Antioxidant single-crystal tungsten powder and nano-tungsten powder and preparation method thereof

Abstract

The present invention provides antioxidant single-crystal tungsten powder and antioxidant nano-tungsten powder. For the antioxidant single-crystal tungsten powder, its microstructure is that the single-crystal tungsten powder is coated with a tungsten carbide phase formed by carbonization of the single-crystal tungsten powder. For the antioxidant nano-tungsten powder, its microstructure is that the nano-tungsten powder is coated with a tungsten carbide phase formed by carbonization of the nano-tungsten powder. The antioxidant single-crystal tungsten powder uses ammonium metatungstate powder as a raw material, forms an aqueous solution therefrom and obtains spherical precursor powder through spray drying, then reduces the precursor powder with hydrogen to obtain single-crystal tungsten powder, and then carbonizes the single-crystal tungsten powder with CO to obtain the antioxidant single-crystal tungsten powder. The antioxidant nano-tungsten powder uses blue tungsten powder as a raw material, reduces it with hydrogen to obtain nano-tungsten powder, and then carbonizes the nano-tungsten powder with CO to obtain the antioxidant nano-tungsten powder. Compared with single-crystal tungsten powder or nano-tungsten powder, the antioxidant property of the antioxidant single-crystal tungsten powder or antioxidant nano-tungsten powder of the present invention is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tungsten powder, and relates to antioxidant tungsten powder and a preparation method thereof. Background Art

[0002] As the fuel of tungsten-based delay composition, tungsten powder is an important component of tungsten-based delay composition. During the storage of tungsten-based delay composition, the main problems are the pre-oxidation of fuel tungsten powder and the premature decomposition of oxidant. The longer the storage time, the more serious the problems of pre-oxidation of fuel tungsten powder and premature decomposition of oxidant, which lead to the aging of tungsten-based delay composition. The pre-oxidation of fuel tungsten powder is that tungsten powder reacts with oxidant in advance to form tungsten trioxide (WO3), which increases WO3 in tungsten-based delay composition, thus changing the composition of tungsten-based delay composition and reducing the thermal conductivity. Because metallic tungsten transfers heat through electron movement and can quickly achieve heat conduction, while WO3 mainly transfers heat through lattice vibration, and the mean free path of lattice vibration is much smaller than that of electrons. At the same time, the presence of WO3 will reduce the maximum reaction zone temperature during the combustion process, and the unreacted gaseous oxygen escapes into the environment, which also leads to the premature decomposition of oxidant, making the combustion reaction incomplete. Therefore, the pre-oxidation of fuel tungsten powder is the main factor affecting the overall characteristics of tungsten-based delay composition.

[0003] To prevent the pre-oxidation of fuel tungsten powder during the storage of tungsten-based delay composition, in principle, it is necessary to make the fuel tungsten powder have antioxidant properties and avoid reacting with oxidant in advance during storage. However, the applicant has not found any technical solutions for antioxidant tungsten powder and its preparation method disclosed in the prior art. Therefore, it is very necessary to develop antioxidant tungsten powder. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide antioxidant tungsten powder and a preparation method thereof. The antioxidant tungsten powder not only greatly improves the antioxidant performance, but also has a simple preparation process and easily accessible raw materials.

[0005] The antioxidant tungsten powder of the present invention has two types. One is antioxidant single-crystal tungsten powder, and the other is antioxidant nano-tungsten powder. For the antioxidant single-crystal tungsten powder, its microstructure is that the single-crystal tungsten powder is coated with tungsten carbide phase formed by carbonization of the single-crystal tungsten powder, and the amount of tungsten carbide phase meets the antioxidant requirement. For the antioxidant nano-tungsten powder, its microstructure is that the nano-tungsten powder (nano-polycrystalline tungsten powder) is coated with tungsten carbide phase formed by carbonization of the nano-tungsten powder, and the amount of tungsten carbide phase meets the antioxidant requirement. Therefore, they belong to a general inventive concept.

[0006] The preparation method of the antioxidant single-crystal tungsten powder of the present invention has the following technological steps:

[0007] (1) Dissolve water-soluble ammonium metatungstate powder in deionized water to form a uniformly mixed ammonium metatungstate solution;

[0008] (2) Spray-dry the ammonium metatungstate solution obtained in step (1) to obtain spherical precursor powder;

[0009] (3) Evenly spread the precursor powder obtained in step (2) in a boat, and then put it into a sintering furnace for reduction treatment with hydrogen to obtain single-crystal tungsten powder;

[0010] (4) Continue to place the single-crystal tungsten powder obtained in step (3) in a boat, and then introduce gaseous carbon source CO into the sintering furnace to perform carbonization treatment on the surface of the single-crystal tungsten powder to obtain oxidation-resistant single-crystal tungsten powder. During the carbonization treatment, the flow rate of CO is 400 mL / min to 800 mL / min, the temperature is 700 °C to 900 °C, and the holding time is the time required for the carbon element content in the oxidation-resistant single-crystal tungsten powder to reach 0.1 wt% to 3.0 wt%.

[0011] In the above method, in step (1), the mass ratio of water-soluble ammonium metatungstate powder to deionized water is preferably 1:5 to 20; in step (2), during the spray-drying treatment, the inlet air temperature is preferably 150 °C to 220 °C, and the feeding rate is preferably 200 mL / h to 600 mL / h; in step (3), during the reduction treatment, the hydrogen flow rate is preferably 400 mL / min to 800 mL / min, the temperature is preferably 700 °C to 1100 °C, and the holding time is preferably 1 h to 3 h.

[0012] In the above method, the laying thickness of the precursor powder or single-crystal tungsten powder in the boat is preferably 2 mm to 4 mm.

[0013] The preparation method of the oxidation-resistant nano tungsten powder of the present invention comprises the following process steps:

[0014] (1) Evenly spread blue tungsten powder in a boat, and then put it into a sintering furnace for reduction treatment with hydrogen to obtain nano tungsten powder;

[0015] (2) Grind the nano tungsten powder obtained in step (1) into completely dispersed nano tungsten powder under vacuum conditions or in an inert gas atmosphere;

[0016] (3) Evenly spread the dispersed nano tungsten powder obtained in step (2) in a boat, and then put it into a sintering furnace to perform carbonization treatment on the surface of the nano tungsten powder with gaseous carbon source CO to obtain oxidation-resistant nano tungsten powder. During the carbonization treatment, the flow rate of CO is 400 mL / min to 800 mL / min, the temperature is 600 °C to 800 °C, and the holding time is the time required for the carbon element content in the oxidation-resistant nano tungsten powder to reach 0.1 wt% to 3.0 wt%.

[0017] In the above method, in step (1), during the reduction treatment, the hydrogen flow rate is preferably 400 mL / min to 800 mL / min, the temperature is preferably 500 °C to 700 °C, and the holding time is preferably 4 h to 12 h.

[0018] In the above method, the laying thickness of blue tungsten powder or nano tungsten powder in the boat is preferably 2 mm to 4 mm.

[0019] It should be noted that: the function of the carbonization treatment in the above method is to form a tungsten carbide phase coating single crystal tungsten powder or nano tungsten powder (nano polycrystalline tungsten powder). However, since the EDS analysis obtains the element content in the substance, although the carbon element content in the antioxidant single crystal tungsten powder or the carbon element content in the antioxidant nano tungsten powder in the above method is not the actual content of the tungsten carbide phase, it can characterize the content trend of the tungsten carbide phase in the antioxidant single crystal tungsten powder and the antioxidant nano tungsten powder.

[0020] The antioxidant single crystal tungsten powder and antioxidant nano tungsten powder described in the present invention can be applied in tungsten-based delay charges, that is, replacing the existing tungsten powder as the fuel in tungsten-based delay charges.

[0021] Compared with the prior art, the method of the present invention has the following beneficial technical effects:

[0022] (1) The method of the present invention uses ammonium metatungstate powder or blue tungsten powder as raw materials to prepare antioxidant single crystal tungsten powder or antioxidant nano tungsten powder, providing a new technical solution for the preparation of antioxidant tungsten powder.

[0023] (2) Experiments show that compared with single crystal tungsten powder or nano tungsten powder, the antioxidant performance of the antioxidant single crystal tungsten powder or antioxidant nano tungsten powder described in the present invention is greatly improved (see Examples 1 and 4).

[0024] (3) Since the antioxidant single crystal tungsten powder or antioxidant nano tungsten powder described in the present invention has excellent antioxidant properties and the tungsten carbide coating phase of the single crystal tungsten powder or nano tungsten powder has stable chemical properties, when the antioxidant single crystal tungsten powder or antioxidant nano tungsten powder described in the present invention is used as the fuel of tungsten-based delay charges, there will be no problems of pre-oxidation of the fuel and pre-decomposition of the oxidant during the normal storage period of tungsten-based delay charges, thus improving the combustion performance of tungsten-based delay charges.

[0025] (4) The raw materials of the method of the present invention are easy to obtain, the equipment used is conventional equipment, and the preparation process is simple. Therefore, it has the advantage of low cost and is convenient for implementation and promotion. Description of the Drawings

[0026] Figure 1 XRD pattern of the single crystal tungsten powder prepared in Example 1 of the present invention.

[0027] Figure 2 SEM image of the single crystal tungsten powder prepared in Example 1 of the present invention.

[0028] Figure 3EDS diagram of the single-crystal tungsten powder prepared in Example 1 of the present invention. Among them, (a) is the TEM dark-field image, (b) is the distribution diagram of O element, and (c) is the distribution diagram of W element.

[0029] Figure 4 TEM diagram of the single-crystal tungsten powder prepared in Example 1 of the present invention. Among them, (a) is the TEM bright-field image, and (b) is the SAED image.

[0030] Figure 5 XRD diagram of the antioxidant single-crystal tungsten powder prepared in Example 1 of the present invention.

[0031] Figure 6 SEM diagram of the antioxidant single-crystal tungsten powder prepared in Example 1 of the present invention.

[0032] Figure 7 EDS diagram of the antioxidant single-crystal tungsten powder prepared in Example 1 of the present invention. Among them, (a) is the EDS layered image, (b) is the distribution diagram of W element, (c) is the distribution diagram of C element, and (d) is the distribution diagram of O element.

[0033] Figure 8 TG-DSC diagram of the single-crystal tungsten powder and the antioxidant single-crystal tungsten powder prepared in Example 1 of the present invention. Among them, (a) is the single-crystal tungsten powder, and (b) is the antioxidant single-crystal tungsten powder.

[0034] Figure 9 XRD diagrams of the single-crystal tungsten powder and the antioxidant single-crystal tungsten powder prepared in Example 1 of the present invention after oxidation at different temperatures. Among them, (a) is the single-crystal tungsten powder, and (b) is the antioxidant single-crystal tungsten powder.

[0035] Figure 10 XRD diagram of the antioxidant single-crystal tungsten powder prepared in Example 2 of the present invention.

[0036] Figure 11 XRD diagram of the antioxidant single-crystal tungsten powder prepared in Example 3 of the present invention.

[0037] Figure 12 XRD diagram of the nano tungsten powder prepared in Example 4 of the present invention.

[0038] Figure 13 SEM diagram of the nano tungsten powder prepared in Example 4 of the present invention.

[0039] Figure 14 EDS diagram of the nano tungsten powder prepared in Example 4 of the present invention. Among them, (a) is the EDS layered image, (b) is the distribution diagram of W element, and (c) is the distribution diagram of O element.

[0040] Figure 15XRD pattern of the antioxidant nano tungsten powder prepared in Example 4 of the present invention.

[0041] Figure 16 SEM image of the antioxidant nano tungsten powder prepared in Example 4 of the present invention.

[0042] Figure 17 EDS pattern of the antioxidant nano tungsten powder prepared in Example 4 of the present invention. Among them, Figure (a) is the EDS layered image, Figure (b) is the distribution map of W element, Figure (c) is the distribution map of C element, and Figure (d) is the distribution map of O element.

[0043] Figure 18 XRD patterns of the nano tungsten powder and the antioxidant nano tungsten powder prepared in Example 4 of the present invention after oxidation at different temperatures. Among them, Figure (a) is the nano tungsten powder, and Figure (b) is the antioxidant nano tungsten powder.

[0044] Figure 19 XRD pattern of the antioxidant nano tungsten powder prepared in Example 5 of the present invention.

[0045] Figure 20 XRD pattern of the antioxidant nano tungsten powder prepared in Example 6 of the present invention. Detailed implementation manners

[0046] The antioxidant single crystal tungsten powder, the antioxidant nano tungsten powder and their preparation methods of the present invention are further described below through examples in combination with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope protected by the present invention.

[0047] In the following embodiments, the raw material ammonium metatungstate powder (average particle size 30um) and blue tungsten powder (average particle size 20um) are both purchased from the market. The sintering furnace is a three-temperature zone tube furnace produced by Beijing Beike Co., Ltd., model BTF-1200C.

[0048] Example 1

[0049] In this embodiment, ammonium metatungstate powder is used as the raw material to prepare antioxidant single crystal tungsten powder, and the process steps are as follows:

[0050] (1) Weigh 100g of ammonium metatungstate powder and 1000g (1L) of deionized water, and then dissolve the ammonium metatungstate powder in deionized water at room temperature and stir to form a uniformly mixed ammonium metatungstate solution;

[0051] (2) Spray-dry the ammonium metatungstate solution obtained in step (1) to obtain 40 g of spherical precursor powder with uniform particle size. The inlet air temperature for spray drying is controlled at 180 °C, and the feeding rate is controlled at 300 mL / h;

[0052] (3) Divide the 40 g of precursor powder obtained in step (2) into 6 equal parts, and evenly spread them on 6 quartz boats. The laying thickness of the precursor powder in each quartz boat is about 4 mm, and then put them into a three-temperature zone tube furnace for reduction treatment with hydrogen to obtain single-crystal tungsten powder. During the reduction treatment, the hydrogen flow rate is 600 mL / min, the temperature is 900 °C, and the holding time is 1.5 h;

[0053] (4) Continue to lay the single-crystal tungsten powder obtained in step (3) in 6 quartz boats, and the 6 quartz boats remain in the three-temperature zone tube furnace. Then, introduce CO gas into the three-temperature zone tube furnace to carry out carbonization treatment on the surface of the single-crystal tungsten powder to obtain oxidation-resistant single-crystal tungsten powder. During the carbonization treatment, the flow rate of CO gas is 600 mL / min, the temperature is 900 °C, and the holding time is 25 min.

[0054] 1. Respectively conduct phase, grain morphology, and element distribution detection and analysis on the single-crystal tungsten powder and oxidation-resistant single-crystal tungsten powder prepared in this example. The detection results are as follows:

[0055] (1) Single-crystal tungsten powder

[0056] The XRD pattern of the single-crystal tungsten powder is as shown in Figure 1 . The phase is W, and the peak intensity is very high, indicating that it is pure W and has good crystallinity; the SEM photograph of the single-crystal tungsten powder is as shown in Figure 2 . It shows that the grain morphology is regular, the size is uniform, the particle size is 100 nm - 500 nm, and it also shows good crystallinity; the TEM image of the single-crystal tungsten powder is as shown in Figure 4 . (a) is the bright-field image of the single-crystal tungsten powder, and (b) is the SAED (selected area electron diffraction) image of the single-crystal tungsten powder. As can be seen from Figure 4 (b), the SAED image is a set of diffraction spots, so it indicates that the tungsten powder prepared in this example is single-crystal tungsten powder (the SAED image of polycrystalline materials is a diffraction ring); the EDS (energy dispersive spectrometer) element distribution of the single-crystal tungsten powder is as shown in Figure 3 . It shows that the distribution of tungsten element and oxygen element is uniform; tested by a nitrogen and oxygen analyzer, the oxygen content in the single-crystal tungsten powder is 0.03 wt%.

[0057] (2) Oxidation-resistant single-crystal tungsten powder

[0058] The XRD pattern of the oxidation-resistant single-crystal tungsten powder is as shown in Figure 5 . The phase composition is W + W2C + WC; the SEM photograph of the oxidation-resistant single-crystal tungsten powder is as shown in Figure 6As shown, it indicates that the morphology is very similar to that of single-crystal tungsten powder; the EDS (energy dispersive spectrometer) element distribution of the antioxidant single-crystal tungsten powder is as Figure 7 shown, indicating that the carbon element on the surface layer is evenly distributed. Combining with the phase composition in the XRD pattern, it shows that the tungsten carbide phase is evenly distributed on the surface of the single-crystal tungsten powder and coats the single-crystal tungsten powder; through the tests of a carbon-sulfur analyzer and a nitrogen-oxygen analyzer, the carbon content in the antioxidant single-crystal tungsten powder is 0.65 wt%, and the oxygen content is 0.05 wt%.

[0059] 2. Oxidation tests and test results of the single-crystal tungsten powder and the antioxidant single-crystal tungsten powder prepared in this example:

[0060] (1) The single-crystal tungsten powder and the antioxidant single-crystal tungsten powder prepared in this example were subjected to thermogravimetric-differential scanning calorimetry analysis in air. The TG-DSC of the single-crystal tungsten powder is as Figure 8 (a) shown, and the TG-DSC of the antioxidant single-crystal tungsten powder is as Figure 8 (b) shown. From Figure 8 (a), Figure 8 (b), it can be seen that the temperature at which the single-crystal tungsten powder begins to be oxidized to WO3 is 425 °C, and the temperature at which the antioxidant single-crystal tungsten powder begins to be oxidized to WO3 is 500 °C. The difference between the two temperatures is 75 °C, indicating that the antioxidant property of the antioxidant single-crystal tungsten powder is greatly improved compared to the single-crystal tungsten powder.

[0061] (2) The single-crystal tungsten powder and the antioxidant single-crystal tungsten powder prepared in this example were respectively subjected to oxidation experiments in oxygen using a single-temperature-zone tube furnace. The XRD of the single-crystal tungsten powder after oxidation at different temperatures is as Figure 9 (a) shown, and the XRD of the antioxidant single-crystal tungsten powder after oxidation at different temperatures is as Figure 9 (b) shown. From Figure 9 (a), Figure 9 (b), it can be seen that the temperature at which the single-crystal tungsten powder begins to be oxidized to WO3 is 425 °C, while the temperature at which the antioxidant single-crystal tungsten powder begins to be oxidized to WO3 is 500 °C. The temperature difference is 75 °C, indicating that the antioxidant property of the antioxidant single-crystal tungsten powder is greatly improved compared to the single-crystal tungsten powder.

[0062] Example 2

[0063] In this example, ammonium metatungstate powder was used as the raw material to prepare antioxidant single-crystal tungsten powder, and the process steps are as follows:

[0064] (1) Weigh 20 g of ammonium metatungstate powder and 400 g (400 mL) of deionized water, and then dissolve the ammonium metatungstate powder in deionized water at room temperature with stirring to form a uniformly mixed ammonium metatungstate solution;

[0065] (2) Spray-dry the ammonium metatungstate solution obtained in step (1) to obtain 7 g of spherical precursor powder with uniform particle size. Control the inlet air temperature of the spray drying at 160 °C and the feeding rate at 200 mL / h;

[0066] (3) Divide the 7 g of precursor powder obtained in step (2) into two equal parts, and evenly spread them on two quartz boats respectively. The laying thickness of the precursor powder in each quartz boat is about 2 mm, and then put them into a three-zone tube furnace for reduction treatment with hydrogen to obtain single-crystal tungsten powder. During the reduction treatment, the hydrogen flow rate is 400 mL / min, the temperature is 800 °C, and the holding time is 2 h;

[0067] (4) Continue to lay the single-crystal tungsten powder obtained in step (3) in two quartz boats, and the two quartz boats continue to be located in the three-zone tube furnace. Then, introduce CO gas into the three-zone tube furnace to carry out carbonization treatment on the surface of the single-crystal tungsten powder to obtain oxidation-resistant single-crystal tungsten powder. During the carbonization treatment, the flow rate of CO gas is 800 mL / min, the temperature is 800 °C, and the holding time is 5 min.

[0068] Perform phase analysis on the oxidation-resistant single-crystal tungsten powder prepared in this example. The XRD pattern is as Figure 10 shown, and the phase composition is W + W2C; tested with a carbon-sulfur analyzer and a nitrogen-oxygen analyzer, the measured carbon content is 0.17 wt%, and the oxygen content is 0.01 wt%.

[0069] Example 3

[0070] In this example, oxidation-resistant single-crystal tungsten powder is prepared using ammonium metatungstate powder as the raw material. The process steps are as follows:

[0071] (1) Weigh 50 g of ammonium metatungstate powder and 250 g (250 mL) of deionized water, and then dissolve the ammonium metatungstate powder in deionized water at room temperature and stir to form a uniformly mixed ammonium metatungstate solution;

[0072] (2) Spray-dry the ammonium metatungstate solution obtained in step (1) to obtain 20 g of spherical precursor powder with uniform particle size. Control the inlet air temperature of the spray drying at 200 °C and the feeding rate at 500 mL / h;

[0073] (3) Divide the 20 g of precursor powder obtained in step (2) into four equal parts, and evenly spread them on four quartz boats respectively. The laying thickness of the precursor powder in each quartz boat is about 3 mm, and then put them into a three-zone tube furnace for reduction treatment with hydrogen to obtain single-crystal tungsten powder. During the reduction treatment, the hydrogen flow rate is 800 mL / min, the temperature is 700 °C, and the holding time is 3 h;

[0074] (4) Continuously lay the single-crystal tungsten powder obtained in step (3) in 4 quartz boats. The 4 quartz boats are still located in the three-zone tubular furnace. Then, introduce CO gas into the three-zone tubular furnace to perform carbonization treatment on the surface of the single-crystal tungsten powder to obtain oxidation-resistant single-crystal tungsten powder. When performing carbonization treatment, the flow rate of CO gas is 400 mL / min, the temperature is 700 °C, and the heat preservation time is 40 min.

[0075] Perform phase analysis on the oxidation-resistant single-crystal tungsten powder prepared in this example. The XRD pattern is as Figure 11 shown. The phase composition is W + W2C + WC; measured by a carbon-sulfur analyzer and a nitrogen-oxygen analyzer, the carbon content is 1.18 wt%, and the oxygen content is 0.08 wt%.

[0076] Example 4

[0077] In this example, blue tungsten powder is used as the raw material to prepare oxidation-resistant nano-tungsten powder. The technological steps are as follows:

[0078] (1) Divide 50 g of blue tungsten powder into 6 equal parts, and evenly spread them on 6 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 3 mm. Then, put them into the three-zone tubular furnace and perform reduction treatment with hydrogen to obtain nano-tungsten powder. When performing reduction treatment, the hydrogen flow rate is 600 mL / min, the temperature is 650 °C, and the heat preservation time is 8 h;

[0079] (2) Place the nano-tungsten powder obtained in step (1) in a glove box and manually grind it with a large mortar for 60 min to obtain completely dispersed nano-tungsten powder;

[0080] (3) Divide the dispersed nano-tungsten powder obtained in step (2) into 6 equal parts, and evenly spread them on 6 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 3 mm. Then, put them into the three-zone tubular furnace and introduce CO gas to perform carbonization treatment on the surface of the nano-tungsten powder to obtain oxidation-resistant nano-tungsten powder. When performing carbonization treatment, the flow rate of CO is 600 mL / min, the temperature is 800 °C, and the heat preservation time is 15 min.

[0081] 1. Perform phase, grain morphology, and element distribution detection and analysis on the nano-tungsten powder and oxidation-resistant nano-tungsten powder prepared in this example respectively. The detection results are as follows:

[0082] (1) Nano-tungsten powder

[0083] The XRD pattern of the nano-tungsten powder is as Figure 12 shown. The phase is W; the SEM photo of the nano-tungsten powder is as Figure 13 shown, indicating that the particle size is uniform, and the particle diameter is about 50 nm; the EDS element distribution of the nano-tungsten powder is as Figure 14As shown, it indicates that the distributions of tungsten and oxygen elements are uniform; tested by a nitrogen and oxygen analyzer, the oxygen content in the nano tungsten powder is 0.82 wt%.

[0084] (2) Anti-oxidation nano tungsten powder

[0085] The XRD pattern of the anti-oxidation nano tungsten powder is as Figure 15 shown, and the phase composition is W + W2C; the SEM photo of the anti-oxidation nano tungsten powder is as Figure 16 shown, indicating that the morphology is very similar to that of the nano tungsten powder; the EDS element distribution of the anti-oxidation nano tungsten powder is as Figure 17 shown, indicating that the carbon element on the surface layer is evenly distributed. Combining with the phase composition in the XRD pattern, it shows that the tungsten carbide phase is evenly distributed on the surface of the nano tungsten powder and coats the nano tungsten powder; tested by a carbon and sulfur analyzer and a nitrogen and oxygen analyzer, the carbon content in the anti-oxidation nano tungsten powder is 1.57 wt%, and the oxygen content is 1.09 wt%.

[0086] 2. Oxidation tests and test results of the nano tungsten powder and anti-oxidation nano tungsten powder prepared in this example:

[0087] The nano tungsten powder and anti-oxidation nano tungsten powder prepared in this example were respectively subjected to oxidation experiments in oxygen using a single-temperature zone tube furnace. The XRD of the nano tungsten powder after oxidation at different temperatures is as Figure 18 (a) shown, and the XRD of the anti-oxidation nano tungsten powder after oxidation at different temperatures is as Figure 18 (b) shown. From Figure 18 (a), Figure 18 (b), it can be seen that the temperature at which the nano tungsten powder starts to be oxidized to WO3 is 250 °C, while the temperature at which the anti-oxidation nano tungsten powder starts to be oxidized to WO3 is 300 °C, and the temperature difference is 50 °C, indicating that the anti-oxidation property of the anti-oxidation nano tungsten powder is greatly improved compared to the nano tungsten powder.

[0088] Example 5

[0089] In this example, blue tungsten powder was used as the raw material to prepare anti-oxidation nano tungsten powder, and the process steps are as follows:

[0090] (1) Divide 20 g of blue tungsten powder into 4 equal parts, and evenly spread them on 4 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 2 mm, and then put them into a three-temperature zone tube furnace for reduction treatment with hydrogen to obtain nano tungsten powder. During the reduction treatment, the hydrogen flow rate is 400 mL / min, the temperature is 600 °C, and the holding time is 4 h;

[0091] (2) Place the nano tungsten powder obtained in step (1) in a glove box and manually grind it with a large mortar for 30 min to obtain completely dispersed nano tungsten powder;

[0092] (3) Divide the dispersed nano tungsten powder obtained in step (2) into 4 equal parts, and evenly spread them on 4 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 2 mm. Then put them into a three-temperature zone tube furnace and introduce CO gas to carry out carbonization treatment on the surface of the nano tungsten powder to obtain antioxidant nano tungsten powder. When carrying out carbonization treatment, the flow rate of CO is 800 mL / min, the temperature is 700 °C, and the holding time is 3 min.

[0093] Perform phase analysis on the antioxidant nano tungsten powder prepared in this example. The XRD pattern is as Figure 19 shown, and the phase composition is W + W2C; measured by a carbon-sulfur analyzer and a nitrogen-oxygen analyzer, the measured carbon content is 0.68 wt%, and the oxygen content is 1.17 wt%.

[0094] Example 6

[0095] In this example, using blue tungsten powder as raw material to prepare antioxidant nano tungsten powder, the technological steps are as follows:

[0096] (1) Divide 60 g of blue tungsten powder into 6 equal parts, and evenly spread them on 6 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 4 mm. Then put them into a three-temperature zone tube furnace and carry out reduction treatment with hydrogen to obtain nano tungsten powder. When carrying out reduction treatment, the hydrogen flow rate is 800 mL / min, the temperature is 550 °C, and the holding time is 12 h;

[0097] (2) Place the nano tungsten powder obtained in step (1) in a glove box and manually grind it with a large mortar for 90 min to obtain completely dispersed nano tungsten powder;

[0098] (3) Divide the dispersed nano tungsten powder obtained in step (2) into 6 equal parts, and evenly spread them on 6 corundum boats respectively. The laying thickness of the blue tungsten powder in each corundum boat is about 4 mm. Then put them into a three-temperature zone tube furnace and introduce CO gas to carry out carbonization treatment on the surface of the nano tungsten powder to obtain antioxidant nano tungsten powder. When carrying out carbonization treatment, the flow rate of CO is 400 mL / min, the temperature is 600 °C, and the holding time is 30 min.

[0099] Perform phase analysis on the antioxidant nano tungsten powder prepared in this example. The XRD pattern is as Figure 20 shown, and the phase composition is W + W2C; measured by a carbon-sulfur analyzer and a nitrogen-oxygen analyzer, the measured carbon content is 2.02 wt%, and the oxygen content is 1.30 wt%.

Claims

1. The antioxidant single-crystalline tungsten powder used as a fuel in tungsten-based delay composition is characterized in that Its microstructure is that the single-crystal tungsten powder is coated with tungsten carbide phase formed by carbonization of the single-crystal tungsten powder, and the amount of the tungsten carbide phase meets the antioxidant requirement; The technological steps of the preparation method are as follows: (1) Dissolve water-soluble ammonium metatungstate powder in deionized water to form a uniformly mixed ammonium metatungstate solution; (2) Perform spray drying treatment on the ammonium metatungstate solution obtained in step (1) to obtain spherical precursor powder; (3) Uniformly spread the precursor powder obtained in step (2) on a boat, and then put it into a sintering furnace for reduction treatment with hydrogen to obtain single-crystal tungsten powder. During the reduction treatment, the hydrogen flow rate is 400 mL / min to 800 mL / min, the temperature is 700 °C to 1100 °C, and the heat preservation time is 1 h to 3 h; (4) Continuously place the single-crystal tungsten powder obtained in step (3) on a boat, and then introduce gaseous carbon source CO into the sintering furnace to perform carbonization treatment on the surface of the single-crystal tungsten powder to obtain antioxidant single-crystal tungsten powder. During the carbonization treatment, the flow rate of CO is 400 mL / min to 800 mL / min, the temperature is 700 °C to 900 °C, and the heat preservation time is the time required when the carbon element content in the antioxidant single-crystal tungsten powder reaches 0.1 wt% to 3.0 wt%.

2. The antioxidant single-crystal tungsten powder used as a fuel in a tungsten-based delay composition according to claim 1, wherein In step (1), the mass ratio of the water-soluble ammonium metatungstate powder to deionized water is 1:5 to 20; in step (2), during the spray drying treatment, the inlet air temperature is controlled at 150 °C to 220 °C, and the feeding speed is controlled at 200 mL / h to 600 mL / h.

3. The antioxidant single crystal tungsten powder used as a fuel in a tungsten-based delay composition according to claim 1 or 2, characterized in that The laying thickness of the precursor powder or single-crystal tungsten powder in the boat is controlled at 2 mm to 4 mm.

4. The antioxidant nano-tungsten powder used as fuel in tungsten-based delay composition is characterized in that Its microstructure is that the nano-tungsten powder is coated with tungsten carbide phase formed by carbonization of the nano-tungsten powder, and the amount of the tungsten carbide phase meets the antioxidant requirement; The technological steps of the preparation method are as follows: (1) Uniformly spread blue tungsten powder on a boat, and then put it into a sintering furnace for reduction treatment with hydrogen to obtain nano-tungsten powder; during the reduction treatment, the hydrogen flow rate is 400 mL / min to 800 mL / min, the temperature is 500 °C to 700 °C, and the heat preservation time is 4 h to 12 h; (2) Grind the nano-tungsten powder obtained in step (1) into completely dispersed nano-tungsten powder under vacuum conditions or under inert gas protection; (3) Uniformly spread the dispersed nano-tungsten powder obtained in step (2) on a boat, and then put it into a sintering furnace to perform carbonization treatment on the surface of the nano-tungsten powder with gaseous carbon source CO to obtain antioxidant nano-tungsten powder. During the carbonization treatment, the flow rate of CO is 400 mL / min to 800 mL / min, the temperature is 600 °C to 800 °C, and the heat preservation time is the time required when the carbon element content in the antioxidant nano-tungsten powder reaches 0.1 wt% to 3.0 wt%.

5. The antioxidant nano-tungsten powder used as a fuel in tungsten-based delay compositions according to claim 4, characterized in that The laying thickness of the blue tungsten powder or nano-tungsten powder in the boat is controlled at 2 mm to 4 mm.

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