Tungsten-zirconium active material and preparation method thereof

Abstract

The invention discloses a tungsten-zirconium active material and a preparation method thereof. The method comprises the following steps: 1, mixing tungsten powder, nickel powder, iron powder and zirconium hydride powder to prepare mixed powder; 2, carrying out one-time compression molding on the mixed powder by adopting a cold isostatic press to obtain a pressed blank; 3, performing vacuum dehydrogenation treatment on the pressed blank by adopting a vacuum degumming furnace to obtain a pre-sintered blank; and 4, carrying out vacuum sintering on the pre-sintered blank by adopting a vacuum sintering furnace to prepare the tungsten-zirconium active material. The powder metallurgy method is adopted, densified sintering is achieved at the low sintering temperature, the problems of tungsten component sedimentation and zirconium powder oxidation are avoided, the tungsten content and the structure uniformity in the tungsten-zirconium active material are improved, the tungsten-zirconium active material with the tungsten mass content as high as 80% is obtained, the material has the remarkable damage effect, armor piercing after-effect is provided for damaged bullet seeds, and the application range of the tungsten-zirconium active material is widened. The method is suitable for the weapon manufacturing field.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and particularly relates to a tungsten-zirconium active material and a preparation method thereof. Background Art

[0002] An active material is a type of compound or mixture that contains explosive groups (or contains oxidants and combustibles). Under the stimulation of a certain external energy, it can independently carry out redox reactions and release a large amount of energy (usually gas and heat). Tungsten-zirconium alloy is a typical active structural material. This material is quite stable at room temperature and has high strength. Under the action of high-speed impact loads, the zirconium element in the tungsten-zirconium alloy is induced to undergo a chemical reaction due to the impact, releasing a large amount of heat. The tungsten-zirconium alloy made using this property can not only use its strength to penetrate the target, but also use its energy release property to cause additional damage to the target, ultimately significantly improving the damage effect of the material on the target and having a very broad application prospect.

[0003] At present, the main method for preparing tungsten-zirconium alloy is vacuum arc melting. This method presses the raw tungsten powder into a billet, then breaks it into particles of a specific particle size, mixes the particles with sponge zirconium in a certain proportion, and conducts multiple meltings through the vacuum arc melting process to finally obtain tungsten-zirconium alloy. However, the arc melting temperature limits the preparation of tungsten-zirconium alloy with a high tungsten content. Moreover, due to the high density of tungsten element, tungsten component sedimentation is likely to occur during arc melting. At the same time, since metallic zirconium powder is extremely easy to oxidize, it is very difficult to prepare a tungsten alloy with uniform structure.

[0004] Although the Chinese invention patent with the application number 201510606975.3, "A Preparation Method of Tungsten-Zirconium Alloy with High Tungsten Content", discloses a method for preparing tungsten-zirconium alloy with a tungsten content of 70% through the combination of powder metallurgy and consumable melting processes, there is currently no report on the method for preparing tungsten-zirconium alloy with a higher tungsten content by powder metallurgy. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of a tungsten-zirconium active material in view of the deficiencies of the above-mentioned prior art. This method uses powder metallurgy. After mixing the raw tungsten powder, nickel powder, iron powder and zirconium hydride powder, it is pressed and then subjected to vacuum dehydrogenation and vacuum sintering to achieve densification sintering at a low sintering temperature, improving the tungsten content and tissue uniformity in the tungsten-zirconium active material, and solving the problem in the prior art that it is difficult to obtain a tungsten-zirconium active material with a high tungsten content and uniform structure due to the limitation of arc melting temperature, tungsten component sedimentation and zirconium powder oxidation.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is: A preparation method of a tungsten-zirconium active material, characterized in that the method comprises the following steps:

[0007] Step 1. Ingredient mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder are mixed to obtain a mixed powder.

[0008] Step 2. Compression: The mixed powder obtained in Step 1 is compression-molded at one time by a cold isostatic press to obtain a green compact.

[0009] Step 3. Vacuum dehydrogenation: The green compact obtained in Step 2 is subjected to vacuum dehydrogenation treatment by a vacuum degreasing furnace to obtain a pre-sintered compact.

[0010] Step 4. Vacuum sintering: The pre-sintered compact obtained in Step 3 is subjected to vacuum sintering by a vacuum sintering furnace to obtain a tungsten-zirconium active material.

[0011] Due to the high melting point of tungsten, the melting temperature of the vacuum arc melting method needs to exceed the melting point of tungsten (above 3500 °C), the equipment cost is high, and the volatilization of nickel and iron is difficult to control; in order to avoid oxidation, it needs to be prepared under high vacuum or high-purity argon protection; at the same time, in order to avoid the coarsening of tungsten grains, the cooling rate needs to be strictly controlled, and cracks are reduced by controlled slow cooling. To solve the above technical problems, the present invention adopts the powder metallurgy method, uses tungsten powder, nickel powder, iron powder and zirconium hydride powder as raw materials, and successively performs compression molding, vacuum dehydrogenation and vacuum sintering to prepare a tungsten-zirconium active material with a high tungsten content. During the vacuum dehydrogenation process, zirconium hydride powder (ZrH2) decomposes into Zr and H2. In the subsequent vacuum sintering process, solid-phase sintering occurs between tungsten powder and Zr, while nickel powder and iron powder, as raw materials for the bonding phase, soften and flow under the action of high temperature, gradually reducing the voids between raw material particles, achieving densification under conditions far lower than the melting point of tungsten, and increasing the tungsten content in the tungsten-zirconium active material.

[0012] The above-mentioned method for preparing a tungsten-zirconium active material is characterized in that the particle size of the tungsten powder in Step 1 is 1 μm to 10 μm, and the mass ratio of the tungsten powder in the mixed powder is 70% to 80%. Usually, the particle sizes of nickel powder, iron powder and zirconium hydride powder are also limited to 1 μm to 10 μm.

[0013] The above-mentioned method for preparing a tungsten-zirconium active material is characterized in that the pressure for the one-time compression molding in Step 2 is 150 MPa to 200 MPa, and the pressure holding time is 0.5 min to 2 min.

[0014] The above-mentioned method for preparing a tungsten-zirconium active material is characterized in that the vacuum degree of the vacuum dehydrogenation treatment in Step 3 does not exceed 6.67×10 -1 Pa.

[0015] The above-mentioned method for preparing a tungsten-zirconium active material is characterized in that the vacuum sintering regime in Step 4 is: when the sintering temperature does not exceed 900 °C, the vacuum degree does not exceed 6.67×10 -2Pa; When the sintering temperature is greater than 900 °C, the vacuum degree does not exceed 6.67×10 -3 Pa.

[0016] Meanwhile, the present invention also discloses a tungsten-zirconium active material, which is characterized in that it is prepared by the above method.

[0017] The present invention has the following advantages compared with the prior art:

[0018] 1. The present invention adopts the powder metallurgy method. After mixing the raw materials of tungsten powder, nickel powder, iron powder and zirconium hydride powder, they are pressed and then subjected to vacuum dehydrogenation and vacuum sintering, so that the Zr solid phase sintered by the decomposition of tungsten powder and zirconium hydride powder is sintered, while nickel powder and iron powder are used as the raw materials of the bonding phase to reduce the voids between the raw material particles, and densification sintering is achieved at a low sintering temperature, increasing the tungsten content in the tungsten-zirconium active material.

[0019] 2. The present invention uses zirconium hydride, which is more chemically stable in an air environment, to replace the metal zirconium powder raw material, effectively avoiding the oxidation failure of the energetic elements zirconium and titanium, and preventing the influence of the easy oxidation of metal zirconium powder on the tissue uniformity of the tungsten-zirconium active material. At the same time, by flexibly adjusting the ratio of the nickel powder and iron powder bonding phase raw materials, the tissue uniformity of the tungsten-zirconium active material is ensured on the premise of ensuring densification sintering, avoiding composition segregation and avoiding adverse effects on the mechanical properties of the tungsten-zirconium active material.

[0020] 3. The present invention uses the powder metallurgy method to prepare a tungsten-zirconium active material with a tungsten mass content as high as 80%. On the premise of ensuring the penetration ability, when impacting the steel plate at a speed above 1200 m / s, the instantaneous energy release is obvious, and the energy release characteristics are significant, with a remarkable damage effect.

[0021] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0022] Figure 1 It is the microstructural photograph of the tungsten-zirconium active material prepared in Example 1 of the present invention.

[0023] Figure 2 It is the microstructural photograph of the tungsten-zirconium active material prepared in Example 2 of the present invention.

[0024] Figure 3 It is the microstructural photograph of the tungsten-zirconium active material prepared in Example 3 of the present invention.

[0025] Figure 4 It is the microstructural photograph of the tungsten-titanium active material prepared in Comparative Example 1 of the present invention. Detailed Embodiments

[0026] Example 1

[0027] This embodiment includes the following steps:

[0028] Step 1, ingredient mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder with a particle size of 1μm to 10μm are proportioned and mixed for 8h to obtain a mixed powder; in the mixed powder, the tungsten powder is 80% by mass percentage, the nickel powder is 4%, the iron powder is 1%, and the zirconium hydride powder is 15%. Moreover, the added mass of the steel balls used as the ball milling medium is 50% of the total mass of the mixed powder;

[0029] Step 2, pressing: The mixed powder obtained in Step 1 is formed by cold isostatic pressing at one time. The pressure for one-time forming is 150MPa, and the pressure holding time is 2min to obtain a green compact with a diameter × height of Φ20mm × 280mm;

[0030] Step 3, vacuum dehydrogenation: The green compact obtained in Step 2 is subjected to vacuum dehydrogenation treatment using a vacuum degreasing furnace. The vacuum degree does not exceed 6.67×10 -1 Pa, the heating rate is 80℃ / h, and there are a total of 5 temperature segments, which are: rising from room temperature to 200℃ and holding for 1h, rising from 200℃ to 400℃ and holding for 1h, rising from 400℃ to 600℃ and holding for 1h, rising from 600℃ to 750℃ and holding for 1h, rising from 750℃ to 900℃ and holding for 1h. After the holding ends, it is cooled by furnace cooling to obtain a pre-sintered blank;

[0031] Step 4, vacuum sintering: The pre-sintered blank obtained in Step 3 is vacuum sintered using a vacuum sintering furnace. When the sintering temperature does not exceed 900℃, the vacuum degree does not exceed 6.67×10 -2 Pa, when the sintering temperature is greater than 900℃, the vacuum degree does not exceed 6.67×10 -3 Pa, and finally it is heated to 1520℃ and held for 30min to obtain a tungsten-zirconium active material.

[0032] Cut an end face sample of the tungsten-zirconium active material prepared in this embodiment for microstructure analysis, and the results are as Figure 1 shown. It can be seen from Figure 1 that the tungsten element is evenly distributed in the microstructure of the tungsten-zirconium active material.

[0033] Embodiment 2

[0034] This embodiment includes the following steps:

[0035] Step 1, ingredient mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder with a particle size of 1μm to 10μm are proportioned and mixed for 8h to obtain a mixed powder; in the mixed powder, the tungsten powder is 80% by mass percentage, the nickel powder is 6%, the iron powder is 4%, and the zirconium hydride powder is 10%;

[0036] Step 2. Compression: Use a cold isostatic press to compress the mixed powder obtained in Step 1 into a single form. The pressure for a single compression molding is 200 MPa, and the pressure holding time is 0.5 min, to obtain a green compact with a diameter × height of Φ20 mm × 280 mm;

[0037] Step 3. Vacuum dehydrogenation: Use a vacuum degreasing furnace to perform vacuum dehydrogenation treatment on the green compact obtained in Step 2. The vacuum degree does not exceed 6.67×10 -1 Pa, the heating rate is 80 °C / h, and there are a total of 5 temperature segments, which are: rising from room temperature to 200 °C and holding for 1 h, rising from 200 °C to 400 °C and holding for 1 h, rising from 400 °C to 600 °C and holding for 1 h, rising from 600 °C to 750 °C and holding for 1 h, rising from 750 °C to 900 °C and holding for 1 h. After the holding ends, cool down with the furnace to obtain a pre-sintered blank;

[0038] Step 4. Vacuum sintering: Use a vacuum sintering furnace to perform vacuum sintering on the pre-sintered blank obtained in Step 3. When the sintering temperature does not exceed 900 °C, the vacuum degree does not exceed 6.67×10 -2 Pa, when the sintering temperature is greater than 900 °C, the vacuum degree does not exceed 6.67×10 -3 Pa, and finally heat up to 1520 °C and hold for 30 min to obtain a tungsten-zirconium active material.

[0039] Cut an end face sample of the tungsten-zirconium active material prepared in this example for microstructure analysis. The results are as Figure 2 shown. It can be seen from Figure 2 that the tungsten element is evenly distributed in the microstructure of the tungsten-zirconium active material.

[0040] Example 3

[0041] This example includes the following steps:

[0042] Step 1. Batching and mixing: Batch and mix tungsten powder, nickel powder, iron powder, and zirconium hydride powder with particle sizes all in the range of 1 μm to 10 μm for 8 h to obtain a mixed powder; in the mixed powder, the tungsten powder is 75% by mass percentage, the nickel powder is 6%, the iron powder is 4%, and the zirconium hydride powder is 15%;

[0043] Step 2. Compression: Use a cold isostatic press to compress the mixed powder obtained in Step 1 into a single form. The pressure for a single compression molding is 150 MPa, and the pressure holding time is 1 min, to obtain a green compact with a diameter × height of Φ20 mm × 280 mm;

[0044] Step 3. Vacuum dehydrogenation: Use a vacuum degreasing furnace to perform vacuum dehydrogenation treatment on the green compact obtained in Step 2. The vacuum degree does not exceed 6.67×10 -1Pa, with a heating rate of 80 °C / h, a total of 5 temperature segments, successively: rising from room temperature to 200 °C and holding for 1 h, rising from 200 °C to 400 °C and holding for 1 h, rising from 400 °C to 600 °C and holding for 1 h, rising from 600 °C to 750 °C and holding for 1 h, rising from 750 °C to 900 °C and holding for 1 h. After the heat preservation ends, it is cooled with the furnace to obtain a pre-sintered blank;

[0045] Step 4. Vacuum sintering: Use a vacuum sintering furnace to perform vacuum sintering on the pre-sintered blank obtained in Step 3. When the sintering temperature does not exceed 900 °C, the vacuum degree does not exceed 6.67×10 -2 Pa, when the sintering temperature is greater than 900 °C, the vacuum degree does not exceed 6.67×10 -3 Pa, and finally raise the temperature to 1460 °C and hold for 60 min to obtain the tungsten-zirconium active material.

[0046] Cut an end face sample of the tungsten-zirconium active material prepared in this example for microstructure analysis, and the results are as Figure 3 shown. It can be seen from Figure 3 that the tungsten element is evenly distributed in the microstructure of the tungsten-zirconium active material.

[0047] Comparative Example 1

[0048] This comparative example includes the following steps:

[0049] Step 1. Batching and mixing: Batch and mix tungsten powder, nickel powder, iron powder and titanium hydride powder with particle sizes all of 1 μm to 10 μm for 8 h to obtain a mixed powder; in the mixed powder, by mass percentage, tungsten powder is 80%, nickel powder is 4%, iron powder is 1%, and titanium hydride powder is 15%, and the added mass of the ball milling medium steel balls used for mixing is 50% of the total mass of the mixed powder;

[0050] Step 2. Pressing: Use a cold isostatic press to press the mixed powder obtained in Step 1 into a shape at one time. The pressure for one-time pressing is 150 MPa, and the pressure holding time is 2 min to obtain a green compact with a diameter × height of Φ20 mm × 280 mm;

[0051] Step 3. Vacuum dehydrogenation: Use a vacuum degreasing furnace to perform vacuum dehydrogenation treatment on the green compact obtained in Step 2. The vacuum degree does not exceed 6.67×10 -1 Pa, with a heating rate of 80 °C / h, a total of 5 temperature segments, successively: rising from room temperature to 200 °C and holding for 1 h, rising from 200 °C to 400 °C and holding for 1 h, rising from 400 °C to 600 °C and holding for 1 h, rising from 600 °C to 750 °C and holding for 1 h, rising from 750 °C to 900 °C and holding for 1 h. After the heat preservation ends, it is cooled with the furnace to obtain a pre-sintered blank;

[0052] Step 4. Vacuum sintering: Use a vacuum sintering furnace to perform vacuum sintering on the pre-sintered blank obtained in Step 3. When the sintering temperature does not exceed 900 °C, the vacuum degree does not exceed 6.67×10 -2 Pa, and when the sintering temperature is greater than 900 °C, the vacuum degree does not exceed 6.67×10 -3 Pa. Finally, heat up to 1520 °C and hold for 30 min to obtain the tungsten-titanium active material.

[0053] Cut an end face sample of the tungsten-zirconium active material prepared in this comparative example for microstructure analysis. The results are as Figure 4 shown. It can be seen from Figure 4 that the tungsten element is relatively evenly distributed in the microstructure of the tungsten-titanium active material, but the titanium element shows lamellar composition segregation with the nickel and iron bonding phase elements.

[0054] Comparing Example 1 of the present invention with Comparative Example 1, it can be seen that the tungsten-zirconium active material prepared in Example 1 has better microstructure uniformity than the tungsten-titanium active material of the same type prepared by the same method in Comparative Example 1, effectively avoiding composition segregation and thus avoiding adverse effects on the mechanical properties of the tungsten-zirconium active material.

[0055] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a tungsten-zirconium active material, characterized in that, The method comprises the following steps: Step 1, ingredient mixing: Mix tungsten powder, nickel powder, iron powder and zirconium hydride powder to obtain a mixed powder; Step 2, pressing: Use a cold isostatic press to press the mixed powder obtained in Step 1 into a green compact at one time; Step 3, vacuum dehydrogenation: Use a vacuum degreasing furnace to perform vacuum dehydrogenation treatment on the green compact obtained in Step 2 to obtain a pre-sintered blank; Step 4, vacuum sintering: Use a vacuum sintering furnace to perform vacuum sintering on the pre-sintered blank obtained in Step 3 to obtain a tungsten-zirconium active material.

2. The preparation method of a tungsten-zirconium active material according to claim 1, characterized in that The particle size of the tungsten powder in Step 1 is 1μm - 10μm, and the mass ratio of the tungsten powder in the mixed powder is 70% - 80%.

3. The preparation method of a tungsten-zirconium active material according to claim 1, characterized in that The pressure for the one-time pressing in Step 2 is 150MPa - 200MPa, and the pressure holding time is 0.5min - 2min.

4. The preparation method of a tungsten-zirconium active material according to claim 1, characterized in that, The vacuum degree of the vacuum dehydrogenation treatment described in step three does not exceed 6.67×10 -1 Pa.

5. The preparation method of a tungsten-zirconium active material according to claim 1, characterized in that The system of vacuum sintering described in Step 4 is as follows: when the sintering temperature does not exceed 900 °C, the vacuum degree does not exceed 6.67×10 -2 Pa; when the sintering temperature is greater than 900 °C, the vacuum degree does not exceed 6.67×10 -3 Pa.

6. A tungsten-zirconium active material, characterized in that, Prepared by the method according to any one of claims 1 - 5.

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