Beryllium tungsten alloy and preparation method thereof

Abstract

The invention discloses a beryllium tungsten alloy and a preparation method thereof, and belongs to the technical field of beryllium alloys. The preparation method comprises the steps that S1, in a glove box filled with inert gas, tungsten salt and PVP with the molar ratio being 1: (2-3) are jointly dissolved in water or a first organic solvent, then beryllium powder and a reducing agent are sequentially added, the mixture is stirred to be uniform and then subjected to a sealed standing reaction for 6-12 h at the temperature ranging from room temperature to 200 DEG C, and a mixture is obtained; after the reaction is finished, a second organic solvent is adopted for cleaning a product, centrifugal separation is conducted, precipitates are taken for vacuum drying, and beryllium tungsten powder is obtained; wherein the concentration of the tungsten salt is 0.1-0.3 mol / L, and the molar ratio of the tungsten salt to the reducing agent is 1: (1-2); s2, the beryllium-tungsten powder is ground and then tableted, and a beryllium-tungsten green body is obtained; and S3, under vacuum or inert gas protection, the beryllium-tungsten blank is sintered, furnace cooling is carried out after sintering is completed, and the beryllium-tungsten alloy which is uniform in component and free of the segregation phenomenon is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of beryllium alloys, and in particular relates to a beryllium-tungsten alloy and a preparation method thereof. Background Art

[0002] Due to its excellent electrical conductivity, high-temperature resistance, and elastic properties, beryllium-tungsten alloy is primarily used in devices such as aviation thermal springs, aircraft instrument mold boxes, and high-temperature relays. Compared to traditional beryllium-copper alloys, beryllium-tungsten alloys can overcome the temperature limit of 150°C for beryllium-copper alloy conductive components, making them more suitable for the high-temperature, high-elasticity alloys used in aerospace applications.

[0003] Currently, there are relatively few domestic manufacturers of beryllium-tungsten alloys, and the performance of the wire and strip they produce is extremely unstable and cannot consistently meet industry demand. Vacuum melting is a common method for preparing beryllium-tungsten alloys, but vacuum melting technology cannot effectively achieve uniform mixing of the molten metal at high temperatures. During the cooling process, a phase interface easily forms between the beryllium and tungsten phases, reducing the uniformity of the alloy's composition. This leads to severe segregation during the alloy melting process, resulting in a decrease in the strength and hardness of the beryllium-tungsten alloy, limiting the alloy's performance and significantly reducing the alloy's yield rate.

[0004] Therefore, the existing technology needs to be improved. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a beryllium tungsten alloy and a preparation method thereof. Based on powder metallurgy technology, uniformly mixed beryllium tungsten powder is obtained by controlling the raw material ratio, reaction temperature and time of the chemical reduction reaction to avoid component segregation after sintering. At the same time, sintering is carried out under vacuum or inert gas protection to reduce the oxygen content in the alloy, thereby improving the purity of the beryllium tungsten alloy.

[0006] A first aspect of the present invention provides a method for preparing a beryllium-tungsten alloy, wherein the molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, and the balance is beryllium;

[0007] The preparation method comprises the following steps:

[0008] Step S1: In a glove box filled with inert gas, a tungsten salt and PVP at a molar ratio of 1:(2-3) are dissolved in water or a first organic solvent, followed by the addition of beryllium powder and a reducing agent. After stirring evenly, the mixture is sealed and allowed to react at room temperature to 200°C for 6-12 hours. After the reaction is completed, the product is washed with a second organic solvent, centrifuged, and the precipitate is vacuum dried to obtain beryllium tungsten powder.

[0009] Wherein, the concentration of the tungsten salt is 0.1-0.3 mol / L, and the molar ratio of the tungsten salt to the reducing agent is 1:(1-2);

[0010] Step S2, grinding the beryllium tungsten powder and pressing it into tablets to obtain a beryllium tungsten blank;

[0011] Step S3, sintering the beryllium tungsten blank under vacuum or inert gas protection, and cooling the blank in the furnace after sintering to obtain a beryllium tungsten alloy;

[0012] The sintering temperature rise rate is 5-10°C / min, the holding temperature is 1050-1200°C, and the holding time is 30-180min.

[0013] According to the preparation method described in the first aspect of the present invention, in the step S1, the tungsten salt is sodium tungstate, ammonium tungstate or tungsten hexachloride.

[0014] According to the preparation method described in the first aspect of the present invention, in step S1, the first organic solvent is N,N-dimethylformamide, n-hexane or toluene.

[0015] According to the preparation method described in the first aspect of the present invention, in step S1, the reducing agent is sodium borohydride or ethylene glycol.

[0016] According to the preparation method described in the first aspect of the present invention, in step S1, the second organic solvent is anhydrous ethanol or anhydrous methanol.

[0017] According to the preparation method described in the first aspect of the present invention, in the step S1, the vacuum drying temperature is 50-80°C and the time is not less than 12 hours.

[0018] According to the preparation method described in the first aspect of the present invention, in step S1, the next raw material is added after the current raw material is stirred evenly.

[0019] According to the preparation method described in the first aspect of the present invention, in the step S2, the tableting pressure is 10-100 MPa.

[0020] According to the preparation method described in the first aspect of the present invention, in the step S3, the sintering heating rate is 6-8°C / min, the holding temperature is 1100-1150°C, and the holding time is 60-120min.

[0021] A second aspect of the present invention provides a beryllium tungsten alloy, which is prepared using the aforementioned preparation method;

[0022] The molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, and the balance is beryllium.

[0023] The solution proposed by the present invention has the following technical effects:

[0024] The present invention is based on powder metallurgy technology. By controlling the raw material ratio, reaction temperature and time of the chemical reduction reaction, uniformly mixed beryllium tungsten powder is obtained to avoid component segregation after sintering. At the same time, sintering is carried out under vacuum or inert gas protection to reduce the oxygen content in the alloy, thereby improving the purity of the beryllium tungsten alloy. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] In a first aspect of this embodiment, a method for preparing a beryllium-tungsten alloy is provided, wherein the molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, and the balance is beryllium;

[0027] The preparation method comprises the following steps:

[0028] Step S1: In a glove box filled with inert gas, a tungsten salt and PVP in a molar ratio of 1:(2-3) are dissolved in water or a first organic solvent, and then beryllium powder and a reducing agent are added in sequence. After stirring evenly, the mixture is sealed and allowed to stand for reaction at room temperature to 200°C for 6-12 hours. After the reaction is completed, the product is washed with a second organic solvent to remove the residual reaction solution and impurities on the surface of the precipitate, centrifuged, and the precipitate is vacuum dried to obtain beryllium tungsten powder.

[0029] The concentration of the tungsten salt is 0.1-0.3 mol / L, and the molar ratio of the tungsten salt to the reducing agent is 1:(1-2).

[0030] Step S2: grinding the beryllium tungsten powder and pressing it into tablets to obtain a beryllium tungsten blank.

[0031] Step S3, in order to remove residual impurities in the beryllium tungsten blank and prevent oxidation during the sintering process of the beryllium tungsten blank, the beryllium tungsten blank is sintered under vacuum or inert gas protection, and cooled in the furnace after sintering to obtain a beryllium tungsten alloy;

[0032] The sintering heating rate is 5-10° C. / min to avoid thermal stress cracking of the beryllium tungsten blank, the holding temperature is 1050-1200° C., and the holding time is 30-180 min.

[0033] The melting point of tungsten (3410°C) is higher than the boiling point of beryllium (2570°C), making it difficult to prepare beryllium-tungsten alloys by smelting. However, alloy powders have high sintering activity. Sintering at temperatures far below the melting point of tungsten can also produce alloy blocks with good density, avoiding the problem of tungsten being difficult to melt during the smelting process. Therefore, this embodiment uses powder metallurgy technology to prepare beryllium-tungsten alloys. In addition, to prevent impurities introduced during the mechanical alloying process from affecting the performance of the powder, this embodiment uses a liquid-phase reduction chemical method to synthesize beryllium-tungsten powder. The beryllium-tungsten powder is then pressed into billets and sintered in a vacuum or inert atmosphere to obtain a beryllium-tungsten alloy with a uniform distribution of components.

[0034] In some embodiments, in step S1, the tungsten salt is sodium tungstate, ammonium tungstate or tungsten hexachloride.

[0035] In some embodiments, in step S1, the first organic solvent is N,N-dimethylformamide, n-hexane or toluene.

[0036] In some embodiments, in step S1, the reducing agent is sodium borohydride or ethylene glycol.

[0037] In some embodiments, in step S1, the second organic solvent is anhydrous ethanol or anhydrous methanol.

[0038] In some embodiments, in step S1, the vacuum drying temperature is 50-80° C., and the time is not less than 12 hours.

[0039] In some embodiments, in step S1, the next raw material is added after the previous raw material is stirred evenly.

[0040] In some embodiments, in step S2, the tableting pressure is 10-100 MPa.

[0041] In this embodiment, the tableting pressure is too low (<10MPa). On the one hand, the bonding force between the beryllium tungsten powder particles is weak, and the porosity of the green body is high, resulting in a significant decrease in the mechanical properties (hardness, flexural strength) after sintering. On the other hand, the beryllium tungsten powder particles are not fully rearranged, and the green body is prone to structural inhomogeneity or local looseness, which may crack during subsequent processing (such as transportation and sintering). On the other hand, too much porosity will hinder the electronic or heat conduction path, affecting functional performance. If the tableting pressure is too high (>100MPa), on the one hand, excessive compression may cause the green body to crack due to elastic recovery during demolding, which is especially sensitive to cemented carbide powder. On the other hand, high pressure accelerates mold loss and increases production costs. On the other hand, the particles may be crushed, changing the initial properties of the powder (such as particle size distribution) and affecting sintering behavior (such as abnormal grain growth). On the other hand, the friction between the powder and the mold wall increases under high pressure, which may lead to uneven density distribution inside the green body (such as density difference between the upper and lower parts).

[0042] In some embodiments, in step S3, the sintering heating rate is 6-8°C / min, the holding temperature is 1100-1150°C, and the holding time is 60-120 min.

[0043] In some embodiments, in step S3, the vacuum degree of sintering is 10 -3 Pa.

[0044] In some embodiments, in step S1 and step S3, the inert gas is high-purity argon.

[0045] In a second aspect of this embodiment, a beryllium-tungsten alloy is provided. The beryllium-tungsten alloy is prepared using the aforementioned preparation method. The molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, with the remainder being beryllium.

[0046] Example 1

[0047] The purpose of this embodiment is to prepare a beryllium-tungsten alloy with a tungsten mole percentage of 12.5%.

[0048] In the first step, in a glove box filled with high-purity argon, sodium tungstate powder and PVP with a molar ratio of 1:2.5 are dissolved in N,N-dimethylformamide and stirred evenly, and then beryllium powder is added. After stirring evenly, sodium borohydride is added, and after stirring evenly again, the mixture is sealed and allowed to react at 100°C for 9 hours. After the reaction is completed, the product is washed with anhydrous ethanol and centrifuged, and the precipitate is vacuum dried to obtain beryllium tungsten powder; wherein the concentration of sodium tungstate is 0.2 mol / L, the molar ratio of sodium tungstate to sodium borohydride is 1:1.5, the vacuum drying temperature is 65°C, and the time is not less than 12 hours.

[0049] In the second step, the beryllium tungsten powder is ground and then pressed into a tablet under a pressure of 50 MPa to obtain a beryllium tungsten blank.

[0050] The third step is to sinter the beryllium tungsten blank under the protection of high-purity argon gas, and then cool it in the furnace after sintering to obtain beryllium tungsten alloy; wherein the sintering heating rate is 7.5°C / min, the holding temperature is 1100°C, and the holding time is 90min.

[0051] Example 2

[0052] The purpose of this embodiment is to prepare a beryllium-tungsten alloy with a tungsten content of 5% by mole.

[0053] In the first step, in a glove box filled with high-purity argon, tungsten hexachloride powder and PVP at a molar ratio of 1:2 are dissolved in water and stirred evenly. Beryllium powder is then added, stirred evenly, and sodium borohydride is added. After stirring evenly again, the mixture is sealed and allowed to react at room temperature for 12 hours. After the reaction, the product is washed with anhydrous ethanol and centrifuged. The precipitate is vacuum dried to obtain beryllium tungsten powder. The concentration of tungsten hexachloride is 0.1 mol / L, the molar ratio of tungsten hexachloride to sodium borohydride is 1:1, the vacuum drying temperature is 50°C, and the time is not less than 12 hours.

[0054] In the second step, the beryllium tungsten powder is ground and then pressed into a tablet under a pressure of 10 MPa to obtain a beryllium tungsten blank.

[0055] The third step is to sinter the beryllium tungsten blank under vacuum, and then cool it in the furnace after sintering to obtain a beryllium tungsten alloy; wherein the sintering heating rate is 5°C / min, the holding temperature is 1050°C, and the holding time is 180min.

[0056] Example 3

[0057] The purpose of this embodiment is to prepare a beryllium-tungsten alloy with a tungsten content of 20% by mole.

[0058] In the first step, in a glove box filled with high-purity argon, ammonium tungstate powder and PVP with a molar ratio of 1:3 are dissolved in n-hexane and stirred evenly, and then beryllium powder is added. After stirring evenly, ethylene glycol is added, and the mixture is stirred evenly again. After sealing and standing at room temperature for 12 hours, after the reaction is completed, the product is washed with anhydrous methanol and centrifuged, and the precipitate is vacuum dried to obtain beryllium tungsten powder; wherein the concentration of ammonium tungstate is 0.3 mol / L, the molar ratio of ammonium tungstate to ethylene glycol is 1:2, the vacuum drying temperature is 80°C, and the time is not less than 12 hours.

[0059] In the second step, the beryllium tungsten powder is ground and then pressed into a tablet under a pressure of 100 MPa to obtain a beryllium tungsten blank.

[0060] The third step is to sinter the beryllium tungsten blank under vacuum, and then cool it in the furnace after sintering to obtain a beryllium tungsten alloy; wherein the sintering heating rate is 10°C / min, the holding temperature is 1200°C, and the holding time is 30min.

[0061] In summary, the solution proposed in the present invention has the following technical effects:

[0062] The present invention is based on powder metallurgy technology. By controlling the raw material ratio, reaction temperature and time of the chemical reduction reaction, uniformly mixed beryllium tungsten powder is obtained to avoid component segregation after sintering. At the same time, sintering is carried out under vacuum or inert gas protection to reduce the oxygen content in the alloy, thereby improving the purity of the beryllium tungsten alloy.

[0063] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing beryllium tungsten alloy, characterized in that: The molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, and the balance is beryllium; The preparation method comprises the following steps: Step S1: In a glove box filled with inert gas, a tungsten salt and PVP at a molar ratio of 1:(2-3) are dissolved in water or a first organic solvent, followed by the addition of beryllium powder and a reducing agent. After stirring evenly, the mixture is sealed and allowed to react at room temperature to 200°C for 6-12 hours. After the reaction is completed, the product is washed with a second organic solvent, centrifuged, and the precipitate is vacuum dried to obtain beryllium tungsten powder. Wherein, the concentration of the tungsten salt is 0.1-0.3 mol / L, and the molar ratio of the tungsten salt to the reducing agent is 1:(1-2); Step S2, grinding the beryllium tungsten powder and pressing it into tablets to obtain a beryllium tungsten blank; Step S3, sintering the beryllium tungsten blank under vacuum or inert gas protection, and cooling the blank in the furnace after sintering to obtain a beryllium tungsten alloy; The sintering temperature rise rate is 5-10°C / min, the holding temperature is 1050-1200°C, and the holding time is 30-180min.

2. The preparation method according to claim 1, characterized in that In the step S1, the tungsten salt is sodium tungstate, ammonium tungstate or tungsten hexachloride.

3. The preparation method according to claim 1, characterized in that In step S1, the first organic solvent is N,N-dimethylformamide, n-hexane or toluene.

4. The preparation method according to claim 1, characterized in that In step S1, the reducing agent is sodium borohydride or ethylene glycol.

5. The preparation method according to claim 1, characterized in that In the step S1, the second organic solvent is anhydrous ethanol or anhydrous methanol.

6. The preparation method according to claim 1, characterized in that In step S1, the vacuum drying temperature is 50-80° C. and the time is not less than 12 hours.

7. The preparation method according to claim 1, characterized in that In step S1, the next raw material is added after the first raw material is evenly stirred.

8. The preparation method according to claim 1, characterized in that In the step S2, the tableting pressure is 10-100 MPa.

9. The preparation method according to claim 1, characterized in that In the step S3, the sintering temperature rise rate is 6-8°C / min, the holding temperature is 1100-1150°C, and the holding time is 60-120 min.

10. A beryllium-tungsten alloy, characterized in that: The beryllium tungsten alloy is prepared by the preparation method described in any one of claims 1 to 9; The molar percentage of tungsten in the beryllium-tungsten alloy is 5-20%, and the balance is beryllium.