CN106735185A - Gradient porous titanium and preparation method thereof - Google Patents

Abstract

The invention relates to the field of porous metal materials, and specifically relates to a gradient porous titanium and a preparation method thereof. Aiming at the problem that the porous titanium prepared by the existing method cannot have both excellent porosity and mechanical properties, the present invention provides a kind of gradient porous titanium and a preparation method thereof, the steps are as follows: a. Titanium powder and pore forming agent are mixed in a weight ratio of 80 to 90 : 10-20 mixed to obtain material A, titanium powder and pore-forming agent in a weight ratio of 55-65: 35-45 to obtain material B, titanium powder and pore-forming agent in a weight ratio of 40-50: 50-60 Mix evenly to obtain material C; b. Add materials A, B, and C to the innermost layer, middle layer, and outermost layer molds respectively; c. Use a hydraulic press to form, pre-sinter in a resistance furnace, and then transfer to a vacuum Sintering and cooling to obtain gradient porous titanium. The gradient porous titanium of the present invention has better mechanical properties and biocompatibility, and can be used as a high-quality hard tissue repair material; the operation method of the present invention is simple, the equipment requirements are not high, and it is convenient for popularization and use.

Description

Gradient porous titanium and its preparation method

technical field

The invention relates to the field of porous metal materials, and specifically relates to a gradient porous titanium and a preparation method thereof.

Background technique

Metal materials are widely used in orthopedics, medical devices, and hard tissue substitutes because of their excellent mechanical properties; titanium and titanium alloys are widely used due to their good biocompatibility, corrosion resistance and good mechanical properties Among them, the most commonly used medical titanium alloy is Ti-6Al-4V, and it is mostly used to prepare medical products with dense tissue, especially in hard tissue repair and replacement. However, since the elastic modulus of this type of alloy tissue is much higher than that of human bone, it is easy to produce stress shielding and cause bone resorption. In order to solve the stress shielding problem of titanium alloys, many scholars began to use porous materials to reduce the elastic modulus, and achieved preliminary results.

The connected pores of porous titanium alloy are conducive to the transmission of nutrients in human body fluids, and the porosity of the product can be adjusted by controlling the process parameters to change its elastic modulus, so that it can match the human bone tissue or muscle tissue, and further improve its biomechanical compatibility. Porous titanium is harmless to the human body and has good compatibility, so it is used in the medical and health industry, such as spraying titanium beads on the surface of the hip joint to form a porous structure for fixation. Similar techniques are also used in dental implants. Porous titanium implant roots are used for the repair of tooth defects. Because bone cells grow into the pores of the implant, the bonding strength between the implant and the bone interface is greatly improved, thus avoiding brittle fracture and ensuring high bonding strength. Because the porous material has an open and porous structure, it allows the in-growth of new bone tissue and the transfer of body fluids. In particular, the strength and Young's modulus of porous materials can be adjusted to match that of natural bone by adjusting the porosity. According to literature reports, the ideal porosity of artificial bone ranges from 30% to 90%. Generally speaking, the higher the porosity, the higher the penetration rate, and the greater the space provided for tissue ingrowth, which is more conducive to the inward growth of surrounding cells. Injection and growth of new bone, and strengthen biological fixation with bone tissue. However, the increase of porosity will reduce the mechanical properties of materials, thus limiting the application of porous materials in various industries.

There are many preparation methods for porous titanium, such as loose packing sintering method, slurry foaming method, bubble method, melt foaming method, metal deposition method, self-propagating high temperature synthesis method, dealloying method, etc., but the current production method Both can only produce porous titanium materials with one porosity, and it is difficult to ensure that the porosity and strength meet the requirements at the same time.

Contents of the invention

The technical problem to be solved by the invention is: the porous titanium prepared by the existing method is difficult to ensure high porosity and at the same time, the mechanical property is also strong enough.

The technical scheme for solving the technical problems of the present invention is to provide a preparation method of gradient porous titanium. The method includes the following steps:

a. Mix titanium powder and pore-forming agent at a weight ratio of 80-90:10-20 to obtain material A, and mix titanium powder and pore-forming agent at a weight ratio of 55-65:35-45 to obtain material B, titanium Mix the powder and pore-forming agent in a weight ratio of 40-50:50-60 to obtain material C;

b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively;

c. It is pressed and formed by a hydraulic press, pre-sintered in a resistance furnace, then sintered in a vacuum, and cooled to obtain gradient porous titanium.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the pore forming agent in step a is ammonium bicarbonate or common salt.

Further, in the above method for preparing gradient porous titanium, the particle size of the pore-forming agent in step a is 100-300 μm.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the particle size of the titanium powder in step a is 5-45 μm.

Further, in the above method for preparing gradient porous titanium, the purity of the titanium powder in step a is greater than 99.5%.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the pressure of the compression molding in step c is 70-150 MPa, and the holding time is 15-20 s.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the sintering temperature during pre-sintering in step c is 120-170° C., the holding time is 4-6 hours, and the heating rate during pre-sintering is 3-6° C./min.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the degree of vacuum during vacuum sintering in step c is 10 ⁻³ to 10 ⁻⁴ Pa.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the sintering temperature of vacuum sintering in step c is 1100-1300°C, the sintering time is 1-4h, and the heating rate is 3-5°C/min.

The present invention also provides a gradient porous titanium prepared by the above method.

Wherein, in the aforementioned gradient porous titanium, the porosity of the outermost layer is 66-72%, the porosity of the middle layer is 51-62%, and the porosity of the innermost layer is 20-32%.

Wherein, among the gradient porous titanium, the compressive strength of the gradient porous titanium is 131.9-165.0 MPa, and the elastic modulus is 3.30-4.72 GPa.

The beneficial effect of the present invention is: the present invention prepares gradient porous titanium with different porosity by limiting the different ratios of titanium powder and pore-forming agent. The compressive strength and elastic modulus of the porous titanium are similar to those of bone tissue, which can effectively avoid Produced by long-term use of "stress shielding", the gradient porous titanium of the present invention has a high porosity in the outer layer, which facilitates the transmission of nutrients in body fluids and the ingrowth of tissues, thereby realizing "biological fixation", and has better mechanical properties and biophase Capacitance, can be used as a high-quality hard tissue repair material; the operation method of the invention is simple, the equipment requirements are not high, and it is convenient for popularization and use.

Description of drawings

Fig. 1 (a) is the microscopic morphology and each layer microstructure diagram of the embodiment of the present invention 3; (b) is the inner layer morphology with 10% pore-forming agent; (c) is the middle layer with 40% pore-forming agent Morphology; (d) is the morphology of the outer layer with 60% pore-forming agent; (e) the morphology under high magnification;

Fig. 2 is the macroscopic morphology (a) and EDS result (b) of the embodiment of the present invention 1;

Fig. 3 is the compressive strength and elastic modulus figure of the three-layer porous titanium of the embodiment of the present invention 1,2,3;

Fig. 4 is a stress-strain curve diagram of the three-layer porous titanium in Example 3 of the present invention.

detailed description

The invention provides a preparation method of gradient porous titanium, which comprises the following steps:

a. Mix titanium powder and pore-forming agent at a weight ratio of 80-90:10-20 to obtain material A, and mix titanium powder and pore-forming agent at a weight ratio of 55-65:35-45 to obtain material B, titanium Mix the powder and pore-forming agent in a weight ratio of 40-50:50-60 to obtain material C;

b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively;

c. It is pressed and formed by a hydraulic press, pre-sintered in a resistance furnace, then sintered in a vacuum, and cooled to obtain gradient porous titanium.

Wherein, in the preparation method of the above-mentioned gradient porous titanium, the pore-forming agent described in step a is ammonium bicarbonate or salt; in order to make the porosity suitable, which is beneficial to tissue ingrowth and the transmission of body fluid nutrients, the particle size of the pore-forming agent of the present invention 100-300 μm.

Wherein, in the preparation method of the above-mentioned gradient porous titanium, in order to make the strength of the gradient porous titanium higher after sintering, the particle size of the titanium powder in step a is controlled to be 5-45 μm; further, in order to enhance the biophase of the gradient porous titanium Capacitive, the purity of titanium powder is greater than 99.5%.

Among them, in the above-mentioned preparation method of gradient porous titanium, the pressure of the press molding in step c is 70-150 MPa, the press time is too short, the blank is easy to disperse, and the time is too long, the sample is too dense and is not conducive to the formation of pores in the later stage. The pressure holding time of the invention is 15-20s.

Among them, in the above-mentioned preparation method of gradient porous titanium, in order to ensure that the pore-forming agent is completely removed in the low-temperature pre-sintering stage and the shape of the pores is maintained, the sintering temperature during the pre-sintering described in step c of the present invention is 120-170° C., and the holding time is 4-100° C. 6h, the heating rate during pre-sintering is 3-6°C/min.

Wherein, in the above-mentioned preparation method of gradient porous titanium, the degree of vacuum during vacuum sintering in step c is 10 ⁻³ to 10 ⁻⁴ Pa.

Wherein, in the preparation method of the above-mentioned gradient porous titanium, in order to slowly release the gas in the micropores and avoid the collapse of the micropores, the sintering temperature of the vacuum sintering in step c of the present invention is 1100-1300°C, and the sintering time is 1-4h , heating rate 3 ~ 5 ℃ / min.

The present invention also provides a gradient porous titanium prepared by the above method.

Wherein, in the aforementioned gradient porous titanium, the porosity of the outermost layer is 66-72%, the porosity of the middle layer is 51-62%, and the porosity of the innermost layer is 20-32%.

Wherein, among the gradient porous titanium, the compressive strength of the gradient porous titanium is 131.9-165.0 MPa, and the elastic modulus is 3.30-4.72 GPa.

The structure of the mold for preparing porous titanium in the present invention is: radial three-layer cylindrical shape, the innermost mold with the smallest diameter, and the lowest proportion of pore-forming agent is added to prepare porous titanium with low porosity (20% to 40%). Guarantee the high strength of porous titanium; the outermost mold with the largest diameter, the highest proportion of pore-forming agent is added, and the porous titanium with high porosity (70%-80%) is prepared to ensure the transmission of body fluid and the growth of tissue The proportion of the pore-forming agent added to the middle layer is in the middle, and the prepared transitional layer (40% to 60%) is convenient for the connection of the inner and outer layers, while ensuring high porosity, it is also guaranteed to have a strong enough porosity that matches the mechanical properties of bone tissue. Titanium makes it the material of choice for replacement or repair of damaged hard tissues in the load-bearing parts of the human body, such as bones, teeth, and joints. Any mold capable of separately pressing the pore-forming agent and titanium powder into three layers is suitable for the present invention.

The above-mentioned content of the present invention will be further described in detail through the specific implementation of the examples below. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples.

The composition of the titanium powder used in Examples 1-3 is shown in Table 1 below, and the particle size of the titanium powder is 20-40 um.

Table 1 Titanium powder composition list

Example 1 Preparation of gradient porous titanium with the technical scheme of the present invention

Prepare gradient porous titanium according to the following method, and the operation process is as follows:

a. Mix titanium powder and pore-forming agent in a weight ratio of 9:1 to obtain material A. Mix titanium powder and pore-forming agent in a weight ratio of 5.5:4.5 to obtain material B. Titanium powder and pore-forming agent in a weight ratio 1:1 mixing to obtain material C;

b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively;

c. Use a hydraulic press to press and form, the pressing pressure is 80MPa, the pressure is kept for 20s, pre-sintered in a resistance furnace, the pre-sintering temperature is 150°C, the temperature is kept for 5h, and the heating and cooling rate is 4°C/min; Carry out vacuum sintering in a vacuum sintering furnace (VMK-1800 type), the sintering temperature is 1200°C, the holding time is 2h, the heating and cooling rate is 4°C/min, when the temperature is lowered to below 400°C, it can be cooled with the furnace to prepare gradient porous titanium .

The surface layer of the gradient porous titanium prepared in Example 1 was removed with sandpaper, followed by ultrasonic cleaning with acetone, ethanol, and distilled water, each superwashed for 5 to 10 minutes, and then dried for 12 hours, and the microscopic morphology and energy spectrum of the gradient porous titanium were observed with a scanning electron microscope. analyze.

Example 2 Preparation of gradient porous titanium with the technical scheme of the present invention

Prepare gradient porous titanium according to the following method, and the operation process is as follows:

a. Mix titanium powder and pore-forming agent at a weight ratio of 5:1 to obtain material A. Mix titanium powder and pore-forming agent at a weight ratio of 6.5:3.5 to obtain material B. Titanium powder and pore-forming agent in a weight ratio Mix 2:3 to obtain material C;

b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively;

c. Compressed and formed by a micro-hydraulic machine, the pressing pressure is 80MPa, the pressure is maintained for 20s, pre-sintered in a resistance furnace, the pre-sintering temperature is 150°C, the temperature is kept for 5h, and the heating and cooling rate is 4°C/min; the pre-sintered sample Place it in a vacuum sintering furnace (VMK-1800 type) for vacuum sintering. The sintering temperature is 1200°C, the holding time is 2h, and the heating and cooling rate is 4°C/min. When the temperature drops below 400°C, it can be cooled with the furnace to obtain gradient porous. titanium.

The surface layer of the gradient porous titanium prepared in Example 2 was removed with sandpaper, followed by ultrasonic cleaning with acetone, ethanol, and distilled water, each superwashed for 5 to 10 minutes, and then dried for 12 hours, and the microscopic morphology and energy spectrum of the gradient porous titanium were observed with a scanning electron microscope. analyze.

Example 3 Prepare gradient porous titanium with the technical solution of the present invention

Prepare gradient porous titanium according to the following method, and the operation process is as follows:

a. Mix titanium powder and pore-forming agent in a weight ratio of 9:1 to obtain material A. Mix titanium powder and pore-forming agent in a weight ratio of 3:2 to obtain material B. Titanium powder and pore-forming agent in a weight ratio Mix 2:3 to obtain material C;

b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively;

c. Compressed and formed by a micro-hydraulic machine, the pressing pressure is 80MPa, the pressure is maintained for 20s, pre-sintered in a resistance furnace, the pre-sintering temperature is 150°C, the temperature is kept for 5h, and the heating and cooling rate is 4°C/min; the pre-sintered sample Place it in a vacuum sintering furnace (VMK-1800 type) for vacuum sintering. The sintering temperature is 1200°C, the holding time is 2h, and the heating and cooling rate is 4°C/min. When the temperature drops below 400°C, it can be cooled with the furnace to obtain gradient porous. titanium.

The surface layer of the gradient porous titanium prepared in Example 3 was removed with sandpaper, followed by ultrasonic cleaning with acetone, ethanol, and distilled water, each superwashed for 5 to 10 minutes, and then dried for 12 hours, and the microscopic morphology and energy spectrum of the gradient porous titanium were observed with a scanning electron microscope. analyze.

The test result of embodiment and comparative example is shown in table 2 below:

Table 2 shows the porosity of gradient porous titanium

Table 3 shows the compressive strength and elastic modulus of gradient porous titanium

Porous titanium material is used as a material for hard tissue repair, and its main performance index is that the compressive strength and elastic modulus are similar to those of bone tissue, so as to avoid the occurrence of "stress shielding" during long-term use; at the same time, the higher the porosity, the more Well, this facilitates the transfer of nutrients in body fluids and the ingrowth of tissues, thereby achieving "biological fixation". The results of the examples show that compared with ordinary single porous titanium, the gradient porous titanium of the present invention can match the mechanical properties with the bone tissue while maintaining the high porosity of the outer layer. Organizational performance requirements for replacement materials.

Claims (10)

1. the preparation method of gradient porous titanium is characterized in that, comprises the following steps: a. Mix titanium powder and pore-forming agent at a weight ratio of 80-90:10-20 to obtain material A, and mix titanium powder and pore-forming agent at a weight ratio of 55-65:35-45 to obtain material B, titanium Mix the powder and pore-forming agent in a weight ratio of 40-50:50-60 to obtain material C; b. Add materials A, B, and C in step a to the innermost, middle, and outermost moulds, respectively; c. It is pressed and formed by a hydraulic press, pre-sintered in a resistance furnace, then sintered in a vacuum, and cooled to obtain gradient porous titanium. 2. The preparation method of gradient porous titanium according to claim 1, characterized in that: the pore forming agent in step a is ammonium bicarbonate or common salt. 3. The preparation method of gradient porous titanium according to claim 1 or 2, characterized in that the particle size of the pore-forming agent in step a is 100-300 μm. 4. The preparation method of gradient porous titanium according to any one of claims 1-3, characterized in that: the particle size of the titanium powder in step a is 5-45 μm. 5. The preparation method of gradient porous titanium according to any one of claims 1-4, characterized in that the purity of the titanium powder in step a is greater than 99.5%. 6 . The preparation method of gradient porous titanium according to any one of claims 1 to 5 , characterized in that: in step c, the compression molding pressure is 70 to 150 MPa, and the holding time is 15 to 20 s. 7. The preparation method of gradient porous titanium according to any one of claims 1-6, characterized in that: the sintering temperature during pre-sintering in step c is 120-170°C, the holding time is 4-6h, and the pre-sintering The heating rate is 3-6°C/min. 8. The preparation method of gradient porous titanium according to any one of claims 1-7, characterized in that: the sintering temperature of vacuum sintering in step c is 1100-1300°C, the sintering time is 1-4h, and the heating rate is 3～5℃/min. 9. The gradient porous titanium prepared by the preparation method described in any one of claims 1-8. 10. The gradient porous titanium according to claim 9, characterized in that: the porosity of the outermost layer is 66-72%, the porosity of the middle layer is 51-62%, and the porosity of the innermost layer is 20-32%.