Method for manufacturing a titanium alloy component

Abstract

The application discloses a preparation method of a titanium alloy part and relates to the technical field of part forming. The preparation method of the titanium alloy part comprises the following steps: uniformly mixing boron carbide powder and silicon carbide powder to obtain a solid mixed infiltrant; embedding a titanium alloy part to be strengthened in the solid mixed infiltrant; and sequentially performing vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain a strengthened titanium alloy part. The application improves the compactness of the titanium alloy part to be strengthened through pressure sintering. Meanwhile, under the joint action of the nitrogen-containing inert atmosphere and the solid mixed infiltrant, nitrogen, boron and carbon are co-permeated on the surface of the titanium alloy, a titanium (nitrogen, boron and carbon) composite hardened layer is formed on the surface of the titanium alloy, and the surface hardness, wear resistance, corrosion resistance and other performances of the titanium alloy part to be strengthened are enhanced, thereby improving the comprehensive performance of the titanium alloy part and widening the application range of the titanium alloy part.

Description

Technical Field

[0001] This application relates to the field of component forming technology, and in particular to a method for preparing titanium alloy components. Background Technology

[0002] Titanium alloys have low density, high specific strength and specific stiffness, and excellent corrosion resistance, high-temperature mechanical properties, fatigue resistance and creep resistance. They have excellent comprehensive properties and have been widely used in aerospace, energy, chemical, medical, automotive and other industries in recent years.

[0003] Currently, near-net-shape forming technologies such as powder injection molding or compression molding can be used to mass-produce titanium alloy parts, reducing raw material consumption and shortening processing cycles, resulting in significant advantages in manufacturing costs and production efficiency. However, under large-scale production conditions, the density of powder metallurgy titanium alloy parts prepared by conventional vacuum sintering after injection molding or compression molding of titanium alloy powder is generally only 95-97%. The residual porosity promotes crack initiation and propagation under high stress, and the surface hardness of titanium alloy materials is relatively low, resulting in poor wear resistance, which limits the application range of titanium alloy parts. Summary of the Invention

[0004] The main objective of this application is to provide a method for preparing titanium alloy parts, aiming to solve the technical problem that limits the application scope of current titanium alloy parts.

[0005] To achieve the above objectives, this application provides a method for preparing titanium alloy parts, the method comprising:

[0006] Weigh out boron carbide powder and silicon carbide powder and mix them evenly to obtain a solid mixed infiltration agent;

[0007] The titanium alloy parts to be strengthened are embedded in the solid mixed infiltration agent, and then subjected to vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere in sequence to obtain the strengthened titanium alloy parts.

[0008] Optionally, the mass percentage of each component in the solid mixed infiltration agent is: 5-40% boron carbide powder and 40-80% silicon carbide powder.

[0009] Optionally, the solid mixed infiltration agent further includes charcoal powder, wherein the mass percentage of the charcoal powder is 0-30%.

[0010] Optionally, the step of embedding the titanium alloy parts to be strengthened within the solid mixed infiltration agent and sequentially performing vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy parts includes:

[0011] The solid mixed infiltration agent is used to completely embed the titanium alloy parts to be strengthened;

[0012] Vacuum sintering is performed on the fully embedded titanium alloy parts to be strengthened.

[0013] Nitrogen-containing inert atmosphere is injected into the vacuum-sintered titanium alloy parts to be strengthened for high-pressure sintering;

[0014] After the titanium alloy parts to be strengthened are cooled to room temperature after high-pressure sintering, the strengthened titanium alloy parts are obtained.

[0015] Optionally, the step of vacuum sintering the fully embedded titanium alloy component to be strengthened includes:

[0016] The titanium alloy parts to be strengthened, which are completely embedded in the sintering boat, are placed into the sintering furnace, and the sintering furnace is evacuated according to the preset vacuum degree.

[0017] The titanium alloy parts to be strengthened are heated to a preset maximum sintering temperature in a vacuum sintering furnace at a preset heating rate, and then held for a first preset duration of sintering.

[0018] Optionally, the step of heating the titanium alloy component to be strengthened to a preset maximum sintering temperature in a vacuum sintering furnace at a preset heating rate includes:

[0019] In a vacuum sintering furnace, the temperature is increased to 1000°C at a heating rate of 4–7°C / min, and then increased from 1000°C to a preset maximum sintering temperature at a heating rate of 2–4°C / min, so as to heat the titanium alloy parts to be strengthened to the preset maximum sintering temperature.

[0020] Optionally, the preset vacuum degree is less than or equal to 100 Pa, the first preset duration is 30 to 60 minutes, and the preset maximum sintering temperature is determined according to the material of the titanium alloy parts to be strengthened.

[0021] Optionally, the step of injecting a nitrogen-containing inert atmosphere into the vacuum-sintered titanium alloy parts to be strengthened for high-pressure sintering includes:

[0022] The titanium alloy parts to be strengthened after vacuum sintering are kept at a preset maximum sintering temperature, and a nitrogen-containing inert atmosphere is injected into the sintering furnace;

[0023] The second preset duration of heat preservation and pressure sintering of the titanium alloy parts to be strengthened under the nitrogen-containing inert atmosphere.

[0024] Optionally, the nitrogen-containing inert atmosphere is a nitrogen-argon mixture, the total pressure of the nitrogen-argon mixture is 2 to 10 bar, the volume percentage of nitrogen in the nitrogen-argon mixture is 10 to 50%, and the second preset duration is 20 to 40 minutes.

[0025] Optionally, the procedure prior to the step of embedding the titanium alloy component to be strengthened within the solid mixed infiltration agent and performing vacuum pressure sintering to strengthen the titanium alloy component includes:

[0026] Weigh out titanium alloy powder, and mix and granulate the titanium alloy powder with a binder to obtain a feedstock.

[0027] The feed is injection molded to obtain a blank, and the blank is degreased;

[0028] The degreased billet is vacuum sintered to obtain titanium alloy parts to be strengthened.

[0029] This application discloses a method for preparing titanium alloy parts. The method involves uniformly mixing boron carbide powder and silicon carbide powder to obtain a solid mixed infiltration agent. The titanium alloy parts to be strengthened are then embedded within the solid mixed infiltration agent, and subsequently subjected to vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy parts. This application improves the density of the strengthened titanium alloy parts through pressure sintering. Simultaneously, the combined action of the nitrogen-containing inert atmosphere and the solid mixed infiltration agent achieves nitrogen, boron, and carbon co-infiltration on the titanium alloy surface, forming a titanium (nitrogen, boron, carbon) composite hardened layer. This enhances the surface hardness, wear resistance, and corrosion resistance of the strengthened titanium alloy parts, thereby improving their overall performance and broadening their application range. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of an embodiment of the method for preparing titanium alloy parts according to this application;

[0031] Figure 2 This is a schematic flowchart illustrating another embodiment of the method for preparing titanium alloy parts according to this application.

[0032] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0033] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] It should be understood that, unless otherwise specified, the experimental methods used in the following embodiments of this application are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments of this application are commercially available.

[0036] Titanium alloys have low density, high specific strength and specific stiffness, and excellent corrosion resistance, high-temperature mechanical properties, fatigue resistance and creep resistance. They have excellent comprehensive properties and have been widely used in aerospace, energy, chemical, medical, automotive and other industries in recent years.

[0037] Currently, near-net-shape forming technologies such as powder injection molding or compression molding can be used to mass-produce titanium alloy parts, reducing raw material consumption and shortening processing cycles, resulting in significant advantages in manufacturing costs and production efficiency. However, under large-scale production conditions, the density of powder metallurgy titanium alloy parts prepared by conventional vacuum sintering after injection molding or compression molding of titanium alloy powder is generally only 95-97%. Residual porosity promotes crack initiation and propagation under high stress, reducing the reliability and service life of titanium alloy applications. On the other hand, the low surface hardness and poor wear resistance of titanium alloy materials also limit the further industrial application of titanium alloy parts. Industrially, methods to improve the density of powder metallurgy titanium alloys mainly employ techniques such as hot isostatic pressing, which suffers from high costs. To improve the wear resistance of titanium alloy parts, industrial processes mainly use surface nitriding, carburizing, or oxygen infiltration to generate a hard phase on the surface, thereby increasing the surface hardness. However, the resulting surface hard phase often has relatively simple properties and generally poor overall performance. Based on the current state of the technology, in order to simultaneously improve the density and surface wear resistance of powder metallurgy titanium alloys, at least two or more hot working processes are required, which significantly increases the complexity and cost of the process, while reducing its stability.

[0038] This application improves the density of the titanium alloy parts to be strengthened through pressure sintering. Simultaneously, under the combined action of a nitrogen-containing inert atmosphere and a solid mixed infiltration agent, nitrogen, boron, and carbon co-infiltration is achieved on the titanium alloy surface, forming a titanium (nitrogen, boron, carbon) composite hardened layer. This enhances the surface hardness, wear resistance, and corrosion resistance of the strengthened titanium alloy parts, thereby improving their overall performance and broadening their application range. Furthermore, this application employs a single-stage sintering method, improving the density and wear resistance of the strengthened titanium alloy parts while effectively reducing process complexity and cost, and improving process stability.

[0039] Reference Figure 1 , Figure 1 This is a schematic flowchart illustrating an embodiment of the method for manufacturing titanium alloy parts according to this application. It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0040] This invention provides a method for preparing titanium alloy parts, the method comprising:

[0041] Step S100: Weigh boron carbide powder and silicon carbide powder and mix them evenly to obtain a solid mixed infiltration agent;

[0042] Step S200: The titanium alloy parts to be strengthened are embedded in the solid mixed infiltration agent, and vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere are performed in sequence to obtain the strengthened titanium alloy parts.

[0043] In this embodiment, it should be noted that the solid mixed infiltration agent is used to infiltrate nitrogen, boron, and carbon into the surface of the titanium alloy component to be strengthened, thereby forming a composite hardened layer. The solid mixed infiltration agent includes at least boron carbide powder and silicon carbide powder, and may also include other additives (such as charcoal) to promote the infiltration rate. The particle size of the boron carbide powder and the silicon carbide powder is between -60 mesh and -200 mesh.

[0044] In this embodiment, it should also be noted that the titanium alloy component to be strengthened can be a powder metallurgy titanium alloy component prepared by injection molding or compression molding followed by vacuum sintering. Of course, other methods can also be used to prepare titanium alloy components requiring performance enhancement. The nitrogen-containing inert atmosphere is a mixture of nitrogen and inert gases.

[0045] In this embodiment, boron carbide powder and silicon carbide powder are selected, weighed according to a preset ratio, and uniformly mixed to obtain a solid mixed infiltration agent. Then, the titanium alloy parts to be strengthened are placed in a sintering boat, and an appropriate amount of the solid mixed infiltration agent is used to completely embed the parts. The sintering boat containing the embedded titanium alloy parts is then placed in a sintering furnace. Vacuum sintering is first performed, with the temperature increased at a preset heating rate to the preset maximum sintering temperature corresponding to the titanium alloy parts, followed by heat preservation sintering. After the vacuum sintering stage is completed, the preset maximum sintering temperature is maintained, and a nitrogen-containing inert atmosphere is introduced into the sintering furnace. Sintering is performed under high pressure and nitrogen-containing inert atmosphere conditions, and after holding at pressure and temperature for a certain time, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0046] The solid mixed infiltration agent comprises the following components in terms of mass percentage: boron carbide powder 5-40%, silicon carbide powder 40-80%. To promote the penetration rate of nitrogen, boron, and carbon into the surface of the titanium alloy parts to be strengthened, the solid mixed infiltration agent also includes charcoal powder, which comprises 0-30% by mass.

[0047] The step S200, which involves embedding the titanium alloy component to be strengthened within the solid mixed infiltration agent and sequentially performing vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy component, includes:

[0048] Step S210: Take the solid mixed infiltration agent and completely embed it into the titanium alloy parts to be strengthened;

[0049] Step S220: Vacuum sinter the fully embedded titanium alloy parts to be strengthened.

[0050] Step S230: Inject a nitrogen-containing inert atmosphere into the vacuum-sintered titanium alloy parts to be strengthened for high-pressure sintering.

[0051] Step S240: After the titanium alloy parts to be strengthened are cooled to room temperature after high-pressure sintering, the strengthened titanium alloy parts are obtained.

[0052] In this embodiment, the solid mixed infiltration agent can be used to completely embed the titanium alloy parts to be strengthened. Then, the titanium alloy parts to be strengthened, completely embedded in the sintering boat, are placed into a sintering furnace, and the sintering furnace is evacuated to a preset vacuum level. In the evacuated sintering furnace, the titanium alloy parts to be strengthened are heated to a preset maximum sintering temperature at a preset heating rate, and held at this temperature for a first preset duration. The titanium alloy parts to be strengthened are maintained at the preset maximum sintering temperature after vacuum sintering, and a nitrogen-containing inert atmosphere is injected into the sintering furnace. The titanium alloy parts to be strengthened are then held at this nitrogen-containing inert atmosphere for a second preset duration under heat and pressure. Finally, after high-pressure sintering, the titanium alloy parts to be strengthened are cooled to room temperature in the furnace to obtain the strengthened titanium alloy parts.

[0053] The step of heating the titanium alloy component to be strengthened to a preset maximum sintering temperature in a vacuum sintering furnace at a preset heating rate includes: heating the component to 1000°C in a vacuum sintering furnace at a heating rate of 4-7°C / min, and then heating the component to 1000°C to the preset maximum sintering temperature at a heating rate of 2-4°C / min, so as to heat the titanium alloy component to be strengthened to the preset maximum sintering temperature.

[0054] The preset vacuum degree is less than or equal to 100 Pa, the first preset duration is 30-60 minutes, and the preset maximum sintering temperature is determined according to the material of the titanium alloy component to be strengthened. Taking TC4 (Ti-6Al-4V) titanium alloy as an example, the preset maximum sintering temperature is generally around 1300℃. That is, the preset maximum sintering temperature is the temperature at which the titanium alloy powder corresponding to the titanium alloy component to be strengthened undergoes the sintering reaction.

[0055] The nitrogen-containing inert atmosphere is a nitrogen-argon mixture, the total pressure of the nitrogen-argon mixture is 2-10 bar, the volume percentage of nitrogen in the nitrogen-argon mixture is 10-50%, and the second preset duration is 20-40 min.

[0056] In one embodiment of this application, boron carbide powder and silicon carbide powder are weighed and uniformly mixed to obtain a solid mixed infiltration agent. The titanium alloy parts to be strengthened are then embedded within the solid mixed infiltration agent and subjected to vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy parts. Thus, this embodiment improves the density of the titanium alloy parts to be strengthened through pressure sintering; simultaneously, under the combined action of the nitrogen-containing inert atmosphere and the solid mixed infiltration agent, nitrogen, boron, and carbon co-infiltration is achieved on the surface of the titanium alloy, forming a titanium (nitrogen, boron, carbon) composite hardened layer. This enhances the surface hardness, wear resistance, corrosion resistance, and other properties of the strengthened titanium alloy parts, thereby improving the overall performance of the titanium alloy parts and broadening their application range. Furthermore, this application uses a single sintering method to improve the density and wear resistance of the strengthened titanium alloy parts, effectively reducing the complexity and cost of the process and improving process stability.

[0057] Reference Figure 2 , Figure 2 This is a schematic flowchart illustrating another embodiment of the method for preparing titanium alloy parts according to this application. It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0058] This invention provides a method for preparing titanium alloy parts. Before step S200, which involves embedding the titanium alloy parts to be strengthened within the solid mixed infiltration agent and then performing vacuum pressure sintering to strengthen the titanium alloy parts, the method includes:

[0059] Step A10: Weigh titanium alloy powder and mix and granulate the titanium alloy powder with a binder to obtain feedstock;

[0060] Step A20: The feed is injection molded to obtain a blank, and the blank is degreased;

[0061] Step A30: Vacuum sintering is performed on the degreased billet to obtain the titanium alloy parts to be strengthened.

[0062] In this embodiment, it should be noted that the adhesive is a solvent used to bond the titanium alloy powder together. Exemplarily, the adhesive can be prepared by mixing polyethylene, paraffin wax, and stearic acid. The adhesive can also be prepared by mixing polyethylene glycol, plasticizer, stearic acid, sodium o-sulfonylbenzoimide, etc. The selected titanium alloy powder and the prepared adhesive are mixed in proportion on a rubber mixing mill for 1.5 to 2 hours, and then granulated on a mixing extruder to further homogenize the feed, resulting in a feedstock. Then, injection molding is performed at a predetermined injection temperature and injection pressure to obtain a blank of the titanium alloy part of the desired shape. An organic solvent is then prepared, which is used to degrease the blank. Exemplarily, the organic solvent can be at least one of anhydrous ethanol, acetone, n-heptane, trichloroethylene, etc. The blank is degreased by immersing it in the organic solvent, then dried and subjected to vacuum thermal degreasing to obtain a degreased blank. Finally, the degreased billet is placed in a vacuum sintering furnace for vacuum sintering, and then cooled to room temperature in the furnace to obtain powder metallurgy titanium alloy parts prepared by injection molding as titanium alloy parts to be strengthened.

[0063] In the second embodiment of this application, titanium alloy powder is weighed and mixed with a binder to obtain a feedstock. The feedstock is then injection molded to obtain a billet, which is then degreased. The degreased billet is then vacuum sintered to obtain the titanium alloy part to be strengthened. This embodiment, using powder injection molding, facilitates the mass production of titanium alloy parts to be strengthened, reduces raw material consumption, shortens the processing cycle, lowers manufacturing costs, and improves production efficiency.

[0064] Example 1

[0065] In this embodiment, boron carbide powder, silicon carbide powder, and charcoal powder of -100 mesh to -200 mesh are first screened and mixed in a three-dimensional mixer for 60 minutes at a mass ratio of 15:70:15 to obtain a solid mixed infiltration agent.

[0066] Powder metallurgy TC4 titanium alloy parts (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300℃ were placed in an alumina sintering boat as titanium alloy parts to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltration agent was used to completely embed the parts.

[0067] The alumina sintering boat containing the embedded titanium alloy parts to be strengthened was placed into a vacuum pressure sintering furnace. The vacuum pressure sintering furnace was then evacuated to below 50 Pa, and the temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, and then increased from 1000℃ to 1300℃ at a rate of 3℃ / min, and held at that temperature for sintering for 50 minutes.

[0068] After the vacuum sintering stage is completed, the sintering temperature is maintained at 1300℃. A nitrogen-argon mixture of 10 bar is introduced into the vacuum pressurized sintering furnace within 10 minutes. The nitrogen in the nitrogen-argon mixture accounts for 20% of the volume. The sintering temperature is maintained at 1300℃ under high pressure nitrogen-argon mixed atmosphere for 25 minutes. After that, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0069] The density of the strengthened titanium alloy parts is increased to 98.5%, and a Ti(N, B, C) composite strengthening phase is formed on the surface. The microhardness reaches HV2300, and the wear resistance is more than 6 times that of the titanium alloy parts to be strengthened. In addition, the surface strengthening phase has good corrosion resistance and relatively low brittleness.

[0070] Example 2

[0071] In this embodiment, boron carbide powder, silicon carbide powder, and charcoal powder of -100 mesh to -200 mesh are first screened and mixed in a three-dimensional mixer for 60 minutes at a mass ratio of 5:80:15 to obtain a solid mixed infiltration agent.

[0072] Powder metallurgy TC4 titanium alloy parts (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300℃ were placed in an alumina sintering boat as titanium alloy parts to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltration agent was used to completely embed the parts.

[0073] The alumina sintering boat containing the embedded titanium alloy parts to be strengthened was placed into a vacuum pressure sintering furnace. The vacuum pressure sintering furnace was then evacuated to below 50 Pa, and the temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, and then increased from 1000℃ to 1300℃ at a rate of 3℃ / min, and held at that temperature for sintering for 50 minutes.

[0074] After the vacuum sintering stage is completed, the sintering temperature is maintained at 1300℃. A nitrogen-argon mixture of 10 bar is introduced into the vacuum pressurized sintering furnace within 10 minutes. The nitrogen in the nitrogen-argon mixture accounts for 20% of the volume. The sintering temperature is maintained at 1300℃ under high pressure nitrogen-argon mixed atmosphere for 25 minutes. After that, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0075] The density of the strengthened titanium alloy parts is increased to 98.1%, the microhardness reaches HV2150, and the surface strengthening phase has good wear resistance and corrosion resistance, and relatively low brittleness.

[0076] Example 3

[0077] In this embodiment, boron carbide powder, silicon carbide powder, and charcoal powder of -100 mesh to -200 mesh are first screened and mixed in a three-dimensional mixer for 60 minutes at a mass ratio of 40:40:20 to obtain a solid mixed infiltration agent.

[0078] Powder metallurgy TC4 titanium alloy parts (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300℃ were placed in an alumina sintering boat as titanium alloy parts to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltration agent was used to completely embed the parts.

[0079] The alumina sintering boat containing the embedded titanium alloy parts to be strengthened was placed into a vacuum pressure sintering furnace. The vacuum pressure sintering furnace was then evacuated to below 50 Pa, and the temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, and then increased from 1000℃ to 1300℃ at a rate of 3℃ / min, and held at that temperature for sintering for 50 minutes.

[0080] After the vacuum sintering stage is completed, the sintering temperature is maintained at 1300℃. A nitrogen-argon mixture of 10 bar is introduced into the vacuum pressurized sintering furnace within 10 minutes. The nitrogen in the nitrogen-argon mixture accounts for 20% of the volume. The sintering temperature is maintained at 1300℃ under high pressure nitrogen-argon mixed atmosphere for 25 minutes. After that, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0081] The density of the strengthened titanium alloy parts is increased to 98.3%, the microhardness reaches HV2200, and the surface strengthening phase has good wear resistance and corrosion resistance, and relatively low brittleness.

[0082] Example 4

[0083] In this embodiment, boron carbide powder, silicon carbide powder, and charcoal powder of -100 mesh to -200 mesh are first screened and mixed in a three-dimensional mixer for 60 minutes at a mass ratio of 20:50:30 to obtain a solid mixed infiltration agent.

[0084] Powder metallurgy TC4 titanium alloy parts (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300℃ were placed in an alumina sintering boat as titanium alloy parts to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltration agent was used to completely embed the parts.

[0085] The alumina sintering boat containing the embedded titanium alloy parts to be strengthened was placed into a vacuum pressure sintering furnace. The vacuum pressure sintering furnace was then evacuated to below 50 Pa, and the temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, and then increased from 1000℃ to 1300℃ at a rate of 3℃ / min, and held at that temperature for sintering for 50 minutes.

[0086] After the vacuum sintering stage is completed, the sintering temperature is maintained at 1300℃. A nitrogen-argon mixture of 10 bar is introduced into the vacuum pressurized sintering furnace within 10 minutes. The nitrogen in the nitrogen-argon mixture accounts for 20% of the volume. The sintering temperature is maintained at 1300℃ under high pressure nitrogen-argon mixed atmosphere for 25 minutes. After that, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0087] The density of the strengthened titanium alloy parts is increased to 97.8%, the microhardness reaches HV2400, and the surface strengthening phase has good wear resistance and corrosion resistance, and relatively low brittleness.

[0088] Example 5

[0089] In this embodiment, boron carbide powder, silicon carbide powder, and charcoal powder of -100 mesh to -200 mesh are first screened and mixed in a three-dimensional mixer for 60 minutes at a mass ratio of 30:70:0 to obtain a solid mixed infiltration agent.

[0090] Powder metallurgy TC4 titanium alloy parts (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300℃ were placed in an alumina sintering boat as titanium alloy parts to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltration agent was used to completely embed the parts.

[0091] The alumina sintering boat containing the embedded titanium alloy parts to be strengthened was placed into a vacuum pressure sintering furnace. The vacuum pressure sintering furnace was then evacuated to below 50 Pa, and the temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, and then increased from 1000℃ to 1300℃ at a rate of 3℃ / min, and held at that temperature for sintering for 50 minutes.

[0092] After the vacuum sintering stage is completed, the sintering temperature is maintained at 1300℃. A nitrogen-argon mixture of 10 bar is introduced into the vacuum pressurized sintering furnace within 10 minutes. The nitrogen in the nitrogen-argon mixture accounts for 20% of the volume. The sintering temperature is maintained at 1300℃ under high pressure nitrogen-argon mixed atmosphere for 25 minutes. After that, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0093] The density of the strengthened titanium alloy parts is increased to 97.5%, the microhardness reaches HV1950, and the surface strengthening phase has good wear resistance and corrosion resistance, and relatively low brittleness.

[0094] Test results

[0095] The experimental results of the above embodiments are shown in Table 1 below:

[0096] Table 1. Test results of each embodiment

[0097]

[0098] The reference examples in Table 1 are powder metallurgy TC4 titanium alloy parts prepared by injection molding. It can be seen that the titanium alloy parts prepared in the above embodiments of this application have significantly improved density, reducing the possibility of crack initiation and propagation under high stress caused by residual porosity. In addition, the titanium alloy parts prepared in the above embodiments have significantly improved hardness. Furthermore, since the surface of the strengthened titanium alloy parts forms a titanium (nitrogen, boron, carbon) composite strengthening phase, compared to strengthening with a single property, the strengthened titanium alloy parts in the embodiments of this application all show corresponding improvements in wear resistance, corrosion resistance, and brittleness. Therefore, the embodiments of this application effectively improve the comprehensive properties of titanium alloy parts, such as density and surface wear resistance. Moreover, the embodiments of this application improve the density and wear resistance of the strengthened titanium alloy parts through a single sintering method, effectively reducing the complexity and cost of the process and improving process stability.

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity / operation / object from another, and do not necessarily require or imply any such actual relationship or order between these entities / operations / objects; the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0100] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0101] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for preparing titanium alloy parts, characterized in that, The preparation method includes: Boron carbide powder and silicon carbide powder are weighed and mixed evenly to obtain a solid mixed infiltration agent; the solid mixed infiltration agent also includes charcoal powder. The titanium alloy parts to be strengthened are embedded in the solid mixed infiltration agent, and vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere are performed in sequence to obtain the strengthened titanium alloy parts. The step of embedding the titanium alloy parts to be strengthened within the solid mixed infiltration agent, and then sequentially performing vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy parts includes: The solid mixed infiltration agent is used to completely embed the titanium alloy parts to be strengthened; Vacuum sintering is performed on the fully embedded titanium alloy parts to be strengthened. A nitrogen-containing inert atmosphere is injected into the vacuum-sintered titanium alloy parts to be strengthened for high-pressure sintering; After the titanium alloy parts to be strengthened are cooled to room temperature after high-pressure sintering, the strengthened titanium alloy parts are obtained. The titanium alloy parts to be strengthened are powder metallurgy titanium alloy parts prepared by vacuum sintering after injection molding or compression molding. The step of vacuum sintering the fully embedded titanium alloy parts to be strengthened includes: The titanium alloy parts to be strengthened, which are completely embedded in the sintering boat, are placed into the sintering furnace, and the sintering furnace is evacuated according to the preset vacuum degree. The titanium alloy parts to be strengthened are heated to a preset maximum sintering temperature at a preset heating rate in a vacuum sintering furnace, and then held for a first preset duration of sintering. The step of heating the titanium alloy parts to be strengthened to a preset maximum sintering temperature in a vacuum sintering furnace at a preset heating rate includes: In a vacuum sintering furnace, the temperature is increased to 1000°C at a heating rate of 4~7°C / min, and then increased from 1000°C to a preset maximum sintering temperature at a heating rate of 2~4°C / min, so as to heat the titanium alloy parts to be strengthened to the preset maximum sintering temperature. The step of injecting a nitrogen-containing inert atmosphere into the vacuum-sintered titanium alloy parts to be strengthened for high-pressure sintering includes: The titanium alloy parts to be strengthened after vacuum sintering are kept at a preset maximum sintering temperature, and a nitrogen-containing inert atmosphere is injected into the sintering furnace; The second preset duration of heat preservation and pressure sintering of the titanium alloy parts to be strengthened under the nitrogen-containing inert atmosphere.

2. The preparation method according to claim 1, characterized in that, The mass percentage of each component in the solid mixed infiltration agent is: 5-40% boron carbide powder and 40-80% silicon carbide powder.

3. The preparation method according to claim 2, characterized in that, The charcoal powder accounts for 0-30% of the total mass.

4. The preparation method according to claim 1, characterized in that, The preset vacuum degree is less than or equal to 100 Pa, the first preset duration is 30 to 60 minutes, and the preset maximum sintering temperature is determined according to the material of the titanium alloy parts to be strengthened.

5. The preparation method according to claim 1, characterized in that, The nitrogen-containing inert atmosphere is a nitrogen-argon mixture, the total pressure of the nitrogen-argon mixture is 2~10 bar, the volume percentage of nitrogen in the nitrogen-argon mixture is 10~50%, and the second preset duration is 20~40 min.

6. The preparation method according to claim 1, characterized in that, The procedure prior to the step of embedding the titanium alloy component to be strengthened within the solid mixed infiltration agent and then performing vacuum pressure sintering to strengthen the titanium alloy component includes: Weigh out titanium alloy powder, and mix and granulate the titanium alloy powder with a binder to obtain a feedstock. The feed is injection molded to obtain a blank, and the blank is degreased; The degreased billet is vacuum sintered to obtain titanium alloy parts to be strengthened.

Images