A method for producing a porous high-temperature-resistant alloy material

Abstract

The application discloses a preparation method of a porous high-temperature-resistant alloy material, and belongs to the technical field of materials. The method comprises the following steps: 1, according to equal atomic ratio, W, Mo, Ta, Nb four kinds of single element spherical powder are weighed; 2, the four kinds of single element spherical powder are mixed to obtain a mixed powder; 3, the mixed powder is added with a binder stearic acid and dissolved in anhydrous ethanol for stirring until drying is completed; 4, green compact is obtained by pressing; 5, after degreasing and pre-sintering, a pre-sintered body is obtained; 6, after sintering, the porous high-temperature-resistant alloy material is obtained. The single element powder of the refractory metal element with equal atomic ratio is used as raw material, the different diffusion rates of different elements lead to the formation of a large number of pores, the porous high-temperature-resistant alloy material with special functions of metal porous materials and good high-temperature performance of refractory high-entropy alloy is prepared, the preparation process is simple, easy to operate, low in cost, friendly to the environment, suitable for large-scale industrial production, and suitable for the fields of sweating cooling, electric contacts, shaped charge liners and the like.

Description

Technical Field

[0001] This invention belongs to the field of porous metal materials technology, specifically relating to a method for preparing porous high-temperature resistant alloy materials. Background Technology

[0002] Porous metallic materials are a new type of lightweight porous metallic material that has emerged with the development of material preparation and processing technologies. Due to their unique pore types and channel structures, porous metallic materials, in addition to possessing the inherent properties of metallic materials, also exhibit special functions such as purification and separation, noise reduction and weight reduction, adsorption and slow release, flame retardancy and explosion protection, and high-efficiency thermal conductivity, thus belonging to the category of functional metallic materials. Porous metallic materials are widely used in filtration and separation equipment in fields such as energy and chemical engineering, aerospace, metallurgy and building materials, weaponry and shipbuilding, machinery and vehicles, and biomedicine. They are key basic materials for improving the quality and efficiency of related industrial engineering, energy conservation and emission reduction, pollution control, and comprehensive utilization of resources and energy.

[0003] High-entropy alloys are novel alloys composed of various materials with equal or near-equal atomic ratios. Compared to conventional metallic materials, high-entropy alloys possess numerous superior properties due to their thermodynamic high-entropy effect, structural lattice distortion effect, kinetic hysteresis diffusion effect, and "cocktail" effect. High-entropy alloys exhibit better strength and toughness, higher high-temperature hardness and phase stability, and excellent wear resistance, making them promising candidates for engineering applications.

[0004] High-entropy alloys composed of refractory metallic elements (such as V, Nb, Ta, Mo, W, Ti, Zr, and Hf) are called refractory high-entropy alloys. When the melting points of the constituent elements are high, the alloy system also has a high melting point. At high temperatures, high-entropy alloys with excellent properties become high-temperature alloys with great potential for industrial applications. Studies have shown that these high-temperature alloys exhibit high hardness, high strength, and phase stability at high temperatures, demonstrating high-temperature performance that is difficult for existing alloys to match, and even surpassing advanced nickel-based high-temperature alloys under certain conditions. Therefore, they have enormous application potential in high-temperature environments.

[0005] As mentioned above, porous high-temperature resistant alloy materials possess both the special functions of the aforementioned porous metallic materials and excellent high-temperature performance, making them promising for applications in areas such as sweating cooling, electrical contacts, electrodes, and shaped charge liner applications. Therefore, exploring a reasonable, efficient, and low-cost method to successfully prepare a porous high-temperature resistant alloy material has significant theoretical and practical value. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method for preparing porous high-temperature resistant alloy materials, addressing the shortcomings of the prior art. This method uses equiatomic refractory metal element powders of W, Mo, Ta, and Nb as raw materials. It utilizes the different diffusion rates of the elements during the sintering process of the four elemental powders to form pores, thus preparing a porous high-temperature resistant alloy material that combines the special functions of porous metallic materials with the excellent high-temperature performance of refractory high-entropy alloys. This solves the problem of the difficulty in forming porous high-temperature resistant alloy materials in the prior art.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing porous high-temperature resistant alloy materials, characterized in that the method includes the following steps:

[0008] Step 1: Weighing raw materials: Weigh out spherical powders of four elemental substances, W, Mo, Ta and Nb, according to their equiatomic ratios, with the particle size of each elemental spherical powder ranging from 1 μm to 52 μm.

[0009] Step 2, Powder Mixing: Use a gyratory mixer to mix the four elemental spherical powders of W, Mo, Ta and Nb weighed in Step 1 for 5 to 12 hours to obtain mixed powder;

[0010] Step 3: Add adhesive: Dissolve the adhesive stearic acid in anhydrous ethanol and add it to the mixed powder obtained in step 2. Stir and then stir under a water bath at 70℃~90℃ until completely dried to obtain a mixed powder containing adhesive.

[0011] Step 4: Green compact pressing: The mixed powder containing binder obtained in step 3 is placed in a rubber mold and then pressed using a cold isostatic press to obtain a green compact;

[0012] Step 5, Degreasing and Pre-sintering: The green body obtained in Step 4 is heated for degreasing and pre-sintering, and then cooled in the furnace to obtain the pre-sintered body;

[0013] Step 6, Sintering: The pre-sintered body obtained in Step 5 is heated and sintered, and then cooled in the furnace to obtain a porous high-temperature resistant alloy material; the porosity of the porous high-temperature resistant alloy material is 40% to 60%, the room temperature compressive strength is 60 MPa to 100 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0014] The method for preparing a porous high-temperature resistant alloy material described above is characterized in that the mass of the binder stearic acid added in step three is 0.7% to 2.0% of the mass of the mixed powder.

[0015] The above-mentioned method for preparing a porous high-temperature resistant alloy material is characterized in that the pressing pressure in step four is 180 MPa to 260 MPa, and the holding time is 1 min to 5 min.

[0016] The above-mentioned method for preparing a porous high-temperature resistant alloy material is characterized in that the degreasing and pre-sintering process in step five is as follows: the green blank is heated to 300℃~500℃ at a rate of 1℃ / min~5℃ / min and held for 2h~6h, and then heated to 1000℃~1300℃ at a rate of 7℃ / min~15℃ / min and held for 1h~4h.

[0017] The above-mentioned method for preparing a porous high-temperature resistant alloy material is characterized in that the sintering process in step six is ​​as follows: the pre-sintered body is heated to 1800℃~2100℃ at a rate of 7℃ / min~15℃ / min and held at that temperature for 2h~5h.

[0018] The above-mentioned method for preparing a porous high-temperature resistant alloy material is characterized in that the degreasing and pre-sintering in step five and the sintering in step six are both carried out in a vacuum sintering furnace, and the vacuum degree does not exceed 9.0 × 10⁻⁶. -2 Pa.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. This invention uses equiatomic ratio refractory metal element powders of W, Mo, Ta, and Nb as raw materials. During the sintering process of the four elemental powders, the interdiffusion of elements forms a WMoTaNb alloy phase. The different diffusion rates of different elements will produce the Kirkendall effect (i.e., partial diffusion), resulting in the formation of a large number of pores and sintering expansion. Thus, a porous high-temperature resistant alloy material that is essentially a refractory high-entropy alloy is prepared, which has the special functions of porous metal materials and the good high-temperature performance of refractory high-entropy alloys.

[0021] 2. This invention modifies the mixed powder by adding the binder stearic acid, which improves the agglomeration performance of the mixed powder and is beneficial for subsequent pressing and molding. At the same time, the residual C element of stearic acid after degreasing and pre-sintering can react with W, Mo, Ta and Nb to activate sintering and thus reduce the sintering temperature.

[0022] 3. The present invention employs degreasing and pre-sintering processes before sintering, which effectively removes stearic acid and allows the powder in the green body to initially melt and bond together, overcoming the problems of low sample strength and difficulty in handling for subsequent sintering after degreasing.

[0023] 4. The porous high-temperature resistant alloy material prepared by this invention has a three-phase structure consisting of WMoTaNb alloy phase, NbC and WC, in which NbC and WC play a precipitation strengthening role, thereby increasing the room temperature compressive strength of the porous high-temperature resistant alloy material to 60MPa to 100MPa, and the porosity to 40% to 60%, which improves the application range of the porous high-temperature resistant alloy material and makes it suitable for fields such as sweating cooling, electrical contacts, and shaped charge covers.

[0024] 5. The preparation process of the present invention is simple, easy to operate, low in cost, environmentally friendly, and suitable for large-scale industrial production.

[0025] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0026] Example 1

[0027] This embodiment includes the following steps:

[0028] Step 1: Weighing raw materials: Weigh out spherical powders of four elemental substances, W, Mo, Ta and Nb, according to their equiatomic ratios, with the particle size of each elemental spherical powder ranging from 1 μm to 52 μm.

[0029] Step 2, Powder Mixing: The four elemental spherical powders of W, Mo, Ta and Nb weighed in Step 1 are mixed for 8 hours using a gyratory mixer to obtain mixed powder;

[0030] Step 3: Adding adhesive: Dissolve the adhesive stearic acid in anhydrous ethanol and add it to the mixed powder obtained in Step 2. Stir and then stir under 80°C water bath conditions until completely dried to obtain a mixed powder containing the adhesive; the mass of the adhesive stearic acid added is 1% of the mass of the mixed powder.

[0031] Step 4: Green compact pressing: The mixed powder containing binder obtained in Step 3 is placed in a rubber mold and then pressed using a cold isostatic press to obtain a green compact; the pressing pressure is 220 MPa and the holding time is 3 min.

[0032] Step 5, Degreasing and Pre-sintering: The green body obtained in Step 4 is placed in a vacuum sintering furnace at a vacuum degree of 8.3 × 10⁻⁶. -3 Under vacuum conditions of Pa, the green body was heated to 400°C at a rate of 2°C / min and held for 4 hours, and then heated to 1200°C at a rate of 10°C / min and held for 2 hours. After cooling in the furnace, a pre-sintered body was obtained.

[0033] Step Six: Sintering: Place the pre-sintered body obtained in Step Five into a vacuum sintering furnace, and sinter at a vacuum degree of 6.2 × 10⁻⁶. -3Under vacuum conditions of Pa, the pre-sintered body was heated to 1950℃ at a rate of 10℃ / min and held for 3h. After cooling in the furnace, a porous high-temperature resistant alloy material was obtained. The porous high-temperature resistant alloy material has a porosity of 48.4%, a room temperature compressive strength of 81MPa, and a three-phase structure consisting of WMoTaNb alloy phase, NbC and WC.

[0034] Example 2

[0035] The difference between this embodiment and Embodiment 1 is that: the mass of the binder stearic acid added in step three is 0.7% of the mass of the mixed powder; the porosity of the porous high-temperature resistant alloy material in step six is ​​41.6%, the room temperature compressive strength is 96 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0036] Example 3

[0037] The difference between this embodiment and Embodiment 1 is that: the mass of the binder stearic acid added in step three is 2.0% of the mass of the mixed powder; the porosity of the porous high-temperature resistant alloy material in step six is ​​58.6%, the room temperature compressive strength is 62 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0038] Example 4

[0039] The difference between this embodiment and Embodiment 1 is that the pressing pressure in step four is 180 MPa; the porosity of the porous high-temperature resistant alloy material in step six is ​​57.8%, the room temperature compressive strength is 64 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0040] Example 5

[0041] The difference between this embodiment and Embodiment 1 is that the pressing pressure in step four is 260 MPa; the porosity of the porous high-temperature resistant alloy material in step six is ​​47.6%, the room temperature compressive strength is 76 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0042] Example 6

[0043] The difference between this embodiment and Embodiment 1 is that: in step five, the green blank is heated to 300°C at a rate of 2°C / min; in step six, the porous high-temperature resistant alloy material has a porosity of 59.3%, a room temperature compressive strength of 61 MPa, and a three-phase structure consisting of WMoTaNb alloy phase, NbC, and WC.

[0044] Example 7

[0045] The difference between this embodiment and Embodiment 1 is that in step five, the green blank is heated to 500°C at a rate of 2°C / min; in step six, the porous high-temperature resistant alloy material has a porosity of 48.1%, a room temperature compressive strength of 74 MPa, and a three-phase structure consisting of WMoTaNb alloy phase, NbC, and WC.

[0046] Example 8

[0047] The difference between this embodiment and Embodiment 1 is that in step six, the pre-sintered body is heated to 1800°C at a rate of 10°C / min; the porous high-temperature resistant alloy material in step six has a porosity of 40.2%, a room temperature compressive strength of 98 MPa, and a three-phase structure consisting of WMoTaNb alloy phase, NbC, and WC.

[0048] Example 9

[0049] The difference between this embodiment and Embodiment 1 is that in step six, the pre-sintered body is heated to 2100°C at a rate of 10°C / min; the porous high-temperature resistant alloy material in step six has a porosity of 45.2%, a room temperature compressive strength of 90 MPa, and a three-phase structure consisting of WMoTaNb alloy phase, NbC, and WC.

[0050] Example 10

[0051] The difference between this embodiment and Embodiment 1 is that the pressing pressure in step four is 210 MPa; in step six, the pre-sintered body is heated to 1960°C, the porosity of the porous high-temperature resistant alloy material is 47.3%, the room temperature compressive strength is 93 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0052] Example 11

[0053] The difference between this embodiment and Embodiment 1 is that in step five, the green blank is placed at 6.7 × 10 -3 Heating to 410°C under vacuum and holding at that temperature, then further heating to 1190°C; the vacuum level in step six is ​​3.5 × 10⁻⁶. -3 Pa, the porosity of the porous high-temperature resistant alloy material is 48.5%, the room temperature compressive strength is 71 MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method of producing a porous high-temperature alloy material, characterized by, The method includes the following steps: Step 1: Weighing raw materials: Weigh out spherical powders of four elemental substances W, Mo, Ta and Nb according to the same atomic ratio, and the particle size of the four elemental spherical powders is 1μm~52μm. Step 2, Powder Mixing: Use a gyratory mixer to mix the four elemental spherical powders of W, Mo, Ta and Nb weighed in Step 1 for 5 to 12 hours to obtain mixed powder; Step 3: Add adhesive: Dissolve the adhesive stearic acid in anhydrous ethanol and add it to the mixed powder obtained in step 2. Stir and then stir under a water bath at 70℃~90℃ until completely dried to obtain a mixed powder containing adhesive. Step 4: Green compact pressing: The mixed powder containing binder obtained in step 3 is placed in a rubber mold and then pressed using a cold isostatic press to obtain a green compact; Step 5, Degreasing and Pre-sintering: The green blank obtained in Step 4 is heated for degreasing and pre-sintering, and then cooled in the furnace to obtain a pre-sintered body; the degreasing and pre-sintering process is as follows: the green blank is heated to 300℃~500℃ at a rate of 1℃ / min~5℃ / min and held for 2h~6h, and then heated to 1000℃~1300℃ at a rate of 7℃ / min~15℃ / min and held for 1h~4h; Step Six, Sintering: The pre-sintered body obtained in Step Five is heated and sintered, and then cooled in the furnace to obtain a porous high-temperature resistant alloy material; the sintering process is as follows: the pre-sintered body is heated to 1800℃~2100℃ at a rate of 7℃ / min~15℃ / min and held for 2h~5h; the porosity of the porous high-temperature resistant alloy material is 40%~60%, the room temperature compressive strength is 60MPa~100MPa, and the microstructure is a three-phase microstructure composed of WMoTaNb alloy phase, NbC and WC.

2. The method of claim 1, wherein the porous high-temperature alloy material is prepared by the steps of: In step three, the amount of stearic acid added as a binder is 0.7% to 2.0% of the mass of the mixed powder.

3. The method of claim 1, wherein the porous high-temperature alloy material is prepared by the steps of: preparing a porous high-temperature alloy material by the method of claim 1; and coating the porous high-temperature alloy material with a coating layer. The pressing pressure in step four is 180MP~260MPa, and the holding time is 1min~5min.

4. The method of claim 1, wherein the porous high-temperature alloy material is prepared by the steps of: The degreasing and pre-sintering described in step five and the sintering described in step six are both carried out in a vacuum sintering furnace, and the vacuum degree does not exceed 9.0 × 10⁻⁶. - 2 Pa.