Biological titanium alloy-hydroxyapatite gradient composite material and spray forming method thereof

Abstract

The invention discloses a biological titanium alloy-hydroxyapatite gradient composite material and a spray forming method thereof.The biological titanium alloy-hydroxyapatite gradient composite material is composed of an alloy phase and a ceramic phase, the alloy phase is a beta-type titanium alloy, the ceramic phase is hydroxyapatite, and the alloy phase is a beta-type titanium alloy. The biological titanium alloy-hydroxyapatite gradient composite material has a three-dimensional gradient structure, and integrates the characteristics of better matched mechanical properties, good corrosion and wear resistance, biocompatibility and the like of beta-type titanium alloy and natural bones and the characteristics of good biological activity, osteoconductivity and the like of hydroxyapatite. The spray forming method comprises the steps of powder slurry preparation, slurry spray forming, formed blank degreasing, sintering and the like, the three-dimensional gradient structure of the beta-type titanium alloy-hydroxyapatite composite material is achieved through the spray forming method, and personalized and high-precision manufacturing of the gradient composite material bone repair implant can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metal-ceramic composite materials, and in particular to a bio-titanium alloy-hydroxyapatite gradient composite material and a spray forming method thereof. Background Art

[0002] Bone injury is one of the most common diseases in the human body. When human bones are impacted by external forces or affected by diseases, they are prone to fractures or wear and tear. Bone transplantation is the main means of treating fractures and bone defects, but the research and development of bone repair materials used in bone transplantation has always been a technical problem that needs to be solved urgently worldwide.

[0003] Natural bone is a typical gradient material, with the outer cortical bone having high density and hardness, while the inner cancellous bone has low density and flexibility. Currently, the widely used biomedical materials in clinical practice, such as metal materials such as stainless steel, cobalt alloy, titanium alloy, polymer materials such as silicone rubber, polymethyl methacrylate, polylactic acid, chitosan and collagen, and ceramic materials such as hydroxyapatite, calcium phosphate and bioglass, are difficult to simultaneously meet the basic requirements of mechanical properties, corrosion resistance, wear resistance, bioactivity and biocompatibility required for bone repair materials. More importantly, these homogeneous composite materials cannot meet the gradient structure requirements of natural bone.

[0004] The manufacture of bone repair materials and bone implants faces the challenges of personalized size, complex shape and structure, and rich in tiny details, which requires personalized design and high-precision manufacturing. In this context, additive manufacturing technology has shown great application potential with its unique advantages of integrated forming and manufacturing. Although some patents have attempted to prepare bone repair materials through additive manufacturing technology, there are still many technical bottlenecks. For example, patents CN108863341A and CN108950305A use laser selective melting and laser cladding technology to prepare titanium alloy-silicate transition layer-hydroxyapatite porous materials, respectively. Although these methods have achieved the preparation of gradient materials to a certain extent, the powder configuration is cumbersome, manual filling is time-consuming, and thermal stress and thermal cracks are easily generated under the action of high-energy lasers, which limits their promotion in practical applications.

[0005] At present, in terms of powder additive manufacturing technology, although laser selective melting (SLM) and laser powder bed melting (LPBF) technologies are relatively mature, they can only realize the preparation of one-dimensional gradient materials, that is, the composition between powder layers (forming direction) can be changed, but the composition within the powder layer (forming cross section) must be the same. Although powder feeding technologies such as laser near-net shaping (LENS) and laser directed energy deposition (LDED) can realize directional supply of powder in three-dimensional directions, the formation of molten pools during the forming process will lead to the expansion of the heat-affected zone, and the material is prone to deformation or thermal cracking.

[0006] Therefore, the research and development of new additive manufacturing technologies for gradient composite materials is particularly important in order to meet the stringent requirements of bone repair materials in terms of mechanical properties, bioactivity and biocompatibility, while achieving personalized design and high-precision manufacturing. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a bio-titanium alloy-hydroxyapatite gradient composite material and its injection molding method, using high-precision additive manufacturing technology to realize the preparation of a three-dimensional gradient composite material combining β-type titanium alloy and hydroxyapatite, and further manufacture bone repair implants that meet the patient's personalized needs.

[0008] The above object of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a bio-titanium alloy-hydroxyapatite gradient composite material, which consists of an alloy phase and a ceramic phase, wherein the alloy phase is a β-type titanium alloy (β-Ti), and the ceramic phase is hydroxyapatite (HA). The bio-titanium alloy-hydroxyapatite gradient composite material has a three-dimensional gradient structure.

[0010] Furthermore, the β-type titanium alloy contains titanium (Ti) and one or more of molybdenum (Mo), niobium (Nb), tantalum (Ta), zirconium (Zr) and tin (Sn).

[0011] The alloy phase provided by the present invention is a novel beta-type titanium alloy formed by adding non-cytotoxic elements such as Mo, Nb, Ta, Zr and Sn to Ti, and the ceramic phase is HA having a chemical composition and crystal structure similar to human bone tissue.

[0012] The present invention also provides a method for spray forming a bio-titanium alloy-hydroxyapatite gradient composite material, comprising the following steps:

[0013] (1) preparing a β-type titanium alloy powder by proportioning a metal powder, mixing the β-type titanium alloy powder with a binder to obtain a β-type titanium alloy slurry; mixing a hydroxyapatite powder with a binder to obtain a hydroxyapatite slurry;

[0014] (2) When the temperature inside the injection chamber of the injection molding machine reaches 100-200° C., the β-titanium alloy slurry and hydroxyapatite slurry obtained in step (1) are respectively injected into two piezoelectric injection valves, and the two piezoelectric injection valves quantitatively spray the β-titanium alloy slurry and hydroxyapatite slurry on the bottom plate according to a pre-set motion trajectory to obtain a bio-titanium alloy-hydroxyapatite gradient composite material formed part;

[0015] (3) subjecting the bio-titanium alloy-hydroxyapatite gradient composite material formed part obtained in step (2) to solvent degreasing treatment and then to thermal degreasing treatment to obtain a bio-titanium alloy-hydroxyapatite gradient composite material degreased part;

[0016] (4) The degreased part of the bio-titanium alloy-hydroxyapatite gradient composite material obtained in step (3) is placed in a high-temperature furnace protected by inert gas, first heated to 850-950°C at a heating rate of 5-10°C / min and kept warm for 1-2 hours, and then heated to 1300-1600°C at a heating rate of 1-3°C / min and kept warm for 2-5 hours to obtain the bio-titanium alloy-hydroxyapatite gradient composite material.

[0017] The spray forming method provided by the present invention comprises the steps of preparing powder slurry, spray forming of slurry, degreasing and sintering of formed blanks, and specifically comprises the operations of preparing β-titanium alloy slurry and hydroxyapatite slurry, quantitative spray forming of double slurries, dissolution and thermal decomposition treatment, and high-temperature sintering. The prepared bio-titanium alloy-hydroxyapatite gradient composite material is composed of biological β-titanium alloys such as titanium-molybdenum, titanium-niobium, and titanium-tantalum, and hydroxyapatite bioceramics, and combines the mechanical properties of β-titanium alloys that are more matched with natural bones, good corrosion resistance and wear resistance, and biocompatibility, and the good biological activity and bone conductivity of hydroxyapatite. The spray forming method realizes the three-dimensional gradient structure of the β-titanium alloy-hydroxyapatite composite material, and can realize personalized and high-precision manufacturing of gradient composite bone repair implants.

[0018] Furthermore, in step (1), the binder consists of paraffin wax (PW), a thermoplastic resin and stearic acid (SA).

[0019] Furthermore, the mass ratio of the paraffin wax, the thermoplastic resin and the stearic acid is (5-15):(75-90):(1-10).

[0020] Furthermore, the thermoplastic resin is selected from one or more of polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polycaprolactone (PCL), polylactic acid (PLA), ethylene-vinyl acetate copolymer (EVA) and polyethylene glycol (PEG).

[0021] Furthermore, in step (1), the metal powder is a spherical powder with a purity greater than 99.99% and a particle size of 300-600 meshes.

[0022] Furthermore, in step (1), the hydroxyapatite powder is a micron-sized and / or nano-sized needle-shaped powder.

[0023] Furthermore, in step (1), the mass ratio of the β-type titanium alloy powder to the hydroxyapatite powder is 10:(0.1-2).

[0024] Furthermore, in step (1), the volume ratio of the β-type titanium alloy powder to the binder is 10:(4-7).

[0025] Furthermore, in step (1), the volume ratio of the hydroxyapatite powder to the binder is 10:(4-7).

[0026] In a specific embodiment, in step (1), β-titanium alloy powder or hydroxyapatite powder is mixed with a binder in a mixer.

[0027] Furthermore, the process parameters of mixing in the mixer are: mixing temperature of 100-250° C., stirring speed of 50-100 r / min, and mixing time of 1-3 h.

[0028] In a specific embodiment, in step (1), according to the composition design theory of β-type titanium alloy, metal powders such as Ti, Mo, Nb, Ta, Zr, Sn, etc. are weighed as needed, and the obtained β-type titanium alloy powder and HA powder (the mass is 1%-20% of the mass of the β-type titanium alloy powder) are respectively fully mixed with 28-41 vol% of a binder in a mixer to prepare β-type titanium alloy slurry and hydroxyapatite slurry.

[0029] Furthermore, in step (2), the process parameters of the quantitative injection of the piezoelectric injection valve are: injection pressure of 0.1-2.0MPa, injection speed of 0.01-0.03Ma, and injection volume of 20-100nL.

[0030] Furthermore, in step (3), water and / or an organic solvent is used for solvent degreasing treatment.

[0031] Furthermore, the organic solvent may be ethanol, n-hexane, etc.

[0032] Furthermore, in step (3), the solvent degreasing treatment is specifically as follows: placing the bio-titanium alloy-hydroxyapatite gradient composite material formed part into a container containing a solvent, and heating it to 25-100° C. in a water bath and keeping it warm for 2-3 hours.

[0033] Furthermore, in step (3), the thermal degreasing treatment is specifically as follows: the bio-titanium alloy-hydroxyapatite gradient composite material formed part after solvent degreasing treatment is placed in a degreasing furnace, first heated from 20-30°C to 200-250°C at a heating rate of 5-10°C / min and kept warm for 1-2h, and then heated to 380-550°C at a heating rate of 1-3°C / min and kept warm for 1-2h.

[0034] Furthermore, in step (3), after the thermal degreasing treatment is completed, the product is cooled in the furnace to obtain a degreased part of the bio-titanium alloy-hydroxyapatite gradient composite material.

[0035] Beneficial effects of the present invention:

[0036] 1. Compared with traditional laser 3D printing technology, the injection molding process provided by the present invention does not require the use of expensive lasers and galvanometers, thereby significantly reducing equipment costs and having excellent maintenance convenience and reliability. Among them, the injection valve is driven by piezoelectric ceramics, supporting multiple injection valves to work simultaneously, and the printing efficiency is 5-6 times that of ordinary laser powder sintering technology. In addition, the present invention can accurately control the movement of the injection valve by adopting position closed-loop control technology, thereby realizing quantitative injection printing, greatly improving the printing quality, and the accuracy can reach 0.01mm.

[0037] 2. The present invention supports the use of a variety of slurryable materials such as metals and non-metals as printing materials, and realizes flexible control of the composition and distribution of three-dimensional gradient materials through a dual nozzle design. In addition, the present invention does not need to rely on an auxiliary heating system, successfully controls the heat-affected range to a very small extent, and can effectively avoid the problem of part deformation caused by thermal stress when printing large-sized parts, ensuring the dimensional accuracy and stability of the printed parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention provides a process flow chart of the injection molding method of the bio-titanium alloy-hydroxyapatite gradient composite material. DETAILED DESCRIPTION

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0041] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0042] The present invention provides a method for spray forming a bio-titanium alloy-hydroxyapatite gradient composite material, comprising the following steps:

[0043] (1) preparing a β-type titanium alloy powder by proportioning a metal powder, mixing the β-type titanium alloy powder with a binder to obtain a β-type titanium alloy slurry; mixing a hydroxyapatite powder with a binder to obtain a hydroxyapatite slurry;

[0044] (2) When the temperature inside the injection chamber of the injection molding machine reaches 100-200° C., the β-titanium alloy slurry and hydroxyapatite slurry obtained in step (1) are respectively injected into two piezoelectric injection valves, and the two piezoelectric injection valves quantitatively spray the β-titanium alloy slurry and hydroxyapatite slurry on the bottom plate according to a pre-set motion trajectory to obtain a bio-titanium alloy-hydroxyapatite gradient composite material formed part;

[0045] (3) subjecting the bio-titanium alloy-hydroxyapatite gradient composite material formed part obtained in step (2) to solvent degreasing treatment and then to thermal degreasing treatment to obtain a bio-titanium alloy-hydroxyapatite gradient composite material degreased part;

[0046] (4) The degreased part of the bio-titanium alloy-hydroxyapatite gradient composite material obtained in step (3) is placed in a high-temperature furnace protected by inert gas, first heated to 850-950°C at a heating rate of 5-10°C / min and kept warm for 1-2 hours, and then heated to 1300-1600°C at a heating rate of 1-3°C / min and kept warm for 2-5 hours to obtain the bio-titanium alloy-hydroxyapatite gradient composite material.

[0047] In a specific embodiment, the process flow chart of the injection molding method of the bio-titanium alloy-hydroxyapatite gradient composite material is as follows Figure 1 As shown, the specific steps include:

[0048] (1) According to the composition design theory of β-titanium alloy, metal powders such as Ti, Mo, Nb, Ta, Zr, and Sn are weighed as needed, and the obtained β-titanium alloy powder and HA powder (the mass of which is 1%-20% of the mass of the β-titanium alloy powder) are fully mixed and stirred with 28-41 vol% of a multi-component binder in a mixer to prepare β-Ti slurry and HA slurry;

[0049] (2) When the temperature inside the injection chamber of the injection molding machine reaches 100-200° C., the β-Ti slurry and HA slurry obtained in step (1) are respectively injected into the piezoelectric injection valve 1 and the piezoelectric injection valve 2, and the two piezoelectric injection valves respectively quantitatively spray the β-Ti slurry and the HA slurry on the bottom plate according to the pre-set motion trajectory to obtain a bio-titanium alloy-hydroxyapatite gradient composite material formed part (β-Ti / HA three-dimensional gradient formed part);

[0050] (3) placing the bio-titanium alloy-hydroxyapatite gradient composite material formed part into a container containing a solvent, heating it to 25-100°C in a water bath and keeping it warm for 2-3 hours, then taking it out; after drying, placing it in a degreasing furnace, first heating it from 20-30°C to 200-250°C at a heating rate of 5-10°C / min and keeping it warm for 1-2 hours, then heating it to 380-550°C at a heating rate of 1-3°C / min and keeping it warm for 1-2 hours, and cooling it with the furnace to obtain a bio-titanium alloy-hydroxyapatite gradient composite material degreased part (β-Ti / HA three-dimensional gradient degreased part) with a certain size, shape and bonding strength;

[0051] (4) The degreased part of the bio-titanium alloy-hydroxyapatite gradient composite material is placed in a high-temperature furnace protected by high-purity argon gas, first heated to 850-950°C in the β phase region of the titanium alloy at a heating rate of 5-10°C / min and kept warm for 1-2 hours, then heated to a sintering temperature of 1300-1600°C at a heating rate of 1-3°C / min and kept warm for 2-5 hours, and then cooled to room temperature with the furnace to obtain the bio-titanium alloy-hydroxyapatite gradient composite material (β-Ti / HA three-dimensional gradient sintered part).

[0052] Example 1

[0053] A method for spray forming a bio-titanium alloy-hydroxyapatite gradient composite material comprises the following steps:

[0054] (1) According to the composition design of Ti-15Mo, 170g of 400-mesh spherical titanium powder with a purity of 99.99% and 30g of 500-mesh spherical molybdenum powder with a purity of 99.99% were weighed and mixed with 26g (40vol%) of a binder (10wt% PW+65wt% PLA+20wt% PEG+5wt% SA) in a mixer at 200°C and 60r / min for 2h to obtain Ti-15Mo slurry; 10g of micron-sized needle-shaped hydroxyapatite powder was weighed according to 5wt% of the metal powder and mixed with 2.2g (40vol%) of a binder (10wt% PW+65wt% PLA+20wt% PEG+5wt% SA) in a mixer at 200°C and 60r / min for 2h to obtain HA slurry.

[0055] (2) When the temperature inside the injection chamber of the injection molding machine reaches 200°C, the Ti-15Mo slurry is injected into the piezoelectric injection valve 1, and the HA slurry is injected into the piezoelectric injection valve 2. The injection molding machine drives the piezoelectric injection valve according to the three-dimensional model of the pre-designed part, and sprays the Ti-15Mo slurry and HA slurry on the TC4 base plate at a spray pressure of 1.0 MPa, a spray speed of 0.02 Ma, and a spray volume of 40 nL to obtain a Ti-15Mo / HA gradient composite molded part.

[0056] (3) The Ti-15Mo / HA gradient composite material formed part is placed in a beaker of water, kept at a constant temperature of 25°C in a water bath for 2 h, and then taken out to dry; then, it is placed in a tubular furnace filled with 99.99% high-purity argon and heated to 200°C at a rate of 10°C / min, then heated to 500°C at a rate of 3°C / min and kept at that temperature for 2 h, and then cooled with the furnace to obtain a Ti-15Mo / HA gradient composite material degreased part.

[0057] (4) The degreased parts of the Ti-15Mo / HA gradient composite material were placed in a high-temperature furnace protected by 99.99% high-purity argon gas, first heated to 900°C in the β phase region of the titanium alloy at a heating rate of 8°C / min and kept warm for 1 h, then heated to 1500°C at a heating rate of 3°C / min and kept warm for 2 h, and then cooled to room temperature with the furnace to obtain the Ti-15Mo / HA gradient composite material.

[0058] The Ti-15Mo alloy and the Ti-15Mo / HA gradient composite material prepared in Example 1 were subjected to friction and wear tests in a simulated body fluid environment. The test method was as follows: the sample was fixed on the platform of the friction and wear testing machine for linear reciprocating motion, and a zirconia ball with a diameter of 10 mm was selected as the counter-grinding material. At a constant temperature of 37±0.5°C, the test load was 30N, the sliding frequency was 1Hz, the friction length was 10mm, and the friction time was 20min.

[0059] The test results are as follows: the Vickers hardness of the Ti-15Mo / HA gradient composite material is 585HV, the friction coefficient is 0.42, and the wear rate is 2.51×10 -4 mm 3 / N·m, which is about 58% lower than that of Ti-15Mo alloy.

[0060] The biocompatibility of Ti-15Mo alloy and Ti-15Mo / HA gradient composite material prepared in Example 1 was tested by in vitro cell culture. The test method was as follows: Ti-15Mo alloy and Ti-15Mo / 5HA gradient composite material were processed into square thin slice samples with a size of 10mm×10mm×2mm by wire cutting, and the entire sample surface was polished and cleaned, and then the sample was sterilized by high-pressure steam. The extract was prepared according to the national standard GB / T 16886.12-2017, and the sterilized sample was placed in a 5mL centrifuge tube and the extraction ratio was 2mL / cm 2 Add serum-containing culture medium (i.e., add 2.5 mL of serum-containing culture medium to each sample for extraction), and place in a constant temperature oscillator for extraction at 37°C for 72 hours. Use a 0.22 μm water filter to remove insoluble impurities in the culture medium after extraction, and store in a refrigerator at 4°C.

[0061] First, mouse osteoblasts (MC3T3-E1) were used for cell proliferation experiments. The temperature was controlled at 37°C, the humidity was increased to 95%, and the CO 2 The concentration was readjusted to 5%, and then the cells were cultured in a constant temperature incubator for proliferation. 10 μL of the mouse osteoblast (MC3T3-E1) suspension in the logarithmic growth phase was taken out and counted, and then the resuspended cells were diluted with α-MEM complete culture medium, and finally 5×10 3 The cells were inoculated into a 96-well sterile plate at a density of 100 μL of extract containing Ti-15Mo alloy or Ti-15Mo / 5HA gradient composite material in each well. The culture time was 1 day, 3 days, 5 days and 7 days, respectively. The cells without sample extract were set as blank control group. After the culture, the extract in the well plate was removed and 100 μL of 10% CCK-8 reagent was added, and the cells were placed in a carbon dioxide incubator at 37°C for 1 hour. The absorbance (OD) at a wavelength of 450 nm was measured using an ELISA instrument, and the proliferation activity of each sample on mouse osteoblasts was calculated using the following formula:

[0062]

[0063] Among them, OD sample, OD blank and OD control represent the OD values ​​of the sample, blank control group and negative control group (the cells in this group grow naturally), respectively.

[0064] Through biocompatibility testing, it was found that after mouse osteoblasts were cultured in the Ti-15Mo alloy group and the Ti-15Mo / 5HA gradient composite material group for 7 days, the cell viability of the Ti-15Mo alloy group was 107.36%, and that of the Ti-15Mo / 5HA gradient composite material group was 113.64%. The number of cells in the extract of the Ti-15Mo / 5HA gradient composite material group was significantly greater than that of the Ti-15Mo alloy group, indicating that the addition of HA makes the gradient composite material exhibit better biocompatibility than the alloy.

[0065] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art should understand that other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A bio-titanium alloy-hydroxyapatite gradient composite material, characterized in that: The bio-titanium alloy-hydroxyapatite gradient composite material consists of an alloy phase and a ceramic phase, the alloy phase is a β-type titanium alloy, the ceramic phase is hydroxyapatite, and the bio-titanium alloy-hydroxyapatite gradient composite material has a three-dimensional gradient structure.

2. The bio-titanium alloy-hydroxyapatite gradient composite material according to claim 1, characterized in that: The β-type titanium alloy contains titanium and one or more of molybdenum, niobium, tantalum, zirconium and tin.

3. The method for preparing the bio-titanium alloy-hydroxyapatite gradient composite material according to claim 1 or 2, characterized in that: The following steps are involved: (1) preparing a β-type titanium alloy powder by proportioning a metal powder, mixing the β-type titanium alloy powder with a binder to obtain a β-type titanium alloy slurry; mixing a hydroxyapatite powder with a binder to obtain a hydroxyapatite slurry; (2) When the temperature inside the injection chamber of the injection molding machine reaches 100-200° C., the β-titanium alloy slurry and hydroxyapatite slurry obtained in step (1) are respectively injected into two piezoelectric injection valves, and the two piezoelectric injection valves quantitatively spray the β-titanium alloy slurry and hydroxyapatite slurry on the bottom plate according to a pre-set motion trajectory to obtain a bio-titanium alloy-hydroxyapatite gradient composite material formed part; (3) subjecting the bio-titanium alloy-hydroxyapatite gradient composite material formed part obtained in step (2) to solvent degreasing treatment and then to thermal degreasing treatment to obtain a bio-titanium alloy-hydroxyapatite gradient composite material degreased part; (4) The degreased part of the bio-titanium alloy-hydroxyapatite gradient composite material obtained in step (3) is placed in a high-temperature furnace protected by inert gas, first heated to 850-950°C at a heating rate of 5-10°C / min and kept warm for 1-2 hours, and then heated to 1300-1600°C at a heating rate of 1-3°C / min and kept warm for 2-5 hours to obtain the bio-titanium alloy-hydroxyapatite gradient composite material.

4. The preparation method according to claim 3, characterized in that: In step (1), the binder consists of paraffin, thermoplastic resin and stearic acid.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the paraffin wax, the thermoplastic resin and the stearic acid is (5-15):(75-90):(1-10).

6. The preparation method according to claim 4, characterized in that: The thermoplastic resin is selected from one or more of polymethyl methacrylate, polyvinyl alcohol, polycaprolactone, polylactic acid, ethylene-vinyl acetate copolymer and polyethylene glycol.

7. The preparation method according to claim 3, characterized in that: In step (1), the mass ratio of the β-type titanium alloy powder to the hydroxyapatite powder is 10:(0.1-2).

8. The preparation method according to claim 3, characterized in that: In step (1), the volume ratio of the β-type titanium alloy powder to the binder is 10:(4-7), and the volume ratio of the hydroxyapatite powder to the binder is 10:(4-7).

9. The preparation method according to claim 3, characterized in that: In step (2), the process parameters of the piezoelectric injection valve for quantitative injection are: injection pressure of 0.1-2.0MPa, injection speed of 0.01-0.03Ma, and injection volume of 20-100nL.

10. The preparation method according to claim 3, characterized in that: In step (3), the thermal degreasing treatment is specifically as follows: the bio-titanium alloy-hydroxyapatite gradient composite material formed part after solvent degreasing treatment is placed in a degreasing furnace, first heated from 20-30°C to 200-250°C at a heating rate of 5-10°C / min and kept warm for 1-2h, and then heated to 380-550°C at a heating rate of 1-3°C / min and kept warm for 1-2h.

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