A titanium alloy and a method for manufacturing the same

Abstract

The application discloses a kind of titanium alloys, the titanium alloy is obtained by titanium alloy powder injection molding;Wherein, the titanium alloy powder includes: titanium alloy ball and TiB2 layer, polyamine layer, graphene oxide layer successively coated on the surface of titanium alloy ball, and the graphene oxide layer contains cerium element.The application also discloses a preparation method of the above-mentioned titanium alloy, comprising the following steps: taking titanium alloy powder and binder mixing, injection molding, degreasing, vacuum sintering at 1000-1100 DEG C for 2-3h, cooling to room temperature, solid solution at 700-720 DEG C for 40-60min, air cooling to room temperature, then heat preservation at 450-470 DEG C for 3-3.5h, and then air cooling to room temperature, to obtain titanium alloy.The titanium alloy has good strength while maintaining good toughness.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy technology, and in particular to a titanium alloy and its preparation method. Background Technology

[0002] Titanium and titanium alloys possess excellent properties such as low density, high specific strength, good plasticity, heat resistance, and corrosion resistance, making them widely used as novel structural materials in aerospace, biomedical, chemical, shipbuilding, and automotive fields, with the aerospace sector being particularly popular. Although titanium is abundant in the Earth's crust, its high melting point, high strength, and high chemical reactivity make it difficult to machine, resulting in consistently high production costs for titanium alloy products. Furthermore, the machineable titanium alloy structural parts are relatively simple, and their design is often limited by the processing methods, preventing them from fully utilizing the material's optimal properties. Against this backdrop, metal powder injection molding technology, which offers high raw material utilization, mass production capabilities, and low production costs, has become one of the most effective techniques for manufacturing titanium and titanium alloy parts.

[0003] The general operation process of powder injection molding technology is as follows: First, the prepared powder and binder are mixed and granulated to prepare granular feedstock. Then, the feedstock is formed into a product preform of a specific shape on an injection molding machine. Finally, the product with the required properties is obtained through debinding and sintering.

[0004] However, it is impossible to achieve both strength and toughness in titanium alloys obtained by injection molding using existing titanium alloy powders. Furthermore, during sintering, titanium metal is highly reactive and is prone to oxidation at around 400°C, generating impurity phases such as titanium oxide, which further reduces the relative density of the sintered alloy. Moreover, with the increase of oxygen content, the toughness of the titanium alloy will further deteriorate. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a titanium alloy and its preparation method. The present invention designs the structure of titanium alloy powder from multiple aspects, such as improving the interfacial bonding force between graphene and titanium alloy, improving sintering density, refining grains and alloy microstructure, so that the titanium alloy obtained by injection molding has good strength while maintaining good toughness.

[0006] This invention proposes a titanium alloy, which is obtained by injection molding of titanium alloy powder;

[0007] The titanium alloy powder comprises: titanium alloy spheres and TiB2 layer, polyamine layer and graphene oxide layer sequentially coated on the surface of the titanium alloy spheres, wherein the graphene oxide layer contains cerium.

[0008] Preferably, the titanium alloy ball is a TC4 titanium alloy ball, wherein the TC4 titanium alloy ball contains 0.2-0.4 wt% Nd.

[0009] Adding an appropriate amount of Nd to titanium alloy spheres can remove oxygen from the titanium alloy during sintering, purify the matrix, and form nano-rare earth oxides, which can refine the grains and internal structure of the titanium alloy, thereby improving the strength and toughness of the titanium alloy.

[0010] The raw materials of the above-mentioned TC4 titanium alloy balls include, by weight percentage: Al 5.8-6.0%, V 4.0-4.2%, O 0.15-0.18%, Nd 0.2-0.4%, C≤0.10%, N≤0.05%, H≤0.015%, with the balance being Ti and unavoidable impurities.

[0011] Preferably, the polyamine is at least one of diethylenetriamine and triethylenetetramine.

[0012] Preferably, the average particle size of the titanium alloy powder is 15-25 μm.

[0013] Preferably, in the preparation of titanium alloy powder, titanium alloy balls are mixed with TiB2 and ball-milled to obtain intermediate ball 1; intermediate ball 1 is mixed with a polyamine aqueous solution and allowed to react statically to obtain intermediate ball 2; intermediate ball 2 is mixed with an aqueous solution of graphene oxide and electrostatically assembled to obtain intermediate ball 3; intermediate ball 3 is mixed with an aqueous solution containing cerium ions, electrostatically adsorbed, and vacuum dried to obtain titanium alloy powder.

[0014] The above-mentioned aqueous solutions containing cerium ions can be cerium chloride aqueous solution, cerium nitrate aqueous solution, etc.

[0015] This invention uses a ball milling method to load TiB2 whiskers onto the surface of titanium alloy balls to obtain intermediate sphere 1. The hydroxyl groups on the surface of intermediate sphere 1 can form chemical bonds with polyamines to form a positively charged polyamine layer. Then, it undergoes electrostatic assembly with negatively charged graphene oxide to form a negatively charged graphene oxide layer, and then with Ce... 3+ Titanium alloy powder is obtained by electrostatic adsorption to fix cerium in the graphene oxide layer.

[0016] The specific structure of the aforementioned titanium alloy powder can avoid the problem of easy oxidation of the titanium alloy surface. During injection molding and sintering, TiB2 whiskers can form a network structure on the surface of the titanium alloy spheres. Polyamines and graphene oxide form a TiC-coated graphene structure, which is tightly connected with the network structure of TiB2 whiskers, thereby improving the interfacial bonding force between the titanium alloy matrix and graphene. This structure can improve the load transfer between the titanium alloy matrix and graphene, significantly improving the strength and toughness of the titanium alloy. Furthermore, TiB2 can further refine the alloy microstructure and improve mechanical strength. In addition, rare earth cerium fixed in the graphene oxide layer can remove oxygen from the oxide film on the surface of the titanium alloy during sintering, eliminate the oxide film, promote the sintering of the titanium alloy, improve the sintering density, and the formed fine high-melting-point rare earth oxides can refine the grains, thereby further improving the mechanical properties of the titanium alloy.

[0017] Preferably, the weight ratio of titanium alloy balls to TiB2 is 10:0.05-0.1.

[0018] Preferably, the ball milling speed is 100-150 rpm and the ball milling time is 3-4 hours.

[0019] Preferably, the reaction is allowed to proceed at room temperature for 0.5-1 hour.

[0020] Preferably, electrostatic assembly is performed at room temperature for 0.5-1 hour.

[0021] Preferably, electrostatic adsorption is performed at room temperature for 0.5-1 h.

[0022] Preferably, the mass fraction of the polyamine aqueous solution is 1-2 wt%.

[0023] Preferably, the mass fraction of the graphene oxide aqueous solution is 0.4-0.6 wt%.

[0024] Preferably, the concentration of cerium ions in the aqueous solution containing cerium ions is 0.02-0.04 mol / L.

[0025] The present invention also proposes a method for preparing the above-mentioned titanium alloy, comprising the following steps: mixing titanium alloy powder with a binder, injection molding, degreasing, vacuum sintering at 1000-1100℃ for 2-3 hours, cooling to room temperature, solution treatment at 700-720℃ for 40-60 minutes, air cooling to room temperature, then holding at 450-470℃ for 3-3.5 hours, and then air cooling to room temperature to obtain the titanium alloy.

[0026] By selecting appropriate sintering and heat treatment processes, this invention can further refine the alloy microstructure and promote the close interaction between the TiB2 network structure and TiC-coated graphene, thereby further improving the mechanical properties of the titanium alloy.

[0027] Beneficial effects:

[0028] The titanium alloy powder described in this invention can, on the one hand, avoid the problem of easy oxidation of the titanium alloy surface; on the other hand, during injection molding and sintering, TiB2 whiskers can form a network structure on the surface of the titanium alloy spheres, and polyamines and graphene oxide form a TiC-coated graphene structure, which is closely connected with the network structure of TiB2 whiskers, thereby improving the interfacial bonding force between the titanium alloy matrix and graphene. This structure can improve the load transfer between the titanium alloy matrix and graphene, thereby significantly improving the strength and toughness of the titanium alloy.

[0029] Furthermore, the rare earth cerium fixed in the graphene oxide layer can remove oxygen from the oxide film on the surface of the titanium alloy during sintering, eliminate the oxide film, promote the sintering of the titanium alloy, increase the sintering density, and cooperate with the Nd inside the titanium alloy spheres. Through the interaction of the fine rare earth oxides formed inside and outside the titanium alloy spheres, the grains and alloy structure are refined, further improving the mechanical properties of the titanium alloy.

[0030] This invention designs the structure of titanium alloy powder from multiple aspects, such as improving the interfacial bonding force between graphene and titanium alloy, increasing sintering density, refining grain size and alloy microstructure, so that the titanium alloy produced by injection molding has good strength while maintaining good toughness. Detailed Implementation

[0031] The technical solution of the present invention will now be described in detail through specific embodiments.

[0032] Example 1

[0033] A titanium alloy, wherein the titanium alloy is obtained by injection molding of titanium alloy powder;

[0034] The titanium alloy powder comprises: TC4 titanium alloy spheres and TiB2 layer, polyamine layer and graphene oxide layer sequentially coated on the surface of the TC4 titanium alloy spheres, wherein the graphene oxide layer contains cerium; the average particle size of the titanium alloy powder is 15 μm.

[0035] The raw materials for TC4 titanium alloy balls, by weight percentage, include: Al 5.9%, V 4.1%, O 0.17%, Nd 0.2%, C≤0.10%, N≤0.05%, H≤0.015%, with the balance being Ti and unavoidable impurities;

[0036] In the preparation of titanium alloy powder, TC4 titanium alloy balls and TiB2 were mixed at a weight ratio of 10:0.05, and ball-milled at 150 rpm for 3 h with stainless steel balls at a ball-to-material ratio of 4:1 to obtain intermediate ball 1. Intermediate ball 1 was mixed with a 2 wt% diethylenetriamine aqueous solution and allowed to stand at room temperature for 0.5 h. After washing with water, intermediate ball 2 was obtained. Intermediate ball 2 was mixed with a 0.6 wt% graphene oxide aqueous solution and allowed to stand at room temperature for electrostatic assembly for 0.5 h. After washing with water, intermediate ball 3 was obtained. Intermediate ball 3 was mixed with a 0.04 mol / L cerium chloride aqueous solution and allowed to stand at room temperature for electrostatic adsorption for 0.5 h. After washing with water, it was vacuum dried to obtain titanium alloy powder.

[0037] The preparation method of the above-mentioned titanium alloy includes the following steps: titanium alloy powder and binder (the binder formula is: 83% PW + 15% LDPE + 2% SA by weight percentage) are mixed in a weight ratio of 1:1 to obtain granular feed, which is then injection molded, degreased by solvent, vacuum sintered in a vacuum sintering furnace at 1000℃ for 3 hours, cooled to room temperature, solution-treated at 700℃ for 60 minutes, air-cooled to room temperature, and then held at 450℃ for 3.5 hours, and then air-cooled to room temperature to obtain titanium alloy.

[0038] Example 2

[0039] A titanium alloy, wherein the titanium alloy is obtained by injection molding of titanium alloy powder;

[0040] The titanium alloy powder comprises: TC4 titanium alloy spheres and a TiB2 layer, a polyamine layer, and a graphene oxide layer sequentially coated on the surface of the TC4 titanium alloy spheres, wherein the graphene oxide layer contains cerium; the average particle size of the titanium alloy powder is 20 μm.

[0041] The raw materials for TC4 titanium alloy balls, by weight percentage, include: Al 5.9%, V 4.1%, O 0.17%, Nd 0.4%, C≤0.10%, N≤0.05%, H≤0.015%, with the balance being Ti and unavoidable impurities;

[0042] In the preparation of titanium alloy powder, TC4 titanium alloy balls and TiB2 were mixed at a weight ratio of 10:0.1, and ball-milled at 100 rpm for 4 hours using stainless steel balls at a ball-to-material ratio of 4:1 to obtain intermediate ball 1. Intermediate ball 1 was mixed with a 1 wt% triethylenetetramine aqueous solution and allowed to react at room temperature for 1 hour. After washing with water, intermediate ball 2 was obtained. Intermediate ball 2 was mixed with a 0.4 wt% graphene oxide aqueous solution and allowed to electrostatically assemble at room temperature for 1 hour. After washing with water, intermediate ball 3 was obtained. Intermediate ball 3 was mixed with a 0.02 mol / L cerium chloride aqueous solution and allowed to electrostatically adsorb at room temperature for 1 hour. After washing with water, it was vacuum dried to obtain titanium alloy powder.

[0043] The preparation method of the above-mentioned titanium alloy includes the following steps: titanium alloy powder and binder (the binder formula is: 83% PW + 15% LDPE + 2% SA by weight percentage) are mixed in a weight ratio of 1:1 to obtain granular feed, which is then injection molded, degreased by solvent, vacuum sintered in a vacuum sintering furnace at 1100℃ for 2 hours, cooled to room temperature, solution-treated at 720℃ for 40 minutes, air-cooled to room temperature, and then held at 470℃ for 3 hours, and then air-cooled to room temperature to obtain titanium alloy.

[0044] Example 3

[0045] A titanium alloy, wherein the titanium alloy is obtained by injection molding of titanium alloy powder;

[0046] The titanium alloy powder comprises: TC4 titanium alloy spheres and TiB2 layer, polyamine layer and graphene oxide layer sequentially coated on the surface of the TC4 titanium alloy spheres, wherein the graphene oxide layer contains cerium; the average particle size of the titanium alloy powder is 15 μm.

[0047] The raw materials for TC4 titanium alloy balls, by weight percentage, include: Al 5.9%, V 4.1%, O 0.17%, Nd 0.3%, C≤0.10%, N≤0.05%, H≤0.015%, with the balance being Ti and unavoidable impurities;

[0048] In the preparation of titanium alloy powder, TC4 titanium alloy balls and TiB2 were mixed at a weight ratio of 10:0.07, and ball-milled at 150 rpm for 3.5 h using stainless steel balls at a ball-to-material ratio of 4:1 to obtain intermediate ball 1. Intermediate ball 1 was mixed with a 1.5 wt% triethylenetetramine aqueous solution and allowed to stand at room temperature for 1 h. After washing with water, intermediate ball 2 was obtained. Intermediate ball 2 was mixed with a 0.5 wt% graphene oxide aqueous solution and allowed to stand at room temperature for electrostatic assembly for 1 h. After washing with water, intermediate ball 3 was obtained. Intermediate ball 3 was mixed with a 0.03 mol / L cerium chloride aqueous solution and allowed to stand at room temperature for electrostatic adsorption for 1 h. After washing with water, it was vacuum dried to obtain titanium alloy powder.

[0049] The preparation method of the above-mentioned titanium alloy includes the following steps: titanium alloy powder and binder (the binder formula is: 83% PW + 15% LDPE + 2% SA by weight percentage) are mixed in a weight ratio of 1:1 to obtain granular feed, then injection molded, solvent degreased, vacuum sintered in a vacuum sintering furnace at 1100℃ for 2.5h, cooled to room temperature, solution-treated at 710℃ for 50min, air-cooled to room temperature, then held at 460℃ for 3h, and then air-cooled to room temperature to obtain titanium alloy.

[0050] Comparative Example 1

[0051] The titanium alloy powder was replaced with the intermediate sphere 3 from Example 3, and the titanium alloy was prepared according to the method of Example 3.

[0052] Comparative Example 2

[0053] The titanium alloy powder was replaced with the intermediate sphere 1 from Example 3, and the titanium alloy was prepared according to the method of Example 3.

[0054] Comparative Example 3

[0055] Titanium alloy powder was prepared by replacing intermediate ball 1 with TC4 titanium alloy ball (the same formula as in Example 3) according to the method of intermediate ball 2 to titanium alloy powder in Example 3, and titanium alloy was prepared by using this titanium alloy powder according to the method of Example 3.

[0056] Comparative Example 4

[0057] Titanium alloy powder was replaced with TC4 titanium alloy balls from Example 3, and titanium alloy was prepared according to the method of Example 3.

[0058] The mechanical properties of the titanium alloys obtained in each group were tested using a universal testing machine, and the results are shown in Table 1.

[0059] Table 1 Test Results

[0060]

[0061]

[0062] As can be seen from Table 1, using the titanium alloy powder with the specific structure described in this invention can improve the tensile strength of the titanium alloy while still maintaining good elongation.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A titanium alloy, characterized in that, The titanium alloy is obtained by injection molding of titanium alloy powder; The titanium alloy powder comprises: titanium alloy spheres and TiB2 layer, polyamine layer and graphene oxide layer sequentially coated on the surface of the titanium alloy spheres, wherein the graphene oxide layer contains cerium.

2. The titanium alloy according to claim 1, characterized in that, The titanium alloy spheres are TC4 titanium alloy spheres, wherein the TC4 titanium alloy spheres contain 0.2-0.4wt% Nd.

3. The titanium alloy according to claim 1 or 2, characterized in that, The polyamine is at least one of diethylenetriamine and triethylenetetramine.

4. The titanium alloy according to claim 1 or 2, characterized in that, The average particle size of the titanium alloy powder is 15-25 μm.

5. The titanium alloy according to claim 1 or 2, characterized in that, In the preparation of titanium alloy powder, titanium alloy balls are mixed with TiB2 and ball-milled to obtain intermediate ball 1; intermediate ball 1 is mixed with a polyamine aqueous solution and allowed to react statically to obtain intermediate ball 2; intermediate ball 2 is mixed with an aqueous solution of graphene oxide and electrostatically assembled to obtain intermediate ball 3; intermediate ball 3 is mixed with an aqueous solution containing cerium ions, electrostatically adsorbed, and vacuum dried to obtain titanium alloy powder.

6. The titanium alloy according to claim 5, characterized in that, The weight ratio of titanium alloy spheres to TiB2 is 10:0.05-0.

1.

7. The titanium alloy according to claim 5, characterized in that, The ball milling speed is 100-150 rpm, and the ball milling time is 3-4 hours.

8. The titanium alloy according to claim 5, characterized in that, Allow the reaction to stand at room temperature for 0.5-1 hour.

9. The titanium alloy according to claim 5, characterized in that, Electrostatic assembly at room temperature for 0.5-1 h.

10. The titanium alloy according to claim 5, characterized in that, Electrostatic adsorption at room temperature for 0.5-1 h.

11. The titanium alloy according to claim 5, characterized in that, The mass fraction of the polyamine aqueous solution is 1-2 wt%.

12. The titanium alloy according to claim 5, characterized in that, The mass fraction of the graphene oxide aqueous solution is 0.4-0.6 wt%.

13. The titanium alloy according to claim 5, characterized in that, In aqueous solutions containing cerium ions, the concentration of cerium ions is 0.02-0.04 mol / L.

14. A method for preparing a titanium alloy as described in any one of claims 1-13, characterized in that, The process includes the following steps: mixing titanium alloy powder with a binder, injection molding, degreasing, vacuum sintering at 1000-1100℃ for 2-3 hours, cooling to room temperature, solution treatment at 700-720℃ for 40-60 minutes, air cooling to room temperature, holding at 450-470℃ for 3-3.5 hours, and then air cooling to room temperature to obtain the titanium alloy.

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