Titanium alloy powder and preparation method thereof

Abstract

The titanium alloy powder comprises a titanium alloy ball, a polyvinyl alcohol layer and a graphene oxide layer, wherein the surface of the titanium alloy ball is sequentially coated with the polyvinyl alcohol layer and the graphene oxide layer; wherein the polyvinyl alcohol layer contains nano Si and nano TiB2. The invention also discloses a preparation method of the titanium alloy powder, which comprises the following steps: coating the surface of a titanium alloy ball with a polyvinyl alcohol aqueous solution containing nano Si and nano TiB2, and drying; and then adding into the graphene oxide dispersion liquid, stirring, carrying out solid-liquid separation, and drying to obtain titanium alloy powder. The invention further discloses a titanium alloy and a preparation method thereof. The titanium alloy disclosed by the invention keeps good toughness while having good strength.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a titanium alloy powder and a preparation method thereof. Background Art

[0002] Titanium alloys have been widely used in aviation, aerospace, biomedicine, chemical industry, shipbuilding, automobile and other fields. Due to the high melting point and strength of titanium and its high chemical activity, the processing of titanium alloy products is difficult, and only products with relatively simple structures can be prepared, which limits the use of titanium alloys.

[0003] Powder pressing and sintering technology can be used to mass produce titanium alloy parts with complex structures, which are in great demand in many fields. However, when the existing titanium alloy powder is pressed and sintered, the resulting titanium alloy often has the problem of significantly reduced toughness and plasticity while improving strength. Therefore, it is necessary to improve it. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a titanium alloy powder and a preparation method thereof. The titanium alloy of the present invention has good strength and maintains good toughness.

[0005] The present invention provides a titanium alloy powder, comprising: a titanium alloy ball and a polyvinyl alcohol layer and a graphene oxide layer sequentially coated on the surface of the titanium alloy ball;

[0006] Among them, the polyvinyl alcohol layer contains nano-Si and nano-TiB2.

[0007] Preferably, the average particle size of the titanium alloy spheres is 60-90 μm.

[0008] Preferably, the weight ratio of titanium alloy ball, nano-Si and nano-TiB2 is 100:1-1.5:0.8-1.

[0009] Preferably, the thickness of the graphene oxide layer is 3-8 nm.

[0010] Preferably, the titanium alloy ball is a TC4 titanium alloy ball.

[0011] Preferably, the TC4 titanium alloy ball contains 0.3-0.4wt% CeSi2 and 0.04-0.06wt% Y.

[0012] The raw materials of the above-mentioned TC4 titanium alloy ball include, by weight percentage: Al 6.1-6.2%, V 4.2-4.3%, Fe0.22-0.24%, CeSi20.3-0.4%, Y 0.04-0.06%, C≤0.10%, N≤0.01%, H≤0.005%, O≤0.15%, and the balance is Ti.

[0013] The present invention also proposes a method for preparing the above-mentioned titanium alloy powder, comprising the following steps: coating a polyvinyl alcohol aqueous solution containing nano-Si and nano-TiB2 on the surface of a titanium alloy ball and drying it; then adding it to a graphene oxide dispersion, stirring, solid-liquid separation, and drying to obtain a titanium alloy powder.

[0014] The present invention coats nano-Si, nano-TiB2 and polyvinyl alcohol on the surface of a titanium alloy ball. The hydroxyl groups of the polyvinyl alcohol layer can be hydrogen-bonded or covalently bonded with active groups (such as carboxyl groups and epoxy groups) in graphene oxide so that the graphene oxide is coated on the surface of the polyvinyl alcohol layer to obtain titanium alloy powder.

[0015] Preferably, in the polyvinyl alcohol aqueous solution, the weight ratio of nano-Si, nano-TiB2, and polyvinyl alcohol is 1-1.5:0.8-1:8-10.

[0016] Preferably, in the polyvinyl alcohol aqueous solution, the mass fraction of polyvinyl alcohol is 4-5wt%.

[0017] Preferably, the solvent of the graphene oxide dispersion is acetone.

[0018] Preferably, the mass fraction of the graphene oxide dispersion is 0.3-0.4wt%.

[0019] Preferably, stirring is carried out at 40-60°C for 1-2 h.

[0020] The present invention also proposes a method for preparing a titanium alloy, comprising the following steps: taking the titanium alloy powder and pressing it into shape; in an inert gas atmosphere, hot pressing and sintering once to remove the polyvinyl alcohol, hot pressing and sintering twice, and cooling to room temperature to obtain the titanium alloy.

[0021] Preferably, the primary hot pressing sintering temperature is 550-650° C., the time is 10-15 min, and the pressure is 4-5 kN.

[0022] Preferably, the temperature of the secondary hot pressing sintering is 1000-1100° C., the time is 8-10 min, the pressure is 40-50 MPa, and the vacuum degree is less than 10 Pa.

[0023] The present invention also provides a titanium alloy, which is prepared according to the preparation method of the titanium alloy.

[0024] The present invention coats titanium alloy balls with polyvinyl alcohol (containing nano-Si and nano-TiB2) and graphene oxide, and then uses them to perform powder pressing and hot pressing sintering. The polyvinyl alcohol can be removed by high-temperature decomposition during the hot pressing sintering, and the graphene can form a three-dimensional reinforcement structure in the titanium alloy and be evenly distributed, thereby avoiding the problem that the graphene and titanium alloy powder are not easy to be evenly dispersed, resulting in reduced strength and toughness.

[0025] During the secondary hot pressing sintering, the Si in nano-silicon and CeSi2 can be completely dissolved in the TC4 titanium alloy matrix, and during the cooling process, the Ti5Si3 phase is formed on the α / β interface and deposited to form a network structure, while the nano-TiB2 on the surface of the titanium alloy ball can react with Ti to form a network structure. The cooperation of these two network structures can greatly improve the strength and toughness of the titanium alloy.

[0026] In addition, the mesh structure formed by nano-TiB2 and Ti can intersperse graphene and adjacent titanium alloy balls to form each other, thereby improving the interface bonding performance between graphene and titanium alloy; and during the sintering process, graphene can form TiC with Ti and pinned in the titanium alloy matrix, thereby further improving the interface bonding performance between graphene and titanium alloy, and through the three-dimensional structure reinforcement phase formed by graphene in the titanium alloy matrix, good load transfer is achieved, thereby improving the strength and toughness of the titanium alloy;

[0027] In addition, the present invention can reduce the oxygen element in the titanium alloy, refine the grains, improve the sintering density, avoid stress concentration at the crack tip, and further improve the toughness of the titanium alloy by introducing appropriate amounts of CeSi2 and Y to cooperate with each other. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described in detail below through specific embodiments.

[0029] Example 1

[0030] A method for preparing titanium alloy powder comprises the following steps:

[0031] According to the weight ratio of nano-Si, nano-TiB2 and polyvinyl alcohol being 1:1:8, nano-Si and nano-TiB2 are added into a polyvinyl alcohol aqueous solution with a mass fraction of 4wt% and ultrasonically mixed, and then evenly sprayed on the surface of a TC4 titanium alloy ball with an average particle size of 60μm, and dried to make the weight ratio of the titanium alloy ball, nano-Si and nano-TiB2 be 100:1:1, to obtain an intermediate ball;

[0032] Then, the mixture was added into a graphene oxide acetone dispersion having a mass fraction of 0.3 wt%, stirred at 60° C. for 1 h, filtered, and dried to obtain a titanium alloy powder;

[0033] Among them, the thickness of the graphene oxide layer is 3nm.

[0034] The raw materials of the TC4 titanium alloy ball include, by weight percentage: Al 6.2%, V 4.2%, Fe 0.24%, CeSi 20.4%, Y 0.04%, C ≤ 0.10%, N ≤ 0.01%, H ≤ 0.005%, O ≤ 0.15%, and the balance is Ti.

[0035] Example 2

[0036] A method for preparing titanium alloy powder comprises the following steps:

[0037] According to the weight ratio of nano-Si, nano-TiB2 and polyvinyl alcohol being 1.5:0.8:10, nano-Si and nano-TiB2 are added into a polyvinyl alcohol aqueous solution with a mass fraction of 5wt% and ultrasonically mixed, and then evenly sprayed on the surface of a TC4 titanium alloy ball with an average particle size of 90μm, and dried, so that the weight ratio of the titanium alloy ball, nano-Si and nano-TiB2 is 100:1.5:0.8, to obtain an intermediate ball;

[0038] Then, the mixture was added into a graphene oxide acetone dispersion having a mass fraction of 0.4 wt%, stirred at 40° C. for 2 h, filtered, and dried to obtain a titanium alloy powder;

[0039] Among them, the thickness of the graphene oxide layer is 6nm.

[0040] The raw materials of the TC4 titanium alloy ball include, by weight percentage: Al 6.1%, V 4.3%, Fe 0.22%, CeSi2 0.3%, Y 0.06%, C ≤ 0.10%, N ≤ 0.01%, H ≤ 0.005%, O ≤ 0.15%, and the balance is Ti.

[0041] Example 3

[0042] A method for preparing titanium alloy powder comprises the following steps:

[0043] According to the weight ratio of nano-Si, nano-TiB2 and polyvinyl alcohol being 1.2:0.9:9, nano-Si and nano-TiB2 are added into a polyvinyl alcohol aqueous solution with a mass fraction of 4.5wt% and ultrasonically mixed, and then evenly sprayed on the surface of a TC4 titanium alloy ball with an average particle size of 80μm, and dried to make the weight ratio of the titanium alloy ball, nano-Si and nano-TiB2 be 100:1.2:0.9, to obtain an intermediate ball;

[0044] Then, the mixture was added into a graphene oxide acetone dispersion having a mass fraction of 0.35 wt%, stirred at 50° C. for 1.5 h, filtered, and dried to obtain a titanium alloy powder;

[0045] Among them, the thickness of the graphene oxide layer is 5nm.

[0046] The raw materials of the TC4 titanium alloy ball include, by weight percentage: Al 6.15%, V 4.25%, Fe 0.23%, CeSi20.35%, Y 0.05%, C≤0.10%, N≤0.01%, H≤0.005%, O≤0.15%, and the balance is Ti.

[0047] Comparative Example 1

[0048] According to the method of Example 3, an intermediate ball was prepared.

[0049] Comparative Example 2

[0050] Titanium alloy powder was prepared in the same manner as in Example 3 except that nano-Si was not added.

[0051] Comparative Example 3

[0052] Without adding nano-TiB2, titanium alloy powder was prepared in the same manner as in Example 3.

[0053] Comparative Example 4

[0054] Without adding nano-Si and nano-TiB2, titanium alloy powder was prepared in the same manner as in Example 3.

[0055] Comparative Example 5

[0056] The TC4 titanium alloy ball has the same formula as the TC4 titanium alloy ball in Example 3.

[0057] Take the alloy balls of Examples 1-3 and Comparative Examples 1-5, and prepare a titanium alloy according to the same method, which specifically includes the following steps: take the alloy balls and press them into shape; in an argon atmosphere, adjust the temperature to 600°C and the pressure to 5 kN to perform a hot pressing sintering for 12 minutes to remove polyvinyl alcohol, then adjust the pressure to 45 MPa and the vacuum degree to less than 10 Pa, raise the temperature to 1050°C at a rate of 100°C / min, perform a secondary hot pressing sintering for 9 minutes, and then cool to room temperature to obtain a titanium alloy.

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

[0059] Table 1 Test results

[0060] Grouping Tensile strength MPa Elongation % Microhardness HV Example 1 1185 13.0 382 Example 2 1163 13.5 374 Example 3 1174 13.3 378 Comparative Example 1 1021 8.2 344 Comparative Example 2 1105 10.8 356 Comparative Example 3 1089 9.7 348 Comparative Example 4 974 6.8 337 Comparative Example 5 963 7.9 332

[0061] It can be seen from Table 1 that the titanium alloy prepared from the titanium alloy powder of the present invention has good strength, hardness and toughness.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A titanium alloy powder, characterized in that: include: A titanium alloy ball and a polyvinyl alcohol layer and a graphene oxide layer sequentially coated on the surface of the titanium alloy ball; Among them, the polyvinyl alcohol layer contains nano-Si and nano-TiB2.

2. The titanium alloy powder according to claim 1, characterized in that: The average particle size of the titanium alloy ball is 60-90 μm; preferably, the weight ratio of the titanium alloy ball, nano-Si and nano-TiB2 is 100:1-1.5:0.8-1; preferably, the thickness of the graphene oxide layer is 3-8 nm.

3. The titanium alloy powder according to claim 1 or 2, characterized in that: The titanium alloy ball is a TC4 titanium alloy ball; preferably, the TC4 titanium alloy ball contains 0.3-0.4wt% CeSi2 and 0.04-0.06wt% Y.

4. A method for preparing the titanium alloy powder according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: coating the surface of a titanium alloy ball with a polyvinyl alcohol aqueous solution containing nano-Si and nano-TiB2, and drying the solution; then adding the solution into a graphene oxide dispersion, stirring the solution, separating the solid from the liquid, and drying the solution to obtain titanium alloy powder.

5. The method for preparing titanium alloy powder according to claim 4, characterized in that: In the polyvinyl alcohol aqueous solution, the weight ratio of nano-Si, nano-TiB2 and polyvinyl alcohol is 1-1.5:0.8-1:8-10; preferably, in the polyvinyl alcohol aqueous solution, the mass fraction of polyvinyl alcohol is 4-5wt%.

6. The method for preparing titanium alloy powder according to claim 4 or 5, characterized in that: The solvent of the graphene oxide dispersion is acetone; preferably, the mass fraction of the graphene oxide dispersion is 0.3-0.4wt%.

7. The method for preparing titanium alloy powder according to any one of claims 4 to 6, characterized in that: Stir at 40-60°C for 1-2h.

8. A method for preparing a titanium alloy, characterized in that: The method comprises the following steps: taking the titanium alloy powder as claimed in any one of claims 1 to 3 and pressing and molding it; hot pressing and sintering once to remove polyvinyl alcohol in an inert gas atmosphere, hot pressing and sintering twice, and cooling to room temperature to obtain a titanium alloy.

9. The method for preparing the titanium alloy according to claim 8, characterized in that: The temperature of the first hot pressing sintering is 550-650°C, the time is 10-15min, and the pressure is 4-5kN; preferably, the temperature of the second hot pressing sintering is 1000-1100°C, the time is 8-10min, the pressure is 40-50Mpa, and the vacuum degree is less than 10Pa.

10. A titanium alloy, characterized in that: It is prepared according to the method for preparing the titanium alloy according to claim 8 or 9.