A braided alumina fiber structure for high-temperature sensor signal transmission and its preparation method

Abstract

This application proposes an alumina fiber braided structure for high-temperature sensor signal transmission and its fabrication method. The fiber braided structure of this invention includes a bottom substrate, a middle sensing layer, and a top composite layer: the bottom substrate uses alumina fiber braided fabric to provide high-temperature resistant substrate support; the middle sensing layer consists of a ceramic fiber paper diaphragm and built-in sensor components, forming a distributed temperature measurement point matrix; the top composite layer is a plain weave fabric of alumina and silicon carbide fibers, coated with a composite ceramic layer on the outside to enhance corrosion resistance. The three-layer structure is bonded together with an interfacial adhesive and then hot-pressed into a single unit. Furthermore, by controlling the thermal expansion coefficients of each layer, a gradient distribution with a lower coefficient in the middle and higher coefficients on both sides is formed, ensuring that the middle sensing layer is in a low-stress state. This solution, through fiber braiding reinforcement and gradient thermal expansion design, achieves structural stability and signal transmission reliability under high-temperature conditions, while also possessing lightweight and flexible adaptability characteristics, effectively avoiding interlayer delamination and overall deformation.

Description

Technical Field

[0001] This invention relates to a braided alumina fiber structure for high-temperature sensor signal transmission and its preparation method, belonging to the technical field of new alumina fiber materials for high-temperature environments. Background Technology

[0002] Alumina fiber woven materials are extensively used in waste incinerators, including in the furnace, flue gas ducts, grate, and cooling water walls. Existing advanced waste incineration equipment monitors temperature at various points, particularly the grate and cooling water walls, where operating temperatures must typically be controlled below 1200℃ to prevent mechanical and heat transfer failures and to protect the overall equipment and personnel safety. For example, on the cooling water walls, not only is temperature monitoring required, but multiple temperature points also need to be monitored. Existing wire harness-type temperature sensors have poor compatibility with the grate and cooler, are difficult to install, and improper installation can lead to delayed thermal response. Therefore, integrating the temperature sensing structure into alumina fiber sheets is an important technological development direction. Preliminary testing has shown that directly integrating temperature sensors into the layers of alumina fiber can easily cause layer delamination and sensor detachment under the high-temperature environment of a waste incinerator due to differences in the thermal expansion coefficients of the layers. In particular, when multi-point monitoring is required, there is no mature integration solution between existing wire harness-type temperature sensors and multi-layer alumina fiber woven fabric. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention aims to provide an alumina fiber braided structure for high-temperature sensor signal transmission and its preparation method.

[0004] According to an embodiment of the present invention, a first embodiment is provided as follows: a high-temperature sensor signal transmission alumina fiber braided structure, comprising a bottom substrate, a middle sensing layer, and a top composite layer sequentially composited from bottom to top; the bottom substrate comprises sintered and shaped alumina fiber braided fabric; the middle sensing layer comprises two diaphragm layers and at least one set of sensor components arranged between the diaphragm layers, the sensor components comprising two wires and at least two high-temperature sensors connected in parallel on the two wires, the two poles of the high-temperature sensors being sintered and fixed on the two wires respectively, and multiple high-temperature sensors on the same sensor component being connected in parallel to form multiple temperature measuring points on a line; the top composite layer comprises a plain weave fabric woven from alumina fiber and silicon carbide fiber; the diaphragm layer of the middle sensing layer is ceramic fiber paper, and the ceramic fiber paper and the alumina fiber braided fabric, and the ceramic fiber paper and the plain weave fabric are respectively bonded together by interface adhesives, and the bottom substrate, the middle sensing layer, and the top composite layer are integrally formed by hot pressing.

[0005] Furthermore, the ceramic fiber paper is an Al2O3-SiO2 ceramic fiber layer with an upper temperature resistance limit of ≥1200℃, and the interface adhesive is a silane coupling agent with a mass fraction of 5%-8%.

[0006] Furthermore, the bottom substrate is sintered at a high temperature of 1000℃-1200℃ to form a sintered neck layer on the surface of the alumina fiber bundle. The diameter of the alumina fiber bundle is 8 micrometers-15 micrometers, and the weaving density of the alumina fiber cloth is 10*10 strands / square centimeter-16*16 strands / square centimeter.

[0007] Furthermore, the mass ratio of alumina fiber to silicon carbide fiber in the plain weave fabric is 7:3-9:1, the fiber bundle diameter of the alumina fiber is 8-10 micrometers, the fiber bundle diameter of the silicon carbide fiber is 10-12 micrometers, and the weaving density of the plain weave fabric is 14*14 threads / square centimeter-16*16 threads / square centimeter.

[0008] Furthermore, the intermediate sensing layer includes m sets of sensor components, each set of sensor components including n high-temperature sensors, wherein the high-temperature sensors are thick-film platinum resistors used to measure ambient temperature.

[0009] Furthermore, the spacing between adjacent sensor components is ≥10 cm, the spacing between thick film platinum resistors on each sensor component is ≥10 cm, and multiple thick film platinum resistors form an m*n temperature measurement point matrix.

[0010] Furthermore, the outer side of the plain weave fabric is coated with a ZS-822 composite ceramic layer.

[0011] Furthermore, the thermal expansion coefficient of the bottom substrate is greater than that of the middle sensing layer, and the thermal expansion coefficient of the top composite layer is greater than that of the middle sensing layer. The gradient of thermal expansion coefficients, which is lower in the middle and higher on both sides, ensures that the middle sensing layer is in a low-stress state to reduce interlayer peel strength and avoid overall deformation.

[0012] Furthermore, the bottom substrate reduces its coefficient of thermal expansion to (4.3-4.7)×10⁻⁶ by controlling the grain size through sintering. -6 / ℃; the intermediate sensing layer adjusts the ratio of Al2O3 to SiO2 to maintain the Al2O3 content at 60%-70%, thereby controlling the coefficient of thermal expansion to (4.0±0.2)×10. -6 / ℃; The top composite layer's coefficient of thermal expansion is controlled at (4.4±0.1)×10 by adjusting the ratio of alumina fiber and silicon carbide fiber. -6 / ℃; meanwhile, the difference in thermal expansion coefficient between adjacent layers is ≤0.5×10 -6 / ℃.

[0013] According to an embodiment of the present invention, utilizing the alumina fiber braided structure for high-temperature sensor signal transmission in the first solution provided by the present invention, a second solution is provided as follows:

[0014] A method for preparing an alumina fiber braided structure for high-temperature sensor signal transmission includes the following steps:

[0015] The bottom substrate is prefabricated by weaving alumina fiber cloth with a fiber bundle diameter of 8-15 micrometers into a base plate fiber cloth with a density of 10*10 strands / square centimeter-16*16 strands / square centimeter. The base plate fiber cloth is sintered at a high temperature of 1200℃ for 2-3 hours, and the grain size is controlled at 50-100 nanometers. During high temperature sintering, the heating rate is 50℃ / min-80℃ / min and the cooling rate is <20℃ / min.

[0016] The intermediate sensing layer is prefabricated by fixing 0.1-0.2 mm diameter nickel-chromium alloy wires in parallel using a tension control device. The spacing between the nickel-chromium alloy wires is 2-3 mm. The thick film platinum resistor has a size of 3 mm × 3 mm × 0.2 mm. The two poles of the thick film platinum resistor are fixed to the adjacent nickel-chromium alloy wires by high-temperature sintering. The ceramic fiber paper is selected as the Al2O3-SiO2 ceramic fiber layer with a thickness of 0.1 mm-0.2 mm. After coating the surface of the ceramic fiber layer with ceramic sol gel, the two ceramic fiber layers are pressed together on the sensor assembly and pressed at 150°C for more than 30 minutes to obtain the intermediate sensing layer.

[0017] The top composite layer is prefabricated by mixing alumina fibers with a diameter of 8-10 micrometers and silicon carbide fibers with a diameter of 10-12 micrometers in a mass ratio of 7:3-9:1 to form a plain weave fabric of 14*14 fibers / square centimeter to 16*16 fibers / square centimeter. The plain weave fabric is then subjected to low-temperature hot pressing.

[0018] The bottom substrate surface is coated with an interface adhesive to bond the middle sensing layer, and then an interface adhesive is coated to bond the top composite layer. The three-layer structure is then formed by low-temperature hot pressing. The overall hot pressing temperature is ≤400℃, the ambient pressure is 0.5-1MPa, the heating rate is 30℃ / min-50℃ / min, and the temperature is maintained for 1 hour to obtain high-temperature sensor signal transmission of alumina fiber braided structure.

[0019] Compared with the prior art, the unique advantages of the technical solution provided in this application are as follows:

[0020] This high-temperature sensor signal transmission alumina fiber braided structure adopts a classic three-layer composite structure, integrating the sensor components into the alumina fiber braided structure. By using alumina fiber cloth sintered and shaped at 1200℃ as the bottom substrate, it retains the high-temperature resistance of ceramic fibers and enhances the deformation resistance of the base layer through the mechanical interlocking of the fibers, while also meeting certain flexible installation requirements. The diaphragm sandwich design of the middle sensor layer uses ceramic fiber paper to achieve electrical insulation and physical protection for the wires and high-temperature sensors. Multiple sensor components form an m*n temperature measurement point matrix to achieve spatially distributed temperature monitoring. The top composite layer is a mixed-weave plain fabric, which utilizes the high strength and oxidation resistance of silicon carbide fibers to enhance the top composite layer's resistance to media erosion. The outer layer can also be coated with a ZS-822 composite ceramic coating to further block high-temperature corrosive media.

[0021] The three-layer composite structure is bonded together by an interfacial adhesive and forms a chemical bond. The layers have physical interlocking of microscopic fiber materials and form a mechanical interlocking. Therefore, the interlayer peel strength of the three-layer composite structure is very high. At the same time, the overall density of the three-layer composite structure is low, which can meet the requirements of lightweight applications. This device has prepared a high-temperature sensor signal transmission alumina fiber braided structure that can meet the requirements of high temperature resistance, stable signal transmission, and overall structural stability and reliability through material selection, structural design, interlayer synergy and preparation parameter control. It has achieved long-term stable temperature monitoring and signal transmission in extreme high temperature environments above 1000℃. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] in:

[0024] Figure 1 This is a schematic diagram of the layer structure of the alumina fiber braided structure for high-temperature sensor signal transmission in one embodiment.

[0025] Figure 2 This is a schematic flowchart illustrating the preparation method of the alumina fiber braided structure for high-temperature sensor signal transmission in one embodiment. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Example 1

[0028] This embodiment provides an alumina fiber braided structure for high-temperature sensor signal transmission for waste incinerator applications. When combining alumina fiber braiding with high-temperature sensor signal transmission components, key issues to be addressed include: selecting suitable high-temperature resistant sensor parts, increasing the bonding strength between the sensor components and the alumina fiber layer, and rationally arranging the sensor temperature measurement points.

[0029] This embodiment specifically provides an alumina fiber braided structure for high-temperature sensor signal transmission, such as... Figure 1 As shown, it includes a bottom substrate 10, a middle sensing layer 20 and a top composite layer 30, which are sequentially laminated from bottom to top.

[0030] The bottom substrate 10 includes sintered and shaped alumina fiber woven fabric;

[0031] Specifically, the bottom substrate 10 is sintered at a high temperature of 1000℃-1200℃ to form a sintered neck layer on the surface of the alumina fiber bundle. The diameter of the alumina fiber bundle is 8 micrometers-15 micrometers, and the weaving density of the alumina fiber cloth is 10*10 strands / square centimeter-16*16 strands / square centimeter.

[0032] For example, using alumina fiber cloth with a purity of ≥99%, a fiber bundle diameter of 12 micrometers, and a weaving density of 14*14 fibers / square centimeter, the alumina fiber cloth is heated to 1100°C in an air atmosphere furnace at a rate of 50°C / minute and held for 2 hours to form a sintered neck layer with a thickness of approximately 1 micrometer on the surface of the fiber bundle, thereby controlling the coefficient of thermal expansion to decrease to 4.5×10⁻⁶. -6 / ℃.

[0033] The intermediate sensing layer 20 includes two diaphragm layers and at least one set of sensor assemblies arranged between the diaphragm layers. Each sensor assembly includes two wires and at least two high-temperature sensors connected in parallel to the two wires. The electrodes of the high-temperature sensors are sintered and fixed to the two wires respectively. Multiple high-temperature sensors on the same sensor assembly are connected in parallel to form multiple temperature measurement points on a line. The intermediate sensing layer 20 includes m sets of sensor assemblies, each set including n high-temperature sensors. The high-temperature sensors are thick-film platinum resistors 22 used to measure ambient temperature. The spacing between adjacent sensor assemblies is ≥10 cm, and the spacing between the thick-film platinum resistors 22 on each sensor assembly is ≥10 cm. Multiple thick-film platinum resistors 22 form an m*n temperature measurement point matrix.

[0034] Specifically, the ceramic fiber paper is an Al2O3-SiO2 ceramic fiber layer with an upper temperature resistance limit of ≥1200℃, and the interface adhesive is a silane coupling agent with a mass fraction of 5%-8%.

[0035] For example, the Al2O3-SiO2 ceramic fiber layer has an Al2O3 content of 65%, a SiO2 content of 35%, a thickness of 0.2 mm, an upper temperature resistance limit of 1300℃, and a thermal expansion coefficient of 4.0 × 10⁻⁶ controlled by the proportioning of the components. -6 / ℃. Four sensor assemblies are set up, m=4. Each sensor assembly contains four thick-film platinum resistors 22, n=4. The dimensions of the thick-film platinum resistors 22 are 3mm×3mm×0.2mm. The two poles of the thick-film platinum resistors 22 are fixed to the nickel-chromium alloy wires 21 by laser sintering with silver paste. The spacing between adjacent sensor assemblies is 15 cm. The spacing between the thick-film platinum resistors 22 on the same sensor assembly is 12 cm, forming a 4*4 temperature measurement point matrix. The nickel-chromium alloy wires 21 are led out from the edge of the middle sensing layer 20 and have a pin structure.

[0036] The top composite layer 30 comprises a plain weave fabric made of a blend of alumina fibers and silicon carbide fibers;

[0037] The plain weave fabric has a mass ratio of alumina fibers to silicon carbide fibers of 7:3-9:1. The diameter of the alumina fiber bundle is 8-10 micrometers, and the diameter of the silicon carbide fiber bundle is 10-12 micrometers. The weave density of the plain weave fabric is 14*14 threads / cm²-16*16 threads / cm². The outer side of the plain weave fabric is also coated with a ZS-822 composite ceramic layer.

[0038] For example, plain weave fabric can be made by mixing alumina fibers with a diameter of 9 micrometers and silicon carbide fibers with a diameter of 11 micrometers at a mass ratio of 8:2, with a weaving density of 15*15 threads / square centimeter and a thermal expansion coefficient controlled at 4.4×10. -6At / ℃, a ZS-822 composite ceramic layer with a thickness of 50 micrometers is sprayed on the outer side of the mixed woven plain fabric. The composition includes zirconium oxide, aluminum oxide and silicon dioxide to improve the overall high temperature resistance and corrosion resistance.

[0039] The diaphragm layer of the intermediate sensing layer 20 is ceramic fiber paper. The ceramic fiber paper is bonded to the alumina fiber woven fabric and to the plain weave fabric respectively by an interface adhesive. The bottom substrate 10, the intermediate sensing layer 20 and the top composite layer 30 are then integrally formed by hot pressing.

[0040] Interface bonding: A 6% by mass silane coupling agent is uniformly coated as an interface adhesive between the bottom substrate 10 and the ceramic fiber paper of the middle sensing layer 20, and between the ceramic fiber paper and the hybrid fabric of the top composite layer 30, with a coating amount of 0.1 g / cm².

[0041] Hot pressing integral molding: The three-layer structure is stacked in sequence and placed in a hot pressing mold. Under nitrogen protection, it is hot pressed at a pressure of 0.8MPa and a temperature of 400℃ for 1 hour, with a heating rate of 40℃ / min, so that the layers can form an integral structure through physical interlocking and chemical bonding.

[0042] After sintering and shaping at 1100℃, the bottom substrate 10 has been tested and found to have a bending strength of 350MPa, allowing for long-term use at 1200℃. The top ZS-822 coating can resist flue gas erosion at 1600℃ and shows no cracking during high-temperature cycling at 1000℃, demonstrating excellent thermal shock stability. The gradient design of the thermal expansion coefficient, with a low center and high sides, keeps the middle sensing layer 20 in a low-stress state, significantly improving the interlayer peel strength compared to traditional planar structures. The silane coupling agent, combined with the mechanical interlocking effect of nanoparticles, results in extremely high interfacial shear strength. The 4×4 matrix temperature measurement point layout achieves planar area coverage; the parallel sensor design reduces the risk of single-point failure. With a small overall thickness and low areal density, while also possessing a certain degree of bending flexibility, it is suitable for complex curved surface equipment, such as the bonding installation of boiler water-cooled walls and furnace grates.

[0043] The core objective of the stepped design of thermal expansion coefficient is to eliminate interlayer thermal stress to avoid structural failure. This is because different materials expand or contract when the temperature changes, and the thermal expansion coefficient determines the degree of deformation. If the difference in thermal expansion coefficient between adjacent layers is too large, interlayer delamination can easily occur during high-temperature cycling due to deformation incompatibility, leading to sensor damage.

[0044] For example, the coefficient of thermal expansion of the bottom substrate 10 is 4.7, the coefficient of thermal expansion of the middle sensing layer 20 is 4.2, and the coefficient of thermal expansion of the top composite layer is 4.5. As a support layer, the coefficient of thermal expansion of the bottom substrate 10 is slightly higher, which can reduce the tensile stress on the middle layer. The core middle sensor layer has the lowest coefficient of thermal expansion, which has good deformation stability and avoids damage to the sensor due to excessive deformation. The coefficient of thermal expansion of the mixed woven plain fabric of the top layer is between that of the bottom and middle layers, which can buffer the deformation difference between the bottom and middle layers. For example, when the bottom layer expands, the top layer can absorb part of the stress first and avoid all the stress from pulling on the device of the middle sensor layer.

[0045] Therefore, during heating: the bottom layer expands more than the top layer, which in turn expands more than the middle layer. The top layer exerts a slight compressive stress on the middle layer, offsetting the tensile stress exerted by the bottom layer on the middle layer. During cooling: the bottom layer contracts more than the top layer, which in turn contracts more than the middle layer. The top layer exerts a slight tensile stress on the middle layer, offsetting the compressive stress exerted by the bottom layer on the middle layer. Ultimately, this keeps the middle sensor layer in a low-stress state.

[0046] This embodiment solves the problems of traditional high-temperature sensor structures such as poor heat resistance, easy delamination between layers, and unstable signals by employing a collaborative approach including gradient design of thermal expansion coefficients, interlayer bonding and interlocking, and integral hot pressing molding. It achieves high-precision, high-reliability distributed temperature measurement in environments up to 1200℃. Its core innovations lie in: utilizing the high-temperature resistance and flexibility of alumina fiber braided structures to overcome the temperature limitations of metal-based materials; balancing structural strength and thermal stress through interlayer thermal expansion gradient and interface enhancement design; and balancing temperature measurement coverage and environmental adaptability through a matrix sensor layout and composite ceramic coating.

[0047] Example 2

[0048] Based on the alumina fiber braided structure for high-temperature sensor signal transmission in Example 1, 5%-8% hollow glass microspheres can be added to the interface adhesive. The hollow glass microspheres have a particle size of 5-20 micrometers and form a flexible buffer layer to enhance the peel strength retention.

[0049] Furthermore, a thermally conductive network is added to the plain weave fabric layer of the top composite layer 30: alumina fibers and silicon carbide fibers are woven alternately in warp and weft, with alumina fibers in the radial direction and silicon carbide fibers in the weft direction. Micro-channels are created at the weaving nodes using a laser similar to that used for laser sintering of the thick-film platinum resistor 22. Specifically, micro-channels are formed at the weaving nodes of the alternately woven plain weave fabric by laser drilling. When coating the ZS-822 composite ceramic layer, 6%-10% by volume of boron carbide nanoparticles are dispersed in the ZS-822 raw material. The micro-boron carbide nanoparticles fill the micro-channels and form a thermally conductive network with the composite ceramic layer, increasing the thermal conductivity of the top composite layer to 2.0-2.5 W / (m·K). This microstructured thermally conductive network further increases the thermal conductivity of the top composite layer 30, thereby improving the response speed of the sensor device.

[0050] Example 3

[0051] like Figure 2 As shown, this embodiment specifically provides a method for preparing an alumina fiber braided structure for high-temperature sensor signal transmission used in waste incinerators, including the following steps:

[0052] S101: The bottom substrate 10 is prefabricated by weaving alumina fiber cloth with a fiber bundle diameter of 8-15 micrometers into a base plate fiber cloth with a density of 10*10 strands / square centimeter-16*16 strands / square centimeter. The base plate fiber cloth is sintered at a high temperature of 1200℃ for 2-3 hours. The grain size is controlled at 50-100 nanometers. During high temperature sintering, the heating rate is 50℃ / min-80℃ / min and the cooling rate is <20℃ / min.

[0053] S102: The intermediate sensing layer 20 is prefabricated by fixing 0.1-0.2 mm diameter nickel-chromium alloy wires 21 in parallel using a tension control device. The spacing between the nickel-chromium alloy wires 21 is 2 mm-3 mm. The thick film platinum resistor 22 has a size of 3 mm × 3 mm × 0.2 mm. The two poles of the thick film platinum resistor 22 are fixed to the adjacent nickel-chromium alloy wires 21 by high-temperature sintering. The ceramic fiber paper is selected as Al2O3-SiO2 ceramic fiber layer with a thickness of 0.1 mm-0.2 mm. After coating the surface of the ceramic fiber layer with ceramic sol gel, the two ceramic fiber layers are pressed together on the sensor assembly and pressed at 150°C for more than 30 minutes to obtain the intermediate sensing layer 20.

[0054] S103: Top composite layer 30 prefabrication, alumina fibers with a fiber bundle diameter of 8-10 micrometers and silicon carbide fibers with a diameter of 10-12 micrometers are mixed and woven into plain weave fabric of 14*14 fibers / square centimeter to 16*16 fibers / square centimeter by mass ratio of 7:3-9:1, and the plain weave fabric is subjected to low temperature hot pressing.

[0055] S104: Apply an interface adhesive to the surface of the bottom substrate 10 to bond the middle sensing layer 20, then apply an interface adhesive to bond the top composite layer 30. The three-layer structure is then hot-pressed as a whole at a low temperature. The hot-pressing temperature of the whole molding is ≤400℃, the ambient pressure is 0.5-1MPa, the heating rate is 30℃ / min-50℃ / min, and the temperature is maintained for 1 hour. High-temperature sensor signal transmission is obtained using an alumina fiber braided structure.

[0056] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application's patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application.

[0057] It should be noted that when an element is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component. It should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0059] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

Claims

1. A braided alumina fiber structure for high-temperature sensor signal transmission, characterized in that, It includes a bottom substrate, a middle sensing layer and a top composite layer, which are stacked sequentially from bottom to top; The bottom substrate comprises sintered and shaped alumina fiber woven fabric; The intermediate sensing layer includes two diaphragm layers and at least one set of sensor assemblies arranged between the diaphragm layers. The sensor assembly includes two wires and at least two high-temperature sensors connected in parallel on the two wires. The high-temperature sensors are thick-film platinum resistors used to measure ambient temperature. The two poles of the high-temperature sensors are sintered and fixed on the two wires respectively. Multiple high-temperature sensors on the same sensor assembly are connected in parallel to form multiple temperature measurement points on a line. The top composite layer consists of a plain weave fabric made of a blend of alumina fibers and silicon carbide fibers; The membrane layer of the middle sensing layer is made of ceramic fiber paper. The ceramic fiber paper is bonded to the alumina fiber woven fabric and to the plain weave fabric respectively by interface adhesive. The bottom substrate, the middle sensing layer and the top composite layer are then hot-pressed into one piece. The coefficient of thermal expansion of the bottom substrate is greater than that of the intermediate sensing layer, the coefficient of thermal expansion of the top composite layer is greater than that of the intermediate sensing layer, and the difference in coefficients of thermal expansion between adjacent layers is ≤0.5×10⁻⁶. -6 / ℃.

2. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 1, characterized in that, The ceramic fiber paper is an Al2O3-SiO2 ceramic fiber layer with an upper temperature resistance limit of ≥1200℃, and the mass fraction of silane coupling agent in the interface adhesive is 5%-8%.

3. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 1, characterized in that, The bottom substrate is sintered at a high temperature of 1000℃-1200℃ to form a sintered neck layer on the surface of the alumina fiber bundle. The weaving density of the alumina fiber cloth is 10x10 strands / square centimeter to 16x16 strands / square centimeter.

4. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 1, characterized in that, The mass ratio of alumina fiber to silicon carbide fiber in the plain weave fabric is 7:3-9:1, and the weaving density of the plain weave fabric is 14x14 threads / cm²-16x16 threads / cm².

5. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 1, characterized in that, The intermediate sensing layer includes m groups of sensor components, and each group of sensor components includes n high-temperature sensors. The spacing between adjacent sensor components is ≥10 cm, the spacing between thick film platinum resistors on each sensor component is ≥10 cm, and multiple thick film platinum resistors form an mxn temperature measurement point matrix.

6. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 1, characterized in that, The plain weave fabric is also coated with a ZS-822 composite ceramic layer on its outer side.

7. The alumina fiber braided structure for high-temperature sensor signal transmission according to claim 2, characterized in that: The bottom substrate reduces its coefficient of thermal expansion to (4.3-4.7)×10⁻⁶ by controlling the grain size through sintering. -6 / ℃; The intermediate sensing layer adjusts the ratio of Al2O3 to SiO2 to maintain an Al2O3 content of 60%-70%, thereby controlling the coefficient of thermal expansion to (4.0±0.2)×10. -6 / ℃; The coefficient of thermal expansion in the top composite layer is controlled at (4.4±0.1)×10 by adjusting the ratio of alumina fiber and silicon carbide fiber. -6 / ℃.

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