Tungsten-zirconium active material and method for producing the same

Abstract

The application discloses a tungsten-zirconium active material and a preparation method thereof, and the method comprises the following steps: firstly, mixing tungsten powder, nickel powder, iron powder and zirconium hydride powder to obtain mixed powder; secondly, adopting a cold isostatic pressing machine to press the mixed powder once to obtain a compact; thirdly, adopting a vacuum degreasing furnace to perform vacuum dehydrogenation treatment on the compact to obtain a pre-sintered compact; and fourthly, adopting a vacuum sintering furnace to perform vacuum sintering on the pre-sintered compact to obtain the tungsten-zirconium active material. The powder metallurgy method is adopted to realize densification sintering at a low sintering temperature, the problems of tungsten component subsidence and zirconium powder oxidation are avoided, the tungsten content and the uniformity of the tungsten-zirconium active material are improved, the tungsten-zirconium active material with a high tungsten mass content of 80% is obtained, the material has a significant damage effect, provides a post-penetration effect for a damage bomb, and is suitable for the field of weapon equipment manufacturing.

Description

TECHNICAL FIELD

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

[0002] Active materials are a kind of compounds or mixtures containing explosive groups (or containing oxidants and combustibles), which can independently undergo oxidation-reduction reactions and release a large amount of energy (usually gas and heat) under the stimulation of certain external energy. Tungsten-zirconium alloy is a typical active structural material, which is quite stable at room temperature and has high strength. Under the action of high-speed impact load, the zirconium element in the tungsten-zirconium alloy is induced to chemical reaction due to impact, and releases a large amount of heat. The tungsten-zirconium alloy made by using this characteristic can not only penetrate the target by using its strength, but also can produce additional damage to the target by using its energy release characteristics, thereby significantly improving the damage effect of the material on the target, and having very broad application prospects.

[0003] At present, the method for preparing the tungsten-zirconium alloy is mainly vacuum arc melting. In this method, the tungsten powder is pressed into a blank, and then broken into particles of a specific particle size. The particles are mixed with sponge zirconium at a certain proportion, and then subjected to multiple melting through a vacuum arc melting process, so as to obtain the tungsten-zirconium alloy. However, the arc melting temperature limits the preparation of high-tungsten-content tungsten-zirconium alloy. In addition, due to the high density of tungsten element, the tungsten component is prone to sedimentation in the arc melting process. Moreover, since the metal zirconium powder is easily oxidized, it is difficult to prepare a high-tungsten alloy with uniform structure.

[0004] Although the Chinese invention patent with the application number 201510606975.3 discloses a method for preparing a tungsten-zirconium alloy with a tungsten content of 70% by combining the powder metallurgy and consumable melting process, there is no report on the method for preparing a tungsten-zirconium alloy with a higher tungsten content by using the powder metallurgy. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a preparation method of a tungsten-zirconium active material in view of the above-mentioned deficiencies of the prior art. In the method, the raw material tungsten powder, nickel powder, iron powder and zirconium hydride powder are mixed, pressed, and subjected to vacuum dehydrogenation and vacuum sintering. The densification sintering is realized at a low sintering temperature, so as to improve the tungsten content and the uniformity of the structure of the tungsten-zirconium active material. The problem that it is difficult to obtain a high-tungsten-content tungsten-zirconium active material with a uniform structure due to the arc melting temperature limitation, tungsten component sedimentation and zirconium powder oxidation in the prior art is solved.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of a tungsten-zirconium active material, characterized in that the method comprises the following steps:

[0007] Step one, ingredient mixing: mix tungsten powder, nickel powder, iron powder and zirconium hydride powder to obtain mixed powder;

[0008] Step two, pressing: use a cold isostatic press to press the mixed powder obtained in step one to obtain a green body;

[0009] Step three, vacuum dehydrogenation: use a vacuum degreasing furnace to treat the green body obtained in step two to obtain a pre-sintered body;

[0010] Step four, vacuum sintering: use a vacuum sintering furnace to sinter the pre-sintered body obtained in step three to obtain a tungsten-zirconium active material.

[0011] Because the melting point of tungsten is high, the melting temperature of the vacuum arc melting method needs to exceed the melting point of tungsten (above 3500℃), the equipment cost is high, and the volatilization of nickel and iron is difficult to control; in order to avoid oxidation, the preparation needs to be carried out under high vacuum or high-purity argon protection; at the same time, in order to avoid tungsten grain coarsening, the cooling rate needs to be strictly controlled, and the crack is reduced by controllable slow cooling. In view of the above technical problems, the present application adopts powder metallurgy method, uses tungsten powder, nickel powder, iron powder and zirconium hydride powder as raw materials, and sequentially carries out pressing, vacuum dehydrogenation and vacuum sintering to prepare a high-tungsten-content tungsten-zirconium active material. In the vacuum dehydrogenation process, the zirconium hydride powder (ZrH2) is decomposed into Zr and H2, and in the subsequent vacuum sintering process, the tungsten powder and Zr are sintered in solid phase, while the nickel powder and iron powder as the adhesive phase raw material soften and flow under high temperature, so that the gap between the raw material particles gradually decreases, and densification is realized under conditions far below the melting point of tungsten, thereby improving the tungsten content in the tungsten-zirconium active material.

[0012] The preparation method of the tungsten-zirconium active material has the characteristics that the particle size of the tungsten powder in step one is 1-10 μm, and the mass percentage of the tungsten powder in the mixed powder is 70-80%. Generally, the particle size of the nickel powder, iron powder and zirconium hydride powder is also limited to 1-10 μm.

[0013] The preparation method of the tungsten-zirconium active material has the characteristics that the pressure of the one-step pressing in step two is 150-200 MPa, and the pressure holding time is 0.5-2 min.

[0014] The preparation method of the tungsten-zirconium active material has the characteristics that the vacuum degree of the vacuum dehydrogenation treatment in step three is not more than 6.67×10 -1 Pa.

[0015] The preparation method of the tungsten-zirconium active material has the characteristics that the vacuum degree of the vacuum sintering in step four is not more than 6.67×10 -2Pa; when the sintering temperature is greater than 900℃, the vacuum degree is not more than 6.67*10 -3 Pa.

[0016] Meanwhile, the application also discloses a tungsten-zirconium active material, which is prepared by the method.

[0017] Compared with the prior art, the application has the following advantages:

[0018] 1. The tungsten-zirconium active material is prepared by adopting the powder metallurgy method, i.e. mixing tungsten powder, nickel powder, iron powder and zirconium hydride powder, pressing, vacuum dehydrogenation and vacuum sintering, so that the Zr solid phase generated by the decomposition of the tungsten powder and the zirconium hydride powder is sintered, and the nickel powder and the iron powder are used as the adhesive phase raw materials to reduce the gap between the raw material particles, realize densification sintering at a low sintering temperature, and improve the tungsten content in the tungsten-zirconium active material.

[0019] 2. The application uses zirconium hydride which is more stable in chemical properties in the air environment to replace the metal zirconium powder raw material, effectively avoids the oxidation failure of the energy-containing elements zirconium and titanium, avoids the influence of the metal zirconium powder on the uniformity of the tungsten-zirconium active material due to easy oxidation, and ensures the uniformity of the tungsten-zirconium active material, avoids component segregation, and avoids the adverse effect on the mechanical properties of the tungsten-zirconium active material by flexibly adjusting the ratio of the nickel powder and the iron powder adhesive phase raw materials under the premise of ensuring densification sintering.

[0020] 3. The tungsten-zirconium active material with a high tungsten mass content of 80% is prepared by adopting the powder metallurgy method, can release energy instantaneously when impacting a steel plate at a speed of more than 1200m / s under the premise of ensuring the penetration ability, has obvious energy release characteristics, and has a significant damage effect.

[0021] The technical solutions of the application are further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The microstructure photo of the tungsten-zirconium active material prepared for the example 1 of the application.

[0023] Figure 2 The microstructure photo of the tungsten-zirconium active material prepared for the example 2 of the application.

[0024] Figure 3 The microstructure photo of the tungsten-zirconium active material prepared for the example 3 of the application.

[0025] Figure 4 The microstructure photo of the tungsten-titanium active material prepared for the comparative example 1 of the application. DETAILED DESCRIPTION

[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 particle sizes of 1μm to 10μm are mixed for 8 hours to obtain a mixed powder. The mixed powder contains 80% tungsten powder, 4% nickel powder, 1% iron powder, and 15% zirconium hydride powder by mass percentage, and the mass of steel balls used in the ball milling media is 50% of the total mass of the mixed powder.

[0029] Step 2, pressing: The mixed powder obtained in Step 1 is pressed into shape in one step using a cold isostatic press. The pressure of one pressing is 150MPa and the holding time is 2min, to obtain a compact with a diameter × height of Φ20mm × 280mm.

[0030] Step 3, Vacuum Dehydrogenation: The pressed preform obtained in Step 2 is subjected to vacuum dehydrogenation in a vacuum degumming furnace, with a vacuum degree not exceeding 6.67 × 10⁻⁶. -1 Pa, heating rate is 80℃ / h, a total of 5 temperature segments, in the following order: room temperature to 200℃ and hold for 1h, 200℃ to 400℃ and hold for 1h, 400℃ to 600℃ and hold for 1h, 600℃ to 750℃ and hold for 1h, 750℃ to 900℃ and hold for 1h, after the holding is completed, the furnace is cooled down to obtain the pre-formed billet;

[0031] Step 4: Vacuum sintering: The pre-sintered billet obtained in Step 3 is sintered in a vacuum sintering furnace. When the sintering temperature does not exceed 900℃, the vacuum degree does not exceed 6.67×10⁻⁶. -2 Pa, when the sintering temperature is greater than 900℃, the vacuum degree does not exceed 6.67×10. -3 Pa, and finally heated to 1520℃ and held for 30 min to obtain tungsten-zirconium active material.

[0032] The end face sample of the tungsten-zirconium active material prepared in this embodiment was cut and analyzed for microstructure. The results are as follows: Figure 1 As shown, from Figure 1 It can be seen that tungsten is evenly distributed in the structure of the tungsten-zirconium active material.

[0033] Example 2

[0034] This embodiment includes the following steps:

[0035] Step 1: Ingredient mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder with particle sizes of 1μm to 10μm are mixed for 8 hours to obtain a mixed powder; the mixed powder contains 80% tungsten powder, 6% nickel powder, 4% iron powder and 10% zirconium hydride powder by mass percentage.

[0036] Step 2, Pressing: The mixed powder obtained in Step 1 is pressed into shape in one step using a cold isostatic press. The pressure of one pressing is 200MPa, and the holding time is 0.5min, to obtain a compact with a diameter × height of Φ20mm × 280mm.

[0037] Step 3, Vacuum Dehydrogenation: The pressed preform obtained in Step 2 is subjected to vacuum dehydrogenation in a vacuum degumming furnace, with a vacuum degree not exceeding 6.67 × 10⁻⁶. -1 Pa, heating rate is 80℃ / h, a total of 5 temperature segments, in the following order: room temperature to 200℃ and hold for 1h, 200℃ to 400℃ and hold for 1h, 400℃ to 600℃ and hold for 1h, 600℃ to 750℃ and hold for 1h, 750℃ to 900℃ and hold for 1h, after the holding is completed, the furnace is cooled down to obtain the pre-formed billet;

[0038] Step 4: Vacuum sintering: The pre-sintered billet obtained in Step 3 is sintered in a vacuum sintering furnace. When the sintering temperature does not exceed 900℃, the vacuum degree does not exceed 6.67×10⁻⁶. -2 Pa, when the sintering temperature is greater than 900℃, the vacuum degree does not exceed 6.67×10. -3 Pa, and finally heated to 1520℃ and held for 30 min to obtain tungsten-zirconium active material.

[0039] The end face sample of the tungsten-zirconium active material prepared in this embodiment was cut and analyzed for microstructure. The results are as follows: Figure 2 As shown, from Figure 2 It can be seen that tungsten is evenly distributed in the structure of the tungsten-zirconium active material.

[0040] Example 3

[0041] This embodiment includes the following steps:

[0042] Step 1: Ingredient mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder with particle sizes of 1μm to 10μm are mixed for 8 hours to obtain a mixed powder; the mixed powder contains 75% tungsten powder, 6% nickel powder, 4% iron powder and 15% zirconium hydride powder by mass percentage.

[0043] Step 2, pressing: The mixed powder obtained in Step 1 is pressed into shape in one step using a cold isostatic press. The pressure of one pressing is 150MPa and the holding time is 1min, to obtain a compact with a diameter × height of Φ20mm × 280mm.

[0044] Step 3, Vacuum Dehydrogenation: The pressed preform obtained in Step 2 is subjected to vacuum dehydrogenation in a vacuum degumming furnace, with a vacuum degree not exceeding 6.67 × 10⁻⁶. -1Pa, the total of 5 temperature sections are as follows: room temperature to 200℃ for 1h, 200℃ to 400℃ for 1h, 400℃ to 600℃ for 1h, 600℃ to 750℃ for 1h, 750℃ to 900℃ for 1h, after the end of the preservation, the furnace cooling is performed, and the pre-sintered compact is prepared;

[0045] Step four, vacuum sintering: the vacuum sintering furnace is used to perform vacuum sintering on the pre-sintered compact obtained in step three, when the sintering temperature is not more than 900℃, the vacuum degree is not more than 6.67×10 -2 Pa, when the sintering temperature is more than 900℃, the vacuum degree is not more than 6.67×10 -3 Pa, and finally the temperature is increased to 1460℃ for 60min, and the tungsten-zirconium active material is prepared.

[0046] The end face sample of the tungsten-zirconium active material prepared in this embodiment is cut for the organization analysis, and the results are shown in the following table: Figure 3 From the table, it can be seen that the tungsten element is uniformly distributed in the organization of the tungsten-zirconium active material. Figure 3

[0047] Comparative example 1

[0048] This comparative example includes the following steps:

[0049] Step one, mixing: the tungsten powder, the nickel powder, the iron powder and the titanium hydride powder with the particle size of 1μm-10μm are mixed for 8h after being mixed, and the mixed powder is prepared; the tungsten powder is 80%, the nickel powder is 4%, the iron powder is 1%, and the titanium hydride powder is 15% in the mixed powder by mass percentage, and the added mass of the ball milling medium steel ball is 50% of the total mass of the mixed powder;

[0050] Step two, pressing: the mixed powder obtained in step one is once-pressed into a compact by using the cold isostatic pressing machine, the pressure of the once-pressed compact is 150MPa, and the pressure holding time is 2min, and the compact with the diameter×height of Φ20mm×280mm is prepared;

[0051] Step three, vacuum dehydrogenation: the vacuum degumming furnace is used to perform vacuum dehydrogenation treatment on the compact obtained in step two, the vacuum degree is not more than 6.67×10 -1 Pa, the total of 5 temperature sections are as follows: room temperature to 200℃ for 1h, 200℃ to 400℃ for 1h, 400℃ to 600℃ for 1h, 600℃ to 750℃ for 1h, 750℃ to 900℃ for 1h, after the end of the preservation, the furnace cooling is performed, and the pre-sintered compact is prepared;

[0052] ​Step 4: Vacuum sintering: The pre-sintered billet obtained in Step 3 is sintered in a vacuum sintering furnace. When the sintering temperature does not exceed 900℃, the vacuum degree does not exceed 6.67×10⁻⁶. -2 Pa, when the sintering temperature is greater than 900℃, the vacuum degree does not exceed 6.67×10. -3 Pa, and finally heated to 1520℃ and held for 30 min to obtain tungsten-titanium active material.

[0053] The end face samples of the tungsten-zirconium active material prepared in this comparative example were cut and analyzed for microstructure. The results are as follows: Figure 4 As shown, from Figure 4 It can be seen that tungsten is relatively evenly distributed in the structure of tungsten-titanium active materials, but titanium and nickel and iron binder phase elements show lamellar component segregation.

[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 tissue uniformity than the tungsten-titanium active material of the same type prepared by the same method in Comparative Example 1, which effectively avoids component segregation and thus avoids adverse effects on the mechanical properties of the tungsten-zirconium active material.

[0055] 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 for preparing a tungsten-zirconium active material, characterized in that, The method includes the following steps: Step 1: Ingredient Mixing: Tungsten powder, nickel powder, iron powder and zirconium hydride powder are mixed to obtain a mixed powder; the mixed powder contains 75%~80% tungsten powder, 4%~6% nickel powder, 1%~4% iron powder and 10%~15% zirconium hydride powder by mass percentage. Step 2, pressing: The mixed powder obtained in Step 1 is pressed into a compact using a cold isostatic press in one step. Step 3, Vacuum Dehydrogenation: The pressed blank obtained in Step 2 is subjected to vacuum dehydrogenation in a vacuum degumming furnace to obtain a pre-formed blank; Step 4: Vacuum sintering: The pre-sintered blank obtained in Step 3 is sintered in a vacuum sintering furnace to obtain tungsten-zirconium active material; the vacuum sintering process is as follows: when the sintering temperature does not exceed 900℃, the vacuum degree does not exceed 6.67×10⁻⁶. - 2 Pa; when the sintering temperature is greater than 900℃, the vacuum degree shall not exceed 6.67×10. -3 Pa, and finally raise the temperature to 1460℃~1520℃ and hold for 30min~60min.

2. The method for preparing a tungsten-zirconium active material according to claim 1, characterized in that, The particle size of the tungsten powder mentioned in step one is 1μm~10μm.

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

4. The method for preparing a tungsten-zirconium active material according to claim 1, characterized in that, The vacuum degree of the vacuum dehydrogenation process in step three shall not exceed 6.67 × 10⁻⁶. -1 Pa.

5. A tungsten-zirconium active material, characterized in that, Prepared by the method described in any one of claims 1 to 4.

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