Tungsten delay powder and preparation process thereof

Abstract

The invention discloses a tungsten delay powder and a preparation process thereof, and belongs to the field of energetic materials. The tungsten delay powder provided by the invention comprises a tungsten powder compound and potassium perchlorate, the tungsten powder compound comprises tungsten powder and barium chromate loaded on the surface of the tungsten powder; the mass ratio of the tungsten powder to the barium chromate to the potassium perchlorate is (30-40): (50-60): 10; according to the invention, the tungsten delay powder is prepared by adopting a dispersion charging mode under specific conditions, so that barium chromate can be loaded on the surface of tungsten powder in a more uniform mode to form a state that the tungsten powder is coated with barium chromate, a structure similar to a core (tungsten powder) and a shell (barium chromate) is presented, and the granularity and form of a tungsten powder compound can be well controlled; and finally, the delay time of the second-level delay powder as a final product can be effectively prolonged, so that the second-level delay powder has a good delay effect and good delay precision.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials, and more specifically, relates to a tungsten-based delayed-action drug and its preparation process. Background Technology

[0002] Delayed-detonation explosives are energetic materials that regulate the duration of ignition or detonation sequences in pyrotechnic devices through stable linear combustion, thereby delaying initiation or ignition. They have irreplaceable application value in military and civilian fields such as missile weapon systems, spacecraft, and conventional weapons. Delay accuracy (referring to the accuracy of the delay time) and delay effect are core indicators for evaluating the performance of delayed-detonation explosives, and their synergistic optimization is crucial to ensuring the reliable operation of pyrotechnic devices. If only the delay effect is guaranteed while accuracy is neglected, the precise control requirements under complex operating conditions cannot be met; conversely, if only accuracy is pursued at the expense of the delay effect, it will lead to deviated detonation timing, failing to meet specific duration requirements.

[0003] As a typical second-level delay agent, tungsten-based delay agents with an action time of 1-2 seconds are widely used in related fields due to their stable combustion characteristics. They are mainly composed of tungsten powder (W), potassium perchlorate (KClO4), and barium chromate (BaCrO4). However, the delay accuracy, delay effect, and safety of existing tungsten-based delay agents still need to be improved.

[0004] Existing research indicates that the delay accuracy, delay effect, and safety of delaying agents are closely related to the formulation parameters, raw material specifications, and preparation process of the delaying agent. Taking tungsten-based delaying agents as an example, higher tungsten powder content results in stronger ignition capability but shorter delay time; finer average particle size of tungsten powder leads to faster burning rate and better delay accuracy; furthermore, the uniformity of mixing of each component directly affects the consistency of combustion of the delaying agent; the performance of delaying agent products obtained from different mixing processes varies significantly, and traditional mechanical granulation processes not only have poor delay accuracy but also pose safety hazards due to mechanical friction generated during the process.

[0005] Therefore, in order to improve the product performance of delay-delay explosives, existing technologies have proposed a variety of solutions: Liu Zhanyang et al. (Liu Zhanyang, Li Xiangyou. Discussion on the delay accuracy control method of W-series delay explosives [J]. Explosive Materials, 2011, 40 (6): 32-33, 36) studied the control of delay accuracy by controlling the specific surface area of ​​tungsten powder and using a high-speed mixer to achieve uniform mixing, but it still uses the traditional mechanical process, which poses a safety hazard; Yi Qi et al. (Yi Qi, Jin-ying W, Xin Z, et al. Co-precipitation preparation and burning performance test of delaycomposition containing barium chromate [J]. Journal of Measurement Science & Instrumentation, 2018, 9(1) The S / BaCrO4 / KClO4 delay agent was prepared by co-precipitation, which yielded a delay agent with a higher ignition point, faster burning rate, and higher delay accuracy, and avoided the safety problems caused by traditional granulation processes. However, its particle size distribution is wide, and the delay accuracy still needs to be improved. Chinese invention applications with publication numbers CN119707601A and CN111718225A improve the delay accuracy of tungsten-based delay agents by adding burning rate regulators such as aluminum nitride and attapulgite powder, or by optimizing the preparation process of barium chromate to refine the particle size and improve the particle size distribution. However, they have high requirements for the strength and dispersibility of the regulators. This increases cost and process complexity; Chinese invention application CN117567224A discloses a delayed-release drug microcapsule based on sodium alginate and its preparation method, aiming to replace the traditional granulation process and solve the safety hazards caused by mechanical friction, but it does not optimize performance such as delay accuracy; Chinese invention application CN103497075A uses the water suspension method to prepare delayed-release drug molding powder, which solves the problems of uneven mixing of binders, uneven drug particles and poor flowability in manual mechanical granulation, thereby improving delay accuracy, but its process steps are complex and particle agglomeration is prone to occur during the process.

[0006] In summary, existing technologies have failed to overcome the synergistic bottleneck of "delay accuracy, delay effect, safety, and ease of scalability." Therefore, in response to the safety hazards, difficulty in balancing accuracy and delay effect, and complexity and difficulty in scalability of existing tungsten-based delay agent preparation processes, there is an urgent need to develop a novel tungsten-based delay agent and its preparation process. Summary of the Invention

[0007] 1. The problem to be solved To address the safety hazards and difficulties in balancing precision and delay effect in existing tungsten-based delay drug preparation processes, this invention provides a novel tungsten-based delay drug and its preparation process.

[0008] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a tungsten-based delay agent, the tungsten-based delay agent comprising a tungsten powder complex and potassium perchlorate; The tungsten powder composite includes tungsten powder and barium chromate loaded on the surface of the tungsten powder; The mass ratio of tungsten powder, barium chromate, and potassium perchlorate is (30~40):(50~60):10; The average particle size of the tungsten-based delay agent is 1~10 μm.

[0009] As a preferred embodiment of any technical solution in the first aspect of the present invention, the average particle size of the tungsten powder composite is 1~8μm; The average particle size of the potassium perchlorate is 5~10 μm.

[0010] As a preferred embodiment of any technical solution of the first aspect of the present invention, the tungsten powder composite is formed by the following process: in a reaction solution containing tungsten powder, barium ions, and chromate ions, barium ions react with chromate ions to generate barium chromate, and barium chromate is deposited on the surface of tungsten powder to obtain the tungsten powder composite.

[0011] The following reactions occur on the surface of tungsten powder: Ba 2+ +CrO4 2- →BaCrO4↓.

[0012] A second aspect of this invention provides a process for preparing a tungsten-based delayed-release drug, comprising the following steps: (1) Prepare a reaction solution containing tungsten powder, barium ions and chromate ions, carry out the reaction, and after the reaction is completed, separate the precipitate to obtain the tungsten powder complex. The molar ratio of barium ions: chromate ions: tungsten powder is (1.25~2.0):(1.25~2.0):1, and the average particle size of the tungsten powder is 1~5μm. The preparation of the reaction solution includes using a dispersed feeding method to contact and mix tungsten powder, barium ions, and chromate ions to obtain the reaction solution; (2) Mix the tungsten powder complex and potassium perchlorate evenly and sieve to obtain the tungsten-based delay drug; The mass ratio of the tungsten powder composite to potassium perchlorate is (85~92):10, and the average particle size of the potassium perchlorate is 5~10μm.

[0013] As a preferred embodiment of any technical solution in the second aspect of the present invention, the preparation of the reaction solution includes: preparing a suspension containing tungsten powder, a solution containing barium ions, and a solution containing chromate ions; mixing the solution containing barium ions and the solution containing chromate ions with the suspension containing tungsten powder in a dispersed feeding manner to obtain the reaction solution in step (1), wherein physical dispersion treatment is performed during the mixing process. Alternatively, prepare a suspension containing tungsten powder and barium ions, and a solution containing chromate ions; mix the solution containing chromate ions with the suspension containing tungsten powder and barium ions in a dispersed manner to obtain the reaction solution in step (1), with physical dispersion treatment during the mixing process; Alternatively, prepare a suspension containing tungsten powder and chromate ions, and a solution containing barium ions; mix the solution containing barium ions with the suspension containing tungsten powder and chromate ions in a dispersed manner to obtain the reaction solution in step (1), with physical dispersion treatment during the mixing process.

[0014] More preferably, in the solution containing barium ions or the suspension containing tungsten powder and barium ions, the concentration of barium ions is 0.6~1.0 mol / L.

[0015] More preferably, the concentration of chromate ions in the solution containing chromate ions or the suspension containing tungsten powder and chromate ions is 0.6~1.0 mol / L.

[0016] It should be noted that the concentrations of barium ions and chromate ions affect the yield and morphology of the tungsten powder complex. Higher concentrations result in faster barium chromate nucleation, smaller particle size, and higher yield, but also wider distribution and lower purity. Lower concentrations result in more regular barium chromate particles and higher purity, but slower nucleation, larger particles, and lower yield. The present invention selects a suitable solution concentration that balances purity, particle size, nucleation rate, and yield.

[0017] As a preferred embodiment of any technical solution in the second aspect of the present invention, the physical dispersion treatment includes any one or more of stirring, oscillation, and ultrasound.

[0018] It should be noted that excessively vigorous physical dispersion treatment can break up the already formed barium chromate particles, resulting in finer barium chromate particle size and potentially wider distribution; excessively slow physical dispersion treatment may lead to excessively high saturation of barium or chromate ions in the mixed solution, resulting in irregular crystallization and easy particle agglomeration.

[0019] Taking stirring as an example, the stirring speed is 400~600 r / min.

[0020] More preferably, the stirring speed is 400~500 r / min.

[0021] Further preferably, the stirring speed in the stirring state is 400 r / min.

[0022] As a preferred embodiment of any technical solution in the second aspect of the present invention, the method of dispersing feeding includes any one of the following: graded quantitative feeding method, atomized dispersion feeding method, and fluidized airflow feeding method.

[0023] As a preferred embodiment of any technical solution of the second aspect of the present invention, in step (1), the conditions for dispersing and feeding include: the gas atmosphere is an inert gas; The airflow velocity is 10~20 Nl / min; The feed rate is 3~5 mL / min.

[0024] The unit of airflow velocity, “Nl / min”, represents the standard liters per minute, indicating the volume of gas passing through per minute at 0°C and 1 standard atmosphere.

[0025] It should be noted that excessively high airflow velocity may result in small barium chromate particles with a wide particle size distribution, while excessively low velocity may lead to prolonged barium chromate formation time and decreased yield. Excessively fast feed rate will result in high supersaturation, small barium chromate size, large quantity, and low purity. Insufficient feed rate will result in insufficient nucleation, large barium chromate size, small quantity, and long cycle.

[0026] Further preferably, the airflow velocity is 15~20 Nl / min; the feed rate is 3~4 mL / min.

[0027] Further preferably, the airflow velocity is 15 Nl / min; the feed rate is 3 mL / min.

[0028] As a preferred embodiment of any technical solution in the second aspect of the present invention, the inert gas includes one or more of nitrogen, argon, and helium.

[0029] As a preferred embodiment of any technical solution in the second aspect of the present invention, in step (1), the conditions for preparing the reaction solution containing tungsten powder, barium ions, and chromate ions include: The reaction temperature is 25~45℃; Reaction time: 10-30 min; Physical dispersion treatment is carried out during the reaction; After the reaction is complete, continue physical dispersion treatment for 30-60 minutes.

[0030] A third aspect of the present invention provides a detonator or blasting device, wherein the detonator or blasting device contains a tungsten-based delay charge provided by any of the technical solutions of the first aspect of the present invention, or a tungsten-based delay charge prepared by any of the technical solutions of the second aspect of the present invention. 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The tungsten-based delay agent provided by the present invention can be loaded with barium chromate on the surface of tungsten powder in a more uniform manner, forming a state of barium chromate coating tungsten powder, presenting a structure similar to core (tungsten powder) and shell (barium chromate), which can effectively extend the delay time of the second-level delay agent and has a good delay effect. Meanwhile, the delay agent provided by this invention has good particle size uniformity and good delay accuracy.

[0031] (2) The preparation process of the tungsten-based delay agent provided by the present invention mixes a solution containing barium ions or chromate ions with a suspension containing tungsten powder (which may also contain barium ions or chromate ions) by dispersing the feed. This allows barium chromate to be loaded onto the surface of the tungsten powder in a more uniform manner, forming a state in which barium chromate coats the tungsten powder, presenting a structure similar to a core (tungsten powder) and a shell (barium chromate). It can also effectively control the particle size and morphology of the tungsten powder composite. Ultimately, it can effectively extend the delay time of the final product, the second-level delay agent, so that it has a good delay effect and good delay accuracy.

[0032] (3) The preparation process of the tungsten-based delay agent provided by the present invention adopts a dispersed feeding method. Under an inert gas atmosphere, a solution containing barium ions or chromate ions is introduced into a suspension containing tungsten powder (which may also contain barium ions or chromate ions) in the form of mist droplets. The coating agent (barium chromate) is precipitated by means of antisolvent action and uniformly coated on the surface of tungsten powder, avoiding the agglomeration of barium chromate particles. Combined with the effect of suitable reaction temperature and physical dispersion treatment, agglomeration is avoided and the uniformity of the formed barium chromate particle size is ensured, which significantly enhances the consistency of the tungsten powder complex and thus improves the delay accuracy of the tungsten-based delay agent.

[0033] (4) The preparation process of the tungsten-based delayed drug provided by the present invention forms the tungsten powder complex in the liquid phase. The granulation process is not subjected to any physical or mechanical action, which avoids the safety hazards caused by physical extrusion and friction between the drug and the granulator in the traditional granulation process, and has better safety.

[0034] (5) The preparation process of the tungsten-based delayed drug provided by the present invention uses simple equipment and steps, and only requires control of the feed rate, stirring rate, air flow rate and solution concentration, which is easy to scale up production. Attached Figure Description

[0035] Figure 1 Here is a SEM image of the raw material tungsten powder; Figure 2 Here is a SEM image of BaCrO4 in Comparative Example 6; Figure 3 Here is a SEM image of W / BaCrO4 from Example 1; Figure 4 EDS diagram of W / BaCrO4 in Example 1; Figure 5 The XRD patterns are shown for BaCrO4 in Comparative Example 6, W / BaCrO4 in Example 1, and W / BaCrO4 / KClO4. Figure 6 The TG curves of the tungsten-based delayed-release drugs in Example 1 and Comparative Example 4 are shown. Figure 7 The DSC curves are for the tungsten-based delayed-release drugs in Example 1 and Comparative Example 4. Detailed Implementation

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0038] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0039] In this document, the endpoints and any values ​​of the disclosed ranges are not limited to the precise ranges or values, which should be understood to include values ​​close to those ranges or values. For numerical ranges, one or more new numerical ranges can be obtained by combining the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges with individual point values, and individual point values ​​with each other, and these numerical ranges should be considered as specifically disclosed herein. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein include both singular and plural indicators. Numerical ranges expressed by endpoints include all numerical values ​​and fractions within the corresponding range, as well as the expressed endpoints, unless the context clearly indicates otherwise.

[0040] In this article, references to “substance” are references to at least one of the substance and its equivalents.

[0041] In this paper, precision is defined as: , in, This represents the maximum burning rate at that temperature. This represents the minimum burning rate at that temperature. This represents the average burning rate at that temperature.

[0042] When an item is described using the combined terms “...and / or ...", the description should be understood to include any one of the listed items and all combinations thereof.

[0043] The present invention will be described below through specific embodiments to make the technical solutions of the present invention easier to understand and master. However, the present invention is not limited thereto, and the described embodiments are only some embodiments of the present invention, not all embodiments. Therefore, they do not limit the present invention in any way. Any non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are all within the protection scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0044] Raw materials and their sources Tungsten powder: with an average particle size of 3 μm, purchased from Nanjing University of Science and Technology Chemical Engineering Co., Ltd. Potassium perchlorate: average particle size 10 μm, purchased from Nanjing University of Science and Technology Chemical Engineering Co., Ltd.; Barium chromate (used in Comparative Example 4): with an average particle size of 1 μm, purchased from Nanjing University of Science and Technology Chemical Engineering Co., Ltd.

[0045] Accuracy test (1) The prepared tungsten-based delayed drug is loaded into the pressing mold and pressed, and the accuracy is tested.

[0046] The mold used for pressing the medicine is a stainless steel mold, and the tube shell is made of 2A12 aluminum alloy with the following specifications: inner diameter 3.50 mm, outer diameter 6.5 mm, and length 16.5 mm.

[0047] The delay drug is injected in four stages, with each stage containing 110 mg of the drug; the input and output stages contain zirconium lead oxide ignition drug, each containing 60 mg.

[0048] (2) Precision (S) is defined as:

[0049] in, This represents the maximum burning rate at that temperature. This represents the minimum burning rate at that temperature. This represents the average burning rate at that temperature.

[0050] Example 1 1. Preparation of tungsten-based delay drugs (1) Preparation of tungsten powder composite 1-1) Prepare a suspension containing tungsten powder and barium ions (denoted as precursor solution 1): Add 3.43 g tungsten powder, 6.656 g barium chloride, 10 mL water and 30 mL ethanol to an Erlenmeyer flask; the concentration of barium chloride at this point is 0.8 mol / L. 1-2) Prepare a solution containing chromate ions (denoted as precursor solution 2). Add 4.192g of sodium chromate, 10 mL of water, and 10 mL of ethanol to a small beaker and mix thoroughly to dissolve; at this point, the concentration of sodium chromate is 0.8 mol / L.

[0051] 1-3) Reaction The conical flask was fixed in a water bath at 45°C and stirred for 20 minutes at a speed of 400 r / min to fully mix the substance (precursor solution 1) in the flask. Subsequently, the precursor solution 2 was sprayed into the precursor solution 1 under stirring in the form of atomized droplets using a dispersed feeding method. The gas atmosphere used for the spraying was nitrogen, and the gas flow rate was 15 Nl / min, corresponding to a feed rate of 3 mL / min for the precursor solution 2. At this point, the molar ratio of barium ions: chromate ions: tungsten powder in the reaction solution is 1.72:1.72:1; Continue stirring the solution (400 r / min) and keep it at 45℃ for 10 min. Then remove the conical flask, stop heating, allow it to cool naturally, and continue stirring for 30 minutes to allow the barium chromate to precipitate completely. The mixture was filtered, the filter material was repeatedly washed with distilled water, and dried in an oven at 45°C to obtain 10.25 g of product, which was a tungsten powder complex (denoted as W / BaCrO4), in which the amount of BaCrO4 was 6.86 g (see Comparative Example 6).

[0052] (2) The W / BaCrO4 obtained in step (1) is granulated so that all particles pass through a 100-mesh standard sieve. The material on the sieve needs to be crushed until it passes through completely (caking may occur during the drying process). This process is repeated three times. 1.14 g of potassium perchlorate is added and mixed evenly on paper. After it is observed to be uniform by the naked eye, it is passed through a 100-mesh sieve eight times (the main purpose is to ensure thorough mixing) to obtain the tungsten-based delay agent (denoted as W / BaCrO4 / KClO4, with an average particle size of approximately 3.956 μm). The mass ratio of W / BaCrO4 to potassium perchlorate is 89.9:10, and the mass ratio of tungsten powder, barium chromate, and potassium perchlorate is approximately 30.1:59.8:10.

[0053] 2. Accuracy Testing The accuracy of the tungsten-based delay agent obtained in step (2) was tested, and the results are shown in Table 1: Table 1. Precision testing of tungsten-based delay drugs in Example 1

[0054] In the table, △L represents the length of the tungsten-based delay charge combustion, △T represents the combustion time of the tungsten-based delay charge combustion, v represents the combustion rate (burning speed), S represents the precision, and numbers 1 to 10 represent 10 sets of parallel experiments, thus providing 10 sets of data. It is 1.96. It is 1.83. The value is 1.8810; the calculated precision is, for example: .

[0055] Examples 2 to Comparative Examples 3 1. Preparation of tungsten-based delay drugs To verify the optimal conditions for realizing the present invention, Examples 2 to 3 employed orthogonal experimental design to study the changes in the concentration of barium chloride in precursor solution 1 (step 1-1), the concentration of sodium chromate in precursor solution 2 (step 1-2), and the airflow velocity, feed rate, and stirring speed in steps 1-3). The corresponding parameters are shown in Table 2. Table 2 Parameter table for Examples 2 to Comparative Examples 3

[0056] Note: The solvents in precursor solution 1 and precursor solution 2 are the same as those in Example 1.

[0057] 2. Accuracy Testing The tungsten-based delay agents obtained in Table 2 were subjected to accuracy testing using the same methods and conditions as in Example 1. The results are shown in Table 3. Table 3. Precision testing of tungsten-based delay agents in Examples 2 to Comparative Examples 3.

[0058] Comparative Example 4 1. Preparation of tungsten-based delay drugs Tungsten-based delay agents were prepared by hand mixing and sieving. 3 g of tungsten powder, 6 g of barium chromate, and 1 g of potassium perchlorate were weighed, mixed evenly on paper, and after being observed to be uniform by the naked eye, the mixture was passed through a 100-mesh sieve eight times. After sieving, the mixture was tested for accuracy.

[0059] 2. Accuracy Testing The tungsten-based delay agent obtained in this comparative example was subjected to accuracy testing under the same methods and conditions as in Example 1. The results are shown in Table 4. Table 4. Accuracy test of tungsten-based delaying agents in Comparative Example 4

[0060] Comparative Example 5 1. Preparation of tungsten-based delay drugs by co-precipitation method (1) Preparation of tungsten powder composite 1-1) Prepare a suspension containing tungsten powder and barium ions (denoted as precursor solution 1): Add 3.51 g tungsten powder, 6.656 g barium chloride, 10 mL water and 30 mL ethanol to a 100 mL beaker as precursor solution 1; at this time, the molar ratio of barium chloride to tungsten powder is 1.68:1, and the concentration of barium chloride is 0.8 mol / L. 1-2) Prepare a solution containing chromate ions (denoted as precursor solution 2). Add 4.192 g of sodium chromate, 10 mL of water, and 10 mL of ethanol to a 50 mL beaker as precursor solution 2, and mix thoroughly to dissolve; at this point, the concentration of sodium chromate is 0.8 mol / L.

[0061] 1-3) Reaction Fix a 100 mL beaker in a 45°C water bath and stir for 20 min at a speed of 400 r / min to thoroughly mix the substance (precursor solution 1) in the flask. Precursor solution 2 was added dropwise to precursor solution 1 while stirring. At this time, the molar ratio of barium ions: chromate ions: tungsten powder in the reaction solution was 1.68:1.68:1. After adding the solution dropwise, continue stirring (400 r / min) and keep the temperature (45℃) for 10 min. Then remove the beaker, stop heating, allow it to cool naturally, and continue stirring for 30 minutes to allow the barium chromate to precipitate completely. The mixture was filtered, the filter material was repeatedly rinsed with distilled water, and then dried in an oven at 45°C. 10.54 g of product was obtained, which was a tungsten powder complex obtained by the co-precipitation method.

[0062] (2) The tungsten powder complex obtained in step (1) is granulated so that all particles pass through a 100-mesh standard sieve. The material remaining on the sieve needs to be crushed until it passes through completely. This process is repeated three times. 1.17 g of potassium perchlorate is added and mixed evenly on paper. After the mixture is observed to be uniform by the naked eye, it is passed through a 100-mesh sieve eight times to obtain the tungsten-based delay agent. The mass ratio of W / BaCrO4 to potassium perchlorate is 90.09:10, and the mass ratio of tungsten powder, barium chromate, and potassium perchlorate is approximately 29.97:60.03:10.

[0063] 2. Accuracy Testing The accuracy of the tungsten-based delay agent obtained in step 3 was tested, and the results are shown in Table 4: Table 4. Accuracy Test of Tungsten-Based Delayed-Release Drugs in Comparative Example 5

[0064] Comparing Examples 1-6 and Comparative Example 4, the results are shown in Tables 1-3. The tungsten-based delay agent prepared by the process provided by the present invention has good precision. The precision values ​​of Examples 1-6 are all less than 5.5%, which is better than the precision of the tungsten-based delay agent obtained by the method in Comparative Example 4. At the same time, the burning speed of the tungsten-based delay agent in Comparative Example 4 is about 5.4 mm / s, which is fast and has poor delay effect, and cannot meet the requirements of second-level delay agents. However, Examples 1-6, which use the preparation process of the present invention, and even Comparative Examples 1-3 with unsatisfactory precision, have a burning speed of about 2 mm / s, which can achieve a better delay effect.

[0065] Comparative Example 5 is a tungsten-based delay agent prepared by an existing co-precipitation method. Compared with Comparative Example 4, it has a certain delay effect, but its accuracy is not good. Comparing the accuracy test results of the tungsten-based delay agents in Example 1 and Comparative Example 5, it can be seen that under the same conditions, the accuracy of the tungsten-based delay agent prepared by the co-precipitation method is 7.55%, while the accuracy of the tungsten-based delay agent prepared by the dispersion feeding method (spray) of the present invention is 3.46%. This shows that the preparation process of the tungsten-based delay agent provided by the present invention has a significant advantage in accuracy compared with the co-precipitation method. Further analysis of Tables 1 and 2 shows that the concentrations of barium chloride in precursor solution 1, sodium chromate in precursor solution 2, and the gas flow rate, feed rate, and stirring speed in steps 1-3) all affect the performance of the final tungsten-based delay agent. The tungsten-based delay agent prepared in Example 1 has the highest precision, i.e., the optimal conditions are achieved when the concentrations of barium chloride and sodium chromate are 0.8 mol / L, the feed rate is 3 mL / min, the stirring speed is 400 r / min, and the gas flow rate is 15 Nl / min in steps 1-3).

[0066] Comparative Example 6 The only differences between this comparative example and Example 1 are: ① no tungsten powder is added in step 1-1), and the product obtained in step (1) of this comparative example is BaCrO4 prepared by dispersion feeding method (spray); ② step (2) is not performed. In this comparative example, the mass of BaCrO4 obtained is 6.86 g. This comparative example is used to verify the structural characteristics of W / BaCrO4 prepared in Example 1.

[0067] Test Example 1 To further verify that the tungsten-based delay drug obtained by the preparation process of the tungsten-based delay drug provided by the present invention has a similar core-shell structure, the BaCrO4 obtained in Comparative Example 6, the W / BaCrO4 obtained in Example 1, and the W / BaCrO4 / KClO4 were characterized by SEM, EDS and XRD.

[0068] Figure 1 The image shows a SEM image of the raw tungsten powder, which is spherical with a particle size of approximately 3 μm. Figure 2 The image shows a SEM image of BaCrO4 in Comparative Example 6. It is rod-shaped with a particle size of approximately 500 nm. Figure 3 The image shows a SEM image of W / BaCrO4 from Example 1. Stacked nano-sized rod-shaped particles, with a particle size as small as 500 nm, appear on the surface of the tungsten powder. The coated tungsten powder was characterized using EDS elemental analysis built into the scanning electron microscope. The analyzed elements were tungsten, chromium, and barium. The characterization results are shown in [Figure 1]. Figure 4 It should be that the barium chromate nanoparticles are coated on the surface of the tungsten powder, forming a tungsten powder composite with a core-shell structure, where the tungsten powder is the core and the barium chromate is the shell.

[0069] Figure 5The XRD patterns of BaCrO4 in Comparative Example 6, W / BaCrO4 and W / BaCrO4 / KClO4 in Example 1 are shown. The characteristic peaks corresponding to barium chromate (22.33°, 24.20°, 25.21°, 26.14°, 28.10°, 30.81°, 32.29° and 41.85°), the characteristic peaks corresponding to tungsten powder (40.14°, 58.17° and 73.10°), and the characteristic peaks corresponding to potassium perchlorate (22.86°, 25.21° and 28.10°) indicate that BaCrO4 was formed on the W surface.

[0070] Test Example 2 To further verify the thermal stability of the tungsten-based delay drug obtained using the preparation process of the tungsten-based delay drug provided by the present invention, thermogravimetric-differential scanning calorimetry (TG-DSC) was used to test the tungsten-based delay drug obtained in Example 1 and the tungsten-based delay drug in Comparative Example 4.

[0071] First, air was selected as the atmosphere, and the heating rate was 10℃ / min. The TG-DSC spectrum was obtained as follows: Figure 6 , Figure 7 As shown. Among them, Figure 7 DSC curve: In the DSC curve of Comparative Example 4, 301℃ is the reaction peak of the pre-ignition reaction, and 475℃ is the main reaction peak, at which point most of the reaction is completed.

[0072] In the DSC curve of Example 1, the pre-ignition reaction of the delay drug system is unaffected, and the reaction peak remains at 301°C. As the temperature continues to rise, the main reaction begins, with a peak temperature of 483°C, indicating a certain degree of delay. This suggests that the stability of the tungsten-based delay drug prepared in this invention is improved to a certain extent.

[0073] Figure 6 The TG curve of tungsten-based delaying agents in air: As can be seen from the curves, when the tungsten-based delay agent in Comparative Example 4 undergoes a pre-ignition reaction at 301℃, there is no significant weight gain, only a slight increase in the curve. This indicates that at this point, the reaction in the tungsten-based delay agent system is mainly between the combustible agent and the oxidant. When the temperature rises to 475℃, as the main reaction proceeds, the TG curve first decreases and then increases. This is because in the initial stage of the reaction, potassium perchlorate decomposes to produce oxygen, and then oxygen from the air participates, oxidizing all the tungsten powder, leading to the subsequent weight gain.

[0074] The TG curve of the tungsten-based delay drug prepared in Example 1 is not significantly different from that prepared by the ordinary hand mixing method (Comparative Example 4), indicating that the tungsten-based delay drug prepared in this invention has good thermal stability.

Claims

1. A tungsten-based delay composition, characterized by, The tungsten-based delay composition comprises a tungsten powder compound and potassium perchlorate; The tungsten powder compound comprises tungsten powder and barium chromate loaded on the surface of the tungsten powder; The mass ratio of the tungsten powder, barium chromate and potassium perchlorate is (30-40):(50-60):10; The average particle size of the tungsten-based delay composition is 1-10 μm.

2. The tungsten-based delay composition of claim 1, wherein The average particle size of the tungsten powder compound is 1-8 μm; The average particle size of the potassium perchlorate is 5-10 μm.

3. The tungsten-based delay composition according to claim 1 or 2, characterized in that, The tungsten powder compound is formed by the following process: in a reaction solution containing tungsten powder, barium ions and chromate ions, the barium ions react with the chromate ions to form barium chromate, and the barium chromate is deposited on the surface of the tungsten powder, thereby obtaining the tungsten powder compound.

4. A process for the preparation of a tungsten-based delay composition, characterized in that, The process comprises the following steps: (1) preparing a reaction solution containing tungsten powder, barium ions and chromate ions, carrying out a reaction, and separating the precipitate after the reaction to obtain the tungsten powder compound; The molar ratio of the barium ions:chromate ions:tungsten powder is (1.25-2.0):(1.25-2.0):1, and the average particle size of the tungsten powder is 1-5 μm; The preparation of the reaction solution comprises contacting and mixing the tungsten powder, barium ions and chromate ions in a dispersed feeding manner to obtain the reaction solution; (2) mixing the tungsten powder compound and potassium perchlorate uniformly and sieving to obtain the tungsten-based delay composition; The mass ratio of the tungsten powder compound and potassium perchlorate is (85-92):10, and the average particle size of the potassium perchlorate is 5-10 μm.

5. The process for preparing a tungsten-based delay composition according to claim 4, characterized in that, The preparation of the reaction solution comprises: preparing a suspension containing tungsten powder, a solution containing barium ions and a solution containing chromate ions; mixing the solution containing barium ions and the solution containing chromate ions in a dispersed feeding manner with the suspension containing tungsten powder to obtain the reaction solution in step (1), and accompanying physical dispersion treatment during the mixing process; Alternatively, a suspension containing tungsten powder and barium ions and a solution containing chromate ions are prepared; the solution containing chromate ions is mixed in a dispersed feeding manner with the suspension containing tungsten powder and barium ions to obtain the reaction solution in step (1), and accompanying physical dispersion treatment during the mixing process; Alternatively, a suspension containing tungsten powder and chromate ions and a solution containing barium ions are prepared; the solution containing barium ions is mixed in a dispersed feeding manner with the suspension containing tungsten powder and chromate ions to obtain the reaction solution in step (1), and accompanying physical dispersion treatment during the mixing process.

6. The process for preparing a tungsten-based delay composition according to claim 5, characterized in that, The physical dispersion treatment comprises any one or more of stirring, oscillation and ultrasonic treatment.

7. The process for the preparation of a tungsten-based delay composition according to any one of claims 4 to 6, characterized in that, The dispersed feeding manner comprises any one of staged quantitative feeding, atomization dispersed feeding and fluidized gas flow feeding.

8. The process for preparing a tungsten-based delay composition according to any one of claims 4 to 6, characterized in that, In step (1), the conditions for the dispersed feeding include: the gas atmosphere is inert gas; The gas flow rate is 10-20 Nl / min; The feeding speed is 3-5 mL / min.

9. The preparation process of the tungsten-based delay composition according to any one of claims 4-6, characterized in that, In step (1), the conditions for preparing the reaction solution containing tungsten powder, barium ions and chromate ions and carrying out a reaction include: The reaction temperature is 25-45℃; The reaction time is 10-30 min; The physical dispersion treatment is continued for 30 to 60 minutes after the reaction. The physical dispersion treatment is continued for 30 to 60 minutes after the reaction.

10. A detonator or blasting device containing the tungsten delay composition according to any one of claims 1 to 3, or prepared by the process according to any one of claims 4 to 9.

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