An antioxidant porous TiAl alloy, its preparation method, and its applications

Abstract

This invention discloses an antioxidant porous TiAl alloy, the raw materials of which include: a mixed powder, nano-B4C, nano-NiO, and nano-SiO2. The mixed powder comprises TiH2 powder and aluminum powder; the Ti content in the mixed powder is 51-53 wt%; the weight ratio of nano-B4C, nano-NiO, and nano-SiO2 to the mixed powder is 2-3:0.5-1.5:2-3:100. This invention also discloses a method for preparing the above-mentioned antioxidant porous TiAl alloy, comprising the following steps: mixing TiH2 powder and aluminum powder to obtain a mixed powder, then adding nano-B4C, nano-NiO, and nano-SiO2 and mixing, pressing into shape, vacuum sintering, soaking in an alkaline solution, and washing with water to obtain the antioxidant porous TiAl alloy. This invention also discloses the application of the above-mentioned antioxidant porous TiAl alloy in filtering high-temperature flue gas. This invention exhibits excellent antioxidant and filtration performance.

Description

Technical Field

[0001] This invention relates to the field of porous alloy technology, and in particular to an antioxidant porous TiAl alloy, its preparation method, and its applications. Background Technology

[0002] Porous metallic materials, as a new type of material combining functionality and structure, have been widely used in sound absorption, energy absorption, fluid distribution, heat exchange, catalysis, and filtration separation, with filtration separation being the most common application. Porous metallic materials can achieve liquid-solid and gas-solid filtration separation of different fluids in the petroleum, petrochemical, fine chemical, and coal chemical industries.

[0003] TiAl porous metals are often used as gas-solid and liquid-solid filtration materials in high-temperature and corrosive environments. However, in high-temperature oxidizing environments, TiAl porous metals will simultaneously generate a mixture of non-protected TiO2 and protective Al2O3, with non-protected TiO2 as the main component. This makes the pores of the porous material easy to be blocked, leading to the failure of the porous metal material. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes an antioxidant porous TiAl alloy, its preparation method and application, and the present invention has good high-temperature antioxidant properties and filtration performance.

[0005] This invention proposes an antioxidant porous TiAl alloy, the raw materials of which include: mixed powder, nano B4C, nano NiO, and nano SiO2, wherein the mixed powder includes: TiH2 powder and aluminum powder;

[0006] The Ti content in the mixed powder is 51-53 wt%.

[0007] The weight ratio of nano B4C, nano NiO, nano SiO2 to the mixed powder is 2-3:0.5-1.5:2-3:100.

[0008] Preferably, the porosity of the oxidation-resistant porous TiAl alloy is 50-52%.

[0009] Preferably, the average particle size of TiH2 powder and aluminum powder is 60-80 μm.

[0010] Preferably, the average particle size of nano B4C, nano NiO, and nano SiO2 is 30-50 nm.

[0011] The present invention also proposes a method for preparing the above-mentioned antioxidant porous TiAl alloy, comprising the following steps: mixing TiH2 powder and aluminum powder to obtain a mixed powder, then adding nano B4C, nano NiO and nano SiO2 and mixing, pressing and molding, vacuum sintering, soaking in an alkaline solution, and washing with water to obtain an antioxidant porous TiAl alloy.

[0012] Preferably, the vacuum sintering procedure is as follows: hold at 130-150℃ for 0.5-1h, raise the temperature to 610-620℃ and hold for 2-2.5h, raise the temperature to 860-880℃ and hold for 3.5-4h, raise the temperature to 1300-1320℃ and hold for 3.5-4h, and finally cool with the furnace to room temperature.

[0013] Preferably, the alkaline solution is a 0.8-1.2 mol / L sodium hydroxide aqueous solution.

[0014] Preferably, soak at room temperature for 1-2 days.

[0015] This invention also proposes the application of the above-mentioned antioxidant porous TiAl alloy in filtering high-temperature flue gas.

[0016] Preferably, it is used in filtering substances with PM < 2.5 μm in high-temperature flue gas.

[0017] This invention uses TiH2 powder and aluminum powder in a suitable ratio as a mixed powder, and then adjusts a suitable vacuum sintering process to obtain a TiAl-based porous alloy through powder metallurgy. By adding appropriate amounts of nano-B4C, nano-NiO, and nano-SiO2, during vacuum sintering, the TiAl alloy microstructure can form uniformly distributed TiB2 phase and Ti2AlC particles at the grain boundaries, improving the toughness and strength of the porous metal. On the other hand, it can form appropriate amounts of Ni2Ti4O phase and Ti5Si3 phase. The two phases work together to prevent Ti from diffusing to the metal surface and O from diffusing to the metal interior, increasing the Al content on the metal surface and thus avoiding the formation of TiO2. Furthermore, it can promote the formation of uniformly distributed nano-Al2O3 on the metal surface and inside the pores, thereby improving the metal's oxidation resistance.

[0018] This invention adjusts appropriate vacuum sintering process parameters to first form micropores in the metal, and then uniformly distributed nano-Al2O3 forms on the metal surface and inside the pores. After a short period of immersion in an alkaline solution of appropriate concentration, a porous nano-Al2O3 layer can continue to grow on the basis of the original nano-Al2O3, thereby giving the porous TiAl alloy both micropores and nanopores. This significantly improves the filtration performance of porous metals, and the formation of the nano-Al2O3 porous layer can further enhance the antioxidant properties.

[0019] Furthermore, the method described in this invention can avoid the problem of uneven distribution of nano-Al2O3 porous layers, which affects filtration performance and antioxidant performance. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0021] The formulations for Examples 1-8 are shown in Table 1.

[0022] Table 1 Formula

[0023] weight ratio <![CDATA[Nano B4C]]> Nano NiO <![CDATA[Nanometer SiO2]]> Mixed powder Example 1 3 1.5 2 100 Example 2 2 0.5 3 100 Example 3 2.5 1 2.5 100 Comparative Example 1 / 1 2.5 100 Comparative Example 2 2.5 / 2.5 100 Comparative Example 3 2.5 1 / 100 Comparative Example 4 4 1 2.5 100 Comparative Example 5 1 1 2.5 100 Comparative Example 6 2.5 1 4 100 Comparative Example 7 2.5 1 1 100 Comparative Example 8 2.5 2 2.5 100

[0024] Note: The mixed powders in Table 1 are TiH2 powder and aluminum powder, with a Ti content of 52wt%. The average particle size of TiH2 powder and aluminum powder is 60μm; the average particle size of nano B4C, nano NiO, and nano SiO2 is 40nm.

[0025] According to the formulations in Table 1, antioxidant porous TiAl alloys were prepared using the same method. The preparation method included the following steps: TiH2 powder and aluminum powder were ball-milled and mixed to obtain a mixed powder. Then, nano B4C, nano NiO, and nano SiO2 were added and ball-milled and mixed. The mixture was then molded under a pressure of 200 MPa and transferred to a heating furnace. The vacuum degree was adjusted to 0.005 Pa for vacuum sintering. The vacuum sintering procedure was as follows: holding at 140℃ for 0.8 h, heating to 620℃ at a rate of 5℃ / min and holding for 2 h, heating to 880℃ at a rate of 5℃ / min and holding for 4 h, heating to 1320℃ at a rate of 5℃ / min and holding for 4 h, and finally cooling to room temperature with the furnace. Then, the mixture was added to a 1 mol / L sodium hydroxide aqueous solution and soaked at room temperature for 2 days. After washing with water and drying, the antioxidant porous TiAl alloy was obtained.

[0026] Comparative Example 9

[0027] An antioxidant porous TiAl alloy was prepared according to the formulation of Example 3, without being soaked in sodium hydroxide aqueous solution.

[0028] The antioxidant porous TiAl alloys prepared in each group were subjected to performance testing, and the results are shown in Table 2.

[0029] The method for detecting the weight gain due to oxidation is as follows: each group of samples is placed in an air environment at 900℃ for 100 hours, then taken out and cooled for 3 hours, and the weight gain of each group of samples is calculated.

[0030] Table 2 Detection Results

[0031]

[0032]

[0033] As shown in Table 2, a porous TiAl alloy with good antioxidant and filtration properties can only be obtained by combining nano-B4C, nano-NiO, and nano-SiO2 and soaking them in sodium hydroxide aqueous solution. Furthermore, when the amount of nano-B4C, nano-NiO, and nano-SiO2 is too high or too low, its high-temperature antioxidant properties and high-temperature flue gas filtration performance for PM < 2.5μm will decrease.

[0034] 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. An antioxidant porous TiAl alloy, characterized in that, Its raw materials include: mixed powder, nano B4C, nano NiO, and nano SiO2, wherein the mixed powder includes: TiH2 powder and aluminum powder; The Ti content in the mixed powder is 51-53 wt%. The weight ratio of nano-B4C, nano-NiO, nano-SiO2 to the mixed powder is 2-3:0.5-1.5:2-3:100; The preparation method of the antioxidant porous TiAl alloy includes the following steps: mixing TiH2 powder and aluminum powder to obtain a mixed powder, then adding nano B4C, nano NiO and nano SiO2 and mixing, pressing and molding, vacuum sintering, soaking in alkaline solution, washing with water to obtain the antioxidant porous TiAl alloy. The vacuum sintering process is as follows: hold at 130-150℃ for 0.5-1h, raise the temperature to 610-620℃ and hold for 2-2.5h, raise the temperature to 860-880℃ and hold for 3.5-4h, raise the temperature to 1300-1320℃ and hold for 3.5-4h, and finally cool to room temperature with the furnace.

2. The antioxidant porous TiAl alloy according to claim 1, characterized in that, The porosity of the oxidation-resistant porous TiAl alloy is 50-52%.

3. The antioxidant porous TiAl alloy according to claim 1 or 2, characterized in that, The average particle size of TiH2 powder and aluminum powder is 60-80μm.

4. The antioxidant porous TiAl alloy according to claim 1 or 2, characterized in that, The average particle size of nano B4C, nano NiO, and nano SiO2 is 30-50 nm.

5. A method for preparing an antioxidant porous TiAl alloy as described in any one of claims 1-4, characterized in that, The process includes the following steps: mixing TiH2 powder and aluminum powder to obtain a mixed powder, then adding nano B4C, nano NiO, and nano SiO2 and mixing them together, pressing and molding, vacuum sintering, soaking in an alkaline solution, and washing with water to obtain an antioxidant porous TiAl alloy.

6. The method for preparing the antioxidant porous TiAl alloy according to claim 5, characterized in that, The alkaline solution is a 0.8-1.2 mol / L sodium hydroxide aqueous solution.

7. The method for preparing the antioxidant porous TiAl alloy according to claim 5, characterized in that, Soak at room temperature for 1-2 days.

8. The application of the antioxidant porous TiAl alloy as described in any one of claims 1-4 in filtering high-temperature flue gas.

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