Preparation method of titanium alloy part

Abstract

The invention 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 steps that boron carbide powder and silicon carbide powder are weighed and evenly mixed, and a solid mixed permeating agent is obtained; and embedding a titanium alloy part to be strengthened in the solid mixed permeating agent, and sequentially carrying out vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy part. According to the method, through pressure sintering, the density of the titanium alloy part to be strengthened is improved; meanwhile, under the combined action of the nitrogen-containing inert atmosphere and the solid mixed permeating agent, nitrogen, boron and carbon co-permeation on the surface of the titanium alloy is achieved, a titanium (nitrogen, boron and carbon) composite hardened layer is formed on the surface of the titanium alloy, the surface hardness, abrasion resistance, corrosion resistance and other performance of the titanium alloy part to be strengthened are enhanced, and therefore the comprehensive performance of the titanium alloy part is improved, and the service life of the titanium alloy part is prolonged. And the application range of the titanium alloy part is widened.

Description

Technical Field

[0001] The present application relates to the technical field of component forming, and in particular to a method for preparing a titanium alloy component. Background Art

[0002] Titanium alloy has low density, high specific strength and specific stiffness, excellent corrosion resistance, high temperature mechanical properties, fatigue resistance and creep resistance, and has good comprehensive performance. In recent years, it has been widely used in aerospace, energy, chemical industry, medical, automobile and other industries.

[0003] Currently, titanium alloy parts can be mass-produced through near-net forming technologies such as powder injection molding or press molding, which reduces raw material consumption, shortens processing cycles, and forms obvious advantages in manufacturing costs and production efficiency. However, under large-scale mass production conditions, the density of powder metallurgy titanium alloy parts prepared by conventional vacuum sintering after titanium alloy powder is injected or pressed is generally 95-97%, and the residual pores promote the initiation and expansion of cracks in the material under high stress. In addition, the surface hardness of titanium alloy materials is low and the wear resistance is poor, which limits the application range of titanium alloy parts. Summary of the invention

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

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

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

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

[0008] Optionally, the mass proportions of the components in the solid mixed infiltrant are: 5-40% of boron carbide powder and 40-80% of silicon carbide powder.

[0009] Optionally, the solid mixed penetrant further includes charcoal powder, and the mass proportion of the charcoal powder is 0 to 30%.

[0010] Optionally, the step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant, and sequentially performing vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy component comprises:

[0011] Using the solid mixed infiltrant to completely embed the titanium alloy component to be strengthened;

[0012] The completely embedded titanium alloy parts to be strengthened are subjected to vacuum sintering;

[0013] Injecting nitrogen-containing inert atmosphere into the titanium alloy parts to be strengthened after vacuum sintering for high-pressure sintering;

[0014] After the titanium alloy component to be strengthened is cooled to room temperature after high pressure sintering, a strengthened titanium alloy component is obtained.

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

[0016] Putting the titanium alloy parts to be strengthened that are completely embedded in the sintering boat into a sintering furnace, and evacuating the sintering furnace according to a preset vacuum degree;

[0017] The titanium alloy component to be strengthened is heated to a preset maximum sintering temperature at a preset heating rate in a vacuum sintering furnace, and is subjected to heat preservation sintering for a first preset duration.

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

[0019] In a vacuum sintering furnace, the temperature is increased to 1000°C at a heating rate of 4-7°C / min, and the temperature is 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 component 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 component to be strengthened.

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

[0022] Maintaining the titanium alloy component to be strengthened after vacuum sintering at a preset maximum sintering temperature and injecting a nitrogen-containing inert atmosphere into the sintering furnace;

[0023] The titanium alloy component to be strengthened is sintered under the nitrogen-containing inert atmosphere at a temperature and pressure maintained for a second preset duration.

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

[0025] Optionally, before the step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant and performing vacuum pressure sintering to strengthen the titanium alloy component, the method includes:

[0026] Weighing titanium alloy powder, and mixing and granulating the titanium alloy powder with a binder to obtain a feed material;

[0027] Injection molding the feed material to obtain a blank, and degreasing the blank;

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

[0029] The present application proposes a method for preparing a titanium alloy component, wherein the preparation method comprises weighing boron carbide powder and silicon carbide powder and uniformly mixing them to obtain a solid mixed impregnant; embedding the titanium alloy component to be strengthened in the solid mixed impregnant, and sequentially performing vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain a strengthened titanium alloy component. The present application improves the density of the titanium alloy component to be strengthened by pressure sintering; at the same time, through the combined action of the nitrogen-containing inert atmosphere and the solid mixed impregnant, nitrogen, boron, and carbon are co-permeated on the surface of the titanium alloy, so that a titanium (nitrogen, boron, and carbon) composite hardened layer is formed on the surface of the titanium alloy, thereby enhancing the surface hardness, wear resistance, corrosion resistance, and other properties of the titanium alloy component to be strengthened, thereby improving the comprehensive performance of the titanium alloy component and broadening the application range of the titanium alloy component. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a process of an embodiment of a method for preparing a titanium alloy component of the present application;

[0031] Figure 2 This is a schematic flow chart of another embodiment of the method for preparing titanium alloy parts of the present application.

[0032] The realization of the purpose, functional features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. These drawings and text descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0033] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] It should be understood that the experimental methods used in the following examples of this application are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples of this application can be obtained from commercial channels unless otherwise specified.

[0036] Titanium alloy has low density, high specific strength and specific stiffness, excellent corrosion resistance, high temperature mechanical properties, fatigue resistance and creep resistance, and has good comprehensive performance. In recent years, it has been widely used in aerospace, energy, chemical industry, medical, automobile and other industries.

[0037] At present, titanium alloy parts can be mass-produced through near-net forming technologies such as powder injection molding or press molding, which reduces raw material consumption, shortens processing cycles, and forms obvious advantages in manufacturing costs and production efficiency. However, under large-scale mass production conditions, the density of powder metallurgy titanium alloy parts prepared by conventional vacuum sintering after titanium alloy powder is injected or pressed is generally 95-97%. The residual pores promote the initiation and expansion of cracks in the material under high stress, reducing the application reliability and service life of titanium alloy. 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. The method of improving the density of powder metallurgy titanium alloy mainly adopts hot isostatic pressing and other technologies in industry, which has the problem of high cost. In order to improve the wear resistance of titanium alloy parts, the industry mainly adopts surface nitriding or carburizing, oxygen permeation and other processes to produce hard phases on the surface to improve the surface hardness of the material, but the properties of the obtained surface hard phase are often relatively single, and the comprehensive performance is general. Based on the above technical status, in order to simultaneously improve the density and surface wear resistance of powder metallurgy titanium alloy, at least two or more hot working steps are required, which significantly increases the complexity and cost of the process and reduces the process stability.

[0038] This application improves the density of the titanium alloy parts to be strengthened by pressure sintering; at the same time, under the joint action of nitrogen-containing inert atmosphere and solid mixed infiltrant, nitrogen, boron and carbon co-penetration on the surface of the titanium alloy is achieved, so that a titanium (nitrogen, boron, carbon) composite hardening layer is formed on the surface of the titanium alloy, which enhances the surface hardness, wear resistance, corrosion resistance and other properties of the titanium alloy parts to be strengthened, thereby improving the comprehensive performance of the titanium alloy parts and broadening the application range of the titanium alloy parts. In addition, this application adopts a single sintering method to improve the density, wear resistance and other properties of the titanium alloy parts to be strengthened, which also effectively reduces the complexity and cost of the process and improves the process stability.

[0039] Reference Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for preparing a titanium alloy component of the present application. It should be noted that although a logical sequence is shown in the flow chart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0040] An embodiment of the present invention provides a method for preparing a titanium alloy component, the method comprising:

[0041] Step S100, weighing boron carbide powder and silicon carbide powder and uniformly mixing them to obtain a solid mixed penetrant;

[0042] Step S200, embedding the titanium alloy component 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 component.

[0043] In this embodiment, it should be noted that the solid mixed penetrant is used to infiltrate nitrogen, boron and carbon into the surface of the titanium alloy part to be strengthened to form a composite hardened layer. The solid mixed penetrant includes at least boron carbide powder and silicon carbide powder, and of course, other additives (such as charcoal) for promoting the penetration rate may also be included. The particle size of the boron carbide powder and the silicon carbide powder is -60 mesh to -200 mesh.

[0044] In this embodiment, it should be noted that the titanium alloy component to be strengthened can be a powder metallurgy titanium alloy component prepared by vacuum sintering after injection molding or press molding. Of course, other methods can also be used to prepare the titanium alloy component whose performance needs to be strengthened. The nitrogen-containing inert atmosphere is a mixed atmosphere of nitrogen and inert gas.

[0045] In this embodiment, boron carbide powder and silicon carbide powder are selected, weighed according to a preset ratio, and evenly mixed to obtain a solid mixed infiltrant. Then the titanium alloy parts to be strengthened can be placed in a sintering boat, and an appropriate amount of solid mixed infiltrant is taken to completely embed the titanium alloy parts to be strengthened. Then the sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a sintering furnace, and vacuum sintering is first performed, and the temperature is increased to the preset maximum sintering temperature corresponding to the titanium alloy parts to be strengthened at a preset heating rate, and heat preservation sintering is performed. After the vacuum sintering stage is completed, the preset maximum sintering temperature is maintained unchanged, a nitrogen-containing inert atmosphere is introduced into the sintering furnace, and sintering is performed under high-pressure nitrogen-containing inert atmosphere conditions. After a certain period of pressure and heat preservation, the temperature is lowered to room temperature to obtain the strengthened titanium alloy parts.

[0046] The weight percentage of each component in the solid mixed penetrant is: 5-40% boron carbide powder, 40-80% silicon carbide powder. In order to promote the penetration rate of nitrogen, boron and carbon into the surface of the titanium alloy part to be strengthened, the solid mixed penetrant also includes charcoal powder, and the weight percentage of the charcoal powder is: 0-30%.

[0047] The step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant in step S200, and sequentially performing vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain a strengthened titanium alloy component includes:

[0048] Step S210, taking the solid mixed infiltrant to completely embed the titanium alloy component to be strengthened;

[0049] Step S220, vacuum sintering the completely embedded titanium alloy component to be strengthened;

[0050] Step S230, injecting nitrogen-containing inert atmosphere into the titanium alloy component to be strengthened after vacuum sintering to perform high pressure sintering;

[0051] Step S240, after the high pressure sintered titanium alloy component to be strengthened is cooled to room temperature, a strengthened titanium alloy component is obtained.

[0052] In this embodiment, the solid mixed infiltrant can be used to completely embed the titanium alloy parts to be strengthened. Then, the titanium alloy parts to be strengthened that are completely embedded in the sintering boat are placed in a sintering furnace, and the sintering furnace is evacuated according to a preset vacuum degree; 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 are kept warm for a first preset duration. The titanium alloy parts to be strengthened after vacuum sintering are maintained at a preset maximum sintering temperature and a nitrogen-containing inert atmosphere is injected into the sintering furnace; the titanium alloy parts to be strengthened are kept warm and pressure-maintained for a second preset duration in the nitrogen-containing inert atmosphere. Then, after the titanium alloy parts to be strengthened after high-pressure sintering are cooled to room temperature with the furnace, a strengthened titanium alloy part is obtained.

[0053] Among them, the step of heating the titanium alloy parts to be strengthened to a preset maximum sintering temperature at a preset heating rate in a vacuum sintering furnace includes: heating the temperature to 1000°C at a heating rate of 4 to 7°C / min in a vacuum sintering furnace, and heating the temperature from 1000°C to the preset maximum sintering temperature at a heating rate of 2 to 4°C / min, so as to heat the titanium alloy parts 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 to 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 about 1300° C. 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 a sintering reaction.

[0055] The nitrogen-containing inert atmosphere is a nitrogen-argon mixed gas, the total pressure of the nitrogen-argon mixed gas is 2 to 10 bar, the volume proportion of nitrogen in the nitrogen-argon mixed gas is 10 to 50%, and the second preset duration is 20 to 40 minutes.

[0056] In one embodiment of the present application, by weighing boron carbide powder and silicon carbide powder and mixing them evenly, a solid mixed infiltrant is obtained. Then the titanium alloy parts to be strengthened are embedded in the solid mixed infiltrant, and vacuum sintering and pressure sintering under a nitrogen-containing inert atmosphere are performed in sequence to obtain the strengthened titanium alloy parts. Thus, the present embodiment improves the density of the titanium alloy parts to be strengthened by pressure sintering; at the same time, under the joint action of the nitrogen-containing inert atmosphere and the solid mixed infiltrant, nitrogen, boron, and carbon co-infiltration on the surface of the titanium alloy is achieved, so that a titanium (nitrogen, boron, and carbon) composite hardening layer is formed on the surface of the titanium alloy, and the surface hardness, wear resistance, and corrosion resistance of the titanium alloy parts to be strengthened are enhanced, thereby improving the comprehensive performance of the titanium alloy parts and broadening the application range of the titanium alloy parts. In addition, the present application adopts a single sintering method to improve the density, wear resistance, and other properties of the titanium alloy parts to be strengthened, and also effectively reduces the cumbersome degree and cost of the process and improves the process stability.

[0057] Reference Figure 2 , Figure 2 This is a flow chart of another embodiment of the method for preparing a titanium alloy component of the present application. It should be noted that although a logical sequence is shown in the flow chart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0058] In an embodiment of the present invention, a method for preparing a titanium alloy component is provided. Before the step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant in step S200 and performing vacuum pressure sintering to strengthen the titanium alloy component, the method comprises:

[0059] Step A10, weighing titanium alloy powder, and mixing and granulating the titanium alloy powder with a binder to obtain a feed material;

[0060] Step A20, injection molding the feed material to obtain a blank, and degreasing the blank;

[0061] Step A30, vacuum sintering the degreased blank to obtain a titanium alloy component to be strengthened.

[0062] In this embodiment, it should be noted that the adhesive is a solvent for bonding the titanium alloy powder together. Exemplarily, the adhesive can be prepared by mixing polyethylene, paraffin and stearic acid. The adhesive can also be prepared by mixing materials such as polyethylene glycol, plasticizer, stearic acid, sodium sulfonylbenzoylmide, etc. The selected titanium alloy powder and the formulated adhesive are mixed in proportion on a rubber mixer for 1.5 to 2 hours, and then granulated on a mixing extruder to make the feed further uniform to obtain the feed. Then, injection molding is performed at a predetermined injection temperature and injection pressure to obtain a blank of a titanium alloy part of the desired shape. Then an organic solvent is configured, and the organic solution is used to solvent degrease the blank. Exemplarily, the organic solvent can be at least one of anhydrous ethanol, acetone, n-heptane, trichloroethylene and other organic solvents. The blank is degreased by immersing the blank in the organic solvent, then drying and vacuum hot degreasing, to obtain a degreased blank. Finally, the degreased blank is placed in a vacuum sintering furnace for vacuum sintering, and then cooled to room temperature in the furnace to obtain a powder metallurgy titanium alloy component prepared by an injection molding process as a titanium alloy component to be strengthened.

[0063] In the second embodiment of the present application, titanium alloy powder is weighed, and the titanium alloy powder is mixed with a binder and granulated to obtain a feed. Then the feed is injection molded to obtain a blank, and the blank is degreased. The degreased blank is then vacuum sintered to obtain a titanium alloy part to be strengthened. This embodiment is conducive to batch preparation of titanium alloy parts to be strengthened by powder injection molding, which reduces raw material consumption, shortens processing cycle, reduces manufacturing costs and improves production efficiency.

[0064] Example 1

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

[0066] A powder metallurgy TC4 titanium alloy component (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300°C was placed in an alumina sintering boat as the titanium alloy component to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltrant was taken to completely embed the component.

[0067] The alumina sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a vacuum pressure sintering furnace. The vacuum pressure sintering furnace is then evacuated to below 50Pa, and then heated from room temperature to 1000°C at a heating rate of 5°C / min, and then heated from 1000°C to 1300°C at a heating rate of 3°C / min, and sintered for 50 minutes.

[0068] After the above-mentioned vacuum sintering stage is completed, the sintering temperature of 1300°C is maintained unchanged, and a 10 bar nitrogen-argon mixed gas is introduced into the vacuum pressure sintering furnace within 10 minutes, wherein the nitrogen volume accounts for 20% of the nitrogen-argon mixed gas. The sintering temperature of 1300°C is maintained under high-pressure nitrogen-argon mixed atmosphere conditions for sintering. The pressure and temperature are maintained for 25 minutes, and then the temperature is lowered to room temperature to obtain strengthened titanium alloy parts.

[0069] The density of the strengthened titanium alloy parts is increased to 98.5%, 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. The surface strengthening phase has good corrosion resistance and relatively low brittleness.

[0070] Example 2

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

[0072] A powder metallurgy TC4 titanium alloy component (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300°C was placed in an alumina sintering boat as the titanium alloy component to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltrant was taken to completely embed the component.

[0073] The alumina sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a vacuum pressure sintering furnace. The vacuum pressure sintering furnace is then evacuated to below 50Pa, and then heated from room temperature to 1000°C at a heating rate of 5°C / min, and then heated from 1000°C to 1300°C at a heating rate of 3°C / min, and sintered for 50 minutes.

[0074] After the above-mentioned vacuum sintering stage is completed, the sintering temperature of 1300°C is maintained unchanged, and a 10 bar nitrogen-argon mixed gas is introduced into the vacuum pressure sintering furnace within 10 minutes, wherein the nitrogen volume accounts for 20% of the nitrogen-argon mixed gas. The sintering temperature of 1300°C is maintained under high-pressure nitrogen-argon mixed atmosphere conditions for sintering. The pressure and temperature are maintained for 25 minutes, and then the temperature is lowered to room temperature to obtain 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 the brittleness is relatively low.

[0076] Example 3

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

[0078] A powder metallurgy TC4 titanium alloy component (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300°C was placed in an alumina sintering boat as the titanium alloy component to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltrant was taken to completely embed the component.

[0079] The alumina sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a vacuum pressure sintering furnace. The vacuum pressure sintering furnace is then evacuated to below 50Pa, and then heated from room temperature to 1000°C at a heating rate of 5°C / min, and then heated from 1000°C to 1300°C at a heating rate of 3°C / min, and sintered for 50 minutes.

[0080] After the above-mentioned vacuum sintering stage is completed, the sintering temperature of 1300°C is maintained unchanged, and a 10 bar nitrogen-argon mixed gas is introduced into the vacuum pressure sintering furnace within 10 minutes, wherein the nitrogen volume accounts for 20% of the nitrogen-argon mixed gas. The sintering temperature of 1300°C is maintained under high-pressure nitrogen-argon mixed atmosphere conditions for sintering. The pressure and temperature are maintained for 25 minutes, and then the temperature is lowered to room temperature to obtain 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 the brittleness is relatively low.

[0082] Example 4

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

[0084] A powder metallurgy TC4 titanium alloy component (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300°C was placed in an alumina sintering boat as the titanium alloy component to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltrant was taken to completely embed the component.

[0085] The alumina sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a vacuum pressure sintering furnace. The vacuum pressure sintering furnace is then evacuated to below 50Pa, and then heated from room temperature to 1000°C at a heating rate of 5°C / min, and then heated from 1000°C to 1300°C at a heating rate of 3°C / min, and sintered for 50 minutes.

[0086] After the above-mentioned vacuum sintering stage is completed, the sintering temperature of 1300°C is maintained unchanged, and a 10 bar nitrogen-argon mixed gas is introduced into the vacuum pressure sintering furnace within 10 minutes, wherein the nitrogen volume accounts for 20% of the nitrogen-argon mixed gas. The sintering temperature of 1300°C is maintained under high-pressure nitrogen-argon mixed atmosphere conditions for sintering. The pressure and temperature are maintained for 25 minutes, and then the temperature is lowered to room temperature to obtain 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 the brittleness is relatively low.

[0088] Example 5

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

[0090] A powder metallurgy TC4 titanium alloy component (prepared by injection molding process, density 96%) obtained by conventional vacuum sintering at 1300°C was placed in an alumina sintering boat as the titanium alloy component to be strengthened, and an appropriate amount of the aforementioned solid mixed infiltrant was taken to completely embed the component.

[0091] The alumina sintering boat containing the titanium alloy parts to be strengthened after embedding treatment is placed in a vacuum pressure sintering furnace. The vacuum pressure sintering furnace is then evacuated to below 50Pa, and then heated from room temperature to 1000°C at a heating rate of 5°C / min, and then heated from 1000°C to 1300°C at a heating rate of 3°C / min, and sintered for 50 minutes.

[0092] After the above-mentioned vacuum sintering stage is completed, the sintering temperature of 1300°C is maintained unchanged, and a 10 bar nitrogen-argon mixed gas is introduced into the vacuum pressure sintering furnace within 10 minutes, wherein the nitrogen volume accounts for 20% of the nitrogen-argon mixed gas. The sintering temperature of 1300°C is maintained under high-pressure nitrogen-argon mixed atmosphere conditions for sintering. The pressure and temperature are maintained for 25 minutes, and then the temperature is lowered to room temperature to obtain 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 the brittleness is relatively low.

[0094] Test results

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

[0096] Table 1 Test results of various embodiments

[0097]

[0098] The reference example described in Table 1 is a powder metallurgy TC4 titanium alloy part prepared by injection molding process. It can be seen from this that the titanium alloy parts prepared in the above embodiment of the present application have a significant improvement in density, reducing the possibility of residual pores causing crack initiation and expansion of titanium alloy parts under high stress. In addition, the titanium alloy parts prepared in the above embodiment have a significant improvement in hardness. And because the surface of the titanium alloy parts after strengthening is formed with a titanium (nitrogen, boron, carbon) composite strengthening phase, therefore, relative to the strengthening of a single characteristic, the wear resistance, corrosion resistance and brittleness of the titanium alloy parts strengthened in the embodiment of the present application have been correspondingly improved. Thus, the embodiment of the present application effectively improves the comprehensive performance of the density and surface wear resistance of the titanium alloy parts, and the embodiment of the present application, through a single sintering method, makes the titanium alloy parts to be strengthened have improved performances such as density and wear resistance, and also effectively reduces the cumbersome degree and cost of the process, and improves the process stability.

[0099] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity / operation / object from another entity / operation / object, and do not necessarily require or imply any such actual relationship or order between these entities / operations / objects; the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0100] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0101] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a titanium alloy component, characterized in that: The preparation method comprises: Weigh boron carbide powder and silicon carbide powder and mix them evenly to obtain a solid mixed penetrant; The titanium alloy parts to be strengthened are embedded in the solid mixed infiltrant, and vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere are performed in sequence to obtain strengthened titanium alloy parts.

2. The preparation method according to claim 1, characterized in that The mass proportions of the components in the solid mixed infiltrant are: 5-40% of boron carbide powder and 40-80% of silicon carbide powder.

3. The preparation method according to claim 2, characterized in that: The solid mixed infiltration agent also includes charcoal powder, and the mass proportion of the charcoal powder is 0-30%.

4. The preparation method according to claim 1, characterized in that: The step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant, and sequentially performing vacuum sintering and pressure sintering in a nitrogen-containing inert atmosphere to obtain the strengthened titanium alloy component comprises: Using the solid mixed infiltrant to completely embed the titanium alloy component to be strengthened; The completely embedded titanium alloy parts to be strengthened are subjected to vacuum sintering; Injecting nitrogen-containing inert atmosphere into the titanium alloy parts to be strengthened after vacuum sintering for high-pressure sintering; After the titanium alloy component to be strengthened is cooled to room temperature after high pressure sintering, a strengthened titanium alloy component is obtained.

5. The preparation method according to claim 4, characterized in that: The step of vacuum sintering the completely embedded titanium alloy parts to be strengthened comprises: Putting the titanium alloy parts to be strengthened that are completely embedded in the sintering boat into a sintering furnace, and evacuating the sintering furnace according to a preset vacuum degree; The titanium alloy component to be strengthened is heated to a preset maximum sintering temperature at a preset heating rate in a vacuum sintering furnace, and is subjected to heat preservation sintering for a first preset duration.

6. The preparation method according to claim 5, characterized in that: The step of heating the titanium alloy component to be strengthened to a preset maximum sintering temperature at a preset heating rate in a vacuum sintering furnace comprises: In a vacuum sintering furnace, the temperature is increased to 1000°C at a heating rate of 4-7°C / min, and the temperature is 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 component to be strengthened to the preset maximum sintering temperature.

7. The preparation method according to claim 5, 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 component to be strengthened.

8. The preparation method according to claim 5, characterized in that: The step of injecting a nitrogen-containing inert atmosphere into the vacuum-sintered titanium alloy component to be strengthened for high-pressure sintering comprises: Maintaining the titanium alloy component to be strengthened after vacuum sintering at a preset maximum sintering temperature and injecting a nitrogen-containing inert atmosphere into the sintering furnace; The titanium alloy component to be strengthened is sintered under the nitrogen-containing inert atmosphere at a temperature and pressure maintained for a second preset duration.

9. The preparation method according to claim 8, characterized in that: The nitrogen-containing inert atmosphere is a nitrogen-argon mixed gas, the total pressure of the nitrogen-argon mixed gas is 2-10 bar, the volume proportion of nitrogen in the nitrogen-argon mixed gas is 10-50%, and the second preset duration is 20-40 minutes.

10. The preparation method according to claim 1, characterized in that: Before the step of embedding the titanium alloy component to be strengthened in the solid mixed infiltrant and performing vacuum pressure sintering to strengthen the titanium alloy component, the method includes: Weighing titanium alloy powder, and mixing and granulating the titanium alloy powder with a binder to obtain a feed material; Injection molding the feed material to obtain a blank, and degreasing the blank; The degreased blank is vacuum sintered to obtain the titanium alloy parts to be strengthened.

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