High-temperature-resistant tungsten-rhenium coaxial hot electrode, thermocouple and application thereof

Abstract

The application discloses a high-temperature-resistant tungsten-rhenium coaxial hot electrode, a hot electrode and an application thereof, which is composed of a tungsten-rhenium alloy wire electrode and a tungsten alloy tube electrode sleeve core, and a dielectric insulation layer is arranged between the two electrodes. A "hot" measurement node is automatically generated on the surface of a measurement end through grinding and polishing, a plurality of friction welding bridges are generated on the dielectric insulation layer between the tungsten-rhenium alloy wire and the tungsten alloy tube due to friction, and a composite material measurement node is formed, in the process of corrosion and / or airflow scouring, the "hot" measurement node at the front end of the measurement end is disabled, and a new "hot" measurement node is generated on the surface of the tungsten-rhenium coaxial hot electrode. The coaxial structure enables the tungsten-rhenium coaxial hot electrode to stably work in an environment above 3000 DEG C, reduces the invalid area of the tungsten-rhenium coaxial hot electrode, effectively reduces the boundary effect of a traditional layered hot electrode, and thus improves the measurement accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tungsten-rhenium thermocouples, in particular to a high-temperature-resistant tungsten-rhenium coaxial hot electrode, a tungsten-rhenium thermocouple and application thereof. BACKGROUND

[0002] The tungsten-rhenium thermocouple gradually replaces the precious metal sensor such as platinum and rhodium in the application of high temperature due to its low price, good thermoelectric potential performance and reliable thermal stability. At present, the tungsten-rhenium thermocouple has been widely applied in metallurgy, industrial control, aerospace and other fields. The accurate measurement of temperature above 2000℃ is imminent, such as explosion field in specific harsh environment, outlet temperature measurement of scramjet engine, and test of thermal efficiency of aero-engine combustion chamber. However, the existing sensing and measuring technology cannot meet these major strategic needs.

[0003] The tungsten-rhenium thermocouple also has a fatal problem. Since the tungsten-rhenium material cannot resist oxidation, it is easy to oxidize and fail in the high-temperature oxygen environment. At present, many anti-oxidation methods have been proposed by manufacturers and scholars, such as coating an anti-oxidation layer on the tungsten-rhenium metal, vacuum sealing and packaging the tungsten-rhenium metal, and filling insulating powder and reducing agent on the tungsten-rhenium metal. These methods have a certain positive effect on improving the oxidation of tungsten-rhenium metal, but they cannot solve the problem of long-term work without failure of the tungsten-rhenium thermocouple in the high-temperature oxygen environment, and cannot break through the problem of limited upper temperature limit of the tungsten-rhenium thermocouple.

[0004] Since the temperature measurement potential of the tungsten-rhenium thermocouple has not been fully stimulated, the upper temperature limit of the tungsten-rhenium thermocouple on the market can only reach 2300℃, while the melting point of metal tungsten and rhenium is above 3100℃. Theoretically, the temperature measurement limit of the tungsten-rhenium thermocouple is about 3100℃. In the high-temperature oxygen environment, the tungsten-rhenium thermocouple is easy to oxidize and fail, causing irreversible damage to the tungsten-rhenium thermocouple. Therefore, the problem of long-term and repeated use of the tungsten-rhenium thermocouple in the oxygen environment above 2300℃ needs to be solved.

[0005] Therefore, the applicant previously designed a tungsten-rhenium thermocouple with a "sandwich" laminated structure which can work for a long time without failure in a high-temperature oxygen environment above 3000℃. However, this "sandwich" laminated structure also has certain defects, that is, it has a large invalid area and has a boundary effect (or edge effect), which will cause certain measurement error. SUMMARY

[0006] One of the purposes of the present application is to overcome the shortcomings of the prior art and provide a high-temperature-resistant tungsten-rhenium coaxial hot electrode.

[0007] Another purpose of the present application is to provide a tungsten-rhenium coaxial thermocouple comprising the above-mentioned tungsten-rhenium coaxial hot electrode.

[0008] Another object of the present invention is to provide an application of the above-mentioned tungsten-rhenium coaxial thermocouple.

[0009] The technical solution of the present invention is as follows:

[0010] A high-temperature resistant tungsten-rhenium coaxial thermoelectric electrode includes a tungsten-rhenium alloy wire, a dielectric insulating layer, and a tungsten alloy tube arranged sequentially from the inside to the outside.

[0011] In this design, one end of the tungsten-rhenium alloy wire, the dielectric insulating layer, and the tungsten alloy tube are flush to form the measuring end. The lengths of the dielectric insulating layer and the tungsten alloy tube are equal, while the length of the tungsten-rhenium alloy wire is greater than the length of the dielectric insulating layer.

[0012] In some possible implementations, the dielectric insulating layer is made of epoxy resin.

[0013] A tungsten-rhenium coaxial thermocouple includes an encapsulated housing, a thermocouple plug, and the aforementioned tungsten-rhenium coaxial thermoelectrodes.

[0014] The encapsulation tube extends along its length, and the rear end of the encapsulation tube is connected to the thermocouple plug via a compression fitting.

[0015] The front end of the encapsulation shell is fitted onto the outer surface of the tungsten alloy tube, and the tungsten-rhenium coaxial thermoelectrode is at least partially housed within the encapsulation shell with the measuring end protruding from the front end of the encapsulation shell.

[0016] In some preferred implementations, the portion of the tungsten alloy tube outside the pressure range of the encapsulated tube is connected to a tungsten alloy wire, and the tungsten alloy tube and the tungsten alloy wire are electrically connected.

[0017] In some preferred implementations, the portion of the outer surface of the tungsten alloy wire that does not contact the tungsten alloy tube is covered with a sealing insulating adhesive.

[0018] In some preferred implementations, the encapsulation housing includes a front clamp and a rear protective sheath;

[0019] The encapsulation shell is fitted onto the outer surface of the tungsten alloy tube by a front-end clamping component;

[0020] Tungsten alloy wires and tungsten rhenium alloy wires pass through the rear protective sheath and are connected to the thermocouple plug, respectively, and are electrically conductive.

[0021] In some preferred implementations, the rear protective sheath is filled with high-temperature insulating powder, which is aluminum oxide.

[0022] In some preferred implementations, the front clamp is made of stainless steel.

[0023] In some preferred implementations, the rear protective sheath is made of stainless steel, high-temperature refractory metals, or their alloys.

[0024] In some preferred implementations, the tungsten-rhenium alloy wire and the end of the tungsten alloy wire are connected to the thermocouple plug by a threaded clamp.

[0025] In one application of the aforementioned tungsten-rhenium coaxial thermocouple, a "thermal" measurement junction is automatically generated on the surface of the measuring end through grinding and polishing. Due to friction, several friction-welded junctions are generated and bridged on the dielectric insulating layer located between the tungsten-rhenium alloy wire and the tungsten alloy tube to form a composite material measurement junction. During corrosion and / or airflow erosion, the "thermal" measurement junction at the front end of the measuring end fails, and a new "thermal" measurement junction is generated on the surface of the tungsten-rhenium coaxial thermocouple.

[0026] The above-mentioned tungsten-rhenium coaxial thermocouple is used to measure the thermal field temperature of core components of aircraft engines.

[0027] Compared with existing technologies, this technical solution has at least the following advantages:

[0028] 1. The tungsten-rhenium coaxial thermoelectric electrode of the present invention adopts a coaxial structure design, which consists of a tungsten-rhenium alloy wire electrode and a tungsten alloy tube electrode core. A dielectric insulating layer is separated between the two electrodes. This coaxial structure can reduce the ineffective area of ​​the tungsten-rhenium coaxial thermoelectric electrode and effectively reduce the boundary effect of traditional sheet thermocouples, thereby improving the accuracy of measurement.

[0029] 2. In a tungsten-rhenium coaxial thermocouple, the tungsten-rhenium alloy wires of the tungsten-rhenium coaxial thermoelectrode and the tungsten alloy wires connected to the tungsten alloy tube are fixed and insulated by a casing to prevent short circuits from occurring during assembly.

[0030] 3. The present invention provides a tungsten-rhenium coaxial thermocouple that can be used repeatedly for a long time. After completing a measurement, the end face of the thermocouple can be ground and polished with sandpaper or gauze until smooth. During the grinding and polishing process, "thermal" measurement nodes will be automatically generated on the surface, which can be reused. It can also self-erode during the measurement process and continuously form new "thermal" measurement nodes.

[0031] 4. This invention effectively solves the problem that current tungsten-rhenium thermocouples are prone to oxidation and failure under ultra-high temperature testing environments, and cause irreversible damage to the sensors. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the tungsten-rhenium coaxial thermoelectric electrode in this embodiment;

[0033] Figure 2 This is a schematic diagram of the tungsten-rhenium coaxial thermocouple in this embodiment.

[0034] Among them, 1-tungsten-rhenium alloy wire, 2-dielectric insulating layer, 3-tungsten alloy tube, 4-tungsten alloy wire, 5-tungsten-rhenium coaxial thermoelectrode, 6-front clamp, 7-rear protective sheath, 8-ferrule connector, 9-thermocouple plug. Detailed Implementation

[0035] It should be noted that the terms "front" and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0036] The high temperature referred to in this application is 2000-3100℃. The specific materials for high-temperature insulating powder and high-temperature refractory metal can be selected according to the temperature required by the test scenario, as long as the melting point is greater than the estimated test temperature.

[0037] This application discloses a tungsten-rhenium coaxial thermocouple, including a tungsten-rhenium coaxial thermoelectrode 5, a packaged shell, a ferrule connector 8, and a thermocouple plug 9. The tungsten-rhenium coaxial thermoelectrode 5 is at least partially housed within the packaged shell and penetrates the shell to connect with the thermocouple plug 9. The packaged shell is connected to the thermocouple plug 9 via the ferrule connector 8.

[0038] The tungsten-rhenium coaxial thermoelectrode 5 includes a tungsten-rhenium alloy wire 1, a dielectric insulating layer 2, and a tungsten alloy tube 3 arranged sequentially from the inside to the outside. The tungsten-rhenium alloy wire 1, the dielectric insulating layer 2, and the tungsten alloy tube 3 form a coaxial "shell-core" composite columnar structure. One end of the tungsten-rhenium alloy wire 1, the dielectric insulating layer 2, and the tungsten alloy tube 3 are flush to form a measuring end, which can contact the object to be measured. The dielectric insulating layer 2 and the tungsten alloy tube 3 are of equal length, and the length of the tungsten-rhenium alloy wire 1 is greater than the length of the dielectric insulating layer 2.

[0039] In this embodiment, the dielectric insulating layer 2 is made of epoxy resin.

[0040] In addition, in this embodiment, the tungsten-rhenium coaxial thermoelectrode 5 also includes a tungsten alloy wire 4, which is connected to the tungsten alloy tube 3 by laser welding. The outer surface of the tungsten alloy wire 4 that is not in contact with the tungsten alloy tube 3 is covered with a sealing insulating adhesive (not shown). The tungsten alloy wire 4 is electrically connected to the tungsten alloy tube 3. The tungsten alloy wire 4 is used to lead out the signal measured by the tungsten alloy tube 3.

[0041] The encapsulation shell includes a front clamp 6 and a rear protective sheath 7, with the front end of the rear protective sheath 7 embedded in the rear end of the front clamp 6. The encapsulation shell is fitted onto the outer surface of the tungsten alloy tube 3 via the front clamp 6, and the measuring end of the tungsten-rhenium coaxial thermoelectrode 5 protrudes from the front end of the front clamp 6. The connection point between the aforementioned tungsten alloy wire 4 and the tungsten alloy tube 3 is outside the pressure range of the encapsulation shell.

[0042] In this embodiment, the measuring end of the tungsten-rhenium coaxial thermoelectrode 5 protrudes from the front end of the front end clamp 6. In other possible implementations, the measuring end of the tungsten-rhenium coaxial thermoelectrode can also be flush with the opening at the front end of the front end clamp, as long as the measuring end can directly contact the object to be measured to measure the temperature.

[0043] The rear protective sheath 7 is filled with high-temperature insulating powder (not shown), which is alumina. Tungsten alloy wire 4 and tungsten rhenium alloy wire 1 pass through the rear protective sheath 7 and are connected to the thermocouple plug 9 by a threaded clamp and are electrically conductive to extract the measurement signal.

[0044] The aforementioned tungsten-rhenium coaxial thermocouple can be used to measure the temperature of the outer surface of an aircraft. Before use, the measuring end of the tungsten-rhenium coaxial thermocouple 5 needs to be ground and polished with a grinder or sandpaper to make the end face smooth. During the grinding and polishing process, exposed "thermal" measuring nodes will automatically form on the surface. Several friction-welded junctions generated by friction are bridged on the dielectric insulating layer 2 located between the tungsten-rhenium alloy wire 1 and the tungsten alloy tube 3 to form a composite material measuring junction. During the test, as the front-end "thermal" measuring node fails, a new "thermal" measuring node will automatically form on the surface of the tungsten-rhenium coaxial thermocouple 5.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature resistant tungsten-rhenium coaxial thermoelectric electrode, characterized in that, It includes, from the inside out, a tungsten-rhenium alloy wire, a dielectric insulating layer, and a tungsten alloy tube; Wherein, one end of the tungsten-rhenium alloy wire, the dielectric insulating layer, and the tungsten alloy tube are flush to form a measuring end, the length of the dielectric insulating layer and the tungsten alloy tube are equal, and the length of the tungsten-rhenium alloy wire is greater than the length of the dielectric insulating layer; The measuring end automatically generates "thermal" measuring nodes on its surface through grinding and polishing. Due to friction, several friction-welded junctions are generated and bridged on the dielectric insulating layer located between the tungsten-rhenium alloy wire and the tungsten alloy tube to form a composite material measuring junction. During corrosion and / or airflow erosion, the "thermal" measuring nodes at the front end of the measuring end fail, and new "thermal" measuring nodes are generated on the surface of the tungsten-rhenium coaxial thermoelectrode.

2. The tungsten-rhenium coaxial thermoelectric electrode as described in claim 1, characterized in that, The dielectric insulating layer is made of epoxy resin.

3. A tungsten-rhenium coaxial thermocouple, characterized in that, Includes a packaged casing, a thermocouple plug, and the tungsten-rhenium coaxial thermoelectrode as described in claim 1 or 2; The encapsulation shell extends along its length, and the rear end of the encapsulation shell is connected to the thermocouple plug via a compression fitting. The front end of the encapsulation shell is sleeved on the outer surface of the tungsten alloy tube, the tungsten-rhenium coaxial thermoelectrode is at least partially housed within the encapsulation shell, and the measuring end protrudes from the front end of the encapsulation shell.

4. The tungsten-rhenium coaxial thermocouple as described in claim 3, characterized in that, The portion of the tungsten alloy tube outside the pressure range of the encapsulated tube shell is connected to a tungsten alloy wire, and the tungsten alloy tube and the tungsten alloy wire are electrically connected.

5. The tungsten-rhenium coaxial thermocouple as described in claim 4, characterized in that, The outer surface of the tungsten alloy wire that is not in contact with the tungsten alloy tube is covered with sealing insulating glue.

6. The tungsten-rhenium coaxial thermocouple as described in claim 4 or 5, characterized in that, The encapsulation housing includes a front clamping component and a rear protective sheath; The encapsulation shell is sleeved on the outer surface of the tungsten alloy tube by the front end clamping member; The tungsten alloy wire and the tungsten rhenium alloy wire respectively pass through the rear protective sheath and are connected to the thermocouple plug and electrically conductive.

7. The tungsten-rhenium coaxial thermocouple as described in claim 6, characterized in that, The rear protective sheath is filled with high-temperature insulating powder, which is aluminum oxide. And / or, the material of the front clamp is stainless steel; And / or, the rear protective sheath is made of stainless steel, high-temperature refractory metals and their alloys.

8. A tungsten-rhenium coaxial thermocouple according to claim 6, characterized in that, The tungsten-rhenium alloy wire and the end of the tungsten alloy wire are connected to the thermocouple plug by a threaded clamp.

9. The application of the tungsten-rhenium coaxial thermocouple according to any one of claims 3-8 in measuring the thermal field temperature of core components of an aircraft engine.

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