Thermocouple sensor in-situ autocatalytic insulating layer and preparation method thereof

Abstract

The invention provides a thermocouple sensor in-situ autocatalysis insulating layer and a preparation method thereof. The preparation method comprises the following steps: placing a preformed thermocouple sensor in a chemical vapor deposition reaction cabin; silane and oxygen are continuously introduced into the reaction cabin, and original gas in the reaction cabin is exhausted; the thermocouple sensor is heated to a certain temperature, and the temperature of the thermocouple sensor is continuously detected in the heating process; and after the temperature of the thermocouple sensor is stable, continuously introducing silane and oxygen to react for a period of time until deposition of the silicon dioxide insulating layer is completed. According to the invention, the thermocouple sensor is heated to a certain temperature, silane and oxygen are introduced, and the catalytic characteristic of the metal material of the thermocouple sensor is utilized to realize in-situ preparation of the silicon dioxide insulating layer, the insulating layer has good deformation follow-up and high-temperature insulating properties, and unification of high-temperature insulating and follow-up deformation capabilities of the thermocouple sensor is realized; and one kind of important common technical requirements of heat flux density measurement in general industrial fields and aerospace engineering are met.

Description

Technical Field

[0001] The present invention relates to the field of general industrial fields and aerospace engineering temperature and heat flux density measurement technology, and in particular to an in-situ autocatalytic insulating layer of a thermocouple sensor and a preparation method thereof. Background Art

[0002] Temperature and heat flux measurement sensors are widely used in general industrial fields and aerospace engineering. Layered temperature sensors are sensors that calculate and identify the heat flux density experienced by the measured object based on the temperature response at different positions of the measured object. They are generally embedded inside the measured object for use. Thermocouple layered temperature sensors are the most common form of layered temperature sensors, and are usually composed of two or more thermocouples arranged at different positions. Traditional thermocouple layered temperature sensors usually use insulating varnish or ceramic sheaths to achieve insulation between them and the measured object. The insulating varnish has good deformation conformability but poor high-temperature resistance, making it difficult to use under high-temperature conditions. The ceramic sheath has good high-temperature insulation performance but usually does not have deformation conformability. In addition, the thermal conductivity between the ceramic sheath and the measured object is quite different, which affects the heat transfer behavior of the measured object and has a significant impact on the measurement accuracy.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide an in-situ self-catalytic insulating layer for a thermocouple sensor and a preparation method thereof. The insulating layer has good deformation conformity and high-temperature insulation performance, overcoming the problems that traditional insulating varnish has poor high-temperature resistance and is difficult to use under high-temperature conditions, and traditional ceramic sleeves have poor deformation conformity, large thermal influence and poor measurement accuracy.

[0005] A first aspect of the present invention provides a method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor, comprising the following steps:

[0006] S1, placing the preformed thermocouple sensor in a chemical vapor deposition reaction chamber;

[0007] S2, continuously introduce silane (SiH4) and oxygen (O2) into the reaction chamber to exhaust the original gas in the reaction chamber;

[0008] S3, heating the thermocouple sensor to a certain temperature, and continuously detecting the temperature of the thermocouple sensor during the heating process;

[0009] S4. After the temperature of the thermocouple sensor is stabilized, silane and oxygen are continuously introduced to react for a period of time until the deposition of the silicon dioxide insulating layer is completed.

[0010] Preferably, the thermocouple sensor is a thermocouple layered temperature sensor.

[0011] Preferably, according to the temperature tolerance range of the measurement object or the measurement target temperature, the thermocouple sensor is selected from any one of K-type, J-type, T-type, E-type, N-type, S-type, R-type, B-type or C-type thermocouple sensors.

[0012] Specifically, the reference operating temperatures of each galvanic sensor are: K type (-200℃~+1350℃), J type (-40℃~+750℃), T type (-200℃~+350℃), E type (-50℃~+900℃), N type (-270℃~+1300℃), S type (+50℃~+1600℃), R type (+50℃~+1700℃), B type (+600℃~+1800℃), and C type (0℃~+2300℃).

[0013] Preferably, in step S2, silane and oxygen are continuously introduced into the reaction chamber for at least 3 minutes to exhaust the original gas (air) in the reaction chamber.

[0014] Preferably, in step S3, according to the impedance characteristics of the thermocouple sensor, the thermocouple is heated by direct current heating to heat the thermocouple sensor to 250° C. to 300° C.

[0015] Preferably, the voltage of the DC power supply is controlled within a range of 28V to 40V, and the current is controlled within a range of 0.5A to 3A.

[0016] Preferably, in step S3, an infrared thermal imager is used to continuously detect the temperature of the thermocouple sensor during the heating process.

[0017] Preferably, the flow ratio of silane to oxygen is controlled at 1:3.

[0018] Preferably, in step S4, the reaction time is controlled within a range of 30 min to 90 min, and the thickness of the silicon dioxide insulating layer generated by the reaction is controlled within a range of 30 μm to 60 μm. This thickness can not only achieve the insulation characteristics of the thermocouple in a high temperature environment, but also maintain the conformal deformation capability of the thermocouple, thereby facilitating the subsequent molding of the overall layered structure.

[0019] A second aspect of the present invention provides an in-situ autocatalytic insulating layer for a thermocouple sensor, which is prepared using the above-mentioned method for preparing an in-situ autocatalytic insulating layer for a thermocouple sensor.

[0020] Preferably, the in-situ autocatalytic insulating layer of the thermocouple sensor is a silicon dioxide insulating layer, and the thickness of the silicon dioxide insulating layer is controlled to be 30 μm to 60 μm.

[0021] A third aspect of the present invention provides a thermocouple sensor, wherein the thermocouple sensor includes the above-mentioned in-situ autocatalytic insulation layer for the thermocouple sensor.

[0022] Preferably, the thermocouple sensor is three groups of K-type thermocouple molded layered temperature sensors, including: a first layer of thermocouple temperature sensors, a second layer of thermocouple temperature sensors and a third layer of thermocouple temperature sensors; the first layer of thermocouple temperature sensors includes: a first layer of thermocouple positive electrodes, a first layer of thermocouple positive and negative electrode welding points and a first layer of thermocouple accessories; the second layer of thermocouple temperature sensors includes: a second layer of thermocouple positive electrodes, a second layer of thermocouple positive and negative electrode welding points and a second layer of thermocouple accessories; the third layer of thermocouple temperature sensors includes: a third layer of thermocouple positive electrodes, a third layer of thermocouple positive and negative electrode welding points and a third layer of thermocouple accessories.

[0023] Preferably, the three groups of K-type thermocouple molded layered temperature sensors adopt an axisymmetric layout, with a molding outer diameter of Φ30mm, the axial projection angle of the three groups of thermocouples is 120°, the welding measuring point position of the thermocouple sensor is located at the axisymmetric center position, the measuring point position of the second layer of thermocouple sensor is 5mm away from the measuring point position of the first layer of thermocouple sensor, the measuring point position of the third layer of thermocouple sensor is 10mm away from the measuring point position of the second layer of thermocouple sensor, and the lead wires of the three groups of thermocouples are enclosed within Φ6mm.

[0024] The present invention has at least the following beneficial effects:

[0025] The present invention heats the thermocouple sensor to a certain temperature, introduces silane and oxygen, and utilizes the catalytic properties of the metal material of the thermocouple sensor to achieve in-situ preparation of a silicon dioxide insulating layer. The insulating layer has good shape-conforming deformation and high-temperature insulation performance, achieving the unity of high-temperature insulation and shape-conforming deformation capabilities of the thermocouple sensor, and meeting an important common technical demand for heat flux density measurement in general industrial fields and aerospace engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a schematic diagram of the structure of three groups of K-type thermocouple formed layered temperature sensors provided by the present invention.

[0028] Figure 2 This is a schematic structural diagram of the first-layer thermocouple temperature sensor provided by the present invention.

[0029] Figure 3 This is a schematic structural diagram of the second-layer thermocouple temperature sensor provided by the present invention.

[0030] Figure 4 This is a schematic structural diagram of the third-layer thermocouple temperature sensor provided by the present invention.

[0031] Explanation of the accompanying symbols: 1. First layer of thermocouple temperature sensor; 1-1. First layer of thermocouple positive electrode; 1-2. First layer of thermocouple positive and negative electrode welding points; 1-3. First layer of thermocouple accessories; 2. Second layer of thermocouple temperature sensor; 2-1. Second layer of thermocouple positive electrode; 2-2. Second layer of thermocouple positive and negative electrode welding points; 2-3. Second layer of thermocouple accessories; 3. Third layer of thermocouple temperature sensor; 3-1. Third layer of thermocouple positive electrode; 3-2. Third layer of thermocouple positive and negative electrode welding points; 3-3. Third layer of thermocouple accessories. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Example

[0036] This embodiment takes the in-situ autocatalytic high-temperature insulating layer preparation method of a K-type thermocouple layered temperature sensor with an outer diameter of Φ30 and three groups of measuring points with a spacing of 10 mm as an example to illustrate the specific implementation scheme of the invention.

[0037] 1. Thermocouple sensor selection

[0038] Preformed K-type thermocouple (NiCr-NiSi) is selected, the diameter of the thermocouple bare wire is 0.15mm, and the length of a single set is 200mm (NiCr length is 100mm, NiSi length is 100mm).

[0039] 2. Thermocouple sensor is powered on for heating

[0040] Prepare three DC power supplies and connect them to the first, second, and third layer thermocouple sensors respectively, control the heating power supply voltage to 36V±2V, and control the heating current to 0.5~1.5A.

[0041] 3. In-situ catalytic insulating layer chemical vapor deposition

[0042] Place three sets of thermocouple sensors connected to the heating power supply in a chemical vapor deposition quartz sealed reaction chamber with a size of Φ200mm×300mm. Connect the two air inlets to silane (SiH4) and oxygen (O2) respectively, and ensure that the air outlet is unobstructed. Adjust the flow rate of silane and oxygen to 3g / min and 9g / min respectively, maintain ventilation for 3 minutes, and exhaust the original air in the quartz chamber. Heat the thermocouple to 300℃ according to the control parameters of step 2. Use an infrared thermal imager to detect the temperature of the thermocouple during the heating process. After the thermocouple temperature stabilizes, continue to keep silane and oxygen ventilation for 60 minutes to complete the chemical vapor deposition of the silicon dioxide insulating layer. The basic principle of this step is:

[0043]

[0044] The thermocouple metal itself is utilized for its chemical vapor deposition reaction autocatalytic properties and self-heating properties when powered on.

[0045] 5. Insulation layer thickness detection

[0046] After 60 minutes of reaction, electron microscopy observation showed that the average thickness of the silicon dioxide insulating layer was 47 μm, and it had good bending and deformation conformability.

[0047] 6. Layered temperature sensor molding

[0048] A layered temperature sensor is formed by depositing three sets of K-type thermocouples with a silicon dioxide insulating layer. Figures 1 to 4 As shown, it includes: a first layer of thermocouple temperature sensors 1, a second layer of thermocouple temperature sensors 2 and a third layer of thermocouple temperature sensors 3; the first layer of thermocouple temperature sensors includes: a first layer of thermocouple positive electrode 1-1, a first layer of thermocouple positive and negative electrode welding points 1-2 and a first layer of thermocouple accessories 1-3; the second layer of thermocouple temperature sensors 2 includes: a second layer of thermocouple positive electrode 2-1, a second layer of thermocouple positive and negative electrode welding points 2-2 and a second layer of thermocouple accessories 2-3; the third layer of thermocouple temperature sensors 3 includes: a third layer of thermocouple positive electrode 3-1, a third layer of thermocouple positive and negative electrode welding points 3-2 and a third layer of thermocouple accessories 3-3.

[0049] Specifically, three groups of K-type thermocouple molded layered temperature sensors adopt an axisymmetric layout, with a molding outer diameter of Φ30mm. The axial projection angle of the three groups of thermocouples is 120°. The thermocouple welding measurement point is located at the center of the axisymmetry. The second layer of thermocouple measurement point is 5mm away from the first layer of thermocouple measurement point. The third layer of thermocouple measurement point is 10mm away from the second layer of thermocouple measurement point. The three groups of thermocouple lead wires are enveloping within Φ6mm, and the preparation of the in-situ self-catalytic silica high-temperature insulation layer K-type thermocouple layered temperature sensor can be completed.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor, characterized in that: The steps include: S1, placing the preformed thermocouple sensor in a chemical vapor deposition reaction chamber; S2, continuously introducing silane and oxygen into the reaction chamber to exhaust the original gas in the reaction chamber; S3, heating the thermocouple sensor to a certain temperature, and continuously detecting the temperature of the thermocouple sensor during the heating process; S4. After the temperature of the thermocouple sensor is stabilized, silane and oxygen are continuously introduced to react for a period of time until the deposition of the silicon dioxide insulating layer is completed.

2. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, characterized in that: The thermocouple sensor is a thermocouple type layered temperature sensor.

3. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, characterized in that: The thermocouple sensor includes any one of a K-type, a J-type, a T-type, an E-type, an N-type, an S-type, an R-type, a B-type or a C-type thermocouple sensor.

4. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, wherein: In step S3, the thermocouple is heated by direct current heating to heat the thermocouple sensor to 250°C to 300°C.

5. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 4, characterized in that: The voltage of the direct current power supply is controlled within a range of 28V to 40V, and the current is controlled within a range of 0.5A to 3A.

6. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, characterized in that: In step S3, an infrared thermal imager is used to continuously detect the temperature of the thermocouple sensor during the heating process.

7. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, characterized in that: The flow ratio of the silane and oxygen is controlled at 1:

3.

8. The method for preparing an in-situ autocatalytic insulating layer of a thermocouple sensor according to claim 1, characterized in that: In step S4, the reaction time is controlled to be 30 min to 90 min, and the thickness of the silicon dioxide insulating layer generated by the reaction is controlled to be 30 μm to 60 μm.

9. An in-situ autocatalytic insulation layer for a thermocouple sensor, characterized in that: The in-situ autocatalytic insulating layer of the thermocouple sensor is prepared by the preparation method of any one of claims 1 to 8.

10. A thermocouple sensor, characterized in that: The thermocouple sensor includes the thermocouple sensor in-situ autocatalytic insulation layer according to claim 9 .

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