Material resistivity testing device under microwave heating environment

Abstract

The utility model relates to the technical field of microwave heating equipment, specifically is a kind of material resistivity testing device under microwave heating environment, including furnace body, furnace body upper end sealing connection has furnace cover, lower end sealing connection has bottom sealing plate;The internal space of furnace body and furnace cover, sealing plate constitutes resonant cavity, and magnetron that emits microwave into resonant cavity is provided on furnace body;Quartz tube is provided in furnace body, and quartz tube and bottom sealing plate, furnace cover are sealing connection between;Heat preservation box is provided in quartz tube, and heat preservation box is spliced structure, including bottom support, fence and box cover;Resistance probe and thermocouple are provided on furnace cover, and resistance probe and thermocouple end portion are inserted into heat preservation box;The device is matched with heat preservation box by quartz tube, realizes the indirect heating of microwave-insensitive material, and the application range of test material is expanded;Heat preservation box adopts spliced structure, and sample is placed conveniently;The sealing connection structure of quartz tube provides basic conditions for subsequent vacuum, atmosphere control.

Description

Technical Field

[0001] This utility model relates to the field of microwave heating equipment technology, specifically a material resistivity testing device under microwave heating environment. Background Technology

[0002] In the field of materials science research, resistivity is an important parameter characterizing the electrical properties of materials. Especially under high-temperature conditions, changes in resistivity directly affect the thermal stability and practical application performance of materials. Traditional resistivity testing methods (such as the four-probe method and the van der Burg method) usually need to be carried out in a constant temperature environment, and the heating methods mostly use conventional heating methods such as resistance furnaces and muffle furnaces.

[0003] In recent years, microwave heating technology has been widely used in the field of materials processing due to its unique advantages (such as rapid heating, selective heating, energy efficiency, etc.). To adapt to this trend, researchers have developed some experimental devices that combine microwave heating with resistivity testing. Existing experimental devices typically perform resistivity testing by integrating resistivity testing electrodes within the microwave cavity.

[0004] During use, the applicant discovered that existing microwave-heated resistivity testing devices still have the following problems: 1. Limited material applicability: There is a lack of effective heating schemes for microwave-insensitive materials (such as metals and highly conductive materials, low dielectric loss materials, and certain polymer materials such as polytetrafluoroethylene), making it impossible to achieve indirect heating mode and greatly limiting the types of materials that can be tested; 2. Limited functionality: It only supports a single environment (atmospheric pressure or air atmosphere) and cannot meet the experimental requirements of vacuum or controlled atmosphere.

[0005] Therefore, there is an urgent need to develop a material resistivity testing device under microwave heating environment with strong material applicability. Utility Model Content

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a material resistivity testing device under microwave heating conditions that can heat microwave-insensitive materials and measure their resistivity at different temperatures.

[0007] The technical solution adopted by this utility model to solve its technical problem is:

[0008] A material resistivity testing device under microwave heating environment includes a furnace body, with a furnace cover sealed to the upper end and a bottom sealing plate sealed to the lower end; the internal space of the furnace body, furnace cover, and bottom sealing plate forms a resonant cavity, and a magnetron is installed on the furnace body to emit microwaves into the resonant cavity; a quartz tube is installed inside the furnace body, and the quartz tube is sealed to the bottom sealing plate and furnace cover; an insulation box is installed inside the quartz tube, and the insulation box has a spliced ​​structure including a base, a surrounding plate, and a box cover; a resistance probe and a thermocouple are installed on the furnace cover, and the ends of the resistance probe and the thermocouple are inserted into the insulation box.

[0009] Compared with the prior art, the outstanding features of this utility model, which adopts the above technical solution, are:

[0010] This device, through the combination of a quartz tube and an insulated chamber, enables indirect heating of microwave-insensitive materials (such as metals and polymers), expanding the range of applicable test materials. The insulated chamber adopts a spliced ​​structure of a base, surrounding panels, and a lid, which facilitates sample placement. The quartz tube is sealed to the bottom sealing plate and the furnace lid, providing a basic condition for subsequent vacuum / atmosphere control.

[0011] As a preferred embodiment, a further technical solution of this utility model is:

[0012] Preferably, it also includes an inlet pipe, a vacuum pipe, and an exhaust pipe, which are installed on the bottom sealing plate or furnace cover. The inlet pipe is connected to an inlet valve, the vacuum pipe is connected to an exhaust valve, and the exhaust pipe is connected to an exhaust valve. The inlet pipe, vacuum pipe, and exhaust pipe, together with the valves, achieve precise control of the atmosphere environment. The independent valve control of each pipeline facilitates rapid switching of experimental conditions and supports various experimental environments such as vacuum, inert gas, and reactive gas.

[0013] Preferably, the inner wall of the enclosure is also provided with a microwave absorbing coating; this can improve microwave absorption efficiency and reduce reflection loss.

[0014] Preferably, a lifting drive mechanism is provided on the outside of the furnace cover. The furnace cover includes a lower connecting cylinder and a top cover. The lower end of the lower connecting cylinder is sealed to the upper end of the furnace body. The top cover is connected to the lifting drive mechanism, which can cover the lower connecting cylinder and lock it in place through a quick-locking mechanism. This facilitates sample loading and device maintenance, enables automated opening of the cover, and improves experimental efficiency.

[0015] Preferably, the lifting drive mechanism includes electric slides on the left and right sides of the furnace cover. The sliders of the electric slides are connected to the top cover to drive the top cover to move up and down. The lifting stroke is precisely controlled to ensure a seal between the top cover and the lower connecting cylinder. At the same time, the dual-side synchronous drive ensures the smooth movement of the top cover.

[0016] Preferably, the sliders of the two electric sliding tables on the left and right sides of the furnace cover are also provided with two guide shafts, and the guide shafts are slidably sleeved on the guide shafts. The sliding sleeves are fixedly connected to the sliders and the top cover.

[0017] Preferably, the quick-locking mechanism includes several connecting seats arranged circumferentially on the outer wall of the lower connecting cylinder. Each connecting seat is hinged with a guide rod, and a handwheel is threaded onto the guide rod. The lower end of the handwheel is rotatably connected to a pressing sleeve via a bearing. The pressing sleeve has a locking tooth on the side near the top cover, and the furnace cover has a locking groove that mates with the locking tooth. The handwheel and pressing sleeve structure enables quick operation with one hand, and the multi-point evenly distributed locking ensures uniform sealing.

[0018] Preferably, a connecting sleeve is provided on the furnace cover, and the connecting sleeve is provided with external threads. The resistance probe and thermocouple are provided with lock nuts that are compatible with the connecting sleeve. A third sealing ring is provided in the lock nut. The resistance probe or thermocouple is connected to the furnace cover through the lock nut and the connecting sleeve. The lock nut and the sealing ring provide double protection for the airtightness of the measuring end, and the standardized interface facilitates probe replacement and maintenance.

[0019] Preferably, the quartz tube, the bottom sealing plate, and the furnace cover form a heating chamber, and a pressure gauge is installed on the furnace cover to detect the pressure inside the heating chamber; this provides a safety guarantee for vacuum or atmosphere experiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the material resistivity testing device in an embodiment of this utility model;

[0021] Figure 2 yes Figure 1 Enlarged structural diagram at point A;

[0022] Figure 3 yes Figure 1 Enlarged structural diagram at point B;

[0023] Figure 4 yes Figure 1 Enlarged structural diagram at point C;

[0024] Figure 5 yes Figure 1 Enlarged structural diagram at point D;

[0025] Figure 6 This is a schematic diagram of the material resistivity testing device in an embodiment of this utility model when the top cover is open.

[0026] Figure 7 This is a schematic diagram of the structure of the insulated box in an embodiment of this utility model;

[0027] Figure 8 This is a top view of the material resistivity testing device in an embodiment of this utility model.

[0028] Explanation of reference numerals in the attached drawings: 1. Furnace body; 2. Magnetron; 3. Furnace cover; 301. Top cover; 3011. Fourth sealing ring; 302. Lower connecting cylinder; 303. Third flange connecting plate; 4. Bottom sealing plate; 401. Annular flange; 5. Quartz tube; 501. First flange connecting plate; 502. Second flange connecting plate; 6. Insulation box; 601. Base support; 602. Enclosure plate; 603. Box cover; 7. Thermocouple; 8. Resistance probe; 801. Alumina ceramic tube; 802. Metal probe; 803. 9. Alumina ceramic connecting plate; 10. Electric slide table; 11. Slider; 12. Quick lock mechanism; 13. Connecting seat; 14. Guide rod; 15. Handwheel; 16. Press sleeve; 17. Clamping tooth; 18. Vacuum tube; 19. Inlet pipe; 20. Caster; 11. Guide shaft; 12. Sliding sleeve; 13. Support frame; 14. Connecting sleeve; 15. Lock nut; 16. Third sealing ring; 17. First sealing ring; 28. Second sealing ring; 29. ​​Wave-absorbing coating; 20. Exhaust pipe. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. The purpose of this description is only to better understand the content of the present invention. Therefore, the examples given do not limit the scope of protection of the present invention.

[0030] like Figures 1 to 8As shown, this embodiment provides a material resistivity testing device under microwave heating environment, including a furnace body 1, with a furnace cover 3 sealed to the upper end and a bottom sealing plate 4 sealed to the lower end; the internal space of the furnace body 1, the furnace cover 3, and the bottom sealing plate 4 constitutes a resonant cavity, and a magnetron 2 is provided on the furnace body 1 to emit microwaves into the resonant cavity; a quartz tube 5 is provided inside the furnace body 1, and the quartz tube 5 is sealed to the bottom sealing plate 4 and the furnace cover 3; a heat preservation box 6 is provided inside the quartz tube 5, and the heat preservation box 6 is a spliced ​​structure, including a base 601, a surrounding plate 602, and a box cover 603; a resistance probe 8 and a thermocouple 7 are provided on the furnace cover 3, and the ends of the resistance probe 8 and the thermocouple 7 are inserted into the heat preservation box 6; the thermocouple 7 is used to monitor the temperature inside the heat preservation box 6 in real time, and the resistance probe 8 is used to measure the resistivity of the material placed in the heat preservation box 6, with the measuring end of the resistance probe 8 in contact with the material; through the resistance probe 8 and the thermocouple 7, the resistivity and temperature can be measured synchronously and accurately at different temperatures. Among them, the magnetron 24 adopts Samsung OM75P(31)ESGN; in this embodiment, four resistance probes 8 are provided, and each resistance probe 8 has an alumina ceramic tube 801 sleeved on the metal probe 802. The four alumina ceramic tubes 801 are all set on an alumina ceramic connecting plate 803 (the alumina ceramic connecting plate 803 and the alumina ceramic tube 801 can be an integrally formed structure). The metal probe 802 is connected to an external resistance measuring instrument through wires to form a four-probe system. Of course, the existing Lucas Labs Pro4-4400 high-temperature four-probe system can also be directly used; the thermocouple 7 adopts a type B thermocouple.

[0031] The connection structure between the resistance probe 8 and the thermocouple 7 is as follows: a connecting sleeve 17 is provided on the furnace cover 3, and the connecting sleeve 17 is provided with external threads. The resistance probe 8 and the thermocouple 7 are provided with lock nuts 18 that are compatible with the connecting sleeve 17. A third sealing ring 1801 is provided in the lock nut 18. The resistance probe 8 or the thermocouple 7 is connected to the furnace cover 3 through the lock nut 18 and the connecting sleeve 17. The lock nut 18 and the sealing ring provide double protection for the airtightness of the measuring end. The standardized interface facilitates probe replacement and maintenance.

[0032] The connection structure between the furnace body 1, the bottom sealing plate 4, and the furnace cover 3 is as follows: A first flange connecting plate 501 is provided at the upper end of the furnace body 1, and a second flange connecting plate 502 is provided at the lower end. The bottom sealing plate 4 is bolted to the furnace body 1 via the second flange connecting plate 502. A third flange connecting plate 303 is provided along the lower edge of the furnace cover 3. The side cross-section of the third flange connecting plate 303 has an inverted L-shaped structure, serving as a connection and sealing mechanism to effectively prevent microwave leakage. The horizontal connecting plate of the third flange connecting plate 303 is connected to the first flange connecting plate... 501 is bolted and fixed; the inner side of the first flange connecting plate 501 is provided with an upper connecting ring groove, and a first sealing ring 19 is provided in the upper connecting ring groove. The outer wall of the quartz tube 5 and the lower end of the vertical connecting plate of the third flange connecting plate 303 abut against the first sealing ring 19; the inner side of the second flange connecting plate 502 is provided with a lower connecting ring groove, and a second sealing ring 20 is provided in the lower connecting ring groove. An annular flange 401 is provided on the bottom sealing plate 4. The outer wall of the quartz tube 5 and the upper end of the annular flange 401 abut against the second sealing ring 20.

[0033] By designing a modular insulated box 6 with a microwave-absorbing coating 21, the application range of microwave thermogravimetric analyzers is significantly expanded. In particular, it solves the technical bottleneck of directly heating low-dielectric-loss materials (such as Al2O3, SiO2, and some polymer materials) in a microwave field. Its core beneficial effects are as follows: 1. Overcoming the selectivity limitations of microwave heating: For some inert materials (such as ceramic catalyst supports and quartz sand), traditional microwave heating efficiency is extremely low. In this design, the inner wall of the insulated box 6 can be coated with a silicon carbide or ferrite microwave-absorbing coating 21, efficiently converting microwave energy into heat energy. The sample is indirectly heated through thermal radiation and convection, enabling materials that cannot absorb microwaves to achieve rapid heating, such as Al2O3 particles rising from room temperature to 800℃ within 5 minutes. 2. Compatibility with complex reaction atmospheres: The modular design of the microwave-absorbing coating 21 and the insulated box 611 allows for flexible replacement of the coating type according to different material characteristics (e.g., SiC is suitable for oxidizing atmospheres, while MoSi2 is suitable for reducing atmospheres), avoiding operational conflicts caused by the material limitations of heating elements in traditional resistance furnaces. For example, in the reduction reaction of metal oxides under H2 atmosphere, the MoSi2 coated insulation box 6 can operate stably at 1000℃ without oxidation. The insulation box 6 can be made of alumina-based ceramic fiber composite material.

[0034] This embodiment fills the gap in the adaptability of traditional microwave thermogravimetric analyzers to low dielectric materials by using a combined heating mechanism of microwave and thermal conduction, and provides a universal solution for the accurate thermal analysis of broad spectrum materials.

[0035] It also includes an inlet pipe 12, a vacuum pipe 11, and an exhaust pipe 22, which are mounted on the bottom sealing plate 4 or the furnace cover 3. The inlet pipe 12 is connected to an inlet valve, the vacuum pipe 11 is connected to an exhaust valve, and the exhaust pipe 22 is connected to an exhaust valve. The vacuum pump can be a Pfeiffer-HiCube-80-Eco. A flow meter is connected to the inlet pipe 12. The quartz tube 5, the bottom sealing plate 4, and the furnace cover 3 form a heating chamber. A pressure gauge is installed on the furnace cover 3 to detect the pressure inside the heating chamber.

[0036] A lifting drive mechanism is provided on the outer side of the furnace cover 3. The furnace cover 3 includes a lower connecting cylinder 302 and a top cover 301. The lower end of the lower connecting cylinder 302 is sealed to the upper end of the furnace body 1. The top cover 301 is connected to the lifting drive mechanism, which can cover the lower connecting cylinder 302 and lock it in place through the lifting drive mechanism 10. This facilitates sample loading and device maintenance, enables automated opening of the cover, and improves experimental efficiency. The lifting drive mechanism includes electric slides 9 on the left and right sides of the furnace cover 3. The sliders 901 of the electric slides 9 are connected to the top cover 301 to drive the top cover 301 to move up and down. Corresponding to the sliders 901 of the two electric slides 9 on the left and right sides of the furnace cover 3, there are also two guide shafts 14. Sliding sleeves 15 are slidably sleeved on the guide shafts 14, and the sliding sleeves 15 are fixedly connected to the sliders 901 and the top cover 301. The quick-lock mechanism 10 includes several connecting seats 1001 arranged circumferentially on the outer wall of the lower connecting cylinder 302. Each connecting seat 1001 is hinged with a guide rod 1002. A handwheel 1003 is threaded onto the guide rod 1002. The lower end of the handwheel 1003 is rotatably connected to a pressing sleeve 1004 via a bearing. The pressing sleeve 1004 is provided with a locking tooth 1005 on the side near the top cover 301. The furnace cover 3 is provided with a locking groove that mates with the locking tooth 1005. The quick-lock mechanism 10 can quickly seal the cavity by synchronously pressing at multiple points (3-6 evenly distributed points).

[0037] When opening the cover, hold the handwheel 1003 and rotate it counterclockwise to disengage the locking teeth 1005 from the slots. Then, pull the guide rod 1002 downwards to open the quick-lock mechanism 10. The electric slide 9 then raises the top cover 301 to the designated height. When closing the cover, the electric slide 9 lowers the top cover 301, pressing it against the lower connecting cylinder 302. Pull the guide rod 1002 upwards, then hold the handwheel 1003 and rotate it clockwise to engage the locking teeth 1005 in the slots, locking the quick-lock mechanism 10. To ensure a tight seal when the top cover 301 is connected to the lower connecting cylinder 302, a fourth sealing ring 3011 is provided inside the top cover 301.

[0038] When using, open the top cover 301, place the material in the insulation box 6, and then close the cover. If a vacuum heating environment is required, close the inlet valve and exhaust valve, open the suction valve, connect the vacuum tube 11 to the vacuum pump, and use the vacuum pump to evacuate the heating chamber with a pressure gauge. If an inert atmosphere heating environment is required, first use the vacuum pump to evacuate the heating chamber to a basic vacuum (recommended ≤10⁻¹Pa), then perform the first replacement. Slowly open the inlet valve, control the gas flow rate with a flow meter (e.g., 200 sccm), and fill with inert gas to atmospheric pressure (pressure gauge shows 101 kPa). Then fully open the exhaust valve to discharge the gas. Repeat the above vacuuming, filling, and venting operations at least 3 times, and finally fill with inert gas to the target pressure (atmospheric pressure or slightly positive pressure). If a special reactive gas is required for the heating reaction, first evacuate to a vacuum level of 10⁻¹Pa using a vacuum pump (evacuation before gas filling results in higher displacement efficiency). Then, fill with high-purity nitrogen to a slightly positive pressure (50 kPa). Repeat the evacuation and nitrogen filling cycle at least three times. Finally, introduce the reactive gas, precisely controlling the flow rate using a flow meter. For processes requiring continuous introduction of reactive gas and discharge of reaction products (such as CVD deposition and gas reduction), a dynamic gas flow system must be established. This means that when introducing the special reactive gas, the exhaust valve must remain open. After the heating reaction is complete, follow the opening procedure to release the quick-lock mechanism 10, open the top cover 301, and remove the material using a special tool.

[0039] In particular, to facilitate the overall movement of this microwave well furnace, casters 13 are installed at the four corners of the bottom of the support frame 16. In this embodiment, the casters 13 can be Foma wheels.

[0040] This application solves the core problems of narrow material applicability and single function in the prior art through modular sealing design, microwave-heat conduction synergistic heating and intelligent environmental control.

[0041] The above description is merely a preferred embodiment of the present utility model and does not limit the scope of the present utility model. All equivalent changes made based on the content of the present utility model specification and its drawings are included within the scope of the present utility model.

Claims

1. A material resistivity testing device under microwave heating environment, comprising a furnace body (1), a furnace cover (3) sealed to the upper end of the furnace body (1), and a bottom sealing plate (4) sealed to the lower end; the internal space of the furnace body (1), the furnace cover (3), and the bottom sealing plate (4) constitutes a resonant cavity, and a magnetron (2) for emitting microwaves into the resonant cavity is provided on the furnace body (1); characterized in that: A quartz tube (5) is installed inside the furnace body (1), and the quartz tube (5) is sealed to the bottom sealing plate (4) and the furnace cover (3); a heat preservation box (6) is installed inside the quartz tube (5), and the heat preservation box (6) is a spliced ​​structure, including a bottom support (601), a surrounding plate (602) and a box cover (603); a resistance probe (8) and a thermocouple (7) are installed on the furnace cover (3), and the ends of the resistance probe (8) and the thermocouple (7) are inserted into the heat preservation box (6).

2. The material resistivity testing device under microwave heating environment according to claim 1, characterized in that: It also includes an air inlet pipe (12), a vacuum pipe (11) and an exhaust pipe (22). The air inlet pipe (12), the vacuum pipe (11) and the exhaust pipe (22) are set on the bottom sealing plate (4) or the furnace cover (3). The air inlet pipe (12) is connected to an air inlet valve, the vacuum pipe (11) is connected to an air extraction valve, and the exhaust pipe (22) is connected to an exhaust valve.

3. The material resistivity testing device under microwave heating environment according to claim 1, characterized in that: The inner wall of the enclosure (602) is also provided with a wave-absorbing coating (21).

4. The material resistivity testing device under microwave heating environment according to claim 1, characterized in that: A lifting drive mechanism is provided on the outside of the furnace cover (3). The furnace cover (3) includes a lower connecting cylinder (302) and a top cover (301). The lower end of the lower connecting cylinder (302) is sealed to the upper end of the furnace body (1). The top cover (301) is connected to the lifting drive mechanism. The lifting drive mechanism can cover the lower connecting cylinder (302) and lock it in place by a quick-locking mechanism (10).

5. The material resistivity testing device under microwave heating environment according to claim 4, characterized in that: The lifting drive mechanism includes electric slides (9) set on the left and right sides of the furnace cover (3). The slider (901) of the electric slide (9) is connected to the top cover (301) to drive the top cover (301) to move up and down.

6. The material resistivity testing device under microwave heating environment according to claim 5, characterized in that: The left and right sides of the furnace cover (3) are corresponding to the sliders (901) of the two electric sliding tables (9), and two guide shafts (14) are also provided. Sliding sleeves (15) are slidably connected on the guide shafts (14), and the sliding sleeves (15) are fixedly connected to the sliders (901) and the top cover (301).

7. The material resistivity testing device under microwave heating environment according to claim 4, characterized in that: The quick-lock mechanism (10) includes several connecting seats (1001) arranged circumferentially on the outer wall of the lower connecting cylinder (302). Each connecting seat (1001) is hinged with a guide rod (1002). A handwheel (1003) is threaded onto the guide rod (1002). The lower end of the handwheel (1003) is rotatably connected to a pressing sleeve (1004) via a bearing. A locking tooth (1005) is provided on the side of the pressing sleeve (1004) near the top cover (301). A slot is provided on the furnace cover (3) to cooperate with the locking tooth (1005).

8. The material resistivity testing device under microwave heating environment according to claim 1, characterized in that: A connecting sleeve (17) is provided on the furnace cover (3). The connecting sleeve (17) is provided with an external thread. The resistance probe (8) and the thermocouple (7) are provided with lock nuts (18) that are compatible with the connecting sleeve (17). A third sealing ring (1801) is provided in the lock nut (18). The resistance probe (8) or the thermocouple (7) is connected to the furnace cover (3) through the lock nut (18) and the connecting sleeve (17).

9. The material resistivity testing device under microwave heating environment according to claim 1, characterized in that: The quartz tube (5) forms a heating chamber with the bottom sealing plate (4) and the furnace cover (3). A pressure gauge is installed on the furnace cover (3) to detect the pressure inside the heating chamber.

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