Sample carrier, system and method for the analysis of energetic materials

Abstract

Sample carrier (1) for a system for the analysis of energetic materials, comprising: - comprising a first support element (2) and a first heating element (6), wherein the heating element (6) is designed as a resistance heater and has at least one first sample area (11) provided for receiving a sample; - comprising a second support element (3, 4) and a second heating element (7), wherein the heating element (7) is designed as a resistance heater and has at least one second sample area (12) provided for contacting the sample, wherein at least one of the support elements is suitable as a sampler; - a device for connecting the support elements (2, 3, 4) with close confinement of the sample between the first sample area (11) and the second sample area (12) without measurable dead volume by pressing the sample areas (11, 12) directly against each other.

Description

[0001] The present invention relates to a sample holder for a system for analyzing energetic materials. It further relates to a system and a method for analyzing energetic materials.

[0002] Energetic materials are substances or mixtures that can release chemical energy in a very short time without requiring the supply of oxygen or other reactants from the environment. Typical examples of energetic materials are propellants and explosives.

[0003] The detection of materials, including energetic materials, using spectroscopic methods is well-established. However, such a procedure requires a library of reference spectra. Substances not yet detected cannot be identified in this way.

[0004] German patent DE 10 2015 118 728 A1 discloses an analysis system for the library-independent, qualitative detection of energetic materials. In this system, a sample of the material to be analyzed is placed in a sample chamber that can be heated from at least two sides and then heated. Pressure sensors can be used to detect an explosive reaction of the sample.

[0005] From US patent 2018 / 0 067 067 A1, a microcalorimeter for the investigation of explosives is known, which has two heating elements for differential measurement.

[0006] US 2010 / 0240140A1 describes a device for analyzing energetic material, consisting of two halves, one half being used for sampling, and the device having a heating element.

[0007] According to WO 2011 / 070 578 A2, sampling is carried out by wiping across a surface. The enclosed sample carrier is then ignited by sparking between the electrodes.

[0008] A disadvantage of the known methods is that sampling is not easily automated and introducing the sample into the sampling chamber requires handling the potentially explosive substance. Furthermore, the thermal contact between the sample and the heating surface is insufficient, so the sample often vaporizes instead of being ignited.

[0009] It is an object of the present invention to provide a sample carrier, a system and a method for analyzing energetic materials that are particularly safe and reliable.

[0010] This problem is solved by the subject matter of the independent patent claims. Further embodiments and advantageous configurations are the subject matter of the dependent claims.

[0011] According to one aspect of the invention, a sample carrier for a system for analyzing energetic materials is provided, comprising a first carrier element. The first carrier element has a first heating element, wherein the heating element is designed as a resistance heater and has at least one first sample area provided for receiving a sample. Furthermore, the sample carrier comprises a second carrier element, which has a second heating element, wherein the heating element is designed as a resistance heater and has at least one second sample area provided for contact with a sample. The sample carrier further comprises a device for connecting the carrier elements, enclosing a sample between the first sample area and the second sample area.

[0012] The sample carrier has the advantage that, by enclosing the sample between the two sample areas, the sample is in contact with a heating element everywhere and can be heated throughout the entire analysis.

[0013] Furthermore, the design of the sample carrier, consisting of at least two support elements, allows for automated sample collection. The sample does not need to be taken with a separate device and applied to the sample area; instead, at least one of the support elements is already designed to act as a sampler. This support element can then be brought into contact with the material to be analyzed, ensuring that a sample of the material remains on the sample area. This sample is then trapped between the two sample areas when the two support elements are subsequently joined together.

[0014] The sample enclosure can be designed as a very tight enclosure, enabling a clear pressure signal. With such a tight enclosure, the sample areas are pressed directly against each other, leaving no measurable dead volume. This also allows the sample holder to be designed very compactly.

[0015] According to one embodiment, the first and / or second sample area has a surface roughness increased compared to the rest of the surface of the first and / or second heating element. This increased surface roughness can be achieved, for example, by structures such as bumps or pores and / or an adhesive coating. The increased surface roughness facilitates the picking up and adhesion of a sample in the sample area, thus enabling the use of the carrier element as a sampler.

[0016] According to one embodiment, the first and / or the second sample area protrudes from other areas of the first and / or second heating element. In other words, the support element in question has a convex surface contour in the sample area.

[0017] With this type of sample area design, it is particularly easy to bring it into contact with the material to be analyzed without having to handle the material with other equipment. This enables particularly safe sampling and analysis.

[0018] According to one embodiment, the first heating element extends along a first longitudinal axis and the second heating element extends along a second longitudinal axis, with the longitudinal axes intersecting when the support elements are connected to one another by means of the device for connecting the support elements. In particular, the longitudinal axes can intersect at a right angle. Such an arrangement ensures that the temperature of the heating elements is particularly high in the intersection area.

[0019] To significantly increase the temperature in the area of ​​the enclosed sample, the first and / or second sample section of the heating elements can have a higher electrical resistance than other sections of the first or second heating element, respectively. This results in particularly strong heating of the heating element in the sample area. The particularly high electrical resistance can be achieved, for example, by reducing the thickness or width of the heating element, or by incorporating openings.

[0020] According to one embodiment, each heating element has two contact holes. A contact pin can be inserted through each of these holes when the sample carrier is placed in a designated receptacle of the system for analyzing energetic materials. The holes can be designed such that their edges clean the surfaces of the contact pins as they are inserted. This can be achieved, in particular, by having areas of the edges that bear resiliently against the respective contact pin and slide closely along it as the contact pin is inserted through the contact hole.

[0021] The first or second support element can have a window transparent to electromagnetic radiation, such as infrared radiation, through which at least one heating element is exposed. For example, the back side of the second sample area can be exposed in the window. This has the advantage of allowing particularly simple and reliable temperature measurement in the sample area.

[0022] The first and second support elements can each have a plastic body to which the first and second heating elements, respectively, are attached. The use of a plastic body offers the advantage that the entire sample carrier can be designed as a disposable item for single use. Suitable materials are, in particular, plastics that do not release volatile substances that could interfere with the analysis, even at elevated temperatures.

[0023] According to one embodiment, a cavity is arranged in the first support element adjacent to the sample area of ​​the heating element. Substances generated during the heating of the sample are released into the cavity. For the analysis of these substances, the cavity is connected to an outlet of the sample carrier, which in turn can be connected to a cavity of a system for analyzing energetic materials. Substances located in the cavity can be analyzed, for example, by gas sensors. Pressure sensors can also be provided to monitor the pressure in the cavity. To prevent impurities from passing from the sample carrier into the cavity, a filter can be provided at the outlet of the sample carrier.

[0024] According to a further aspect of the invention, a system for analyzing energetic materials is provided with a receptacle for the described sample carrier, wherein the system further comprises contact pins for electrical contacting the heating elements of the sample carrier when it is arranged in the receptacle, and at least one pressure sensor for determining a pressure signal of a sample.

[0025] In addition, the system can also include gas sensors for analyzing gases produced when heating a sample, as well as a device for measuring temperature using infrared radiation.

[0026] The system enables fast and reliable analysis of even unknown materials and largely automated, and therefore less dangerous, sampling and analysis.

[0027] According to one embodiment, the system further comprises a device for generating a negative pressure in a measuring area of ​​the pressure sensor. This device may, for example, be a fan or a pump that removes gas from the measuring area of ​​the pressure sensor.

[0028] This embodiment has several advantages. Firstly, the device for generating a vacuum provides a way to remove gases after an analysis and thus purge the system. Secondly, when a vacuum is generated before the measurement, the measurement is taken against a low background, resulting in a particularly clear pressure signal.

[0029] According to a further aspect of the invention, a method for analyzing energetic materials is described, comprising taking a sample of a material by means of a first heating element designed as a resistance heater by bringing a sample area of ​​the heating element into contact with the material, and enclosing the sample between the first heating element and a second heating element also designed as a resistance heater. Furthermore, the method comprises heating the sample by energizing the heating elements and recording a pressure signal by means of at least one pressure sensor.

[0030] According to one embodiment, the method further includes generating a negative pressure in a measuring area of ​​the pressure sensor before heating the sample.

[0031] After the analysis has been completed, a vacuum can be created again to remove released gases from the system and to purge it. Embodiments of the invention are explained in more detail below with reference to schematic figures. Fig. 1 shows a longitudinal section through a sample holder according to a first embodiment of the invention; Fig. 2 shows an opposite Fig. 1 longitudinal section rotated by 90° through the sample carrier; Fig. Figure 3 shows two heating elements of the sample carrier in a perspective view; Fig. 4 shows the heating elements according to Fig. 3 in a side view; Fig. 5 shows a detail from Fig. 3; Fig. Figure 6 shows a perspective view of a first support element for a sample carrier according to a second embodiment of the invention; Fig. Figure 7 shows a longitudinal section through the support element according to Fig. 6; Fig. 8 shows a opposite Fig. 7 longitudinal section rotated by 90 degrees; Fig. Figure 9 shows a longitudinal section through a second support element for the sample carrier according to the second embodiment of the invention; Fig. 10 shows one opposite Fig. 9 longitudinal sections rotated by 90 degrees; Fig. Figure 11 shows a perspective view of the sample carrier according to the second embodiment of the invention; Fig. Figure 12 shows a longitudinal section through the sample holder according to Fig. 11 and Fig. 13 shows a opposite Fig. 12 longitudinal sections rotated by 90 degrees through the sample carrier.

[0032] The Fig. 1 and Fig. Figure 2 shows sections along the longitudinal axis L through a sample carrier 1 for a system for analyzing energetic materials according to an embodiment of the invention.

[0033] In the illustrated embodiment, the sample carrier 1 comprises two assemblies that can be connected to one another. The first assembly comprises a first support element 2, which is made of plastic, for example, polyamide. The second assembly comprises a second support element 3 and a third support element 4, which are also made of plastic, for example, polyamide, and are connected to one another via a snap-fit ​​connection 10. The second assembly has a recess 17 into which the first support element 2 can be inserted. The components described in the illustrations are located between the two assemblies. Fig. 3 - 5 heating elements 6, 7 shown in more detail are arranged, wherein in the Fig. 1 and Fig. 2 only the second heating element 7 is visible.

[0034] As in the Fig. As shown in Figures 3 to 5, the heating elements 6, 7 each comprise a metal strip, for example made of a constantan foil, with a centrally arranged sample area. Furthermore, each heating element 6, 7 has two contact holes 13 for electrical contact. In the embodiment shown here, each heating element 6, 7 also has mounting sections 14, which are arranged at both ends of the heating elements 6, 7 and are angled when the heating elements 6, 7 are mounted. The heating elements 6, 7 are attached to the support elements 2, 3, 4 by means of the mounting sections 14.

[0035] To attach the first heating element 6 to the first support element 2, the second support element 2 has a circumferential groove 5 into which an O-ring can be inserted. To prepare the first support element 2 for sampling, the first heating element 6 is placed onto an upper contour 20 of the first support element 2, and the fastening sections 14 are clamped by means of the O-ring inserted into the groove 5. Thus, the first heating element 6 is easily fixed to the first support element 2.

[0036] To prepare the second assembly, consisting of the second support element 3 and the third support element 4, for sampling or analysis, the second heating element 7 is clamped between a lower contour 21 of the third support element 4 and an upper contour 22 of the second support element 3. When the first support element 2 is then inserted into the recess 17 in the second assembly, the sample areas 11, 12 of the two heating elements 6, 7 are aligned.

[0037] In the illustrated embodiment, the sample holder 1 has three support elements 2, 3 and 4. However, it is also conceivable to provide only two support elements if the second heating element 7 is attached in a different way.

[0038] In the third support element 4 a window 15 transparent to infrared radiation is arranged, behind which the second sample area 12 is exposed for a temperature measurement.

[0039] The sample areas 11, 12 of the heating elements 6, 7 exhibit increased surface roughness, for example in the form of bumps or pores, to improve sample adhesion. This is not shown in the figures.

[0040] Furthermore, the heating elements 6, 7 in the sample areas 11, 12 have a number of through-holes 16, which can be introduced, for example, by laser drilling or punching. The through-holes 16 serve to increase the electrical resistance of the heating elements 6, 7 in the sample areas 11, 12.

[0041] The sampling and analysis procedure is as follows: the first support element 2, equipped with the first heating element 6, is brought into contact with the material to be analyzed. This is particularly simplified by the fact that the upper contour 20 of the first support element 2 is convex with the first sample area 11. This causes a sample of the material to adhere to the first sample area 11 of the first heating element 6.

[0042] The first support element 2, thus fitted with the sample, is inserted into the recess 17 in the second support element 3 and pressed in until the surfaces of the first support element 2 and the second support element 3 are flush with a first side 8 of the sample carrier 1. In this position, the first support element 2 is frictionally connected to the second support element 3 via the O-ring inserted into the groove 5. The O-ring inserted into the groove 5, together with the dimensions of the recess 17 and the first support element 2, thus forms a device for connecting the support elements 2 and 3, enclosing the sample between the first sample area 11 and the second sample area 12. The sample areas 11 and 12 of the heating elements 6 and 7 lie on top of each other, and the sample is thus tightly enclosed between the heating elements 6 and 7.

[0043] The sample carrier 1 is then inserted into a designated receptacle of a system (not shown) for the analysis of energetic materials. Contact pins of the system penetrate holes 18 of the third support element 4, which are exposed on a second side 9 of the sample carrier 1, and come into contact with the heating elements 6, 7 in the area of ​​the contact holes 13. Since the contact holes 13 have a smaller diameter than the holes 18, but have incised edges, as also shown in Fig. As can be seen in Figure 3, the material of the heating elements 6, 7 can bend in the edge region of the contact holes 13 and fit snugly against the contact pins. This also allows the contact pins to be cleaned during insertion and removal. The heating elements 6, 7 are energized via the contact pins and the electrical contact in the area of ​​the contact holes 13. The temperature rises and, due to the overlap of the heating elements 6, 7 and the particularly high electrical resistance in the sample areas 11, 12, reaches a maximum there.

[0044] If the sample to be analyzed is an energetic material, it will be ignited when a material-dependent temperature threshold is exceeded, and a pressure sensor in the system will register a corresponding pressure increase.

[0045] The sample or its reaction products are accessible for analysis via a cavity 19 located below the sample areas 11, 12 between the first support element 2 and the third support element 4, with an outlet 23 at which a filter can be inserted. The system may, in particular, include gas sensors for this purpose.

[0046] The Fig. Figures 6 to 13 show a second embodiment of a sample carrier. These figures show... Fig. 6 to 8 different views of a first support element 2', which Fig. 9 and Fig. 10 two different views of a second support element 3' and the Fig. 11 to 13 different views of the entire sample carrier 1', which includes the first support element 2' and the second support element 3'.

[0047] The in Fig. The first support element 2' shown in Figures 6 to 8 differs from the one shown in the Fig. 1 and Fig. The difference between the first embodiment shown in Figure 2 and the second embodiment is mainly that the heating element 6' is attached to the first support element 2' in a different manner. According to the second embodiment, the first support element 2' has projections 24 on two opposite sides, which extend from a side surface of the support element 2'. The heating element 6' has a hole 27 in each of its two end regions, through which the projections 24 can be guided. The projections 24 can be resilient to simplify the attachment of the heating element 6'. Furthermore, the heating element 6' can be made of a somewhat flexible material, for example, a constantan film. For mounting on the support element 2', the heating element 6' can first be attached on one side by guiding one of the projections 24 through one of the holes 27.The heating element 6' is then clamped to the opposite side of the support element 2' and the second projection 24 is guided through the corresponding hole 27.

[0048] Furthermore, according to the second embodiment, the first support element 2' has locking hooks 25 on two opposite sides which engage with a projection of the second support element, as shown by the Fig. 12 and Fig. 13 is set out.

[0049] In the Fig. 7 and Fig. Figure 8, which shows sectional views of the first support element 2' rotated 90° relative to each other, also shows a threaded bore 26 extending from the first side 8 into the first support element 2'. The threaded bore 26 allows a threaded rod, not shown in the figures, to be attached to the first support element 2' in order to carry out sampling in the least risky way possible. The first support element 2', which can have a diameter of a few centimeters, can then be inserted into a container containing an unknown substance to be tested using the threaded rod. Subsequently, the first support element 2' can be inserted into the designated recess of the second support element, either using the threaded rod or after removing the threaded rod.

[0050] The second support element 3' according to the second embodiment is in the Fig. 9 and Fig. Figure 10 shows two sectional views rotated 90° relative to each other. The second support element 3' differs from the one shown in the Fig. 1 and Fig. The difference shown in Figure 2 is mainly due to the way the second heating element 7' is attached, which in this case is also achieved by guiding projections 28 on opposite sides of the second support element 3' through holes 29 at two ends of the second heating element 7'. The attachment of the second heating element 7' to the second support element 3' is thus analogous to the attachment of the first heating element 6' to the first support element 2'.

[0051] Furthermore, the second support element 3', which according to the second embodiment, unlike the first embodiment, can be formed in one piece, has a shoulder 30 surrounding or at least partially surrounding the recess 17, against which the locking hooks 25 of the first support element 2' engage when the first support element 2' is inserted far enough into recess 17. In this position, the sample areas 11', 12' of the heating elements 6', 7' then lie on top of each other and enclose the sample between them.

[0052] This position is in the Fig.Figures 11 to 13 show the entire sample carrier 1' according to the second embodiment. In this position, the first support element 2' is fully inserted into the recess 17 of the second support element 3' and locked onto it. Areas of the heating elements 6', 7' are exposed in the holes 18 for electrical contact for resistance heating. Below the sample areas 11', 12' is the cavity 19, through which the sample or its reaction products are accessible for analysis.

[0053] Through a window 15 on a second side 9 of the sample carrier 1', the sample area 12' of the second heating element 7' is accessible for an infrared temperature measurement, as described in connection with the first embodiment. Reference symbol list 1, 1' Sample carrier 2, 2' first support element 3, 3' second support element 4 third support element 5 Nut 6, 6' first heating element 7, 7' second heating element 8 first page 9 second page 10 rest connection 11 Sample area 12 Sample area 13 contact holes 14 Fastening section 15 windows 16 through hole 17 Exclusion 18 holes 19 Cavity 20 contour 21 contour 22 contour 23 Exit 24 lead 25 locking hooks 26 threaded holes 27 holes 28 lead 29 holes Paragraph 30

Claims

[1] Sample carrier (1) for a system for the analysis of energetic materials, comprising: - comprising a first support element (2) and a first heating element (6), wherein the heating element (6) is designed as a resistance heater and has at least one first sample area (11) provided for receiving a sample; - comprising a second support element (3, 4) and a second heating element (7), wherein the heating element (7) is designed as a resistance heater and has at least one second sample area (12) provided for contacting the sample, wherein at least one of the support elements is suitable as a sampler; - a device for connecting the support elements (2, 3, 4) with close confinement of the sample between the first sample area (11) and the second sample area (12) without measurable dead volume by pressing the sample areas (11, 12) directly against each other. [2] Sample carrier (1) according to claim 1, wherein the first and / or the second sample area (11, 12) has a surface roughness increased compared to the rest of the surface of the first and / or second heating element (6, 7). [3] Sample carrier (1) according to claim 1 or 2, wherein the first and / or the second sample area (11, 12) protrudes over other areas of the first and / or second heating element (6, 7). [4] Sample carrier (1) according to one of the preceding claims, wherein the first heating element (6) extends along a first longitudinal axis and the second heating element (7) extends along a second longitudinal axis, the longitudinal axes intersecting when the carrier elements (2, 3, 4) are connected to each other by means of the device for connecting the carrier elements (2, 3, 4). [5] Sample carrier (1) according to one of the preceding claims, wherein the first and / or the second sample area (11, 12) has a greater electrical resistance than other sections of the first or second heating element (6, 7). [6] Sample carrier (1) according to one of the preceding claims, wherein each heating element (6, 7) has two contact holes (13). [7] Sample carrier (1) according to one of the preceding claims, wherein at least one carrier element (2, 3, 4) has a window (15) transparent to electromagnetic radiation in which an area of ​​at least one heating element (6, 7) is exposed. [8] Sample carrier (1) according to one of the preceding claims, wherein the first carrier element (2) and the second carrier element (3, 4) each have a plastic body on which the first heating element (6) and the second heating element (7) are arranged respectively. [9] Sample carrier (1) according to one of the preceding claims, wherein a cavity (19) is arranged in the first carrier element (2) adjacent to the sample area (11) of the heating element (6). [10] System for analyzing energetic materials with a receptacle for a sample carrier (1) according to any one of claims 1 to 9, wherein the system further comprises: - Contact pins for electrical contacting the heating elements (6, 7) of the sample holder (1) when it is arranged in the holder, and - at least one pressure sensor to determine a pressure signal from the sample. [11] System according to claim 10, further comprising gas sensors for analyzing gases produced when the sample is heated. [12] System according to claim 10 or 11, further comprising a device for generating a vacuum in a measuring range of the pressure sensor. [13] Methods for analyzing energetic materials, comprising - Taking a sample of a material by means of a first heating element (6) designed as a resistance heater by bringing a sample area (11) of the heating element (6) into contact with the sample; - tightly enclosing the sample between the first heating element (6) and a second heating element (7) also designed as a resistance heater with a second sample area (12) without measurable dead volume, by pressing the sample areas (11, 12) directly against each other; - Heating the sample by energizing the heating elements (6, 7) and - Recording a pressure signal using at least one pressure sensor. [14] Method according to claim 13, wherein a negative pressure is generated in a measuring area of ​​the pressure sensor before the sample is heated.

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