CN114384113A - Single-side method double-probe explosive thermal conductivity coefficient measurement method - Google Patents

Single-side method double-probe explosive thermal conductivity coefficient measurement method Download PDF

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CN114384113A
CN114384113A CN202111352258.4A CN202111352258A CN114384113A CN 114384113 A CN114384113 A CN 114384113A CN 202111352258 A CN202111352258 A CN 202111352258A CN 114384113 A CN114384113 A CN 114384113A
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temperature
sample
probe
measurement
contact
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CN114384113B (en
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王晓红
陈曼
温晓燕
赵嘉静
高朗华
孙晓朋
康莹
何少蓉
张皋
王一凯
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Xian Jiaotong University
Xian Modern Chemistry Research Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity

Abstract

The invention discloses a single-side method double-probe explosive thermal conductivity coefficient measuring method, which comprises the steps of placing a sample to be measured on a sample bearing platform of a measuring system, and closing a box door; setting the temperature in the constant temperature box as T, wherein the T is any one temperature within the range of-50-70 ℃, adjusting a temperature detector to enable a contact of a probe to be in close contact with the surface of a sample to be measured after the temperature in the constant temperature box is stable, starting measurement, stopping measurement after the measurement time exceeds 10 minutes, obtaining m groups of measurement results of the current position of the sample to be measured, and calculating the heat conductivity coefficient value; adjusting the contact position of a probe contact of the temperature detector and a sample to be detected to obtain the heat conductivity coefficients of different positions; repeating the above process to obtain the heat conductivity coefficients of different temperature points; the invention has the advantages of rapid and convenient measurement process, realization of simultaneous measurement of a plurality of samples and continuous measurement of a plurality of temperature points at one time, reduction of measurement errors caused by environmental temperature change in multiple measurements and improvement of accuracy.

Description

Single-side method double-probe explosive thermal conductivity coefficient measurement method
Technical Field
The invention belongs to the technical field of measurement of thermal physical properties of explosives and powders, and particularly relates to a single-side method double-probe measurement method for thermal conductivity of explosives and powders.
Background
In the research of the formula design and the shaping of explosives and powders, in order to ensure the environmental use safety of explosives and powders products, it is necessary to master the heat-conducting property and the related data of the explosives and powders and related materials within the temperature range of (-50-70) DEG C. With the development of novel high-energy explosive charging, missile charging, propellants, novel energetic materials and products thereof, the thermal conductivity coefficients and accurate measurement of the explosives and related materials have extremely important theoretical and practical significance for material selection, formula design, performance estimation and simulation, product shaping and theoretical model establishment of the novel explosives and related products. At present, the heat conductivity coefficient test methods for explosives and related materials mainly comprise a protective hot plate heat conductivity coefficient measurement method, a DSC method, a micro-calorimetry method and a laser scintillation method.
The hot plate protection method requires that a sample is a round sample or a square sample, the processed sample has a flat and smooth surface without pores, oil stains and mechanical damage, the explosive needs to be tabletted, the heat conductivity coefficient is less than 1.5W/m.K, the temperature of a heating plate is not more than 333K when the explosive and the fire are measured, and the temperature of the heating plate is not more than 400K when the coating layer and the heat insulation layer are measured. The method has the problems that the size and the amount of a sample are large, a protective plate is required to pressurize and tighten the sample during testing, and a hot plate is ensured to be in close contact with the surface of the sample, so that local heat accumulation of the sample to be tested can be caused to form a hot spot due to overhigh local temperature, and potential safety hazards exist in the heat conductivity coefficient test of a novel high-damage energetic material; micro heat quantityThe method requires that the outer diameter and the inner diameter of a charge column are concentric, the surface of the inner diameter is smooth and lossless, the test range of the heat conductivity coefficient is 0.001-0.5W/m.K, the temperature range is-50 ℃, and the method has the problems of large sample preparation difficulty, large danger, very accurate size requirement, large measurement error caused by size error, and a heating unit is arranged in an inner hole during test, so that the potential safety hazard is serious for the existing novel explosive material, the test time is very long, and the heat conductivity coefficient of one sample at one temperature point usually needs 24 hours; the DSC method requires that a sample is a right cylinder, the end face is smooth and clean, no crack exists, the heat conductivity coefficient is less than 1.5W/m.K, and the DSC method has the problems that the sample amount is too small, the uniformity is difficult to ensure, the test accuracy is poor, the sample needs a special test support, the operation is complex, the test time is long, and 5 hours are needed for completing the heat conductivity coefficient test of one sample at one temperature point. Sample size in laser scintillation method is
Figure BDA0003356226160000021
Or
Figure BDA0003356226160000022
The thickness is 2-3 mm, the test temperature range can reach-125-2000 ℃, and the thermal conductivity coefficient range can reach 0.1-2000W/mK. Meanwhile, because the laser beam has larger instantaneous energy, the laser beam is used for energetic materials such as explosives and powders and the like, which easily causes safety problems such as combustion, explosion and the like.
In summary, the existing methods and technologies have the following disadvantages:
1) the traditional heat shield plate method and the laser scintillation heat conductivity coefficient test method require overlarge sample size and are suitable for heat conductivity coefficient test of materials such as refractory heat preservation, ceramic fiber, felt, textile fabrics, plates, bricks and the like; the latter is suitable for testing medium and high thermal conductivity coefficient materials, such as metal materials, due to the limitation of the testing principle. Aiming at the special inflammable and explosive properties of explosive materials, both the two devices can not meet the requirement of testing the heat conductivity coefficient of the novel explosive materials.
2) The method for measuring the thermal conductivity of the explosive and fire material specified by the standard cannot meet the requirement of accurately measuring the thermal conductivity of the existing explosive and fire material and product at present due to the large sample preparation difficulty, high danger, overlong test period, defects of the method, aging elimination of instruments and equipment and the like, and is rarely used in scientific research and production.
Disclosure of Invention
Aiming at the problems, the invention provides a single-side method double-probe method for measuring the thermal conductivity of explosives and powders, so as to achieve the effects of rapidness, safety, capability of covering a plurality of temperature points in the life cycle temperature range of the explosives and powders product and accurate acquisition of the thermal conductivity of the explosives and powders.
The invention is realized by adopting the following technical scheme:
the method for measuring the thermal conductivity of the single-side method double-probe explosives and powders is characterized in that the measurement is carried out by adopting a single-side method double-probe explosives and powders thermal conductivity measurement system, wherein the single-side method double-probe explosives and powders thermal conductivity measurement system comprises a constant temperature box, a sample bearing platform for placing a sample and a temperature detector for detecting the temperature of the sample; the sample bearing table and the temperature detector are both arranged in the constant temperature box, and the temperature detector is arranged above the sample bearing table; the temperature detector comprises a thermopile and two probes respectively connected to the cold end and the hot end of the thermopile;
the specific measurement method comprises the following steps:
step 1, putting a sample to be tested on a sample bearing table of the single-side method double-probe explosive thermal conductivity coefficient measurement system, and closing a box door; the sample to be measured is processed to have a flat and smooth surface without pores, oil stains and mechanical damage;
step 2, setting the temperature in the constant temperature box as T, wherein the T is any one temperature within the range of-50-70 ℃, adjusting the temperature detector to enable the contact of the probe to be in close contact with the surface of the sample to be measured after the temperature in the constant temperature box is stable, starting measurement, stopping measurement after the measurement time exceeds 10 minutes, and obtaining the current position of the sample to be measuredM sets of measurements, each set of measurements including a thermopile hot end temperature θl1Cold end temperature theta of thermopile12And two probe tip bottom temperatures θ01、θ02Calculating the heat conductivity value corresponding to each group of measurement results by adopting a formula,
Figure BDA0003356226160000031
Figure BDA0003356226160000041
Figure BDA0003356226160000042
Figure BDA0003356226160000043
in the formula, A1、A2、A3All represent intermediate quantities, R is the radius of the probe tip, R iscIs the contact thermal resistance of the probe contact, s is the axial cross-sectional area of the probe, l is the length of the probe, p is the perimeter of the probe, h is the heat exchange coefficient of the air convection surface, and lambdatThe thermal conductivity of the probe material;
finally obtaining m heat conductivity coefficient measurement results of the current position of the sample to be measured;
step 3, adjusting the contact position of the probe contact of the temperature detector and the sample to be measured for multiple times, ensuring that the contact position of the probe contact is different from the contact position of the surface of the sample to be measured each time, and measuring according to the measuring mode of the step 2 after adjusting the contact position each time;
finally obtaining n multiplied by m heat conductivity coefficient measurement results, wherein n is the contact position adjustment times of the probe contact and the sample to be measured;
step 4, resetting the temperature in the constant temperature box to the required temperature point according to the test requirements if the measurement results of other temperature points within the range of-50 to 70 ℃ are required, setting the temperature sequence from high temperature to low temperature for measurement, and repeating the steps 2 to 3 to obtain the measurement results of the thermal conductivity coefficients of all the required temperature points;
step 5, taking the average value of the m heat conductivity coefficient results of each temperature point and each measurement position of the sample to be measured as the heat conductivity coefficient value of one temperature point and one measurement position; then, carrying out the same processing on the data of the n measurement positions to obtain n heat conductivity values of the sample to be measured at one temperature point, and taking the average value of the n heat conductivity values as the heat conductivity value of the sample to be measured at one temperature point;
finally, the heat conductivity values corresponding to all required temperature points of the sample to be tested are obtained.
Preferably, m is more than or equal to 10; n is more than or equal to 6.
Preferably, the door of the incubator is an automatic opening and closing door controlled by the pressure of an air compressor, and when the pressure of the air compressor reaches 7-10 atmospheric pressures, the door of the incubator can be tightly closed.
Preferably, the sample bearing platform comprises a support and a tray, the tray can rotate, and when the contact position of the contact of the temperature detector and the sample to be measured is adjusted: firstly, the temperature detector is adjusted to enable the contact of the probe to be away from the sample to be measured, then the sample to be measured is rotated to a certain angle, and then the temperature detector is adjusted to enable the contact of the probe to be in close contact with the surface of the sample to be measured again.
Preferably, the number of the samples to be detected is at least 3, each tray is provided with a sample to be detected which is made of the same material, has the same size and specification, and each sample to be detected corresponds to one temperature detector.
Preferably, the sample to be detected is a round sample.
Preferably, a first-stage differential thermocouple is arranged in the probe and used for measuring the temperature of the bottom of the probe contact, and a second-stage differential thermocouple is arranged in the thermopile and used for measuring the temperature of the cold end and the hot end of the thermopile; the first-stage differential thermocouple and the second-stage differential thermocouple are respectively connected with the data acquisition and processing unit.
Preferably, the contact of the probe is provided in a frustum shape.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method can realize the measurement of a plurality of temperature points within the range of (-50-70) DEG C in the life cycle of the explosive, the measurement process is quick and convenient, and the measurement of one temperature point of one sample only needs a few minutes; and simultaneously, the simultaneous measurement of a plurality of samples and the continuous measurement of a plurality of temperature points can be realized, the measurement error caused by the change of the environmental temperature in multiple measurements is effectively reduced, and the measurement accuracy is greatly improved.
(2) The invention adopts a single-side method double-probe measurement principle, can realize small-area contact between the contact and the explosive sample, and avoids the potential safety hazard of heat effect caused by long-time contact.
Other advantages of the present invention are described in detail in the detailed description of the invention.
Drawings
Fig. 1 is a block diagram of a thermal conductivity measurement system according to embodiment 1.
FIG. 2 is a schematic diagram of the measurement method of the present invention.
Fig. 3 is a schematic diagram of the structure of the temperature detector of the present invention.
The various reference numbers in the figures illustrate:
1-a thermostat, 2-a sample bearing table, 3-a temperature detector, 4-a data acquisition and processing unit, 5-a temperature control system, 6-a sample to be tested and 7-an air compressor;
31-thermopile, 32-probe, 33-first order differential thermocouple, 34-second order differential thermocouple; 321-contacts.
Detailed Description
The invention discloses a single-side method double-probe explosive thermal conductivity coefficient measuring method, which is based on the heat transfer principle and combined with the Peltier principle, and is used for transiently obtaining the thermal conductivity coefficient value of an explosive material under a certain temperature condition by tracking and detecting the temperature change of contact points of the upper ends of probes of two temperature detectors and the two ends of a thermopile and contact points of the lower ends of the probes and the surface of the explosive material.
The physical meaning of the thermal conductivity, i.e., thermal conductivity, is the amount of heat per unit surface area per unit time at a temperature difference of 1 ℃ per unit thickness of the material under stable heat transfer conditions. The method is characterized in that the heat transferred in unit thickness and unit time under the condition of unit temperature gradient and unit heat conduction area is a parameter for representing the heat conduction performance of a material, and is expressed by lambda, and the unit is W/(mK). The general mathematical expression is shown as formula (1):
Q＝λ*(A/S)*ΔT (1)
in the formula: q- - -the heat per unit time flowing through the sample, in W; a- - - -area of object, unit is m2(ii) a S- - - -object thickness in m; delta T-the temperature difference between the cold and hot surfaces of the object, and the unit is K.
FIG. 1 is a schematic thermal diagram of the process of the present invention, wherein a) is a theoretical model; b) is a dual bending feature of the temperature field on the surface of the specimen. In FIG. 1,. DELTA.TLTemperature difference, Δ T, for two probe 31 tips to contact the material to be measuredL＝θ01-θ02，θ01、θ02Respectively representing the bottom temperatures of the two probe contacts; delta THTemperature difference, Δ T, across the probe after a certain current is applied to the thermopile 32H＝θl1-θl2，θl1、θl2Respectively representing the hot end temperature of the thermopile 32 and the cold end temperature of the thermopile, U0The set test temperature for the incubator at the time of the test. The relation between the heat conductivity coefficient of the material to be measured and the probe parameter and the probe temperature difference can be deduced by the hemispherical heat conduction model, as shown in formula (2).
Figure BDA0003356226160000071
Then the process of the first step is carried out,
Figure BDA0003356226160000072
wherein:
Figure BDA0003356226160000073
Figure BDA0003356226160000074
A1，A2，A3all represent intermediate quantities, R is the radius of the probe tip, RcIs the contact resistance of the probe tip,
Figure BDA0003356226160000075
represents the intermediate calculation amount, s is the axial cross-sectional area of the probe, l is the length of the probe, p is the perimeter of the probe, h is the heat exchange coefficient of the air convection surface, and lambdatThe thermal conductivity of the probe material; will be provided with
Figure BDA0003356226160000076
Substituting into the above formula, one can obtain:
Figure BDA0003356226160000077
Figure BDA0003356226160000081
Figure BDA0003356226160000082
it can be seen that R, Rc,p,h,λtAnd s, l are both physical parameters associated with the temperature probe, and are constant over a limited temperature interval for a model of a particular physical property. For a fixed material to be measured and temperature field, Δ T is given at constant current to the thermopileHIs a constant value, λ0Only with Δ TLIt is related. Therefore, the heat conductivity coefficient of the sample to be tested can be obtained by testing the temperature difference at the two ends of the probe.
The invention is not limited to the following specific embodiments, and various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction, as long as the invention does not depart from the idea of the invention, and the invention should be also considered as the disclosure of the invention.
Example 1
As shown in fig. 2, the single-side method dual-probe thermal conductivity measurement system for explosives and powders described in this embodiment includes an incubator 1, a sample carrier 2, a temperature detector 3, and a data acquisition and processing unit 4, where the sample carrier 2 is used to place a sample to be measured, the temperature detector 3 is used to detect the temperature of the sample, the sample carrier 2 and the temperature detector 3 are both disposed in the incubator 1, and the temperature detector 3 is disposed above the sample carrier 2.
The sample plummer 2 of this embodiment includes support and tray, and the sample that awaits measuring is placed to the tray, and temperature detector sets up in the tray top, and the tray can the rotation, realizes that temperature detector 3 is to the measurement of the different positions of the sample that awaits measuring. Specifically, the temperature detector 3 is suspended above the tray by a support capable of moving up and down, so that the temperature detector 3 is convenient to move.
The temperature detector 3 comprises a thermopile 31 and two probes 32, the two probes 32 are respectively connected to the cold end and the hot end of the thermopile 31, the thermopile 3 is connected with a constant current power supply, a contact 321 of the probes 32 is in a frustum shape, and the contact area between the contact 321 and the sample 6 to be measured is increased, as shown in fig. 3.
The temperature detector 3 of the invention adopts the Bohr effect principle to measure the temperature of the sample, namely, two different metals form a closed loop, when a constant current source inputs a certain current to the thermopile 31, the two ends of the thermopile 31 generate a constant temperature difference, the heat is transferred to the contact 321 direction through the heat probe, the contact 321 is closely contacted with the sample to be measured, the temperature theta of the two probe contacts 321 is01、θ02The temperature θ across the thermopile 31, measured by a first stage differential thermocouple 33l1、θl2As measured by the second stage differential thermocouple 34.
The first-stage differential thermocouple 33 and the second-stage differential thermocouple 34 of the temperature detector 3 are connected with the data acquisition and processing unit 4, the measurement results are transmitted to the data acquisition and processing unit 4, and the data are processed and analyzed through a heat conductivity coefficient calculation model (namely formula (3)) of the data acquisition and processing unit 4, so that the heat conductivity coefficients of the explosive material under different temperature conditions are obtained.
As can be seen from FIG. 2, the data collecting and processing unit 4 is further connected with the sample holder and the incubator 1, and the data collecting and processing unit 4 controls the lifting of the temperature detector 3 holder and the rotation of the sample carrier 2 tray. A temperature control meter and a temperature sensor are also arranged in the incubator 1 and are connected with the data acquisition and processing unit 4, so that the temperature in the incubator 1 can be controlled and adjusted.
In order to adjust the temperature at the two ends of the temperature detector thermopile 31, the present embodiment further provides a temperature control system 5, as shown in fig. 2, the temperature control system 5 is used to provide a constant current for the temperature detector 3 by using a constant current power supply, so that the two ends of the temperature detector thermopile 31 generate a constant temperature, and simultaneously, the interference of electromagnetic signals is filtered, and the stability and reliability of the output current signals are ensured.
Example 2
The embodiment discloses a method for measuring the thermal conductivity of a single-sided method double-probe explosive, which adopts the measuring system described in embodiment 1 to carry out measurement, and the specific measuring method comprises the following steps:
step 1, putting a sample to be tested on a tray of a sample bearing platform 2, and closing a box door. The environmental temperature of the sample to be detected is room temperature, generally 15-30 ℃, and the environmental humidity is not more than 80% RH;
wherein, the processing of the sample to be measured requires that the surface is flat and smooth, and has no air holes, oil stains and mechanical damage. The round sample to be tested is preferably selected according to the embodiment, the round sample is consistent with the processing technology of the explosive material, the uniformity of the sample in the measurement process can be ensured, and the round sample is consistent with the structural shape of the detector and the numerical simulation model.
The general sample that awaits measuring is 3 at least, has placed the sample that awaits measuring that the same dimension specification of a material is the same in every tray, and every sample that awaits measuring corresponds a temperature detector, does the parallel test, promotes the measuring result accuracy, and the detailed size of the probe of different temperature detectors can slightly differ because of machining error, and for the convenience of distinguishing, every temperature detector has a serial number.
The door of the constant temperature box 1 is an automatic opening and closing door controlled by the pressure of the air compressor 7, and when the pressure of the air compressor 7 reaches 7-10 atmospheric pressures, the door can be tightly closed.
Step 2, setting the temperature in the incubator 1 as T, wherein T is any one temperature within the range of minus 50-70 ℃, adjusting the temperature detector 3 to enable the contact 321 of the probe to be in close contact with the surface of the sample to be measured after the temperature in the incubator 1 is stable, measuring the temperature difference between the two probes 32, stopping measurement after the measurement time exceeds 10 minutes, and obtaining m groups of measurement results of the current position of the sample to be measured, wherein m is more than or equal to 10; each set of measurement results comprises the temperature theta of the hot end of the thermopilel1Cold end temperature theta of thermopilel2And two probe tip bottom temperatures θ01、θ02Calculating the heat conductivity coefficient corresponding to each group of measurement results by adopting a formula (3) according to the four temperature values;
finally obtaining m heat conductivity coefficient measurement results of the current position of the sample to be measured;
step 3, adjusting the contact position of the contact 321 of the temperature detector 3 and the sample to be measured for multiple times, ensuring that the contact position of the contact 321 and the surface of the sample to be measured is different every time, and measuring according to the measuring mode of the step 2 after adjusting the contact position every time;
preferably, when the contact position of the contact 321 of the temperature detector 3 with the sample to be measured is adjusted: firstly, the position of the temperature detector 3 is adjusted to enable the contact 321 of the probe to leave the sample to be detected, then the tray is rotated to a certain angle, and then the temperature detector 3 is adjusted to enable the contact 321 of the probe to be in close contact with the surface of the sample to be detected again.
Finally obtaining n multiplied by m temperature difference measurement results, wherein n is the contact position adjustment times of the probe contact and the sample to be measured, and n is more than or equal to 6;
step 4, according to the test requirements, if the measurement results of other temperature points within the range of-50 to 70 ℃ are required, resetting the temperature in the incubator 1 to the required temperature point, and paying attention to the fact that the temperature sequence is set from high temperature to low temperature for measurement, so that the influence on the accuracy of the measurement results due to water vapor condensation can be avoided; repeating the steps 2 to 3 to obtain the measurement results of all required temperature points;
step 5, taking the average value of the m heat conductivity coefficient results of each temperature point and each measurement position of the sample to be measured as the heat conductivity coefficient value of one temperature point and one measurement position; then, carrying out the same processing on the data of the n measurement positions to obtain n heat conductivity values of the sample to be measured at one temperature point, and taking the average value of the n heat conductivity values as the heat conductivity value of the sample to be measured at one temperature point; finally, the heat conductivity values corresponding to all required temperature points of the sample to be tested are obtained.
The repeatability and accuracy of the measurement method described in the above example were verified as follows:
the test conditions of the measurement system were: the current amount is 0.8-1A; temperature range: the temperature is 50 ℃ below zero to 70 ℃, each temperature is 10 ℃ apart and is used as a temperature point, the measurement range of the temperature detector is 0.02W/(m.K) to 2.00W, the constant temperature time of each temperature point of the constant temperature box is not less than 30min, and the measurement frequency is 10 s.
The sample to be tested is
Figure BDA0003356226160000121
And 4 identical samples to be tested are arranged at each temperature point of the round sample for parallel test.
When the contact position of the contact 321 and the sample to be measured is adjusted, the temperature detector 3 is adjusted to ascend to enable the contact 321 of the probe to leave the sample to be measured, then the tray is rotated by 60 degrees clockwise, and then the temperature detector 3 is adjusted to descend to enable the contact 321 of the probe to be in close contact with the surface of the sample to be measured again, so that 6 times of measurement results can be obtained at one temperature point, namely n is 6. Each temperature point takes 10 results per rotation angle, i.e. m is 10.
In the following specific embodiments, the values of the parameters are respectively: the temperature detector is a copper detector, the inner diameter of the probe is 0.5mm, the outer diameter of the probe is 1.2mm, the length l of the probe is 12mm, and the contact area of the equal conical caps is 3mm2I.e. pi R2＝3mm,λtIs the heat conductivity coefficient of copper, and h is the heat exchange coefficient of the air convection surface.
In the measurement process, the test time is set to be 5 minutes, the test temperature is 25 ℃, the constant current is 1A, the rotation angle is 60 degrees, and the lifting distance of the temperature detector is 2 cm.
(1) Repeatability test
The self-developed large thermal coefficient standard materials of organic glass, borosilicate glass, quartz glass and TF-3 glass are used in the experiment, 11 times of measurement are independently carried out by adopting the method under the same test condition at the room temperature of 25 ℃, and the experimental data are shown in the following table 1.
TABLE 1 method repeatability test data
Figure BDA0003356226160000122
Figure BDA0003356226160000131
As can be seen from the experimental data results in Table 1, the repeatability of the method of the present invention is less than or equal to 3.0% relative to the standard deviation.
(2) Accuracy test
The method of the invention is adopted to measure the thermal conductivity of standard substances of organic glass, borosilicate glass, quartz glass and TF-1 glass developed by Russian Siberian measurement research institute at room temperature of 25 ℃, and the measurement result is compared with the standard value given by Russian Siberian measurement research institute to obtain the thermal conductivity of the standard substances of organic glass, borosilicate glass, quartz glass and TF-1 glass
Figure BDA0003356226160000132
When the uncertainty of the standard substance is k-2 as a criterion, U is addedrel3.0%. The verification results are shown in table 2.
TABLE 2 method accuracy verification data
Figure BDA0003356226160000133
As can be seen from the results in Table 2, the test results obtained by the measurement method of the present invention for the four standard substances were all in accordance with the standard values
Figure BDA0003356226160000134
The measurement method is accurate and reliable.
In addition, the standard organic glass is also tested by using a hot wire method and the measuring method of the invention, the value of the organic glass obtained by using the hot wire method is 0.2052W/(m.K), and the coefficient of thermal conductivity of the organic glass obtained by using the method of the invention is 0.2036W/(m.K).

Claims (8)

1. The method for measuring the thermal conductivity of the single-side method double-probe explosives and powders is characterized in that the following single-side method double-probe explosives and powders thermal conductivity measurement system is adopted for measurement, and the single-side method double-probe explosives and powders thermal conductivity measurement system comprises a constant temperature box (1), a sample bearing platform (2) for placing a sample and a temperature detector (3) for detecting the temperature of the sample; the sample bearing table (2) and the temperature detector (3) are both arranged in the constant temperature box (1), and the temperature detector (3) is arranged above the sample bearing table (2); the temperature detector (3) comprises a thermopile (31) and two probes (32) which are respectively connected to the cold end and the hot end of the thermopile (31);
the specific measurement method comprises the following steps:
step 1, putting a sample to be tested on a sample bearing table (2) of the single-sided method double-probe explosive thermal conductivity coefficient measurement system, and closing a box door; the sample to be measured is processed to have a flat and smooth surface without pores, oil stains and mechanical damage;
step 2, setting the temperature in the constant temperature box (1) as T, wherein the T is any one temperature within the range of minus 50-70 ℃, adjusting the temperature detector (3) to enable the contact of the probe (32) to be in close contact with the surface of the sample to be measured after the temperature in the constant temperature box (1) is stable, starting measurement, stopping measurement after the measurement time exceeds 10 minutes, and obtaining m groups of measurement results of the current position of the sample to be measured, wherein each group of measurement results comprises the temperature theta of the hot end of the thermopile (31)l1Cold end temperature theta of thermopilel2And the contact bottom temperatures theta of the two probes (32)01、θ02Calculating the heat conductivity value corresponding to each group of measurement results by adopting a formula (3),
Figure FDA0003356226150000011
Figure FDA0003356226150000012
Figure FDA0003356226150000021
Figure FDA0003356226150000022
in the formula, A1、A2、A3All represent intermediate quantities, R is the radius of the probe tip, R iscIs the contact thermal resistance of the probe contact, s is the axial cross-sectional area of the probe, l is the length of the probe, p is the perimeter of the probe, h is the heat exchange coefficient of the air convection surface, and lambdatThe thermal conductivity of the probe material;
finally obtaining m heat conductivity coefficient measurement results of the current position of the sample to be measured;
step 3, adjusting the contact position of a probe (32) contact of the temperature detector (3) and the sample to be measured for multiple times, ensuring that the contact position of the probe (32) and the surface of the sample to be measured is different each time, and measuring according to the measuring mode of the step 2 after adjusting the contact position each time;
finally obtaining n multiplied by m heat conductivity coefficient measurement results, wherein n is the contact position adjustment times of the probe contact and the sample to be measured;
step 4, resetting the temperature in the constant temperature box (1) to the required temperature point according to the test requirement if the measurement results of other temperature points within the temperature range of-50-70 ℃ are required, setting the temperature sequence from high temperature to low temperature for measurement, and repeating the steps 2 to 3 to obtain the heat conductivity coefficient measurement results of all the required temperature points;
step 5, taking the average value of the m heat conductivity coefficient results of each temperature point and each measurement position of the sample to be measured as the heat conductivity coefficient value of one temperature point and one measurement position; then, carrying out the same processing on the data of the n measurement positions to obtain n heat conductivity values of the sample to be measured at one temperature point, and taking the average value of the n heat conductivity values as the heat conductivity value of the sample to be measured at one temperature point;
finally, the heat conductivity values corresponding to all required temperature points of the sample to be tested are obtained.
2. The method for measuring the thermal conductivity of the single-sided double-probe explosives and powders of claim 1, wherein m is more than or equal to 10; n is more than or equal to 6.
3. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 1, wherein the door of the incubator (1) is automatically opened and closed under the control of the pressure of an air compressor, and the door can be tightly closed when the pressure of the air compressor reaches 7-10 atmospheres.
4. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 1, wherein the sample carrying platform (2) comprises a bracket and a tray, the tray can rotate, and when the contact position of the contact (321) of the temperature detector (3) and the sample to be measured is adjusted: firstly, the temperature detector (3) is adjusted to enable the contact (321) of the probe to leave the sample to be detected, then the sample to be detected is rotated to a certain angle, and then the temperature detector (3) is adjusted to enable the contact (321) of the probe to be in close contact with the surface of the sample to be detected again.
5. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 2, wherein the number of the samples to be measured is at least 3, each tray is provided with a sample to be measured which is made of the same material, has the same size and specification, and each sample to be measured corresponds to one temperature detector.
6. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 1, wherein the sample to be measured is a round sample.
7. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 1, characterized in that a first-stage differential thermocouple (33) is arranged in the probe (32) and used for measuring the temperature of the bottom of a contact of the probe (32), and a second-stage differential thermocouple (34) is arranged in the thermopile (31) and used for measuring the temperature of the cold end and the hot end of the thermopile (31); the first-stage differential thermocouple (33) and the second-stage differential thermocouple (34), and the first-stage differential thermocouple (33) and the second-stage differential thermocouple (34) are respectively connected with the data acquisition and processing unit (4).
8. The single-sided method double-probe explosive thermal conductivity measurement method according to claim 1, wherein the contact of the probe (32) is provided in a frustum shape.
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