Method for measuring the combustion heat release rate of an energetic material

Abstract

The application discloses a kind of energetic material combustion heat release rate determination methods.The disclosed method includes the heat capacity of the heat system of oxygen bomb calorimeter is obtained by calibrating heat system E ;The oxygen bomb calorimeter after calibration is used to determine the combustion heat release of the energetic material to be measured with mass m Grams, record the water temperature data of the water where the oxygen bomb calorimeter is located after ignition, obtain the change curve T-t of water temperature T and time t;The curve T-t is first-order differentiated to obtain the (dT / dt)-t curve, and the peak value of the (dT / dt)-t curve is obtained;Then calculate the maximum heat release rate of the energetic material to be measured.The application develops a new test function on the basis of traditional calorimeter principle, provides a method for determining the combustion heat release rate of energetic material based on oxygen bomb calorimeter, can obtain more energetic material energy release data information, and provides technical support for the application research of energetic material in propellant.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, specifically relating to a method for determining the combustion heat release rate of energetic materials based on an oxygen bomb calorimeter. Background Technology

[0002] Energetic materials are substances that can release a large amount of energy and gas through chemical reactions after receiving certain external stimuli. Their energy release characteristics directly affect the selection and design of propellant formulations, and thus affect the energy characteristics of solid propellants such as specific impulse, heat of explosion, and characteristic velocity.

[0003] The oxygen bomb calorimeter mainly consists of an oxygen bomb, an inner cylinder, an outer cylinder, a stirrer, and a calorimeter. Its testing principle involves placing the sample into the oxygen bomb, filling it with oxygen at a certain pressure, and allowing the sample to burn completely in the oxygen environment. The released heat is transferred to the water medium through the oxygen bomb, causing a temperature rise. By measuring the temperature rise of the water, the heat of combustion is calculated based on the specific heat capacity of the calorimeter system. Researchers have conducted studies on the effects of various sample processing methods and experimental parameters on the characteristics of energetic materials, achieving a basic determination of the heat of combustion in energetic materials. However, further exploration of the combustion process has not been conducted. The application of the oxygen bomb calorimeter in energetic materials is currently limited to obtaining only the heat of combustion parameters, and its testing applications require further development. Summary of the Invention

[0004] In view of the defects or deficiencies of the prior art, the present invention provides a method for measuring the combustion heat release rate of energetic materials.

[0005] Therefore, the method for determining the combustion heat release rate of energetic materials provided by the present invention uses an oxygen bomb calorimeter to determine the combustion heat release rate of energetic materials, and the method includes the following steps:

[0006] S1, calibrate the calorimetric system of the oxygen bomb calorimeter to obtain the heat capacity of the calorimetric system. E The unit is J / ℃; S2, using a calibrated oxygen bomb calorimeter, for a mass of... m The test energetic material was subjected to combustion exothermic measurement. Oxygen was introduced during the measurement. After ignition, the water temperature of the water environment in which the oxygen bomb calorimeter was located was recorded to obtain the curve Tt of water temperature T versus time t. The test energetic material was either a solid energetic material or a liquid energetic material. For liquid energetic materials, a combustible capsule pretreatment was performed before the test. S3, perform the first derivative of the curve Tt to obtain the (dT / dt)-t curve, and obtain the peak value of the (dT / dt)-t curve. ; S4, the maximum exothermic rate of the energetic material under test is calculated using equation (1). : (1).

[0007] An alternative is to calibrate the calorimetric system of the oxygen bomb calorimeter using benzoic acid as a standard reference.

[0008] An alternative approach is to calibrate the calorimetric system of the oxygen bomb calorimeter multiple times to obtain multiple calibrated values ​​of the heat capacity of the calorimetric system. E＇ Heat capacity of the calorimetric system E Select several calibration values ​​with a range not exceeding 40 J / ℃. E＇ The average value.

[0009] An alternative solution is that the aforementioned m The value is 0.5~1 g.

[0010] Alternatively, the oxygen filling pressure can be 1.5~3.5 MPa.

[0011] An alternative approach is to smooth the Tt curve before performing S3; and to smooth the (dT / dt)-t curve before obtaining the peak value of the (dT / dt)-t curve. .

[0012] An alternative approach is to use a three-point Savitzky-Golay smoothing method for the smoothing process.

[0013] An alternative approach is to utilize the heat Q released by the combustion of energetic materials and the maximum heat release rate of the energetic materials. Characterize the energy release of energetic materials; The maximum heat release rate of the energetic material Obtained using the method described above; The heat Q released by the combustion of the energetic material is obtained using the above S1 and S2 and equation (2): (2) This refers to the final water temperature after ignition during the S2 test. The water temperature before ignition during the S2 test.

[0014] An alternative approach is to have the same or a difference of less than 1% in the calorific value of the various energetic materials; the energy release characteristics of the various energetic materials are evaluated using the above method, and the larger the maximum heat release rate, the more violent the reaction of the corresponding material.

[0015] An alternative approach is that the multiple energetic materials are the same energetic material from different production batches.

[0016] This invention utilizes an oxygen bomb calorimeter to ignite and burn energetic materials. During the process, the change in heat released by the combustion reaction per unit mass of energetic material is directly proportional to the change in water temperature. The heat release rate curve of the energetic material combustion process can be calculated through the water temperature change rate-time curve, and this can be used to further characterize the energy release effect of the energetic material.

[0017] Compared with other existing reaction exothermic testing methods (such as DSC), this invention characterizes the exothermic energy release under ignition and combustion reaction conditions, which is closer to the actual operating conditions and obtains more multidimensional data information, providing a more comprehensive understanding of the energy release during the combustion process of energetic materials; the test can be performed using existing instruments, making it simple to operate and highly scalable. Attached Figure Description

[0018] Figure 1 The dT / dt-t curves are for several energetic plasticizers in Example 1 of this invention; Figure 2 For the comparison of data before and after pretreatment of liquid energetic materials in the comparative example of this invention, A: Extreme difference in combustion energy release, B: Extreme difference in maximum heat release rate; Figure 3 The dT / dt-t curves are for several elemental and composite explosives in Example 2 of this invention. Figure 4 These are the dT / dt-t curves of different batches of HMX in Embodiment 3 of the present invention. Detailed Implementation

[0019] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0020] The present invention will be further described in detail below through specific embodiments. However, it should be noted that the present invention is not limited thereto, and all technologies implemented according to the present invention are within the scope of protection of the present invention. In all embodiments of the present invention, an IKA C6000 oxygen bomb calorimeter was used for measurement.

[0021] Example 1: This embodiment uses the method of the present invention to test the combustion heat release rate and characterize the energy release characteristics of several different types of liquid energetic plasticizers shown in Table 1. The specific method includes the following steps: The calorimetric system of the oxygen bomb calorimeter was calibrated multiple times using benzoic acid. The average of five calibration values ​​with a range not exceeding 40 J / ℃ was taken as the system's heat capacity. E =8045 J / ℃.

[0022] Weigh approximately 0.5 g (accurate to 0.0001 g) of the liquid energetic plasticizers shown in Table 1, and use a pipette to transfer the sample into a combustible capsule to obtain the combustion sample to be tested. The combustion sample to be tested was placed in the crucible of an oxygen bomb calorimeter. Oxygen was slowly introduced into the oxygen bomb calorimeter at 2.8 MPa. The oxygen bomb calorimeter was then placed in a certain amount of water, and the sample was ignited to burn in the calorimeter. Time-water temperature data were collected to obtain the water temperature-time curve Tt. The Tt curve was then processed using Origin data processing software to perform first-order differentiation and smoothing to obtain the (dT / dt)-t curve. Figure 1 As shown), the maximum combustion heat release rate is then calculated using equations (1) and (2). v max The heat Q released by combustion is shown in Table 1.

[0023] Table 1 Results of combustion exothermic rates of several energetic plasticizers

[0024] As shown in Table 1, the three energetic plasticizers release energy during combustion. Q The (J / g) conditions vary greatly, with the heat release order being BUNENA > DIANP > TMETN. The maximum heat release rate is consistent with the heat release order, being BUNENA > DIANP > TMETN, indicating that BUNENA not only has a high calorific value but also releases energy quickly, resulting in the most vigorous reaction.

[0025] Comparative example: The difference between this comparative example and Example 1 is that the TMETN and DIANP test samples were directly added to the crucible of the calorimetric bomb without pretreatment, and multiple tests were performed. The energy release from each combustion was then statistically analyzed. Q and multiple maximum heat release rates v max The range (the difference between the maximum and minimum values) is shown in the results. Figure 2 The results clearly show that after pretreatment, the combustion energy release ranges of TMETN and DIANP decreased from 328 J / g and 495 J / g to 63 J / g and 104 J / g, respectively. Figure 2 A), the range of maximum heat release rates decreased from 5.39 J / g℃ and 10.99 J / g℃ to 1.07 J / g℃ and 4.69 J / g℃, respectively. Figure 2 B) indicates that the stability of the test results for liquid energetic materials is greatly improved after pretreatment.

[0026] Example 2: This embodiment uses the method of the present invention to test the combustion heat release rate and characterize the energy release characteristics of several solid elemental and composite explosives shown in Table 2, specifically including the following steps: The calorimetric system of the oxygen bomb calorimeter was calibrated multiple times using benzoic acid. The average of five calibration values ​​with a range not exceeding 40 J / ℃ was taken as the system's heat capacity. E =8045 J / K.

[0027] Approximately 0.5 g (accurate to 0.0001 g) of the explosive sample to be tested was placed in the crucible of the oxygen bomb calorimeter; Oxygen was slowly introduced at 3.0 MPa, and then the oxygen bomb calorimeter was placed in a certain amount of water. The sample was ignited and burned in the calorimeter to obtain the water temperature-time curve. The Tt curve was then processed by first-order differentiation and smoothing using data processing software to obtain the (dT / dt)-t curve. Figure 3 Then, the maximum combustion heat release rate is calculated using equations (1) and (2). v max The heat Q released by combustion is shown in Table 2.

[0028] Table 2 Results of the combustion heat release rate of several single-element and composite explosives

[0029] As shown in Table 2, the heat release of the HMX / FOX7 complex is... Q The calorific value (J / g) is between that of HMX and FOX7, and its calorific value increases with the increase of the high-energy substance HMX in the composite. However, the maximum exothermic rate does not follow this trend; instead, it increases with the increase of FOX7 content. This is because the thermal decomposition temperature of FOX7 is lower than that of HMX, and the presence of FOX7 in the composite system promotes the decomposition and combustion of HMX. Therefore, although the total calorific value of HMX / FOX7-3:7 is lower than that of HMX / FOX7-5:5, its combustion exothermic rate is faster and the reaction is more vigorous. This also shows that adding the measurement of combustion exothermic rate to the determination of the calorific value of energetic materials can more comprehensively and accurately characterize the energy release characteristics of energetic materials, providing more sufficient data support for practical applications.

[0030] Example 3: This embodiment uses the method of the present invention to characterize the combustion energy release characteristics of different batches of HMX, specifically including the following steps: The calorimetric system of the oxygen bomb calorimeter was calibrated multiple times using benzoic acid. The average of five calibration values ​​with a range not exceeding 40 J / ℃ was taken as the system's heat capacity. E =8045 J / ℃.

[0031] Approximately 0.5 g (accurate to 0.0001 g) of the explosive sample to be tested was placed in the crucible of the oxygen bomb calorimeter, and oxygen was slowly introduced at 3.0 MPa. The oxygen bomb calorimeter was then placed in a certain amount of water, and the sample was ignited to burn in the oxygen bomb calorimeter. The water temperature-time curve was obtained, and the Tt curve was subjected to first-order differentiation and smoothing using data processing software to obtain the (dT / dt)-t curve. Figure 4 The maximum combustion heat release rate was calculated, and the results are shown in Table 3.

[0032] Table 3 Results of heat release rates of HMX combustion in different batches

[0033] As shown in Table 3, although the calorific values ​​of the two batches of HMX are basically the same, their maximum heat release rates differ significantly. The second batch sample releases heat faster and reacts more violently. This indicates that this method can obtain more material property parameters and evaluate the energy release characteristics of materials from more dimensions.

[0034] The preferred embodiments described above in conjunction with the accompanying drawings are preferred but not intended to limit the invention. The various specific technical features described above can be combined in any suitable form without contradiction, and this invention will not elaborate on them one by one. Any simple modifications or alterations made by those skilled in the art, such as arbitrary combinations or equivalent substitutions, to the technical solutions without departing from the scope of the technical solutions do not affect the essence of the technical solutions and still fall within the protection scope of the technical solutions represented by the embodiments of this invention.

Claims

1. A method for determining the combustion heat release rate of energetic materials, characterized in that, The combustion heat release rate of energetic materials was determined using an oxygen bomb calorimeter. The method includes the following steps: S1, calibrate the calorimetric system of the oxygen bomb calorimeter to obtain the heat capacity of the calorimetric system. E The unit is J / ℃; S2, using a calibrated oxygen bomb calorimeter, for a mass of... m The test energetic material was subjected to combustion exothermic measurement. Oxygen was introduced during the measurement. After ignition, the water temperature of the water environment in which the oxygen bomb calorimeter was located was recorded to obtain the curve Tt of water temperature T versus time t. The test energetic material was either a solid energetic material or a liquid energetic material. For liquid energetic materials, a combustible capsule pretreatment was performed before the test. S3, perform the first derivative of the curve Tt to obtain the (dT / dt)-t curve, and obtain the peak value of the (dT / dt)-t curve. ; S4, the maximum exothermic rate of the energetic material under test is calculated using equation (1). : （1）。 2. The method for determining the combustion heat release rate of energetic materials according to claim 1, characterized in that, The calorimetric system of the oxygen bomb calorimeter was calibrated using benzoic acid standard material.

3. The method for determining the combustion heat release rate of energetic materials according to claim 2, characterized in that, The calorimetric system of the oxygen bomb calorimeter was calibrated multiple times to obtain calibrated values ​​of the heat capacity of multiple calorimetric systems. E＇ Heat capacity of the calorimetric system E Select several calibration values ​​with a range not exceeding 40 J / ℃. E＇ The average value.

4. The method for determining the combustion heat release rate of energetic materials according to claim 1, characterized in that, The aforementioned m The value is 0.5~1 g.

5. The method for determining the combustion heat release rate of energetic materials according to claim 1, characterized in that, The pressure at which oxygen is introduced is 1.5~3.5 MPa.

6. The method for determining the combustion heat release rate of energetic materials according to claim 1, characterized in that, After smoothing the Tt curve, S3 is performed; after smoothing the (dT / dt)-t curve, the peak value of the (dT / dt)-t curve is obtained. .

7. The method for determining the combustion heat release rate of energetic materials according to claim 1, characterized in that, The smoothing process described uses a three-point Savitzky-Golay smoothing method.

8. A method for characterizing the energy release of energetic materials, characterized in that, Utilizing the heat Q released by the combustion of energetic materials and the maximum heat release rate of energetic materials Characterize the energy release of energetic materials; The maximum heat release rate of the energetic material Obtained by the method described in any one of claims 1-7; The heat Q released by the combustion of the energetic material is obtained using S1 and S2 as described in claim 1 and formula (2): （2） This refers to the final water temperature after ignition during the S2 test. The water temperature before ignition during the S2 test.

9. A method for evaluating the energy release characteristics of various energetic materials, characterized in that, The various energetic materials have the same or a difference of less than 1% in their calorific value; the energy release characteristics of the various energetic materials are evaluated using the method described in any one of claims 1-7, and the larger the maximum heat release rate, the more violent the reaction of the corresponding material.

10. The method for evaluating the energy release characteristics of various energetic materials according to claim 9, characterized in that, The various energetic materials mentioned are the same energetic material from different production batches.

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