CN112577849B - Explosive isothermal thermal decomposition pressure measuring device - Google Patents
Explosive isothermal thermal decomposition pressure measuring device Download PDFInfo
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Abstract
The application discloses explosive isothermal thermal decomposition pressure measuring device solves the problems that in the prior art, the testing dosage is small, the long-term static pressure tolerance is poor, the measurement applicability is poor, and the pressure tracking time is short. This application mainly comprises sample cell, pressure nut, clamping ring, sealing ring, sealed pad, adopts pressure sensor to track the pressure variation time course curve of the long-time isothermal decomposition process of explosive, has the advantage that resistant static pressure performance is excellent, pressure tracking is long, can realize that the full decomposition process pressure variation of explosive measures.
Description
Technical Field
The application belongs to the technical field of explosive performance testing, and relates to an explosive isothermal thermal decomposition pressure measuring device, which is suitable for continuous tracking measurement of pressure changes of explosives and powders in the isothermal thermal decomposition process.
Background
The thermal decomposition of the explosives and powders is an important form of slow chemical change of the explosives and powders, the research on the thermal decomposition process of the explosives and powders has important significance for researching the stability, thermal explosion, deflagration and the like of the explosives and powders, particularly, the explosives and powders are similar to a long-time isothermal process under a storage condition, and the thermal accumulation accelerated reaction is generated due to the fact that heat released by the thermal decomposition of the explosives and powders is not easy to dissipate under the condition, or deflagration or detonation is caused due to the generation of an autocatalytic accelerated reaction, a chain reaction and the like. According to the characteristics of isothermal thermal decomposition reaction, the thermal decomposition process of explosives and powders is usually measured by methods of gas measurement, heat measurement, weight loss measurement, thermal analysis and the like, although thermal analysis means such as DSC, TG and the like are developed relatively mature, a thermal decomposition reaction kinetic equation of explosives and powders materials can be fitted through tests, the gas release amount and gas pressure of thermal decomposition of explosives and powders materials in the practical application process are also characteristic parameters which are mainly concerned by researchers, wherein the basic thermal stability parameter-vacuum thermal stability of explosives and powders is expressed by adopting the gas release amount mL/g per unit mass, and the volume of decomposed gas pressure at constant temperature for a certain time is converted into the volume under a standard state during the test.
The test for measuring the thermal decomposition pressure of the explosive is the vacuum thermal stability test, the GJB772A-97 method 501.2 of the national military standard is specified in detail, a glass instrument is generally adopted to measure the decomposition gas pressure of 5g of samples at constant temperature (100 ℃, 120 ℃ or 150 ℃), 40h or 48h, and the pressure is not more than 2mL/g as the qualified criterion. The vacuum thermal stability test is suitable for passing examination of the basic thermal stability of explosive materials, the measurement only aims at limited constant temperature time, meanwhile, the glass instrument has limited tolerance capacity to long-time high pressure, the pressure measurement converts the height of mercury columns in capillary tubes into a pressure value of a test terminal point, and real-time change of the pressure of a gas product in the thermal decomposition process of the explosive cannot be obtained. In order to obtain the real-time pressure change process in the thermal decomposition process of the energetic material, a dynamic vacuum stability test method (DVST) is developed, pressure and temperature sensors are all arranged in a glass test tube, and the test method for continuously tracking the change of the internal pressure and temperature of a system along with the time is provided, so that a new technical approach is provided for researching the stability, the compatibility and the long storage life of the energetic material. However, the DVST test system adopts a 25mL glass tube as a reaction measuring tube, the loading capacity does not exceed 1g, and the pressure resistance of the glass tube is not enough to support higher gas pressure accumulated for a long time when a sample is completely decomposed. Although the above method obtains data about the stability of explosives and powders, the application of explosives and powders is more concerned about the whole decomposition process of explosives and powders and the decomposition amount at each decomposition moment, so that the pressure of the fully decomposed product under a certain amount of explosive (generally, the whole decomposition process at 150 ℃ lasts for more than 3 days), but the test explosive amount of the current test method is small, the long-time pressure accumulation process of the whole decomposition process cannot be measured, and the current test method cannot be used for researching the whole decomposition process of explosives and powders.
In summary, the prior art has the following disadvantages: (1) The test loading is not more than 1g, the sample amount is small, the heat accumulation in the thermal decomposition process of the sample is weakened, and the difference from the actual application condition is large; (2) The reaction vessel adopts a glass instrument, is sealed by a glass ground plug, has poor pressure resistance of the system, and cannot be used for long-time continuous high-pressure tracking measurement in the full decomposition process of explosives and powders.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a device for measuring isothermal thermal decomposition pressure of explosives, which comprises a sample cell, a pressing nut, a pressing ring, a sealing ring and a sealing gasket;
the sample cell is of a cylindrical structure with an opening at one end, the inner diameter is 25 mm-30 mm, the inner height is 60 mm-80 mm, the wall thickness is 5 mm-6 mm, an annular hanging lug is arranged 2 mm-3 mm away from the opening end of the sample cell, the annular width is 5 mm-6 mm, the thickness is 3 mm-4 mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug;
the pressing nut is in a cylindrical shape with a central through hole with the diameter of 35 mm-42 mm, is matched with the pressing nut through threads, and is divided into an upper, a middle and a lower three-stage structures, wherein the upper stage has the outer diameter of 44 mm-52 mm and the height of 4mm, the middle stage has the outer diameter of 53 mm-60 mm and the height of 16 mm-18 mm, and the lower stage has the circumscribed circle of hexagonal prism of 42 mm-52 mm and the height of 9 mm-10 mm;
the pressing screw cap is of a two-stage columnar structure, is vertically communicated through a central through hole with the diameter of 6-7 mm, the upper end of the pressing screw cap is a hexagonal prism with internal threads, the diameter of an external circle is 30mm, the height and the internal diameter of the threads are matched with the threads of a selected pressure sensor, the lower end of the pressing screw cap is a hexagonal prism with internal threads, the diameter of the external circle is 64-74 mm, the height of the external circle is 34-38 mm, the internal diameter of the threads is 53-60 mm, the height of the threads is 18-20 mm, three platforms are arranged behind the threads, the diameters are 50-56 mm, 45-54 mm and 35-42 mm from bottom to top in sequence, and the depths of the platforms are 5mm, 3.5mm and 3mm from bottom to top in sequence;
the outer diameter of the compression ring is 50 mm-56 mm, the inner diameter is 35 mm-42 mm, and the thickness is 2mm;
the outer diameter of the sealing ring is 50 mm-56 mm, the inner diameter is 35 mm-42 mm, and the thickness is 3-4 mm;
the outer diameter of the sealing gasket is 38 mm-54 mm, the inner diameter is 28 mm-42 mm, the thickness is 0.5mm, and a V-shaped pressure groove with the width of 1mm is arranged along the annular center;
the sample cell, the pressing nut and the pressing ring are made of stainless steel, the sealing ring is made of polytetrafluoroethylene, and the sealing gasket is made of red copper;
the pressure nut and the pressure nut are connected through threads to realize the sealing of the sample cell, the sealing gasket is positioned between the hanging lug of the sample cell and the pressure nut, and the pressure ring and the sealing ring are positioned between the hanging lug of the sample cell and the pressure nut from bottom to top.
During measurement, a proper amount of test sample is loaded into a sample cell, a sealing ring, a pressure ring and a pressure nut are sequentially penetrated into the sample cell from top to bottom, the sealing gasket is placed on a hanging lug positioned on the sample cell, a V-shaped pressure groove of the sealing gasket is matched with a V-shaped groove in the annular center of the hanging lug, the pressure nut is sleeved on the sample cell and fastened with the pressure nut through threads, and finally the upper end of the pressure nut is connected with a pressure sensor through threads to finish the assembly of the pressure measuring device; according to test requirements, a heating sleeve or a heating coil is adopted to provide corresponding constant temperature conditions for the measuring device, and the output cable of the pressure sensor is connected with a data acquisition instrument to measure the pressure change time-course curve of the isothermal decomposition process of the sample.
The principle of the invention is as follows:
the isothermal thermal decomposition characteristic of the explosive material is a core parameter of storage stability in the application process, the decomposition amount of the explosive slowly increases along with the time extension at constant temperature and releases stage gas products, a certain pressure is formed in a storage space (a shell), meanwhile, the pressure acts on the explosive to accelerate the decomposition of the explosive, a certain temperature gradient is generated due to the fact that the large amount of explosive in the application process forms heat accumulation in the explosive, and the central temperature is higher than the external temperature generally, so that the decomposition of the internal material is accelerated. Aiming at the characteristics of thermal decomposition of explosive materials, the isothermal decomposition pressure measurement of the explosive materials has two difficulties, namely simulating the heat accumulation effect of actual large-dose explosive loading through the control of experimental explosive loading, and improving the pressure resistance and the sealing performance of a measuring device to meet the requirement of high-temperature long-time pressure measurement.
The heat accumulation in the thermal decomposition process of the explosive material is mainly determined by the thickness of a layering layer, a certain explosive effect exists at the same time, the internal temperature distribution of four explosive quantities such as 2g, 10g, 100g, 1000g and the like at the constant temperature of 150 ℃ is researched by adopting an explosive sample with the charging length-diameter ratio of 1, and the heat accumulation is selected from the following stepsWhen the temperatures of the core and the surface are compared, the temperature of the 2g sample is basically not different, and the temperature of the core is higher than that of the surface after the sample amount exceeds (including) 10g, so that the heat accumulation phenomenon is shown. The application adopts the same cylindrical charge casing as the actual charge, so its heat accumulation is mainly influenced by the diameter and the height of charge inner space, because the isothermal decomposition experiment adopts side direction heating and the temperature generally is more than 150 ℃ far above the normal temperature, the temperature gradient of sample side direction is no longer obvious after the constant temperature for a certain time, therefore mainly consider the axial heat accumulation of sample, the experiment has studied the charge draw ratio of 0.6, 1, 1.5, 2 under the constant temperature of 150 ℃ sample axial temperature distribution, draw ratio 1.6 sample temperature is basically even, draw ratio surpasses (includes) 1 after, there is obvious temperature gradient axially, the central temperature ratio shows about 2 ℃ higher than from top to bottom. The application is therefore based on a bulk density of the explosive material of 0.5g/cm 3 ～1.0g/cm 3 The specific size of the application is determined by the loading amount of 15 g-30 g and the length-diameter ratio of more than 1, and the heat accumulation in the thermal decomposition process of the explosive can be reflected to a certain degree.
The time for decomposing explosives and powders at equal temperature varies with the temperature, and in order to improve the experimental efficiency without causing thermal explosion of samples (the thermal explosion damages devices and sensors), the temperature is generally selected to be about 150 ℃, the thermal decomposition process of the explosives and powders lasts for more than 3 days at the temperature, and the pressure after full decomposition can reach about 10 atmospheric pressures, namely about 1 MPa. Aiming at the requirements of long-time pressure measurement on the pressure resistance and the sealing property of the device, the steel thermal decomposition reaction container is adopted, so that the pressure resistance of the device is improved; the utility model provides a pressurized is from tight seal structure, pass through during the assembly press the nut and press screw nut between the screw nut screw fastening make sealing ring and sealed the pad produce certain deformation, make the sample cell reach initial sealing state, sealing ring and sealed resilience force of filling up are balanced about the hangers this moment, along with sample decomposition production pressure, pressure leads to pressing the nut to receive ascending effort and press the screw nut to receive ascending effort, further compression sealing ring makes its resilience force increase, break sealing ring and sealed original power balance of filling up, it is that both form the power balance again that sealing ring kick-backs slightly and the sealed pad of compression, finally, show for sealing ring and sealed pad constantly mutual compression in the sample decomposition process, guarantee that measuring device reliably seals all the time.
The application has the advantages that: (1) The test explosive amount exceeds 15g, so that the heat accumulation in the thermal decomposition process of the explosive can be reflected to a certain degree, and the condition is similar to the actual application condition; (2) The steel thermal decomposition reaction vessel is adopted, a pressure-bearing self-tightening sealing structure is designed, the pressure resistance and the sealing performance of the measuring device under continuous high pressure generated by explosive decomposition are ensured, and long-time continuous high-pressure tracking measurement in the whole decomposition process is realized.
Drawings
The present application will be described in further detail with reference to the drawings and the following detailed description.
FIG. 1 is a structural view of an isothermal thermal decomposition pressure measuring device for explosives and powders;
FIG. 2 is a block diagram of component 1 of FIG. 1;
FIG. 3 is a block diagram of element 2 of FIG. 1;
FIG. 4 is a block diagram of part 3 of FIG. 1;
FIG. 5 is a schematic view of an assembly for thermal decomposition pressure measurements using the present application;
FIG. 6 is a pressure-time curve of the test of example 1 of the present application;
fig. 7 is a pressure-time curve of the test of example 2 of the present application.
In the figure: 1-a sample pool, 2-a pressing nut, 3-a pressing nut, 4-a pressing ring, 5-a sealing ring, 6-a sealing gasket, 7-a pressure sensor, 8-a heating sleeve and 9-a gunpowder and explosive sample.
Detailed Description
The present application is further illustrated below with reference to examples.
Example 1
Referring to fig. 1 to 5, the present embodiment provides a specific structure and an example of use of an isothermal thermal decomposition pressure measurement device for explosives and powders. The device for measuring the isothermal thermal decomposition pressure of explosives and powders at least comprises a sample cell 1, a pressing nut 2, a pressing nut 3, a pressing ring 4, a sealing ring 5 and a sealing gasket 6.
Referring to fig. 2, the sample cell 1 is a tubular structure with an opening at one end, the inner diameter is 25mm, the inner height is 60mm, the wall thickness is 5mm, an annular hanging lug 1-1 is arranged 2mm away from the opening end of the sample cell 1, the width of the hanging lug 1-1 is 5mm, the thickness is 3mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug 1-1.
Referring to fig. 3, the pressing nut 2 is a cylinder with a central through hole with the diameter of 35mm, and is matched with the pressing nut 3 through threads, the pressing nut 2 is divided into an upper, a middle and a lower three-stage structures, the upper stage has the outer diameter of 44mm and the height of 4mm, the middle stage has the outer diameter of 53mm and the height of 16mm, and the lower stage has the outer diameter of 42mm and the height of 9mm.
Referring to fig. 4, the press nut 3 is a two-stage columnar structure, is vertically communicated through a central through hole with the diameter of 6mm, and is provided with a hexagonal prism with internal threads at the upper end, the diameter of a circumscribed circle is 30mm, the height is 18mm, the internal diameter of the threads is 20mm, and the height of the threads is 18mm; the 3 lower extremes of gland nut are the hexagonal prism of internal thread, circumscribed circle diameter 64mm, high 34mm, and screw thread internal diameter 53mm, screw thread height 18mm have three platform behind the screw thread, and the diameter is 50mm, 45mm, 35mm in proper order from bottom to top, and the platform degree of depth is 5mm, 3.5mm, 3mm from bottom to top in proper order.
The compression ring 4 has an outer diameter of 50mm, an inner diameter of 35mm and a thickness of 2mm; the outer diameter of the sealing ring 5 is 50mm, the inner diameter is 35mm, and the thickness is 3mm; the outer diameter of the sealing gasket 6 is 45mm, the inner diameter is 35mm, the thickness is 0.5mm, and a V-shaped pressure groove with the width of 1mm is formed along the annular center; the sample cell 1, the pressing nut 2, the pressing nut 3 and the pressing ring 4 are made of stainless steel, the sealing ring 5 is made of polytetrafluoroethylene, and the sealing gasket 6 is made of red copper; the pressure nut 2 and the pressure nut 3 are connected through threads to realize the sealing of the sample cell 1, the sealing gasket 6 is positioned between the hanging lug 1-1 of the sample cell 1 and the pressure nut 3, and the pressure ring 4 and the sealing ring 5 are positioned between the hanging lug 1-1 of the sample cell 1 and the pressure nut 2 from bottom to top
Referring to fig. 5, when the device is used, a proper amount of explosive and fire test samples 9 are loaded into a sample cell 1, the sample cell 1 sequentially penetrates a sealing ring 5, a pressing ring 4 and a pressing nut 2 from top to bottom, the sealing gasket 6 is placed on a hanging lug 1-1 of the sample cell 1, a V-shaped pressing groove of the sealing gasket 6 is matched with a V-shaped groove in the annular center of the hanging lug 1-1, the pressing nut 3 is sleeved on the sample cell 1 and is fastened with the pressing nut 2 through threads, finally, the upper end of the pressing nut 3 is connected with a pressure sensor 7 through M20 threads, the pressing nut 3 and the pressure sensor 7 are directly sealed through an O-shaped ring of the sensor, sample assembly is completed, a heating sleeve 8 is adopted to provide corresponding constant temperature conditions for a measuring device, the pressure sensor output cable is connected with a data acquisition instrument, and a pressure process curve when the explosive and fire test samples 9 are subjected to isothermal decomposition is measured.
The principle of the invention is as follows:
the isothermal thermal decomposition characteristic of the explosive material is a core parameter of storage stability in the application process, the decomposition amount of the explosive slowly increases along with the time extension at constant temperature and releases stage gas products, a certain pressure is formed in a storage space (a shell), meanwhile, the pressure acts on the explosive to accelerate the decomposition of the explosive, a certain temperature gradient is generated due to the fact that the large amount of explosive in the application process forms heat accumulation in the explosive, and the central temperature is generally higher than the external temperature, so that the decomposition of the internal material is accelerated. Aiming at the characteristics of thermal decomposition of explosive materials, the isothermal decomposition pressure measurement of the explosive materials has two difficulties, namely simulating the heat accumulation effect of actual large-dose explosive loading through the control of experimental explosive loading, and improving the pressure resistance and the sealing performance of a measuring device to meet the requirement of high-temperature long-time pressure measurement.
The heat accumulation in the thermal decomposition process of the explosive material is mainly determined by the thickness of a layering layer and has a certain explosive effect, an explosive sample with the charging length-diameter ratio of 1 is adopted to research the internal temperature distribution of four explosive quantities of 2g, 10g, 100g, 1000g and the like at a constant temperature of 150 ℃, the temperatures of a center and a surface are selected for comparison, the temperature of the 2g sample is basically not different, the temperature of the center is higher than that of the surface after the sample quantity exceeds (includes) 10g, and the heat accumulation phenomenon is shown. The application adopts the same cylindrical powder charge casing as the actual powder charge, therefore its heat accumulation is mainly influenced by the diameter and the height in powder charge inner space, because the isothermal decomposition experiment adopts side direction heating and temperature generally is more than 150 ℃ far above normal temperature, the temperature gradient of sample side direction is no longer obvious after the constant temperature for a certain time, therefore mainly consider the axial heat accumulation of sample, the experimental study powder charge draw ratio 1, 1.5, 2 sample axial temperature distribution under the 150 ℃ constant temperature, draw ratio 1.6 is basically even, draw ratio exceeds (includes) 1 after, there is obvious temperature gradient in the axial, the central temperature ratio shows all about 2 ℃ higher than from top to bottom.This example therefore depends on the bulk density of the explosive material being 0.5g/cm 3 ～1.0g/cm 3 The specific size of the present application is determined by the charge amount of 15g and the length-diameter ratio of more than 1, and the heat accumulation in the thermal decomposition process of explosives and powders can be reflected to a certain extent.
The time for decomposing explosives and powders at equal temperature varies with the temperature, and in order to improve the experimental efficiency without causing thermal explosion of samples (the thermal explosion damages devices and sensors), the temperature is generally selected to be about 150 ℃, the thermal decomposition process of the explosives and powders lasts for more than 3 days at the temperature, and the pressure after full decomposition can reach about 10 atmospheric pressures, namely about 1 MPa. Aiming at the requirements of long-time pressure measurement on the pressure resistance and the sealing performance of the device, the steel thermal decomposition reaction container is adopted, so that the pressure resistance of the device is improved; the design receives the pressure from tight seal structure, pass through during the assembly press nut 2 and press between the nut 3 screw-thread fastening make sealing ring 5 and sealed 6 produce certain deformation, make sample cell 1 reach initial seal state, the resilience force of sealing ring 5 and sealed 6 is balanced about hangers 1-1 this moment, along with sample decomposition production pressure, pressure leads to pressing nut 2 to receive ascending effort and pressing nut 3 to receive ascending effort, further compression sealing ring 5 makes its resilience force increase, break the original power balance of sealing ring 5 and sealed 6, sealing ring 5 kick-backs slightly and compression sealed 6 is that both reform transform power balance, finally, show for sealing ring 5 and sealed 6 constantly mutual compression in sample decomposition process, guarantee measuring device reliably sealed all the time.
The isothermal thermal decomposition pressure measuring device for the explosives and powders manufactured by the method is used for measuring isothermal thermal decomposition pressure of certain aluminum-containing explosives and powders, a sample is a powdery explosive, the test explosive is 15g, the assembly of the measuring device is completed by referring to fig. 5, the constant temperature is provided by a heating sleeve, the temperature control precision is +/-1 ℃, the range of a pressure sensor is 2MPa, the output cable of the pressure sensor is connected with a data acquisition instrument, the sampling frequency is 1Hz, and a pressure change time-course curve of the isothermal decomposition process of the sample is obtained, as shown in fig. 6. The change process of the pressure of the full decomposition process of 15g of explosive under a certain heat accumulation condition along with time is obtained by the test and is similar to the actual application condition; a steel thermal decomposition reaction container is adopted, a pressure-bearing self-tightening sealing structure is designed, the pressure resistance and the sealing performance of a measuring device under continuous high pressure generated by explosive decomposition are ensured, the isothermal full-decomposition final state pressure of a sample at 160 ℃ reaches 880kPa, the whole measurement duration reaches 5000min (more than 80 h), and long-time continuous high-pressure tracking measurement in the full-decomposition process is realized.
Example 2
Referring to fig. 1 to 5, the present embodiment provides a specific structure and an example of use of an isothermal thermal decomposition pressure measuring device for explosives and powders. The device for measuring the isothermal thermal decomposition pressure of explosives and powders at least comprises a sample cell 1, a pressing nut 2, a pressing nut 3, a pressing ring 4, a sealing ring 5 and a sealing gasket 6.
Referring to fig. 2, a sample cell 1 is a cylindrical structure with an opening at one end, the inner diameter is 30mm, the inner height is 80mm, the wall thickness is 6mm, an annular hanging lug 1-1 is arranged at a position 3mm away from the opening end of the sample cell 1, the annular width is 6mm, the thickness is 4mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug 1-1;
referring to fig. 3, the pressing nut 2 is a column with a central through hole with a diameter of 42mm, and is in threaded fit with the pressing nut 3, the pressing nut 2 is divided into an upper, a middle and a lower three-stage structures, the upper stage has an outer diameter of 52mm and a height of 4mm, the middle stage has an outer diameter of 60mm and a thread height of 18mm, and the lower stage has a hexagonal prism circumscribed circle with a diameter of 52mm and a height of 10mm.
Referring to fig. 4, the press nut 3 is a two-stage columnar structure, the upper end of the press nut is a hexagonal prism with internal threads, the diameter of an external circle is 30mm, the height and the internal diameter of the screw thread are matched with the threads of a selected pressure sensor, the lower end of the press nut 3 is a hexagonal prism with internal threads, the diameter of the external circle is 74mm, the height of the external circle is 38mm, the internal diameter of the screw thread is 60mm, the height of the screw thread is 20mm, three platforms are arranged behind the screw thread, the diameters of the platforms are 56mm, 54mm and 42mm from bottom to top in sequence, and the depth of the platforms is 5mm, 3.5mm and 3mm from bottom to top in sequence.
The compression ring 4 has an outer diameter of 56mm, an inner diameter of 42mm and a thickness of 2mm; the outer diameter of the sealing ring 5 is 56mm, the inner diameter is 42mm, and the thickness is 4mm; the outer diameter of the sealing gasket 6 is 54mm, the inner diameter of the sealing gasket is 42mm, the thickness of the sealing gasket is 0.5mm, and a V-shaped pressure groove with the width of 1mm is formed in the annular center; the sample cell 1, the pressing nut 2, the pressing nut 3 and the pressing ring 4 are made of stainless steel, the sealing ring 5 is made of polytetrafluoroethylene, and the sealing gasket 6 is made of red copper; the pressure nut 2 and the pressure nut 3 are connected through threads to achieve sealing of the sample cell 1, the sealing gasket 6 is located between the hanging lug 1-1 of the sample cell 1 and the pressure nut 3, and the pressing ring 4 and the sealing ring 5 are located between the hanging lug 1-1 of the sample cell 1 and the pressure nut 2 from bottom to top.
Referring to fig. 5, when the device is used, a proper amount of explosive and fire test samples 9 are loaded into a sample cell 1, the sample cell 1 sequentially penetrates a sealing ring 5, a pressing ring 4 and a pressing nut 2 from top to bottom, the sealing gasket 6 is placed on a hanging lug 1-1 of the sample cell 1, a V-shaped pressing groove of the sealing gasket 6 is matched with a V-shaped groove in the annular center of the hanging lug 1-1, the pressing nut 3 is sleeved on the sample cell 1 and is fastened with the pressing nut 2 through threads, finally, the upper end of the pressing nut 3 is connected with a pressure sensor 7 through M20 threads, the pressing nut 3 and the pressure sensor 7 are directly sealed through an O-shaped ring of the sensor, sample assembly is completed, a heating sleeve 8 is adopted to provide corresponding constant temperature conditions for a measuring device, the pressure sensor output cable is connected with a data acquisition instrument, and a pressure process curve when the explosive and fire test samples 9 are subjected to isothermal decomposition is measured.
The principle of the invention is as follows:
the constant temperature thermal decomposition characteristic of the explosive material is a core parameter of storage stability in the application process, the decomposition amount of the explosive slowly increases along with the prolonging of time at constant temperature and releases stage gas products, a certain pressure is formed in a storage space (a shell), meanwhile, the pressure acts on the explosive to accelerate the decomposition of the explosive, a certain temperature gradient is generated due to the fact that the large amount of explosive in the application process forms heat accumulation in the explosive, and the central temperature is generally higher than the external temperature, so that the decomposition of the internal material is accelerated. Aiming at the characteristics of thermal decomposition of explosive materials, the isothermal decomposition pressure measurement of the explosive materials has two difficulties, namely simulating the heat accumulation effect of actual large-dose explosive loading through the control of experimental explosive loading, and improving the pressure resistance and the sealing performance of a measuring device to meet the requirement of high-temperature long-time pressure measurement.
The heat accumulation in the thermal decomposition process of the explosive material is mainly determined by the thickness of a layering layer, a certain explosive effect exists at the same time, the internal temperature distribution of four explosive quantities of 2g, 10g, 100g, 1000g and the like at the constant temperature of 150 ℃ is researched by adopting an explosive sample with the charging length-diameter ratio of 1,the temperature of the center and the surface are selected for comparison, the temperature of a 2g sample is basically not different, and the heat accumulation phenomenon is shown when the temperature of the center is higher than that of the surface after the sample amount exceeds (including) 10 g. The application adopts the same cylindrical charge casing as the actual charge, so its heat accumulation is mainly influenced by the diameter and the height of charge inner space, because the isothermal decomposition experiment adopts side direction heating and the temperature generally is more than 150 ℃ far above the normal temperature, the temperature gradient of sample side direction is no longer obvious after the constant temperature for a certain time, therefore mainly consider the axial heat accumulation of sample, the experiment has studied the charge draw ratio of 0.6, 1, 1.5, 2 under the constant temperature of 150 ℃ sample axial temperature distribution, draw ratio 1.6 sample temperature is basically even, draw ratio surpasses (includes) 1 after, there is obvious temperature gradient axially, the central temperature ratio shows about 2 ℃ higher than from top to bottom. The present application thus relies on the bulk density of the explosive material being 0.5g/cm 3 ～1.0g/cm 3 The specific size of the application is determined by the following formula (1), wherein the charge amount is 30g, and the length-diameter ratio is more than 1, so that the heat accumulation in the thermal decomposition process of the explosive can be reflected to a certain extent.
The time for decomposing explosives and powders at equal temperature varies with the temperature, and in order to improve the experimental efficiency without causing thermal explosion of samples (the thermal explosion damages devices and sensors), the temperature is generally selected to be about 150 ℃, the thermal decomposition process of the explosives and powders lasts for more than 3 days at the temperature, and the pressure after full decomposition can reach about 10 atmospheric pressures, namely about 1 MPa. Aiming at the requirements of long-time pressure measurement on the pressure resistance and the sealing performance of the device, the steel thermal decomposition reaction container is adopted, so that the pressure resistance of the device is improved; the design receives the pressure from tight seal structure, pass through during the assembly press nut 2 and press between the nut 3 screw-thread fastening make sealing ring 5 and sealed 6 produce certain deformation, make sample cell 1 reach initial seal state, the resilience force of sealing ring 5 and sealed 6 is balanced about hangers 1-1 this moment, along with sample decomposition production pressure, pressure leads to pressing nut 2 to receive ascending effort and pressing nut 3 to receive ascending effort, further compression sealing ring 5 makes its resilience force increase, break the original power balance of sealing ring 5 and sealed 6, sealing ring 5 kick-backs slightly and compression sealed 6 is that both reform transform power balance, finally, show for sealing ring 5 and sealed 6 constantly mutual compression in sample decomposition process, guarantee measuring device reliably sealed all the time.
The manufactured device for measuring the isothermal thermal decomposition pressure of the explosives and powders is used for measuring the isothermal thermal decomposition pressure of certain aluminum-containing explosives, a sample is powdery explosive, the test explosive amount is 30g, the assembly of the measuring device is completed by referring to fig. 5, the constant temperature is provided by a heating sleeve, the temperature control precision is +/-1 ℃, the range of a pressure sensor is 2MPa, the output cable of the pressure sensor is connected with a data acquisition instrument, the sampling frequency is 1Hz, and the pressure change time-course curve of the isothermal decomposition process of the sample is obtained, as shown in fig. 7. The change process of the pressure of the full decomposition process of 30g of explosive under a certain heat accumulation condition along with time is obtained by the test and is similar to the actual application condition; a steel thermal decomposition reaction container is adopted, a pressure-bearing self-tightening sealing structure is designed, the pressure resistance and the sealing performance of a measuring device under continuous high pressure generated by explosive decomposition are ensured, the isothermal full-decomposition final-state pressure of a sample at 150 ℃ reaches 890kPa, the whole measurement duration reaches 6300min (more than 100 h), and long-time continuous high-pressure tracking measurement of the full-decomposition process is realized.
Claims (3)
1. The device for measuring the isothermal thermal decomposition pressure of explosives and powders is characterized by comprising a sample cell (1), a pressing nut (2), a pressing nut (3), a pressing ring (4), a sealing ring (5) and a sealing gasket (6);
the sample cell (1) is of a cylindrical structure with an opening at one end, the inner diameter is 25 mm-30 mm, the inner height is 60 mm-80 mm, the wall thickness is 5 mm-6 mm, an annular hanging lug (1-1) is arranged 2 mm-3 mm away from the opening end of the sample cell (1), the annular width is 5 mm-6 mm, the thickness is 3 mm-4 mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug (1-1);
the pressing nut (2) is in a cylindrical shape with a central through hole with the diameter of 35 mm-42 mm, is matched with the pressing nut (3) through threads, and is divided into an upper-level structure, a middle-level structure and a lower-level structure, wherein the upper-level structure has the outer diameter of 44 mm-52 mm and the height of 4mm, the middle-level structure has the outer diameter of 53 mm-60 mm and the height of 16 mm-18 mm, and the lower-level hexagonal prism has the circumscribed circle with the diameter of 42 mm-52 mm and the height of 9 mm-10 mm;
the pressing screw cap (3) is of a two-stage columnar structure, the pressing screw cap is vertically communicated through a central through hole with the diameter of 6-7 mm, the upper end of the pressing screw cap is a hexagonal prism with internal threads, the diameter of an external circle is 30mm, the height and the internal diameter of the threads are matched with the threads of a selected pressure sensor, the lower end of the pressing screw cap (3) is a hexagonal prism with internal threads, the diameter of the external circle is 64-74 mm, the height of the external circle is 34-38 mm, the internal diameter of the threads is 53-60 mm, the height of the threads is 18-20 mm, three platforms are arranged behind the threads, the diameters are 50-56 mm, 45-54 mm and 35-42 mm from bottom to top in sequence, and the depths of the platforms are 5mm, 3.5mm and 3mm from bottom to top in sequence;
the compression ring (4) has an outer diameter of 50-56 mm, an inner diameter of 35-42 mm and a thickness of 2mm;
the outer diameter of the sealing ring (5) is 50 mm-56 mm, the inner diameter is 35 mm-42 mm, and the thickness is 3-4 mm;
the outer diameter of the sealing gasket (6) is 38 mm-54 mm, the inner diameter is 28 mm-42 mm, the thickness is 0.5mm, and a V-shaped pressure groove with the width of 1mm is arranged along the annular center;
the sample cell (1), the pressing nut (2), the pressing nut (3) and the pressing ring (4) are made of stainless steel, the sealing ring (5) is made of polytetrafluoroethylene, and the sealing gasket (6) is made of red copper;
the pressure nut (2) and the pressure nut (3) are connected through threads to realize the sealing of the sample cell (1), the sealing gasket (6) is positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (3), and the pressure ring (4) and the sealing ring (5) are positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (2) from bottom to top;
during assembly, the sealing ring (5) and the sealing gasket (6) are deformed to a certain extent through the threaded fastening between the pressing nut (2) and the pressing nut (3), so that the sample pool (1) reaches an initial sealing state, the resilience force of the sealing ring (5) and the sealing gasket (6) is balanced up and down on the hangers (1-1), pressure is generated along with the decomposition of a sample, the pressure causes the pressing nut (2) to be subjected to upward acting force and the pressing nut (3) to be subjected to upward acting force, the sealing ring (5) is further compressed to increase the resilience force, the original force balance of the sealing ring (5) and the sealing gasket (6) is broken, the sealing ring (5) is slightly rebounded and the sealing gasket (6) is compressed to form force balance again, and finally the sealing ring (5) and the sealing gasket (6) are continuously compressed mutually in the sample decomposition process, so that the explosive temperature and heat decomposition pressure measuring device is guaranteed to be sealed reliably all the time;
the device for measuring the isothermal thermal decomposition pressure of the explosives and powders is suitable for the situation that a test sample is powdery explosives, the test explosive amount is 30g, the isothermal full decomposition final state pressure reaches 890kPa at 150 ℃, and the whole measurement duration time reaches 6300min.
2. The apparatus for measuring isothermal thermal decomposition pressure of explosives and powders according to claim 1, wherein: the sample cell (1) is of a cylindrical structure with an opening at one end, the inner diameter is 25mm, the inner height is 60mm, the wall thickness is 5mm, an annular hanging lug (1-1) is arranged 2mm away from the opening end of the sample cell (1), the annular width is 5mm, the thickness is 3mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug (1-1);
the pressing nut (2) is in a cylindrical shape with a central through hole with the diameter of 35mm, is matched with the pressing nut (3) through threads, and is divided into an upper stage structure, a middle stage structure and a lower stage structure, wherein the upper stage structure is 44mm in outer diameter and 4mm in height, the middle stage structure is 53mm in outer diameter and 16mm in thread height, and the lower stage structure is 42mm in diameter of an external circle of a hexagonal prism and 9mm in height;
the pressing screw cap (3) is of a two-stage columnar structure, is vertically communicated through a central through hole with the diameter of 6mm, the upper end of the pressing screw cap is a hexagonal prism with an internal thread, the diameter of an external circle is 30mm, the height and the internal diameter of the thread are matched with the threads of a selected pressure sensor, the lower end of the pressing screw cap (3) is a hexagonal prism with an internal thread, the diameter of the external circle is 64mm, the height of the external circle is 34mm, the internal diameter of the thread is 53mm, the height of the thread is 18mm, three platforms are arranged behind the threads, the diameters of the platforms are 50mm, 45mm and 35mm from bottom to top in sequence, and the depths of the platforms are 5mm, 3.5mm and 3mm from bottom to top in sequence;
the outer diameter of the compression ring (4) is 50mm, the inner diameter is 35mm, and the thickness is 2mm;
the outer diameter of the sealing ring (5) is 50mm, the inner diameter is 35mm, and the thickness is 3;
the outer diameter of the sealing gasket (6) is 38mm, the inner diameter is 28mm, the thickness is 0.5mm, and a V-shaped pressure groove with the width of 1mm is formed along the annular center;
the sample cell (1), the pressing nut (2), the pressing nut (3) and the pressing ring (4) are made of stainless steel, the sealing ring (5) is made of polytetrafluoroethylene, and the sealing gasket (6) is made of red copper;
the pressure nut (2) and the pressure nut (3) are connected through threads to realize the sealing of the sample cell (1), the sealing gasket (6) is positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (3), and the pressure ring (4) and the sealing ring (5) are positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (2) from bottom to top.
3. The apparatus for measuring isothermal thermal decomposition pressure of explosives and powders according to claim 1, wherein:
the sample cell (1) is of a cylindrical structure with an opening at one end, the inner diameter is 30mm, the inner height is 80mm, the wall thickness is 6mm, an annular hanging lug (1-1) is arranged at a position 3mm away from the opening end of the sample cell (1), the annular width is 6mm, the thickness is 4mm, and a V-shaped groove with the width of 1mm is arranged along the annular center of the hanging lug (1-1);
the pressing nut (2) is in a cylindrical shape with a central through hole with the diameter of 42mm, is in threaded fit with the pressing nut (3), and is divided into an upper-level structure, a middle-level structure and a lower-level structure, wherein the upper-level structure is 52mm in outer diameter and 4mm in height, the middle-level structure is 60mm in outer diameter and 18mm in thread height, and the lower-level structure is 52mm in outer circle diameter and 10mm in height;
the pressing screw cap (3) is of a two-stage columnar structure, is vertically communicated through a central through hole with the diameter of 7mm, the upper end of the pressing screw cap is a hexagonal prism with internal threads, the diameter of an external circle is 30mm, the height and the internal diameter of the threads are matched with the threads of a selected pressure sensor, the lower end of the pressing screw cap (3) is a hexagonal prism with internal threads, the diameter of the external circle is 74mm, the height of the external circle is 38mm, the internal diameter of the threads is 60mm, the height of the threads is 20mm, three platforms are arranged behind the threads, the diameters of the platforms are 56mm, 54mm and 42mm from bottom to top in sequence, and the depths of the platforms are 5mm, 3.5mm and 3mm from bottom to top in sequence;
the outer diameter of the compression ring (4) is 56mm, the inner diameter is 42mm, and the thickness is 2mm;
the outer diameter of the sealing ring (5) is 56mm, the inner diameter is 42mm, and the thickness is 4mm;
the outer diameter of the sealing gasket (6) is 54mm, the inner diameter of the sealing gasket is 42mm, the thickness of the sealing gasket is 0.5mm, and a V-shaped pressure groove with the width of 1mm is formed in the center of the ring;
the sample cell (1), the pressing nut (2), the pressing nut (3) and the pressing ring (4) are made of stainless steel, the sealing ring (5) is made of polytetrafluoroethylene, and the sealing gasket (6) is made of red copper;
the pressure nut (2) and the pressure nut (3) are connected through threads to realize the sealing of the sample cell (1), the sealing gasket (6) is positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (3), and the pressure ring (4) and the sealing ring (5) are positioned between the hanging lug (1-1) of the sample cell (1) and the pressure nut (2) from bottom to top.
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