is good, pores of each level are mutually interconnected and pores at different levels are also mutually interconnected, which can hilly satisfy the infiltration and transmission of tissue fluid, achieving the excretion of products of the protein degradation and metabolites, thus it is a real biological regeneration material.

Embodiment 2

[0063] The porous material of the present embodiment is porous silicon carbide with two-levels pores, wherein the cavity walls of the first-level pore cavities, which are uniformly distributed and interconnected, are provided with uniformly distributed and interconnected second-level pore cavities, and the pores of two levels are also interconnected with each other, forming a three-dimensional interconnection.

[0064] The preparation method is as follow.

[0065] (1) The preparation of materials.

[0066] Use silicon carbide powder with particle size of 1-10 m and urea with particle size of 35-70 m as a pore-forming agent for the smallest-level cavities of the porous material, uniformly mix them, use 35-70 m starch as a binder, formulate a slurry by silicon carbide powder, urea, starch and distilled water in a volume ratio of 4:1.5:1:12.

[0067] Uniformly fill the slurry into a polyester foam having a pore diameter of 600-900 m by foam dipping method to form a green body and get it dried, and then get smashed to obtain the mixed grains with particle size of 35-70 m containing a raw material, a pore-forming agent and a polyester foam.

[0068] (2) Uniformly mix the mixed grains with the methyl cellulose having particle size of 700-950 m in a volume ratio of 4:1, put them into a closed mould to press into a compact green body.

[0069] (3) Perform the vacuum sintering to the compact green body; the sintered body is subjected to conventional follow-up treatment according to the silicon carbide process to obtain the porous silicon carbide with two levels of pores.

[0070] According to the method of Embodiment 1, the pore diameter of the first-level pore cavities is 630-860 m, the pore diameter of second-level pore cavities is 25-60 m. Wherein, the pore cavities with pore diameter of 71030 m account for 89% of the first-level pore cavities, and the pore cavities with pore diameter of 4510 m account for 83% of the second-level pore cavities. The porosity of the first-level pore cavities is 51% and the porosity of the second-level pore cavities is 12%.

[0071] The material can be used for separation of solids and liquids, achieving hierarchical filtration, pores of two levels filter particles with different sizes respectively, to avoid the accumulation of particles in one side of the material to achieve efficient separation.

Embodiment 3

[0072] The porous material in this embodiment is porous niobium and has three levels of pores. Wherein, the cavity walls of the uniformly distributed and interconnected first-level pore cavities are provided with the uniformly distributed and interconnected second-level pore cavities. The cavity walls of the second-level pore cavities are provided with uniformly distributed and interconnected third-level pore cavities; and the cavities of each levels are also interconnected, forming a three-dimensional interconnection. The porous material of each level is a continuous structure body, the porous material of each level fully occupies the inside space of the entire material body.

[0073] The preparation method is as follow.

[0074] (1) The preparation of materials.

[0075] Use niobium powder with particle size of 1-10 m as raw material, use methylcellulose with particle size of 200-500 nm as a pore-forming agent for the smallest-level pore cavities of porous material, use polystyrene with particle size of 200-500 nm as a binder, formulate a slurry by niobium powder, methylcellulose, polystyrene and distilled water in a volume ratio of 4:1:1:12.

[0076] Use a polyester foam with a pore diameter of 500-800 m, the slurry is uniformly filled by the foam dipping method to form a green body and get it dried, and then get smashed to obtain mixed grains with particle size of 30-70 m containing raw materials, a pore-forming agent and a polyester foam.

[0077] (2) Uniformly mix the mixed grains and ethylcellulose with particle size of 30-70 m in a volume ratio of 5:2, after that, uniformly pour them into a three-dimensional interconnected polyester foam with a strut diameter of 500-650 m and a pore size of 660-870 m. Then put the polyester foam into a closed mould to press into a compact green body.

[0078] (3) Perform vacuum sintering to the compact green body; the sintered body is subjected to conventional follow-up heating treatment according to the niobium material process to obtain porous niobium with three levels of pores.

[0079] According to the method of Embodiment 1, the pore size of the first-level pore cavities is 450-560 m, the pore size of the third-level pore cavities is 150-400 nm, and the pore size of the second-level pore cavities is 25-60 m. Wherein, the pore cavities with pore size of 51050 m account for 85% of the first-level pore cavities, the pore cavities with pore size of 4510 m account for 82% of the second-level pore cavities, the pore cavities with pore size of 27040 nm account for 88% of the third-level pore cavities. The porosity of the first-level pore cavities is 61%, the porosity of the second-level pore cavities is 9%, and the porosity of the third-level pore cavities is 5%.

[0080] Test according to the standard of Embodiment 1, the compressive strength of the material of this embodiment is 24 MPa, the elastic modulus is 0.62 GPa, which is very close to the elastic modulus of human cancellous bone and can be used as the bone implant materials. Similar to the embodiment 1, it is a real biological regeneration material.