A method for testing the thermal decomposition temperature rise characteristics of explosive charge

Abstract

This invention specifically relates to a method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant charges. A DTA thermal analyzer is used to establish temperature difference-temperature curves for pyrotechnic propellants of different masses in loose packaging. The potential damage to the DTA analyzer during the testing process is used as an evaluation index to select the amount of pyrotechnic propellant to be tested to characterize its thermal decomposition temperature rise characteristics. The pyrotechnic propellant is then compressed using the specified compression parameters at the specified amount to obtain the test charge. A temperature difference-temperature curve is established using the DTA thermal analyzer at a heating rate not exceeding 5°C / min to determine whether a violent explosion occurs. The initial decomposition temperature, peak decomposition temperature, and peak temperature difference of the charge are obtained, and the thermal decomposition temperature rise characteristics of the pyrotechnic propellant charge are analyzed. This method has the advantages of closely approximating actual application conditions and providing highly accurate test results.

Description

Technical Field

[0001] This invention relates to the field of pyrotechnic agents and thermal analysis testing, specifically to a method for testing the thermal decomposition temperature rise characteristics of pyrotechnic agent columns. Background Technology

[0002] Compared to pyrotechnic powders, pyrotechnic charge pellets exhibit significant advantages in energy release control, safety, ease of operation, and compatibility with pyrotechnic devices. These advantages have led to widespread attention in numerous pyrotechnic applications. Researching the thermal decomposition temperature rise characteristics of pyrotechnic charge pellets is irreplaceable and crucial for ensuring safety during use, guaranteeing the reliability of pyrotechnic performance, meeting the specific needs of different application scenarios, and even promoting the development of pyrotechnics and related industries. Its importance is self-evident.

[0003] Currently, research on the thermal decomposition temperature rise characteristics of pyrotechnic agents mainly focuses on loosely packed powder materials, lacking direct studies on the thermal decomposition temperature rise characteristics of pyrotechnic agent charges. When pyrotechnic agent powder is in a loosely packed state, the spacing between particles is relatively large, and their interactions and energy transfer mechanisms differ significantly from those of charged charges. When a pyrotechnic agent undergoes thermal decomposition upon receiving external heat input, the internal particles are tightly compressed, resulting in a more ordered charge exhibiting temperature rise characteristics different from its loosely packed powder state. Therefore, relying solely on research findings on the thermal decomposition temperature rise characteristics of pyrotechnic agents in their loosely packed powder state is insufficient to provide a reliable and accurate reference for the temperature rise characteristics of pyrotechnic agent charges, thus hindering the development of a more solid theoretical basis and technical support for the rational use and safety assurance of pyrotechnic agent charges in various application scenarios. Summary of the Invention

[0004] This invention addresses the current lack of direct research on the thermal decomposition temperature rise characteristics of pyrotechnic propellant charges by providing a method for testing these characteristics. This invention is based on a differential thermal analyzer (DTA) and is used to determine the thermal decomposition temperature rise characteristics of pyrotechnic propellant charges. The method of this invention has the advantages of closely resembling the actual application conditions of the tested samples and providing highly accurate test results.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns, comprising the following steps:

[0006] (1) Screening of the amount of pyrotechnic agents to be tested in thermal decomposition

[0007] Based on the differential thermal analysis (DTA) test method, temperature difference-temperature curves of pyrotechnic agents of different masses in loose state were established using a DTA thermal analyzer. The temperature difference-temperature curves in loose state were used to determine whether pyrotechnic agents of different masses would damage the DTA thermal analyzer. The evaluation index was whether the test process would damage the DTA thermal analyzer and thus affect the normal conduct of subsequent tests. The amount of pyrotechnic agent to be tested was selected to characterize the thermal decomposition temperature rise characteristics of pyrotechnic agent columns.

[0008] (2) Pressing the test column of pyrotechnic agent

[0009] The pyrotechnic agent is compressed according to the actual pyrotechnic agent column compression parameters. The amount of pyrotechnic agent is the amount of pyrotechnic agent to be tested selected in step (1) to obtain the pyrotechnic agent column to be tested.

[0010] (3) Conduct thermal decomposition temperature rise characteristics test of pyrotechnic propellant columns.

[0011] A temperature difference-temperature curve was established using a DTA thermal analyzer at a heating rate of no more than 5 °C / min for the test pyrotechnic agent column to determine whether the column exploded violently. The initial decomposition temperature and peak decomposition temperature of the column that did not explode violently were obtained, as were the initial decomposition temperature and peak temperature of the column that exploded violently.

[0012] (4) Analyze the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns.

[0013] For propellant columns pressed under actual pressing parameters, the thermal decomposition temperature rise characteristics of the propellant columns are characterized by their initial decomposition temperature, peak decomposition temperature, and peak temperature difference. For a series of propellant columns formed under non-actual pressing parameters, the variation law between the initial decomposition temperature, peak decomposition temperature, and peak temperature difference of different columns is investigated, and the thermal decomposition temperature rise characteristics of the propellant columns are inferred.

[0014] The method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns of the present invention is carried out under specific working conditions. These specific working conditions are those existing in actual application scenarios, such as aerospace, military ammunition, and industrial blasting. For different application scenarios and different charge structure requirements, pyrotechnic propellants are compressed into columns with different structures under different pressing parameters.

[0015] As a further limitation of the technical solution of the present invention, the amount of the test substance in step (1) is divided into two categories: 1) If the loosely packed pyrotechnic agent with a mass equal to the actual mass of the pyrotechnic agent column does not damage the DTA thermal analyzer during the test, the amount of the test substance is the actual amount of the pyrotechnic agent column; 2) If the loosely packed pyrotechnic agent with a mass equal to the actual mass of the pyrotechnic agent column damages the DTA thermal analyzer during the test, the amount of the test substance is a series of amounts of the pyrotechnic agent column that will not damage the DTA thermal analyzer during the test and are less than the actual amount of the pyrotechnic agent column. At least one of the amounts in the series is infinitely close to the actual mass of the pyrotechnic agent column, and the series of amounts is not less than 3.

[0016] As a further limitation of the technical solution of the present invention, the test column in step (2) is divided into two categories: 1) If the pyrotechnic agent under the test amount can be pressed into shape under the actual pressing parameters and the size meets the sample testing requirements of the DTA thermal analyzer, the test column is a column pressed into shape under the actual pressing parameters; 2) If the pyrotechnic agent under the test amount cannot be pressed into shape under the actual pressing parameters, or the size of the pressed column does not meet the sample testing requirements of the DTA thermal analyzer, the test column is a series of columns pressed into shape under non-actual pressing parameters. At least one of the test columns in the series has a pressing parameter that is infinitely close to the actual pressing parameter of the pyrotechnic agent column, and the series of columns has no less than 3 types.

[0017] As a further limitation of the technical solution of the present invention, the evaluation criteria for whether the drug column in step (3) has exploded violently are: 1) if a clear explosion sound is emitted during the thermal decomposition of the drug column or the glass container holding the drug column is broken during the test, the drug column is considered to have exploded violently; 2) if no clear explosion sound is emitted during the thermal decomposition of the drug column and the glass container holding the drug column is not broken during the test, the drug column is considered not to have exploded violently.

[0018] As a further limitation of the technical solution of the present invention, the initial decomposition temperature in step (3) is the temperature corresponding to the intersection of the tangent at the maximum slope of the temperature difference-temperature curve during the rising stage and the baseline before the peak appears.

[0019] As a further limitation of the technical solution of the present invention, the decomposition peak temperature in step (3) is the temperature corresponding to the extreme value of the curve in the temperature difference-temperature curve of the explosive charge that has not undergone violent explosion, within the temperature range in which the corresponding peak appears.

[0020] As a further limitation of the technical solution of the present invention, the peak temperature of the temperature difference in step (3) is the temperature corresponding to the extreme value of the curve in the temperature difference-temperature curve of the explosive charge that occurs before the explosion, within the temperature range of the last peak before the explosion.

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

[0022] (1) Compared with other DTA testing methods, the method of the present invention increases the amount of test sample and improves the instrument response.

[0023] (2) The method of the present invention avoids misjudgment of the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns caused by the amount of test sample.

[0024] (3) The method of the present invention avoids misjudgment of the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns caused by insufficient packing of test samples in non-propellant column state, which prevents the smooth transfer of energy released by the reaction of pyrotechnic propellant.

[0025] (4) The method of the present invention is particularly suitable for testing the thermal decomposition temperature rise characteristics of pyrotechnic agents in actual production and operation. Attached Figure Description

[0026] Figure 1 This is the temperature difference-temperature curve of the drug column sample established in Example 1 of the present invention.

[0027] Figure 2 This is the temperature difference-temperature curve of the drug column sample established in Example 2 of the present invention.

[0028] Figure 3 This is the temperature difference-temperature curve of the drug column sample established in Example 3 of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. Example 1

[0030] A method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns under specific working conditions includes the following steps:

[0031] (1) First, temperature difference-temperature curves of RDX (rhexane) in loose state with different masses were established using a DTA thermal analyzer. The mass of the RDX column under specific operating conditions was 50 mg. The DTA thermal analyzer was not damaged during the test of the thermal decomposition temperature rise characteristics of RDX by gradually increasing the loose test amount from 10 mg to 50 mg. Therefore, 50 mg was selected as the test amount for the thermal decomposition temperature rise characteristics of this RDX column.

[0032] (2) Under this specific operating condition, 50 mg RDX needs to be compressed into a drug column with a diameter of 3.5 mm. After compressing 50 mg RDX under the RDX drug column compression parameters under this specific operating condition, a 3.5 mm diameter RDX drug column with good molding effect can be obtained. The size of this drug column meets the sample testing requirements of the DTA thermal analyzer. Therefore, this size drug column is determined as the RDX test drug column in the subsequent thermal decomposition temperature rise characteristic test.

[0033] (3) The temperature difference-temperature curve of the RDX test column at a heating rate of 5 ℃ / min was established using a DTA thermal analyzer. The curve is shown in Figure 1. Figure 1 As shown. During the test, the RDX propellant did not emit a clear explosion sound, nor did it cause the glass test tube containing the propellant to break; no violent explosion occurred.

[0034] (4) By Figure 1 It is known that the RDX column exhibits an endothermic peak and an exothermic peak at temperatures above 200 °C. The endothermic peak is the endothermic melting peak of RDX, and the exothermic peak is the exothermic decomposition peak of RDX. RDX decomposes and releases heat shortly after it begins to melt. The initial decomposition temperature of the RDX column is 209.92 °C, and the peak decomposition temperature is 219.66 °C. Example 2

[0035] A method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns under specific working conditions includes the following steps:

[0036] (1) First, temperature difference-temperature curves of loosely packed octogen (hereinafter referred to as HMX) of different masses were established using a DTA thermal analyzer. The mass of the HMX column under specific operating conditions was 50 mg. The DTA thermal analyzer was not damaged during the test of the thermal decomposition temperature rise characteristics of the loosely packed HMX column by gradually increasing the amount of HMX to be tested from 10 mg to 50 mg. Therefore, 50 mg was selected as the amount of HMX to be tested for the thermal decomposition temperature rise characteristics.

[0037] (2) Under this specific operating condition, 50 mg HMX needs to be compressed into a 4.0 mm diameter column. The 4.0 mm HMX column cannot meet the sample testing requirements of the DTA thermal analyzer. Therefore, columns with diameters of 2.5, 3.0, and 3.5 mm were tested. After compressing 50 mg HMX under the HMX column compression parameters under this specific operating condition, HMX columns with diameters of 2.5, 3.0, and 3.5 mm with good molding effect can be obtained. The dimensions of this series of columns can meet the sample testing requirements of the DTA thermal analyzer. Therefore, this series of columns was determined as the HMX test columns for subsequent thermal decomposition temperature rise characteristics testing.

[0038] (3) The temperature difference-temperature curve of the HMX test column at a heating rate of 5 ℃ / min was established using a DTA thermal analyzer. The curve is shown in Figure 1. Figure 2 As shown. During the test, the HMX propellant did not emit a clear explosion sound, nor did it cause the glass test tube containing the propellant to break; no violent explosion occurred.

[0039] (4) By Figure 2It is known that the HMX propellant column exhibits a decomposition exothermic peak at temperatures above 250 °C. The initial decomposition temperatures of the 2.5, 3.0, and 3.5 mm HMX propellant columns are 275.81, 275.68, and 275.66 °C, respectively, and the peak decomposition temperatures are 277.15, 276.90, and 276.58 °C, respectively. Changing the diameter of the HMX propellant column did not significantly alter its thermal decomposition process, initial decomposition temperature, or peak decomposition temperature. Therefore, it is speculated that the thermal decomposition temperature rise characteristics of the 4.0 mm diameter HMX propellant column are similar to those of the 2.5, 3.0, and 3.5 mm HMX propellant columns. Example 3

[0040] A method for testing the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns under specific working conditions includes the following steps:

[0041] (1) First, a temperature difference-temperature curve was established for lead stearate (LTNR) of different masses in loose state using a DTA thermal analyzer. The mass of the LTNR column under specific operating conditions was 30 mg. During the thermal decomposition temperature rise characteristic test of loose LTNR, which was gradually increased from 2 mg to 18.8 mg, it was found that loose LTNR would emit a clear explosion sound and cause the glass test tube containing the column to break, resulting in a violent explosion. When the LTNR test amount was 18.8 mg, the temperature sensor was severely deformed. In order to ensure that subsequent tests could be carried out normally and smoothly, 12.5, 15.0 and 18.8 mg were selected as the test amounts for the thermal decomposition temperature rise characteristics of this LTNR column.

[0042] (2) Under this specific operating condition, LTNR needs to be compressed into a cartridge with a diameter of 2.6 mm. After compressing 12.5, 15.0, and 18.8 mg LTNR under the LTNR cartridge compression parameters under this specific operating condition, LTNR cartridges with a diameter of 2.6 mm and good molding effect can be obtained. This cartridge size meets the sample testing requirements of the DTA thermal analyzer. Therefore, a series of cartridges of this size were selected as the LTNR test cartridges for subsequent thermal decomposition temperature rise characteristic tests.

[0043] (3) The temperature difference-temperature curve of the LTNR test column at a heating rate of 5 ℃ / min was established using a DTA thermal analyzer. The curve is shown in Figure 1. Figure 3 As shown. During the test, LTNR will emit a clear explosion sound and cause the glass test tube containing the propellant to shatter, resulting in a violent explosion.

[0044] (4) By Figure 3It is known that the LTNR pellet exhibits an endothermic peak and an exothermic peak at temperatures above 100 °C. The endothermic peak is the melting endothermic peak of the LTNR, and the exothermic peak is the decomposition exothermic peak of the LTNR. The LTNR pellet explodes at the moment the exothermic peak reaches its peak value, and the subsequent temperature difference-temperature curve can no longer reflect the thermal decomposition temperature rise characteristics of the LTNR pellet. The initial decomposition temperatures of 12.5, 15.0, and 18.8 mg LTNR pellets are 266.49, 264.90, and 265.26 °C, respectively, and the peak temperature difference temperatures are 267.95, 266.44, and 266.37 °C, respectively. Changing the LTNR pellet dosage did not significantly alter its thermal decomposition process, initial decomposition temperature, or peak temperature difference. Therefore, it is speculated that the thermal decomposition temperature rise characteristics of the 30 mg LTNR pellet are similar to those of the 12.5, 15.0, and 18.8 mg LTNR pellets.

[0045] The specific operating conditions described in the above embodiments represent actual application scenarios, such as aerospace, military ammunition, and industrial blasting. For different application scenarios and with varying charge structure requirements, pyrotechnic agents are compressed into propellant grains of different structures under different compression parameters. This invention aims to test the temperature rise characteristics of pyrotechnic agent propellant grains under all operating conditions. The testing principle is: when it is possible to completely simulate actual application conditions (including the actual charge quantity and propellant grain structure), direct testing is conducted; when it is not possible to completely simulate actual application conditions, the testing should be as close to the actual situation as possible, using data from testing propellant grains of different masses and structures to predict their temperature rise characteristics in actual applications.

Claims

1. A method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column, characterized in that, Includes the following steps: (1) Screening of the amount of pyrotechnic agents to be tested in thermal decomposition Based on the DTA test method, a temperature difference-temperature curve of pyrotechnic agents of different masses in loose state was established using a DTA thermal analyzer. The temperature difference-temperature curve of the loose state was used to determine whether pyrotechnic agents of different masses would damage the DTA thermal analyzer. The test quantity was selected to characterize the thermal decomposition temperature rise characteristics of pyrotechnic agents by using whether the test process would damage the DTA thermal analyzer as the evaluation index. (2) Pressing the test column of pyrotechnic agent The pyrotechnic agent is compressed according to the actual pyrotechnic agent column compression parameters. The amount of pyrotechnic agent is the amount of pyrotechnic agent to be tested selected in step (1) to obtain the pyrotechnic agent column to be tested. (3) Conduct thermal decomposition temperature rise characteristics test of pyrotechnic propellant columns. A temperature difference-temperature curve was established using a DTA thermal analyzer at a heating rate of no more than 5 °C / min for the test pyrotechnic agent column to determine whether the column exploded violently. The initial decomposition temperature and peak decomposition temperature of the column that did not explode violently were obtained, as were the initial decomposition temperature and peak temperature of the column that exploded violently. (4) Analyze the thermal decomposition temperature rise characteristics of pyrotechnic propellant columns. For propellant columns pressed under actual pressing parameters, the thermal decomposition temperature rise characteristics of the propellant columns are characterized by their initial decomposition temperature, peak decomposition temperature, and peak temperature difference. For a series of propellant columns formed under non-actual pressing parameters, the variation law between the initial decomposition temperature, peak decomposition temperature, and peak temperature difference of different columns is investigated, and the thermal decomposition temperature rise characteristics of the propellant columns are inferred.

2. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The quantity of the pyrotechnic agent to be tested in step (1) is divided into two categories: 1) If the loosely packed pyrotechnic agent with a mass equal to the actual mass of the pyrotechnic agent column does not damage the DTA thermal analyzer during the test, the quantity of the pyrotechnic agent to be tested is the actual quantity of the pyrotechnic agent column; 2) If the loosely packed pyrotechnic agent with a mass equal to the actual mass of the pyrotechnic agent column damages the DTA thermal analyzer during the test, the quantity of the pyrotechnic agent to be tested is a series of quantities that will not damage the DTA thermal analyzer during the test and are less than the actual quantity of the pyrotechnic agent column. At least one quantity in the series of quantities is infinitely close to the actual mass of the pyrotechnic agent column, and there are no less than 3 quantities in the series of quantities.

3. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The test columns in step (2) are divided into two categories: 1) If the pyrotechnic agent under the test quantity can be pressed into shape under the actual pressing parameters and the size meets the sample testing requirements of the DTA thermal analyzer, the test column is a column pressed into shape under the actual pressing parameters; 2) If the pyrotechnic agent under the test quantity cannot be pressed into shape under the actual pressing parameters, or the size of the pressed column does not meet the sample testing requirements of the DTA thermal analyzer, the test column is a series of columns pressed into shape under non-actual pressing parameters. At least one of the test columns in the series has a pressing parameter that is infinitely close to the actual pressing parameter of the pyrotechnic agent column. There are no less than 3 types of test columns in the series.

4. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The evaluation criteria for whether the drug column in step (3) has exploded violently are: 1) If a clear explosion sound is emitted during the thermal decomposition of the drug column or the glass container holding the drug column is broken during the test, the drug column is considered to have exploded violently; 2) If no clear explosion sound is emitted during the thermal decomposition of the drug column and the glass container holding the drug column is not broken during the test, the drug column is considered not to have exploded violently.

5. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The initial decomposition temperature in step (3) is the temperature corresponding to the intersection of the tangent at the maximum slope of the temperature difference-temperature curve during the rising phase and the baseline before the peak appears.

6. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The decomposition peak temperature in step (3) is the temperature corresponding to the extreme value of the curve within the temperature range where the corresponding peak appears in the temperature difference-temperature curve of the charge without violent explosion.

7. The method for testing the thermal decomposition temperature rise characteristics of a pyrotechnic agent column according to claim 1, characterized in that, The peak temperature of the temperature difference in step (3) is the temperature corresponding to the extreme value of the curve in the temperature difference-temperature curve of the explosive charge that is in the range of the last peak before the explosion.

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