Method for determining critical moisture content of explosive material

Abstract

The application discloses a method for determining critical moisture content of explosive material, which comprises the following steps: obtaining explosive material with different moisture contents and determining the moisture contents; researching thermal decomposition characteristics and determining a moisture content interval of thermal explosion experiment; obtaining an isothermal delay period of the explosive material with a certain moisture content through the thermal explosion experiment; obtaining isothermal delay periods of the explosive material with different moisture contents; and analyzing the relationship between the isothermal delay period and the moisture content to determine the critical moisture content of the explosive material. The method can be used to obtain the critical moisture content of the explosive material with a certain size, and has more guiding significance for safety engineering application of the explosive.

Description

Technical Field

[0001] This invention belongs to the field of explosives technology, and mainly relates to the study of the thermal stability of elemental explosive materials and materials, and particularly to a method for determining the critical moisture content of explosive materials. Background Technology

[0002] In the synthesis and production of explosives, the thermal stability of explosives and their materials is affected by moisture content. This is especially true for high-energy, highly reactive materials during processes such as drying, calendering, screw pressing, and water removal. When exposed to external heat, water-containing explosives and their materials interact with water internally, altering the internal heat conduction. This can lead to premature decomposition of the material under heat, potentially causing accidental combustion or explosion. Furthermore, as moisture content increases, it inhibits decomposition beyond a certain point. Therefore, a critical moisture content exists in the study of the thermal stability of explosives, at which point the thermal stability is most significantly affected. Thus, the study of the critical moisture content is of great importance in the research of explosive thermal stability and in the field of safe production.

[0003] Existing research generally uses the initial decomposition temperature or lag period to determine the critical moisture content of explosive materials. Currently, the following problems exist in the research process of critical moisture content of explosive materials: (1) Existing methods usually use differential scanning calorimetry or microcalorimetry to determine the initial decomposition temperature of explosive materials with different moisture contents. The sampling amount is generally at the milligram level, which has the problem of uneven sampling. Especially for materials with mixed components, it is easy to misjudge the experimental results and cannot obtain the influence law of actual moisture content on isothermal lag period; (2) Compared with the materials in the explosive process, milligram-level samples can be used for physicochemical property analysis, but milligram-level samples have poor representativeness and cannot study the influence of size effect on critical moisture content. Summary of the Invention

[0004] To address the technical problems of differential scanning calorimetry or microcalorimetry, such as uneven milligram-level sampling leading to misinterpretation of results, unclear patterns, and inability to perform size effect analysis, the present invention aims to provide a method for determining the critical moisture content of explosive materials.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for determining the critical moisture content of explosives, characterized by comprising the following steps:

[0007] Step 1: Obtain explosive materials with different moisture contents and determine the moisture content.

[0008] The moisture content of the explosive material was obtained by oven drying. The moisture content of the explosive material was calculated according to the moisture content formula in formula (1) and recorded.

[0009]

[0010] In formula (1): W is the moisture content of the explosive material (%); m1 is the sum of the mass of the explosive material sample and the container before drying (g); m2 is the sum of the mass of the explosive material sample and the container after drying (g); m is the mass of the dried explosive material sample (g).

[0011] Step 2: Study the thermal decomposition characteristics and determine the water content range for the thermal explosion experiment.

[0012] Differential scanning calorimetry was used to quickly obtain and record the thermal decomposition characteristic values ​​of explosive materials with different moisture contents, analyze the law of change of thermal decomposition characteristics of explosive materials with moisture content, and determine the range of moisture content variation of explosive materials for thermal explosion experiments; at the same time, it was determined that the isothermal test temperature of thermal explosion experiments was at least 30°C lower than the initial decomposition temperature of explosive materials.

[0013] Step 3: Obtain the isothermal hysteresis period of a certain moisture content explosive material through thermal explosion experiments.

[0014] Based on the range of moisture content variation determined in step two, select a certain moisture content of explosive material obtained in step one, fill it into a semi-sealed cylindrical aluminum container of a certain size, and conduct an experiment using an explosive thermal stability test device under isothermal conditions to test and record the isothermal hysteresis period of the explosive material.

[0015] Step 4: Based on the moisture content range determined in Step 2, repeat Step 3 to obtain the isothermal lag time of explosive materials with different moisture contents.

[0016] Step 5: Analyze the relationship between isothermal lag period and moisture content to determine the critical moisture content of the explosive material.

[0017] Based on the results obtained in step four, plot the isothermal lag period on the vertical axis with water content as the abscissa to obtain the curve of isothermal lag period changing with water content. Fit the curve and select the points corresponding to the minimum and maximum water content as tangents. The water content corresponding to the intersection of the two tangents is the critical water content.

[0018] The method for determining the critical moisture content of explosives in this invention brings about the following beneficial effects:

[0019] (1) It avoids the problem of misjudgment of results caused by insufficient or uneven sampling when using differential scanning calorimetry or microcalorimetry to obtain the isothermal hysteresis period.

[0020] (2) This method can be used to obtain the critical moisture content of explosive materials of a certain size, making the sample more representative and more instructive for the safe engineering application of explosives. Attached Figure Description

[0021] Figure 1 This is the fitting curve of the moisture content and isothermal lag period of a certain explosive modified double-base propellant material, and the determination result of the critical moisture content.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0023] Regarding the thermal stability study of explosive materials containing moisture, the applicant determined the isothermal hysteresis period through thermal explosion experiments on explosive materials of a certain size, and provided a relatively accurate method for determining the critical moisture content of explosive materials, which is carried out according to the following steps:

[0024] Step 1: Obtain explosive materials with different moisture contents and determine the moisture content.

[0025] The moisture content of the explosive material was obtained by oven drying. The moisture content of the explosive material was calculated according to the moisture content formula in formula (1) and recorded.

[0026]

[0027] In formula (1): W is the moisture content of the explosive material (%); m1 is the sum of the mass of the explosive material sample and the container before drying (g); m2 is the sum of the mass of the explosive material sample and the container after drying (g); m is the mass of the dried explosive material sample (g).

[0028] Step 2: Study the thermal decomposition characteristics and determine the water content range for the thermal explosion experiment.

[0029] Differential scanning calorimetry was used to quickly obtain and record the thermal decomposition characteristic values ​​of explosive materials with different moisture contents, analyze the law of change of thermal decomposition characteristics of explosive materials with moisture content, and determine the range of moisture content variation of explosive materials for thermal explosion experiments; at the same time, it was determined that the isothermal test temperature of thermal explosion experiments was at least 30°C lower than the initial decomposition temperature of explosive materials.

[0030] Step 3: Obtain the isothermal hysteresis period of a certain moisture content explosive material through thermal explosion experiments.

[0031] Based on the range of moisture content variation determined in step two, select a certain moisture content of explosive material obtained in step one, fill it into a semi-sealed cylindrical aluminum container of a certain size, and conduct an experiment using an explosive thermal stability test device under isothermal conditions to test and record the isothermal hysteresis period of the explosive material.

[0032] Step 4: Based on the moisture content range determined in Step 2, repeat Step 3 to obtain the isothermal lag time of explosive materials with different moisture contents.

[0033] Step 5: Analyze the relationship between isothermal lag period and moisture content to determine the critical moisture content of the explosive material.

[0034] Based on the results obtained in step four, plot the isothermal lag period on the vertical axis with water content as the abscissa to obtain the curve of isothermal lag period changing with water content. Fit the curve and select the points corresponding to the minimum and maximum water content as tangents. The water content corresponding to the intersection of the two tangents is the critical water content.

[0035] The following are specific embodiments provided by the inventor.

[0036] Example 1:

[0037] The determination of the critical moisture content of a modified double-base propellant material for a certain explosive will be used as an example for specific explanation.

[0038] The moisture content of 11 types of modified double-base propellant materials for a certain explosive was obtained by oven drying method and named GX-1, GX-2, GX-3, GX-4, GX-5, GX-6, GX-7, GX-8, GX-9, GX-10 and GX-11 in sequence. The corresponding moisture content was calculated and is shown in Table 1.

[0039] Table 1: Moisture content and isothermal hysteresis period of a modified double-base propellant for a certain explosive.

[0040]

[0041] Using a sealed stainless steel crucible, differential scanning calorimetry was employed to rapidly obtain the thermal decomposition characteristics of four materials: GX-1, GX-6, GX-7, and GX-8, as shown in Table 2. All four materials, modified from a certain explosive and containing different moisture contents, exhibited two decomposition exothermic peaks (T0, T0, T0). p1 and T p2 The initial decomposition temperature (T0) of the anhydrous material GX-1 is higher than that of the aqueous materials GX-6, GX-7, and GX-8, but the initial decomposition temperatures of the three aqueous materials remain almost unchanged; the decomposition peak temperature T... p1 T p2 There was no significant change with varying moisture content; however, with increasing moisture content, the decomposition heat (ΔH) of a certain modified double-base propellant material for explosives increased. d The moisture content was reduced. Based on the above analysis, a thermal explosion experiment was conducted on a certain explosive calender material with a moisture content of 10% to 40%.

[0042] Table 2: Thermal decomposition characteristics of four types of modified double-base propellant materials for a certain explosive.

[0043]

[0044]

[0045] Eight types of modified double-base propellant materials of a certain explosive, including GX-3 to GX-10 with a moisture content range of 10% to 40%, were selected and filled into a Φ50mm×50mm aluminum cylindrical semi-sealed container. A thermal explosion experiment was conducted at a constant temperature of 140℃ using an explosive thermal stability test device. The measured isothermal hysteresis times are shown in Table 1.

[0046] Based on the experimental results in Table 1, a graph was plotted with water content as the x-axis and isothermal lag period as the y-axis. Figure 1 The curve of isothermal lag period as a function of water content was obtained. The relationship between isothermal lag period and water content was analyzed. The curve was fitted and the points corresponding to the minimum and maximum water content were selected as tangents. The x-coordinate of the intersection of the two tangents is the critical water content of a certain explosive modified double base propellant material, which is 33.48%.

Claims

1. A method for determining the critical moisture content of explosives, characterized in that, Follow these steps: Step 1: Obtain explosive materials with different moisture contents and determine the moisture content. The moisture content of the explosive material was obtained by oven drying. The moisture content of the explosive material was calculated according to the moisture content formula in formula (1) and recorded. （1） In formula (1): W The moisture content of explosives is expressed in % (%). m 1 represents the sum of the mass of the explosive sample and the container before drying, in grams; m 2 represents the sum of the mass of the dried explosive sample and the container, in grams; m The mass of the dry explosive sample is expressed in grams. Step 2: Study the thermal decomposition characteristics and determine the water content range for the thermal explosion experiment. Differential scanning calorimetry was used to quickly obtain and record the thermal decomposition characteristic values ​​of explosive materials with different moisture contents, analyze the law of change of thermal decomposition characteristics of explosive materials with moisture content, and determine the range of moisture content variation of explosive materials for thermal explosion experiments; at the same time, it was determined that the isothermal test temperature of thermal explosion experiments was at least 30°C lower than the initial decomposition temperature of explosive materials. Step 3: Obtain the isothermal hysteresis period of a certain moisture content explosive material through thermal explosion experiments. Based on the range of moisture content variation determined in step two, select a certain moisture content of explosive material obtained in step one, fill it into a semi-sealed cylindrical aluminum container of a certain size, and conduct an experiment using an explosive thermal stability test device under isothermal conditions to test and record the isothermal hysteresis period of the explosive material. Step 4: Based on the moisture content range determined in Step 2, repeat Step 3 to obtain the isothermal lag time of explosive materials with different moisture contents. Step 5: Analyze the relationship between isothermal lag period and moisture content to determine the critical moisture content of the explosive material. Based on the results obtained in step four, plot the isothermal lag period on the vertical axis with water content as the abscissa to obtain the curve of isothermal lag period changing with water content. Fit the curve and select the points corresponding to the minimum and maximum water content as tangents. The water content corresponding to the intersection of the two tangents is the critical water content.

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