Porous and high-hardness titanium alloy material as well as preparation method and application thereof

Abstract

The invention provides a porous and high-hardness titanium alloy material and a preparation method and application thereof. The preparation method comprises the following steps: carrying out surface modification on a titanium alloy matrix material by adopting a micro-arc oxidation technology so as to form a ceramic coating with a porous structure on the titanium alloy matrix material to obtain a first intermediate material; etching the first intermediate material by adopting argon plasma to form atomic vacancies on the ceramic coating to obtain a second intermediate material; and the second intermediate material is subjected to plasma nitriding treatment through a hollow cathode plasma nitriding technology, the nitriding temperature is 500 DEG C or below, and the porous and high-hardness titanium alloy material is obtained. According to the preparation method, nitriding can be achieved under the low-temperature condition of 500 DEG C or below, a good porous structure is maintained, and the prepared titanium alloy material is high in hardness and excellent in abrasion resistance and corrosion resistance; the problem that an existing nitriding technology needs to be carried out at the high temperature of 700 DEG C, and consequently a porous structure deforms is solved.

Description

Technical Field

[0001] This invention belongs to the field of medical bone implant device manufacturing, specifically relating to a porous and high-hardness titanium alloy material, its preparation method, and its application. Background Technology

[0002] Titanium alloys have become a leading material in the biomedical field due to their excellent biocompatibility, superior mechanical properties, good corrosion resistance, and moderate elastic modulus. Micro-arc oxidation (MAO) technology can create porous coatings on the surface of titanium alloys, possessing a large specific surface area and interconnected channels, making them ideal carriers for loading and sustained-release active substances such as drugs, growth factors, and antibacterial agents. The porous structure formed after MAO provides physical space and anchoring points for osteocyte inward growth, proliferation, and differentiation. The elastic modulus of the porous structure can be designed to more closely resemble that of natural bone, reducing stress shielding effects, preventing surrounding bone resorption, and promoting early and stronger osseointegration. However, compensating for the porous structure generated by MAO can affect the hardness and wear resistance of titanium alloys; therefore, surface nitriding is often used to improve the hardness and wear resistance of titanium alloys.

[0003] However, existing surface nitriding processes are typically carried out at temperatures above 700°C. High-temperature nitriding leads to coarse grains, introduces high residual stress, results in a porous microstructure, causes defects and deformation, and degrades performance. In some existing technologies, the ion nitriding temperature for titanium alloys is 870-890°C, with a holding time of 8-10 hours. This high temperature can cause phase transformations when processing titanium alloys, such as TA series alloys, reducing the mechanical properties of the substrate and rendering the workpiece unusable. Furthermore, temperatures above 700°C can deform titanium alloy structural components and destroy the porous structure created by micro-arc oxidation, hindering precise control of workpiece porosity and dimensions. While lowering the temperature can reduce the amount of deformation in the substrate, even under longer nitriding times (e.g., over 10 hours), the nitrided layer depth remains shallow. Summary of the Invention

[0004] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions: The first aspect of the present invention provides a method for preparing a porous and high-hardness titanium alloy material, comprising: The surface of the titanium alloy substrate material is modified by micro-arc oxidation technology to form a ceramic coating with a porous structure on the titanium alloy substrate material, thereby obtaining the first intermediate material. The first intermediate material is etched using argon plasma to form atomic vacancies on the ceramic coating, thereby obtaining the second intermediate material; The second intermediate material is subjected to plasma nitriding treatment using hollow cathode plasma nitriding technology. The nitriding temperature of the plasma nitriding treatment is below 500℃, resulting in a porous and high-hardness titanium alloy material.

[0005] The preparation method provided by this invention first performs micro-arc oxidation on the titanium alloy substrate to form a porous ceramic coating. Then, argon plasma etching is used to etch the oxide surface of the micro-arc oxidized titanium alloy, creating atomic vacancies for subsequent nitrogen infiltration. This allows for subsequent nitriding at lower temperatures below 500°C using hollow cathode plasma nitriding technology, solving the problem that existing nitriding processes require high temperatures of 700°C, which leads to deformation and destruction of the porous structure. The titanium alloy material prepared by this invention not only maintains the porous structure of the micro-arc oxidation stage but also exhibits high hardness, improved wear resistance, and corrosion resistance.

[0006] It should also be noted that the order of micro-arc oxidation, sub-plasma etching, and plasma nitriding is particularly important for obtaining porous and high-hardness titanium alloy materials. If the titanium alloy substrate is nitrided first, the thickness of the nitrided layer is generally a few micrometers. However, during the micro-arc oxidation process, the surface of the titanium alloy will undergo varying degrees of dissolution or corrosion in the electrolyte. The surface modification layer formed by micro-arc oxidation can reach hundreds of micrometers and is relatively rough, which means that the nitrided layer formed first cannot be retained and will not achieve the desired effect.

[0007] In some embodiments, the argon plasma etching conditions include: an etching gas pressure of 5 Pa to 10 Pa, a bias voltage of 3 kV to 5 kV during etching, and an etching time of 60 min to 120 min. For example, etching the oxide surface of a titanium alloy micro-arc oxidation process using high-density argon plasma generated by the hollow cathode effect before nitriding can create atomic vacancies for subsequent nitrogen infiltration, enabling nitriding at lower temperatures and with higher efficiency.

[0008] In some embodiments, the nitriding temperature is 400℃~500℃, for example, any one value or any two values ​​between 400℃, 420℃, 450℃, 470℃, 490℃, and 500℃.

[0009] In some embodiments, the process conditions of the hollow cathode plasma nitriding technology include: nitriding gas pressure of 200 Pa to 240 Pa, bias voltage of 700 V to 800 V during nitriding, and nitriding time of 5 h to 8 h.

[0010] In some embodiments, the plasma nitriding treatment specifically includes: placing the intermediate material in a hollow cathode plasma nitriding device, evacuating to below 3.0 Pa, setting the nitriding gas pressure to 200 Pa to 240 Pa and the bias voltage during nitriding to 700 V to 800 V, then introducing nitrogen gas, and performing plasma nitriding treatment at below 500 °C for 5 to 8 hours.

[0011] The "micro-arc oxidation-argon plasma etching-hollow cathode plasma nitriding" method provided by this invention can obtain a thicker nitriding layer at a lower temperature and in a shorter time. In some embodiments, a nitriding layer with a thickness of more than 20µm can be obtained, which solves the problem that lowering the nitriding temperature in the prior art will result in a shallower nitriding layer.

[0012] Under the aforementioned plasma nitriding process conditions, the high-density plasma generated by the hollow cathode effect fully ionizes the nitrogen gas, resulting in a nitrogen ion density more than 100 times higher than that in conventional nitriding techniques. Therefore, high-rate nitriding can be achieved at relatively low temperatures. Furthermore, this plasma nitriding process does not require the introduction of hydrogen gas, thus avoiding the damage to the porous structure formed by micro-arc oxidation caused by hydrogen.

[0013] In some embodiments, the micro-arc oxidation technology specifically includes: using graphite as the cathode and the titanium alloy substrate material as the anode, placing the titanium alloy substrate material in an electrolyte containing 15 g / L to 30 g / L of silicate and 3 g / L to 6 g / L of strong alkali, and performing micro-arc oxidation at 15 V to 20 V and 40 °C to 60 °C.

[0014] The silicate includes, for example, one or more combinations of Na2SiO3, K2SiO3, etc., but is not limited thereto; the strong base may be, for example, one or more combinations of sodium hydroxide, potassium hydroxide, etc., but is not limited thereto.

[0015] In some embodiments, the preparation method further includes: polishing the titanium alloy substrate material, and then performing surface modification using the micro-arc oxidation technology. The polishing process can reduce the surface roughness of the titanium alloy substrate material to below Ra 0.8, for example, Ra 0.2 to 0.8.

[0016] A second aspect of the present invention provides a porous and high-hardness titanium alloy material, which is prepared by the preparation method described in any of the above technical solutions.

[0017] In some embodiments, the porosity of the titanium alloy material is 17% to 33%. Based on the porosity of the intermediate material formed by micro-arc oxidation, the porous and high-hardness titanium alloy material prepared by the preparation method provided by the present invention has a porosity retention rate of more than 20%.

[0018] In some embodiments, the hardness of the titanium alloy material is 1100 HV to 1300 HV.

[0019] In some embodiments, the thickness of the nitrided layer obtained by the plasma nitriding treatment is 20 µm or more.

[0020] A third aspect of the present invention provides the application of the aforementioned porous and high-hardness titanium alloy material in the preparation of biological implants.

[0021] A fourth aspect of the present invention provides a biological implant comprising the aforementioned porous and high-hardness titanium alloy material.

[0022] Compared with existing technologies, the present invention has at least the following beneficial effects: The preparation method provided by the present invention first performs micro-arc oxidation to form a porous ceramic coating, and then etches the ceramic coating with argon plasma to create atomic vacancies for subsequent nitrogen infiltration. This allows for plasma nitriding at lower temperatures below 500°C using hollow cathode plasma nitriding technology, solving the problem in existing nitriding processes that require 700°C, which leads to deformation and destruction of the porous structure. Furthermore, after nitriding, the porous structure from the micro-arc oxidation stage remains well maintained, and the hardness, wear resistance, and corrosion resistance are significantly improved. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the hollow cathode ion nitriding device used in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional morphology diagram of the porous and high-hardness titanium alloy material obtained in Example 1 of the present invention; Figure 3 The images show the XRD patterns of the titanium alloy materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 of this invention, as well as the untreated TC4 titanium alloy matrix material. Detailed Implementation

[0025] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0026] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are any testing methods known in the art.

[0027] Example 1

[0028] This embodiment provides a porous and high-hardness titanium alloy material and its preparation method, specifically including the following steps: (1) The TC4 titanium alloy matrix material was made into a sample with a specification of 30 mm × 30 mm × 6 mm. The surface was polished by sandpaper and diamond polishing paste in turn to remove the oxide layer on the surface and make the surface roughness Ra about 0.2. Then it was immersed in petroleum ether, acetone, alcohol and deionized water in turn and ultrasonicated for 20 min to remove the surface oil. Then it was dried with nitrogen. (2) The TC4 titanium alloy substrate material treated in step (1) is placed in an electrolyte containing 15 g / L Na2SiO3 and 3 g / L NaOH for micro-arc oxidation treatment. During the treatment, the graphite sheet is used as the cathode and the titanium alloy substrate is used as the anode. The anodic oxidation is carried out at 15V and 40℃. Finally, a ceramic coating with a porous structure is formed on the TC4 titanium alloy substrate material to obtain the first intermediate material. (3) The ceramic coating on the first intermediate material is etched by high-density argon plasma generated by the hollow cathode effect. Specifically, the etching pressure is 5 Pa, the bias voltage during etching is 3 kV, and the etching time is 60 min, thereby forming atomic vacancies on the ceramic coating and obtaining the second intermediate material. (4) The first intermediate material was nitrided using hollow cathode plasma nitriding technology. Figure 1 This is a schematic diagram of the hollow cathode ion nitriding device used in Example 1. Specifically, it includes: after etching, adjusting the gas pressure to 220 Pa, setting the bias voltage to 750 V, then introducing high-purity N2, and performing plasma nitriding treatment at a temperature of 500 ℃ for 5 h to obtain a porous and high-hardness titanium alloy material.

[0029] Figure 2 This is a cross-sectional morphology image of the porous and high-hardness titanium alloy material obtained in this embodiment, such as... Figure 2As shown, its surface has a porous structure. The porosity of the first intermediate material formed in step (2) of this embodiment is about 27%. After being treated by the hollow cathode plasma nitriding technology in step (3), the porous structure is well maintained, and the final porosity still reaches 25%. This is because the method used in this invention creates atomic vacancies for subsequent nitrogen infiltration through argon plasma etching, thereby enabling nitriding at a relatively low temperature of 500 °C, avoiding damage to the porous structure at high temperatures. Moreover, the hollow cathode plasma nitriding technology used in this invention has a high nitriding rate.

[0030] Example 2

[0031] Example 2 is basically the same as Example 1, except that: Step (3) of Example 2 is as follows: High-density argon plasma generated by hollow cathode effect is used to etch the ceramic coating on the first intermediate material, the etching pressure is 10 Pa, the bias voltage during etching is 5 kV, and the etching time is 120 min. Step (4) of Example 2 is as follows: the intermediate material is nitrided using hollow cathode plasma nitriding technology. Specifically, after etching, the gas pressure is adjusted to 240 Pa, the bias voltage is set to 700 V, and then high-purity N2 is introduced. The plasma nitriding treatment is carried out at a temperature of 500℃ for 8 hours to obtain a porous and high-hardness titanium alloy material.

[0032] Example 3

[0033] Example 3 is basically the same as Example 1, except that step (2) of Example 3 is: The TC4 titanium alloy substrate material treated in step (1) was placed in an electrolyte containing 30 g / L Na2SiO3 and 3 g / L NaOH for micro-arc oxidation treatment. During the treatment, a graphite sheet was used as the cathode and the titanium alloy substrate was used as the anode. Anodizing was performed at 20 V and 40 °C. Finally, a ceramic coating with a porous structure was formed on the TC4 titanium alloy substrate material to obtain the first intermediate material.

[0034] The rest is the same as in Example 1, and will not be described again here.

[0035] Example 4

[0036] Example 4 is basically the same as Example 1, except that the nitriding temperature in step (4) of Example 4 is 400°C.

[0037] The rest is the same as in Example 1, and will not be described again here.

[0038] Comparative Example 1

[0039] (1) The TC4 titanium alloy matrix material was made into a sample with a specification of 30 mm × 30 mm × 6 mm. The surface was polished by sandpaper and diamond polishing paste in turn to remove the oxide layer on the surface and make the surface roughness Ra about 0.2. Then it was immersed in petroleum ether, acetone, alcohol and deionized water in turn and ultrasonicated for 20 min to remove the surface oil. Then it was dried with nitrogen. (2) The TC4 titanium alloy substrate material treated in step (1) is placed in an electrolyte containing 15 g / L Na2SiO3 and 3 g / L NaOH for micro-arc oxidation treatment to form a ceramic coating with a porous structure on the TC4 titanium alloy substrate material.

[0040] Comparative Example 2

[0041] (1) The TC4 titanium alloy matrix material was made into a sample with a specification of 30 mm × 30 mm × 6 mm. The surface was polished by sandpaper and diamond polishing paste in turn to remove the oxide layer on the surface and make the surface roughness Ra about 0.2. Then it was immersed in petroleum ether, acetone, alcohol and deionized water in turn and ultrasonicated for 20 min to remove the surface oil. Then it was dried with nitrogen. (2) The intermediate material is subjected to nitriding treatment using hollow cathode plasma nitriding technology, specifically including: placing the intermediate material obtained in step (2) into a hollow cathode ion nitriding device (see schematic diagram of the device structure as shown in the figure). Figure 1 The sample was placed on the sample holder (as shown) and put into the ion nitriding furnace. The vacuum inside the furnace was evacuated to below 3.0 Pa, the gas pressure was adjusted to 220 Pa, the bias voltage was set to 750 V, and then high-purity N2 was introduced. Plasma nitriding treatment was carried out at a temperature of 500 °C for 5 h.

[0042] Figure 3 These are XRD curves of the titanium alloy materials prepared in Example 1, Comparative Example 1, and Comparative Example 2, as well as the TC4 titanium alloy matrix material without any treatment.

[0043] Comparative Example 3

[0044] The only difference between Comparative Example 3 and Example 1 is that the nitriding process in step (3) of Comparative Example 3 is as follows: The sample was placed in an ion nitriding furnace, the furnace vacuum was evacuated to below 3.0 Pa, the gas pressure was adjusted to 300 Pa, and then NH3 was introduced. Nitriding was performed at 700℃ for 10 h, with the high temperature driving the N2 flow. Thermal decomposition generates highly reactive nitrogen atoms. The N in the gas phase rapidly diffuses to the substrate surface and attaches to the defect sites on the substrate surface through physical adsorption. Subsequently, it is converted to chemical adsorption, and after adsorption, it breaks through the atomic barrier between the substrate and enters the interstitial space.

[0045] The nitriding method used in Comparative Example 3 had a higher temperature, which destroyed the porous structure generated by micro-arc oxidation. The porosity of the final titanium alloy sample was reduced to 6%. Furthermore, the efficiency of this nitriding treatment was lower than that of Example 1, and the wear resistance and wear resistance of the resulting titanium alloy sample were significantly lower than those of Example 1, with a hardness of 550 HV.

[0046] The samples prepared in the above embodiments and comparative examples were tested for hardness, wear resistance and corrosion resistance. The hardness test method was as follows: the hardness of the titanium alloy samples in the embodiments was measured by Vickers hardness tester, and the test force was 500g.

[0047] The wear resistance test method was as follows: the wear resistance of the samples in the examples was measured using a reciprocating CSM friction tester (TRN 0204015, Switzerland). The load during the friction test was 5 N, the number of revolutions was 20,000 revolutions, and the mating balls were GCr15 mating balls.

[0048] The corrosion resistance test method was as follows: the corrosion resistance of the samples in the examples was measured using an electrochemical workstation (Autolab, PGSTAT302N). The samples were subjected to potentiodynamic polarization test, with a test range of -0.8~1 V, and the test solution was a 3.5 wt% sodium chloride solution.

[0049] The results are shown in Table 1.

[0050] Table 1

[0051] As shown in Table 1, the titanium alloy material prepared in Example 1 has significantly higher hardness than Comparative Examples 1 and 2, and its wear rate and corrosion current density are significantly lower than those of Comparative Examples 1 and 2. This is because Comparative Example 1 only performed micro-arc oxidation treatment on the titanium alloy matrix material without nitriding. The resulting sample has a large number of micron-sized pores on its surface, which significantly reduces the effective bearing area of ​​the oxide film. Under external force, stress concentration easily occurs, resulting in low hardness and poor wear and corrosion resistance. In contrast, Comparative Example 2 only performed nitriding treatment on the titanium alloy matrix material without micro-arc oxidation treatment. The resulting sample is brittle and has high residual stress. In this case, the interface between the nitrided layer and the substrate is prone to becoming the initiation source of fatigue cracks, leading to a decrease in fatigue life. The presence of surface defects after nitriding results in low hardness and poor wear and corrosion resistance.

[0052] In summary, the preparation method provided by this invention first prepares a porous structure beneficial to the biomedical field on the surface of a titanium alloy substrate material using micro-arc oxidation technology, and then performs plasma nitriding treatment at low temperature using hollow cathode plasma nitriding technology. This maintains the porous structure while improving hardness and wear resistance, solving the problems of low hardness in micro-arc oxidation porous structures and deformation of titanium alloys due to high temperatures in existing nitriding techniques. The method provided by this invention is simple and easy to operate, and the prepared titanium alloy material exhibits excellent hardness, wear resistance, and corrosion resistance, possessing significant industrial application value in the field of biomedical implants.

[0053] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0054] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0055] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements in the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed, but rather to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A method for preparing a porous and high-hardness titanium alloy material, characterized in that, include: The surface of the titanium alloy substrate material is modified by micro-arc oxidation technology to form a ceramic coating with a porous structure on the titanium alloy substrate material, thereby obtaining the first intermediate material. The first intermediate material is etched using argon plasma to form atomic vacancies on the ceramic coating, thereby obtaining the second intermediate material; The second intermediate material is subjected to plasma nitriding treatment using hollow cathode plasma nitriding technology. The nitriding temperature of the plasma nitriding treatment is below 500℃, resulting in a porous and high-hardness titanium alloy material.

2. The preparation method according to claim 1, characterized in that: The nitriding temperature is 400℃~500℃.

3. The preparation method according to claim 1, characterized in that: The argon plasma etching conditions include: etching gas pressure of 5 Pa to 10 Pa, bias voltage of 3 kV to 5 kV during etching, and etching time of 60 min to 120 min. And / or, the process conditions of the hollow cathode plasma nitriding technology include: nitriding gas pressure of 200Pa~240Pa, bias voltage of 700V~800V during nitriding, and nitriding time of 5h~8h.

4. The preparation method according to claim 3, characterized in that, Specifically, it includes: The intermediate material is placed in a hollow cathode plasma nitriding apparatus, the vacuum is evacuated to below 3.0 Pa, the nitriding pressure is set to 200 Pa to 240 Pa, the bias voltage during nitriding is 700 V to 800 V, and then nitrogen gas is introduced. The plasma nitriding treatment is carried out at below 500 °C for 5 h to 8 h.

5. The preparation method according to claim 1, characterized in that: Using graphite as the cathode and the titanium alloy substrate as the anode, the titanium alloy substrate is placed in an electrolyte containing 15 g / L to 30 g / L of silicate and 3 g / L to 6 g / L of strong alkali, and subjected to micro-arc oxidation at 15 V to 20 V and 40 °C to 60 °C. And / or, the preparation method further includes: polishing the titanium alloy substrate material and then performing surface modification using the micro-arc oxidation technology.

6. The preparation method according to claim 5, characterized in that, The silicate includes Na2SiO3, At least one of K2SiO3, wherein the strong base includes at least one of sodium hydroxide and potassium hydroxide.

7. A porous and high-hardness titanium alloy material, characterized in that, It is prepared by any one of claims 1 to 6.

8. The porous and high-hardness titanium alloy material according to claim 7, characterized in that: The porosity of the titanium alloy material is 17%~33%; and / or the hardness of the titanium alloy material is 1100HV~1300HV. And / or, the thickness of the nitrided layer obtained by the plasma nitriding treatment is 20µm or more.

9. The use of the porous and high-hardness titanium alloy material as described in claim 7 or 8 in the preparation of biological implants.

10. A biological implant, characterized in that, This includes the porous and high-hardness titanium alloy material as described in claim 7 or 8.

Images