1. A bionic human bone manufacturing method based on 3D printing is characterized by comprising the following steps:

s1, uniformly mixing the ceramic raw materials, drying and sieving to prepare 3D printing slurry; the ceramic raw material contains A-type silicon nitride and B-type silicon nitride in a preset proportion;

s2, performing 3D printing according to a preset bionic human bone first layer model to obtain a first biscuit;

s3, degreasing and sintering the first biscuit to obtain a first layer of ceramic piece, and measuring the shrinkage rate of the first layer of ceramic piece;

s4, performing 3D printing on a preset bionic human bone second layer model by using a ceramic raw material containing single A-type silicon nitride or single B-type silicon nitride to obtain a second biscuit;

s5, degreasing and sintering the second blank to obtain a second layer of ceramic piece, and measuring the shrinkage rate of the second layer of ceramic piece;

and S6, adjusting the proportion of the A-type silicon nitride and the B-type silicon nitride in the ceramic raw material of the first ceramic piece according to the difference between the shrinkage rate of the second layer of ceramic piece and the shrinkage rate of the first layer of ceramic piece, and obtaining the bionic human bone through pulping, printing, degreasing and sintering.

2. The method for manufacturing the bionic human bone based on 3D printing according to claim 1, wherein the A-type silicon nitride is alpha-phase silicon nitride, the purity is more than 99.8, and the median particle size is 0.5-2 μm.

3. The method for manufacturing the bionic human bone based on 3D printing according to claim 1, wherein the B-type silicon nitride is alpha-phase silicon nitride, the purity is more than 99.8, and the median particle size is 2-5 μm.

4. The method for manufacturing the bionic human bone based on 3D printing according to claim 1, wherein the ceramic raw material is composed of silicon nitride, a sintering aid and a silane coupling agent; the silicon nitride is A-type silicon nitride and/or B-type silicon nitride; the silicon nitride accounts for 86-94 wt% of the sum of the silicon nitride and the sintering aid; the silane coupling agent accounts for 1-3 wt% of the sum of the silicon nitride and the sintering aid.

5. The method for manufacturing a biomimetic human bone based on 3D printing according to claim 4, wherein the sintering aid is selected from any two of aluminum oxide, yttrium oxide, and magnesium oxide.

6. The method for fabricating a biomimetic human bone based on 3D printing according to claim 4, wherein the silane coupling agent is selected from at least one of KH550, KH560 and KH 570.

7. The method for manufacturing a biomimetic human bone based on 3D printing according to claim 1, wherein when preparing the 3D printing paste, the method further comprises adding a resin, a photoinitiator and a dispersant to the ceramic raw material; the solid phase content of the slurry is 30-40 vol%.

8. The 3D printing-based biomimetic human bone manufacturing method of claim 7, wherein the resin is selected from at least one of BPA10EODMA, HDDA, PPTTA, n-octanol.

9. The method for manufacturing the bionic human bone based on 3D printing according to claim 1, wherein the degreasing mode is a combination of vacuum degreasing and air degreasing.

10. A biomimetic human bone based on 3D printing, prepared by the method of any one of claims 1-9.

Background

With the continuous development of economy, science and technology and medicine, the life of people is continuously prolonged, and the senile osteoarthritis is increasingly serious. Meanwhile, accidents such as industry, traffic, sports and the like can cause certain bone trauma, and the problems all affect the life quality of human beings. The implantation or replacement of the bionic human bone can greatly relieve the pain of people and improve the life quality of patients with bone injury. The bionic human bone materials researched and applied at present mainly comprise: (1) stainless steel, titanium alloy, cobalt-chromium-molybdenum alloy and other metal materials. Metal materials have been widely used because of their high strength, high toughness, and good workability. However, the metal material has the problems of easy corrosion, poor fatigue resistance, stress shielding, metal ion diffusion and the like, and further application of the metal material in the bionic medical material is limited. (2) Ceramic materials such as hydroxyapatite and silicon nitride. The ceramic material has high strength, high hardness, good corrosion resistance and excellent biological inertia, so the ceramic material is more suitable for being applied to the field of bionic medical materials. Due to the characteristics of high hardness and low toughness of ceramic materials, complex structural parts or parts with higher geometric curved surfaces are difficult to process by traditional processing methods (such as grinding, injection molding and the like). In addition, the bionic human bone has a complex structure and uniqueness, so that the traditional preparation technology cannot meet the design requirements. Therefore, the application of the ceramic bionic material is greatly limited.

The 3D printing has the characteristic of mold-free molding, and can prepare a complex structure according to individual requirements, so that a feasible method is provided for the preparation of the bionic human bone. The currently common 3D printing method is as follows: (1) fused Deposition Modeling (FDM), which is commonly used in engineering plastic materials, has the following advantages: the operation is simple, the maintenance cost is low, and the system is safe to operate. The main disadvantages are: the forming precision is lower than that of an SLA process, and the forming speed is relatively slow. (2) Selective laser sintering/selective laser melting (SLS/SLM), commonly used for plastic, metal, ceramic or glass materials, has the advantages: the support of an SLA mode is not required to be designed, and the range of molding materials is wide. The disadvantages are as follows: the equipment cost is very high, toxic gas can be generated in the forming process, and the forming surface is rough and has matched surfaces which need secondary treatment. (3) Digital Light Processing (DLP), commonly used for ceramic materials, has the advantages: the molding process has high automation degree, high dimensional precision and high system resolution, and can be used for manufacturing models or parts with complex structures. The disadvantages are as follows: the printed parts are brittle and easy to break. In summary, DLP printing is better in consideration of the material, performance and structure of the bionic human skeleton. Because the mechanical property and the structure of each layer of human skeleton are inconsistent, the performance and the structure of the human skeleton are difficult to meet by using a single material for printing, and multiple materials are required for printing. The existing problem of multi-material printing is that due to different shrinkage rates of different materials after sintering, stress is generated at the interface of different materials, so that cracks can be generated on the joint surface of different materials. For example: in the technology of the bioceramic human skeleton, the skeleton consists of compact bone and spongy bone, the porosity of the compact bone and the spongy bone are different, and sintering shrinkage behaviors of the compact bone and the spongy bone are required to be matched when the compact bone and the spongy bone are co-fired after being printed and sintered by DLP. When a mismatch occurs, stress is created at the interface of the two materials, which results in deformation of the ceramic skeleton and difficulty in controlling the dimensional accuracy of the hole. When the sintering shrinkage behaviors are not matched, one side is subjected to a large tensile force, cracks occur between interfaces, cracks are generated, and bending deformation is performed in a direction in which the shrinkage rate is large.

In order to reduce the mismatch of sintering shrinkage, in the case of a fixed composition and particle size of the cancellous bone material, the shrinkage behavior of the cortical bone material must be as close as possible by adjusting the parameters of the cortical bone material. The traditional biological ceramic human skeleton technology usually adopts single powder to prepare compact bone material, the parameters of the particle size distribution, the specific surface area, the powder morphology and the like are determined, and the adjustment space of the corresponding sintering shrinkage rate is limited. Therefore, when a mismatch occurs in the co-firing shrinkage, it is difficult to achieve effective adjustment by a single powder.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and provides a bionic human bone based on 3D printing and a manufacturing method thereof. The principle is that when the small particle powder and the large particle powder are ball-milled together, the small particle powder is filled in the gap between the large particles, thereby changing the relative density, linear shrinkage and bending strength of the sintered sample.

Specifically, the invention provides the following technical scheme:

a bionic human bone manufacturing method based on 3D printing comprises the following steps:

s1, uniformly mixing the ceramic raw materials, drying and sieving to prepare 3D printing slurry; the ceramic raw material contains A-type silicon nitride and B-type silicon nitride in a preset proportion;

s2, performing 3D printing according to a preset bionic human bone first layer model to obtain a first biscuit;

s3, degreasing and sintering the first biscuit to obtain a first layer of ceramic piece, and measuring the shrinkage rate of the first layer of ceramic piece;

s4, performing 3D printing on a preset bionic human bone second layer model by using a ceramic raw material containing single A-type silicon nitride or single B-type silicon nitride to obtain a second biscuit;

s5, degreasing and sintering the second blank to obtain a second layer of ceramic piece, and measuring the shrinkage rate of the second layer of ceramic piece;

and S6, adjusting the proportion of the A-type silicon nitride and the B-type silicon nitride in the ceramic raw material of the first ceramic piece according to the difference between the shrinkage rate of the second layer of ceramic piece and the shrinkage rate of the first layer of ceramic piece, and obtaining the bionic human bone through pulping, printing, degreasing and sintering.

Specifically, by preparing a plurality of first biscuits with different gradient proportions of A-type silicon nitride and B-type silicon nitride, powder raw materials with different proportions of particle sizes can be better adjusted to match the shrinkage rate of the second-layer ceramic piece according to the proportion and shrinkage rate of the A-type silicon nitride and the B-type silicon nitride.

Specifically, the ceramic raw material is dried at 50-70 ℃ and sieved by a 80-120 mesh sieve.

Specifically, if the ceramic raw material contains both type A silicon nitride and type B silicon nitride, in the blending step, a planetary ball mill is used for ball milling at 320-.

Specifically, the ratio of the type a silicon nitride to the type B silicon nitride in the ceramic raw material of the first ceramic piece is adjusted according to the difference between the shrinkage rate of the second layer of ceramic piece and the shrinkage rate of the first layer of ceramic piece. For example, if the shrinkage of the first layer of ceramic part is smaller, the ratio of the type a silicon nitride to the type B silicon nitride is properly increased; if the shrinkage rate of the first layer of ceramic piece is larger, the ratio of the A-type silicon nitride to the B-type silicon nitride is properly reduced.

Furthermore, the A-type silicon nitride is alpha-phase silicon nitride, the purity is more than 99.8, and the median particle size is 0.5-2 μm.

Furthermore, the B-type silicon nitride is alpha-phase silicon nitride, the purity is more than 99.8, and the median particle size is 2-5 μm.

Further, the ceramic raw material consists of silicon nitride, a sintering aid and a silane coupling agent; the silicon nitride is A-type silicon nitride and/or B-type silicon nitride; the silicon nitride accounts for 86-94 wt% of the sum of the silicon nitride and the sintering aid; the silane coupling agent accounts for 1-3 wt% of the sum of the silicon nitride and the sintering aid.

Further, the sintering aid is selected from any two of alumina, yttria and magnesia.

Further, the silane coupling agent is selected from at least one of KH550, KH560 and KH 570.

Further, when preparing the 3D printing paste, the method also comprises the step of adding resin, photoinitiator and dispersant into the ceramic raw material.

Further, the solid content of the 3D printing paste is 30 to 40 vol%, preferably 33 to 37 vol%, and most preferably 35 vol%.

Further, the resin is selected from at least one of BPA10EODMA, HDDA, PPTTA and n-octanol.

Further, the degreasing mode is a combination of vacuum degreasing and air degreasing, and the degreasing is a vacuum and air 2-step degreasing method.

Further, the sintering temperature is 1600-.

The invention also provides a bionic human bone based on 3D printing, which is prepared by the method.

Compared with the prior art, the invention can achieve the following technical effects:

according to the method for manufacturing the bionic human bone based on 3D printing, the proportion of the A-type silicon nitride and the B-type silicon nitride contained in the ceramic raw material of the first layer of ceramic part is matched with the shrinkage rate of the second layer of ceramic part, so that the bionic human bone with the porosity and the bending strength changing in a gradient manner can be manufactured; cracks and bending of a connecting interface caused by mismatch of shrinkage rates of compact bone and cancellous bone can be effectively avoided; the invention utilizes different particle diameters of single powder, adopts a mode of compounding A-type silicon nitride and B-type silicon nitride, can adjust the shrinkage rate of a sample and the bending strength after sintering, and when the proportion of the A-type silicon nitride and the B-type silicon nitride is a certain value, the bending strength of the sintered sample reaches a peak value.

Drawings

FIG. 1 is a 3D printed biomimetic human bone model, wherein (a) is a single layer model and (b) is a biomimetic human bone model having two layers;

FIG. 2 is a graph of the results of comparative bionic human bone example 1 after sintering due to inconsistent shrinkage of adjacent layers;

FIG. 3 is a diagram of a bionic human bone in example 1 of preparing a bionic human bone;

FIG. 4 is the SEM topography of the biomimetic human bone of FIG. 3;

FIG. 5 is a flow chart of a process for making a first layer of ceramic article according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments. It is apparent that the embodiments to be described below are only a part of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is to be understood that the terminology used in the description of the embodiments of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the invention. As used in the description of embodiments of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Examples

Referring to fig. 5, the present embodiment provides a method for manufacturing a bionic human bone based on 3D printing:

the ceramic raw materials used include: a-type silicon nitride, B-type silicon nitride, a sintering aid and a silane coupling agent.

a) Setting the initial ratio of A-type silicon nitride to B-type silicon nitride in the ceramic raw material;

b) ball-milling each component in the ceramic raw material for 6 hours at 350r/min by using a planetary ball mill, and uniformly mixing;

c) drying at 60 deg.C, sieving with 100 mesh sieve;

d) designing a first layer model in the bionic human bone;

e) adding resin, a photoinitiator and a dispersant into the uniformly mixed ceramic raw materials to prepare 3D printing slurry, and performing 3D printing molding;

f) degreasing;

g) sintering the ceramic at 1800 ℃ to obtain a first layer of ceramic piece, and measuring the shrinkage rate of the first layer of ceramic piece;

h) designing a second layer model in the bionic human bone;

i) preparing a ceramic raw material by using any type A silicon nitride or type B silicon nitride to prepare 3D printing slurry, and performing 3D printing according to a preset bionic human bone second layer model to obtain a second biscuit; degreasing and sintering the second biscuit to obtain a second layer of ceramic piece, and measuring the shrinkage rate of the second layer of ceramic piece;

j) correspondingly adjusting the proportion of A-type silicon nitride to B-type silicon nitride in the ceramic raw materials of the first ceramic piece according to the shrinkage rate of the second layer of ceramic piece;

k) designing the whole bionic human bone model, preparing the proportion of A-type silicon nitride and B-type silicon nitride in different layers of ceramic raw materials, and obtaining the bionic human bone through pulping, printing, degreasing and sintering.

In specific implementation, the silicon nitride (the sum of the type a silicon nitride and the type B silicon nitride) in the ceramic raw material in the step a) accounts for 90 wt% of the total powder (the sum of the silicon nitride and the sintering aid).

In specific implementation, the A-type silicon nitride in the step a) is an alpha phase, the purity is more than 99.8, and the median particle size is 0.7 μm.

In specific implementation, the B-type silicon nitride in the step a) is an alpha phase, the purity is more than 99.8, and the median particle size is 2.4 μm.

In specific implementation, the sintering aid in the step a) is alumina and yttria, and accounts for 6 wt% of the total powder (the sum of silicon nitride and the sintering aid).

In specific implementation, the silane coupling agent in the step a) is KH560, and accounts for 1.5 wt% of the total powder (the sum of the silicon nitride and the sintering aid).

In specific implementation, the resin in step e), i) comprises BPA10EODMA, HDDA, PPTTA and n-octanol.

In a specific implementation, the solid content of the slurry in the step e) and i) is 35 vol%.

In specific implementation, the degreasing in the step f) and the step k) is a vacuum and air 2-step degreasing method.

In a specific implementation, the forming mode in the step e), i) and k) is DLP printing.

In specific implementation, the silicon nitride powder used in the step i) is alpha-phase, has a purity of more than 99.8 and a median particle size of 1.7 μm, and accounts for 90 wt% of the total powder (the sum of the silicon nitride and the sintering aid).

In specific implementation, the sintering aid used in step i) is magnesium oxide and yttrium oxide, and accounts for 6 wt% of the total powder (the sum of silicon nitride and the sintering aid).

According to the method described in the above examples, the initial proportions of type a silicon nitride and type B silicon nitride of the ceramic raw material in step a) were set to 0:10, 3:7, 5:5, 7:3, 10:0, respectively, and each was sintered to porcelain to obtain a first layer ceramic article. Shrinkage and other properties of the first ceramic part were measured at different initial ratios of type a silicon nitride to type B silicon nitride. The results are given in table 1 below.

TABLE 1 Properties of first layer ceramic articles obtained with different initial ratios of type A silicon nitride to type B silicon nitride

Numbering of first layer ceramic pieces	11	12	13	14	15
						Mass ratio of A-type silicon nitride to B-type silicon nitride	0:10	3:7	5:5	7:3	10:0
Linear shrinkage ratio/%	19.77	22.04	26.13	27.34	31.10
						Porosity/%	32.84	28.16	23.32	2.81	3.73
Flexural strength/MPa	248.23	333.64	468.25	728.7	625.3

According to the method described in the above example, the proportions of the sintering aid for the ceramic raw material in step i) were set to 6 wt%, 8 wt%, 10 wt%, 12 wt%, respectively, and each was sintered to form a ceramic article of the second layer. And measuring the shrinkage and other properties of the second layer of ceramic piece obtained by different proportions of the sintering aid. The results are given in table 2 below.

TABLE 2 Properties of the second layer of ceramic parts obtained with different proportions of sintering aid

Numbering of the second layer of ceramic parts	21	22	23	24
					Proportion of sintering aid/wt%	6	8	10	12
Linear shrinkage ratio/%	21.41	22.63	27.76	28.60
					Porosity/%	40.01	38.62	36.84	34.40
Flexural strength/MPa	300.14	320.42	350.23	371.45

Bionic human bone example 1

Referring to fig. 1, the ratio of type a silicon nitride to type B silicon nitride in the first layer of ceramic material was adjusted by the shrinkage of the second layer of ceramic part, No. 21, based on the performance results of tables 1 and 2. The proportion of A-type silicon nitride and B-type silicon nitride in the first layer of ceramic raw material for preparing the bionic human bone is 2: 8, the obtained first layer ceramic piece has a linear shrinkage of 21.39%, a porosity of 30.62% and a bending strength of 272.86 MPa. The whole bionic human bone after sintering is shown in figure 3, the shrinkage rates of the first layer of ceramic piece and the second layer of ceramic piece are matched, and the joint surface cannot be bent or cracked; fig. 4 shows the SEM morphology of the bionic human bone of the present embodiment, where the left side of fig. 4 is the second layer of ceramic, and the right side of fig. 4 is the first layer of ceramic.

Bionic human bone example 2

Based on the performance results in tables 1 and 2, the ratio of type a silicon nitride to type B silicon nitride in the first layer ceramic material was adjusted by the shrinkage ratio of the second layer ceramic part numbered 22. The proportion of A-type silicon nitride to B-type silicon nitride in the first layer of ceramic raw material for preparing the bionic human bone is 3.4: 6.6, the obtained first layer ceramic piece has the corresponding linear shrinkage rate of 22.60%, the porosity of 27.34% and the bending strength of 350.68 MPa. The shrinkage rates of the first layer of ceramic piece and the second layer of ceramic piece are matched, and the joint surface can not be bent or cracked.

Bionic human bone example 3

Based on the performance results in tables 1 and 2, the ratio of type a silicon nitride to type B silicon nitride in the first layer ceramic material was adjusted by the shrinkage ratio of the second layer ceramic part numbered 23. The proportion of A-type silicon nitride to B-type silicon nitride in the first layer of ceramic raw material for preparing the bionic human bone is 7.6: 2.4, the obtained first layer ceramic piece has a linear shrinkage of 27.73%, a porosity of 3.34% and a bending strength of 680.25 MPa. The shrinkage rates of the first layer of ceramic piece and the second layer of ceramic piece are matched, and the joint surface can not be bent or cracked.

Bionic human bone example 4

Based on the performance results in tables 1 and 2, the ratio of type a silicon nitride to type B silicon nitride in the first layer ceramic material was adjusted by the shrinkage ratio of the second layer ceramic of No. 24. The proportion of A-type silicon nitride to B-type silicon nitride in the first layer of ceramic raw material for preparing the bionic human bone is 7.8: 2.2, the obtained first layer ceramic piece has a linear shrinkage of 28.58%, a porosity of 3.56% and a bending strength of 662.45 MPa. The shrinkage rates of the first layer of ceramic piece and the second layer of ceramic piece are matched, and the joint surface can not be bent or cracked.

Bionic human bone comparative example 1

According to the performance results of tables 1 and 2, the bionic human bone is obtained by using the first layer ceramic part with the number 12 and the second layer ceramic part with the number 21, and the sintered result is shown in fig. 2, and the joint surface is bent and cracked due to the inconsistent shrinkage rates of the adjacent layers.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

While the invention has been described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.