Non-packaged high-temperature-resistant thin film temperature sensor manufactured in situ by laser and preparation method thereof

Abstract

The invention discloses a laser in-situ manufactured unpackaged high-temperature-resistant thin film temperature sensor and a preparation method thereof, a high-temperature insulating material is used as a substrate, a temperature-sensitive thin film precursor layer is formed by coating titanium boride-based precursor ink on the surface of the substrate, and conduction among titanium boride micro-nano particles is realized through laser sintering after curing, so that the temperature-sensitive thin film temperature sensor is obtained. The temperature sensitive layer with excellent conductivity is obtained through laser-induced passivation, and glass-phase silicon borate formed through laser-induced passivation makes up the defects of titanium boride micro-nano particles, so that the oxidation resistance at high temperature is obtained, and the laser sintering and passivation technological process of converting titanium boride and silicon carbide mixed ink from powder-liquid-solid-function is achieved; and the temperature sensor is successfully applied to high-temperature temperature sensing. Compared with the prior art, based on the laser one-step processing technology, rapid in-situ preparation of the sensor can be achieved, and needed patterns can be accurately processed.

Description

Technical Field

[0001] The present invention belongs to the technical field of extreme environment sensors and relates to a non-packaged high-temperature resistant thin film temperature sensor manufactured in situ by laser and a preparation method thereof. Background Art

[0002] Many industrial fields, such as aerospace, power generation, metallurgy and chemical industry, often involve extreme high temperature conditions in their production environment. In extremely high temperature environments, temperature monitoring is essential to ensure the safe operation of the system. Temperature sensors can provide accurate temperature data, help prevent accidents caused by overheating, protect equipment from damage, thereby increasing the overall safety of the system, and also help optimize the production process, improve energy efficiency, reduce energy waste, reduce the emission of harmful substances, and improve environmental performance.

[0003] Under these conditions, conventional temperature sensors cannot work properly, so specially designed high temperature resistant temperature sensors are needed to ensure accurate monitoring and control of the process. Currently, the temperature sensors used in extreme high temperature environments mainly include thermocouples, infrared sensors, fiber optic temperature sensors, etc. However, they all have disadvantages such as being unable to be conformally attached, requiring the use of special subsequent circuits, being complex to install, and possibly affecting the operation of the device to be monitored.

[0004] High temperature resistant thin film temperature sensors have the advantages of strong adaptability, can be manufactured in situ on the substrate to be monitored, high precision, fast response, and easy integration. Currently, high temperature resistant thin film temperature sensors are mostly based on precious metals such as platinum, sintered ceramics, etc., which have high costs, complex preparation processes, long preparation times, and require an anti-oxidation protective layer. The thermal resistance thin film temperature sensor based on platinum precious metal (a high-temperature platinum thin film resistance temperature sensor and its preparation method, application number 202110017510.X) has high cost and low sensitivity, which limits its application in high-precision occasions; the indium tin oxide-indium oxide thin film thermocouple (a method for preparing crystal plane preferentially oriented indium tin oxide-indium oxide thin film thermocouple, application number 202110423427.2) has good performance, but cannot break through the problem that thermocouples require cold end compensation and special subsequent processing circuits; the thin film temperature sensor based on polymer-converted ceramic precursor (a method for preparing a polymer precursor high-temperature ceramic thin film sensor, application number 202310860565.6) has excellent performance and low cost, but its preparation usually requires long-term high-temperature pyrolysis in a high-temperature furnace, which is time-consuming and energy-intensive, and requires packaging layer protection. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a laser in-situ manufactured, non-packaged, high-temperature resistant thin film temperature sensor and a preparation method thereof. The high-temperature resistant thin film temperature sensor is prepared by laser one-step sintering and induced passivation. The sensor has a more convenient processing method, extremely fast processing speed, lower cost, and a wider measurement range.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A non-packaged high-temperature thin-film temperature sensor manufactured in situ by laser comprises a high-temperature substrate, a sensitive film, a connecting layer, a lead wire and a connecting protective layer. The sensitive film is prepared on the high-temperature substrate and is formed by laser sintering and induced passivation of a titanium boride-based precursor ink to form a titanium boride conductive path protected by glass phase borosilicate anti-oxidation. The conduction between titanium boride micro-nano particles in the precursor ink is achieved by laser sintering, and at the same time, the laser induced passivation forms glass phase borosilicate to protect the titanium boride conductive path from oxidation. The high-temperature substrate is an insulating ceramic such as alumina ceramic and silicon carbide ceramic. The sensitive film has a negative temperature-sensitive characteristic. The connecting layer is arranged on the sensitive film according to the lead-out position required by the wire for connecting the lead wire. The connecting protective layer covers the connecting layer for suppressing fracture failure caused by the difference in thermal expansion between the connecting layer and the sensitive film. The connecting layer is a high-temperature resistant paste such as silver paste and silver palladium paste. The lead wire is located between the connecting layer and the connecting protective layer and is used to lead out the electrical signal of the sensitive film. The lead wire is a precious metal wire such as platinum wire.

[0008] Another object of the present invention is to provide a method for preparing a non-packaged high-temperature resistant thin film temperature sensor manufactured by laser in-situ, the steps comprising:

[0009] Step 1: Prepare the precursor ink, and select the appropriate amount of solvent to be added according to the different film-forming methods to be used later to achieve the appropriate ink concentration;

[0010] Step 2: Pretreatment of high temperature substrates. Appropriate cleaning and drying methods can be selected for different high temperature substrates to remove impurities on their surfaces.

[0011] Step 3: Precursor film preparation, suitable film forming technology and film forming parameters can be selected according to the prepared ink concentration;

[0012] Step 4: Using laser direct writing technology on a high-temperature substrate, the parameters are adjusted to accurately process precursor films of different film thicknesses to obtain sensitive films with specified patterns;

[0013] Step 5: Apply the connection layer and fix the lead wire to make it well connected with the sensitive film in step 4;

[0014] Step 6: Prepare a connection protection layer by drop coating the precursor ink on the connection layer of the sample obtained in step 5.

[0015] Further, the precursor ink described in step 1 is prepared, wherein the precursor ink is composed of titanium boride powder, silicon carbide powder, isopropanol, glycerol and polyvinyl pyrrolidone, and is prepared by adding titanium boride powder and silicon carbide powder in batches to a functional solvent obtained by mixing isopropanol, glycerol and polyvinyl pyrrolidone, and ultrasonically dispersing; wherein the amount ratio of titanium boride powder, silicon carbide powder, polyvinyl pyrrolidone, glycerol and isopropanol is: 2.8-3.2g: 0.4-0.8g: 0.4-0.5g: 0.2-0.4g: 4-6mL, the particle size of titanium boride powder is preferably 1-3μm, and the particle size of silicon carbide is preferably 0.5-0.7μm. According to a specific embodiment of the present invention, its specific preparation steps can be:

[0016] (1) Use a microbalance to weigh 0.446 g of polyvinyl pyrrolidone and 0.3 g of glycerol into a reagent bottle;

[0017] (2) Use a pipette to measure 5 ml of isopropanol and inject it into the reagent bottle in (1);

[0018] (3) Add a magnetic rotor and stir on a magnetic stirring table for 1 hour (1000 rpm, 60 degrees Celsius);

[0019] (4) adding 1 g of titanium diboride and 0.2 g of silicon carbide to the completely clarified solvent after stirring;

[0020] (5) Disperse in an ultrasonic cell disruptor for 2 minutes;

[0021] (6) Repeat (4) and (5) three times.

[0022] Furthermore, the high temperature substrate described in step 2 can be a high temperature resistant and insulating substrate such as alumina ceramics, silicon carbide ceramics, etc.

[0023] Furthermore, the high temperature substrate pretreatment is ultrasonic alcohol cleaning, ultrasonic water cleaning, and drying. According to a specific embodiment of the present invention, the specific steps may be:

[0024] (1) Place the alumina ceramic substrate in alcohol and sonicate for 2 minutes;

[0025] (2) placing the alumina ceramic substrate in deionized water and ultrasonicating it for 2 minutes;

[0026] (3) Finally, the alumina ceramics were dried in a vacuum drying oven at 60 degrees Celsius;

[0027] Furthermore, the precursor film preparation method described in step 3 can prepare the film on a high-temperature substrate by spin coating, or by any coating method such as drip coating, scraping, dispensing, direct ink writing (DIW), screen printing, etc. Different methods require different viscosities of the precursor ink, which can be achieved by adjusting the amount of isopropyl alcohol and glycerol added.

[0028] Furthermore, the thin film can be prepared on the high-temperature substrate by spin coating. According to a specific embodiment of the present invention, the specific steps may be:

[0029] (1) placing the high-temperature substrate treated in step 2 in a spin coater, turning on the air pump to evacuate the substrate, and achieving adsorption and fixation of the high-temperature substrate;

[0030] (2) drop a small amount of precursor ink on the center of the hot substrate and spin coat at a speed of 400 rpm for 3 seconds;

[0031] (3) Fill in the area on the high-temperature substrate where the ink is not spin-coated, then drop 2-3 ml of the precursor ink in the center of the high-temperature substrate and spin-coat at a speed of 500 rpm for 15 seconds;

[0032] (4) After spin coating, remove the high-temperature substrate, place it on a heating table, and dry it at 60 degrees Celsius for 5 minutes.

[0033] Furthermore, the laser direct writing described in step 4 is to sinter the precursor ink coating on the high-temperature substrate according to the designed pattern by using laser integration technology on the high-temperature substrate, utilizing the photothermal effect and photochemical reaction of the laser, inducing passivation to form titanium boride with glass phase borosilicate protection, and obtaining a temperature-sensitive film. The laser direct writing technology, according to a specific embodiment of the present invention, has the following specific steps:

[0034] (1) Use Auto CAD software to draw the pattern to be processed and import it into the laser control software;

[0035] (2) The energy density is 6.4 J / mm 2 The 532nm continuous green light is used to quickly sinter the precursor to form a temperature-sensitive film.

[0036] Furthermore, the connection layer described in step 5 is a high temperature resistant conductive paste, such as silver paste, silver palladium paste, etc., the lead wire is a high temperature resistant precious metal wire, such as platinum wire, etc., the connection of the sensitive film, the connection layer, and the lead wire, the lead wire is fixed by coating the precursor ink on the required position of the sensitive film, pressing the lead wire by covering it with alumina ceramic and keeping it at 80 to 150 degrees Celsius for 1 hour, so that the connection layer is cured to achieve electrical conduction between the sensitive film and the lead wire; according to a specific embodiment of the present invention, the specific steps may be:

[0037] (1) A platinum wire with a diameter of 0.2 mm was embedded in a D3*1 mm alumina ceramic sheet with a 0.25 mm diameter slot;

[0038] (2) Hand-coat 02H-1805 silver-palladium paste on both ends of the sensitive film as a connecting layer;

[0039] (3) The alumina ceramic embedded with platinum wire is pressed onto the connection layer, and a 50 g weight is pressed onto the ceramic. The entire device is dried at 130 degrees Celsius for 1 hour to solidify the connection layer, so that electrical conduction is established between the sensitive film and the lead wire.

[0040] Furthermore, the purpose of the connection protection layer in step 6 is to suppress the fracture between the connection layer and the sensitive film due to the difference in thermal expansion coefficient. According to a specific embodiment of the present invention, the specific steps may be:

[0041] (1) Apply a small amount of precursor ink on the connecting layer;

[0042] (2) Heat and dry on a heating table (80 degrees Celsius) for 10 minutes.

[0043] The beneficial technical effects of the present invention are:

[0044] 1. The sensor of the present invention can be conformally manufactured in situ on the insulating component to be detected. Compared with thermocouples, optical fiber temperature sensors, etc., it does not require installation and does not require a dedicated subsequent processing circuit.

[0045] 2. The sensor of the present invention is a thin film structure, and the thickness of the sensitive film is within 100 microns, which has almost no impact on the normal operation of the components to be detected (such as aircraft engines, turbine blades, etc.).

[0046] 3. The raw materials of the sensor ink of the present invention are mainly based on titanium boride and silicon carbide powder, which are low in cost compared to precious metals such as platinum.

[0047] 4. The sensor of the present invention can realize temperature detection from room temperature to 950 degrees Celsius, has extremely excellent cyclability in detection from room temperature to 800 degrees Celsius, and can be used for more than 20 hours at a high temperature of 800 degrees Celsius.

[0048] 5. The sensor preparation process of the present invention is simple and the preparation time is short. Compared with the traditional high-temperature sintering ceramic technology (usually more than 5 hours, some require special gas atmosphere), the use of laser rapid sintering in the present invention can achieve conductive connection and temperature sensitivity of the precursor film within two minutes (in air). BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 1 is a schematic diagram of the structure of an embodiment of a thermal resistance type high temperature resistant thin film temperature sensor of the present invention, wherein a is a schematic diagram of the sensor structure, and b is a diagram of the sensor structure;

[0051] Figure 2 This is a preparation flow chart of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0052] Figure 3 It is a test platform for the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0053] Figure 4 This is a diagram showing the processing result of the temperature sensitive layer in the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0054] Figure 5 is a diagram of the processing results of laser patterning in some specific examples of the present invention;

[0055] Figure 6 1 is a SEM micrograph of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention, wherein a is before the high temperature test, b is after the high temperature test, and the scale bars are both 10 microns;

[0056] Figure 7 This is a Raman characterization diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention before and after the test;

[0057] Figure 8 This is an XPS characterization diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention before and after the test;

[0058] Fig. 9 This is a FTIR characterization diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0059] Fig.10 It is a contour diagram of the square resistance of the film after high temperature test under different ratios of ink and different laser processing energy density of the present invention;

[0060] Fig.11 It is a calibration diagram of the thermal sensitivity performance of the sensitive layer of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention; Fig.12 It is a hysteresis curve diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention at 100-800 degrees Celsius;

[0061] Fig.13 It is a 100-800 degrees Celsius repeatability test diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0062] Fig.14 This is a long-term stability test diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention at 800 degrees Celsius;

[0063] Fig.15 This is a temperature step test diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0064] Fig.16 It is a temperature-sensitive characteristic diagram of the connection layer, substrate, and original ink of the thermal resistance type high-temperature resistant thin film temperature sensor of the present invention;

[0065] Fig.17 This is a graph showing the adhesion test of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0066] Fig.18 It is a response diagram of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention to transient flame;

[0067] Fig.19 It is a characterization diagram of wear resistance and vibration of the thermal resistance type high temperature resistant thin film temperature sensor of the present invention;

[0068] In the figure: A1, high temperature substrate; A2, sensitive film; A3, connecting layer; A4, lead wire; A5, connecting protection layer. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0070] The high temperature resistant temperature sensor of the present invention utilizes the thermal resistance characteristics of semiconductors. When the temperature rises, the migration speed of carriers and holes in the semiconductor increases, which is manifested as a decrease in bulk resistance on a macro scale. In the preparation process of the sensitive film, the instantaneous high temperature of the laser is utilized, and the light-heat conversion of the laser is better realized by adding silicon carbide, so the sintering of the film precursor can be achieved in a very short time. While laser sintering forms a conductive path for the film, it promotes the formation of silicon borate, thereby improving the antioxidant ability of the sensitive film at high temperatures.

[0071] A laser in-situ manufactured non-packaged high temperature resistant thin film temperature sensor, such as Figure 1 As shown, it is a thermal resistance temperature sensor, including an insulating high-temperature substrate A1, a sensitive film A2, a connecting layer A3, a lead wire A4 and a connecting protective layer A5. The sensitive film A2 is prepared on the high-temperature substrate A1 by laser sintering. The high-temperature substrate A1 is an insulating ceramic such as alumina ceramics and silicon carbide ceramics. The sensitive film A2 has a negative temperature-sensitive characteristic. The connecting protective layer A5 covers the connecting layer A3 to suppress fracture failure caused by the thermal expansion difference between the connecting layer A3 and the sensitive film A2. The connecting layer A3 is a high-temperature resistant paste such as silver paste and silver-palladium paste. The lead wire A4 is located between the connecting layer A3 and the connecting protective layer A5, and is used to lead out the electrical signal of the sensitive film A2. The lead wire A4 is a precious metal wire such as platinum wire.

[0072] According to a specific example of the present invention, a method for preparing a non-packaged high-temperature resistant thin film temperature sensor manufactured by laser in-situ is provided, the steps comprising:

[0073] Step 1: Use a microbalance to weigh 0.446 g of polyvinyl pyrrolidone and 0.3 g of glycerol and place them in a reagent bottle. Use a pipette to measure 5 ml of isopropanol and inject it into the reagent bottle. Add a magnetic rotor to the reagent bottle and stir on a magnetic stirring table for 1 hour (set at 1000 rpm and 60 degrees Celsius) to obtain a functional solvent.

[0074] Step 2: Use a microbalance to weigh 1g of titanium boride powder with a particle size of 1 to 3 microns and 0.2g of silicon carbide powder with a particle size of 0.5 to 0.7 microns, add them to the functional solvent prepared in step 1, and disperse them in an ultrasonic cell disruptor for two minutes to obtain a uniformly dispersed ink. Repeat step 2 for a total of 3 times to obtain a precursor ink;

[0075] Step 3: Select 96α-alumina ceramic with an application temperature of 300 to 1700 degrees Celsius as a high-temperature substrate, and pretreat the high-temperature substrate, wherein the pretreat is performed by placing the alumina ceramic substrate in alcohol and ultrasonicating for 2 minutes; then placing the alumina ceramic substrate in deionized water and ultrasonicating for 2 minutes; and finally drying the alumina ceramic in a vacuum drying oven at 60 degrees Celsius;

[0076] Step 4: Preparation of precursor film. Place the cleaned high-temperature substrate after treatment in a spin coater, turn on the air pump to evacuate, and achieve adsorption and fixation of the high-temperature substrate; drop a small amount of precursor ink in the center of the high-temperature substrate, and use a spin coating speed of 400 rpm for 3 seconds to achieve preliminary coating of the precursor ink on the high-temperature substrate; for the areas on the high-temperature substrate where the ink is not spin-coated, use a pipette to dip a small amount of ink to repair, and then drop 2-3 ml of precursor ink in the center of the high-temperature substrate, and use a spin coating speed of 500 rpm for 15 seconds; remove the high-temperature substrate after spin coating, place it on a heating table, and dry it at 60 degrees Celsius for 5 minutes to complete the preparation of the precursor film;

[0077] Step 5: Use Auto CAD software to draw the pattern to be processed and import it into the laser control software Ezcard; use an energy density of 6.4 J / mm 2 The 532nm continuous green light is used to rapidly sinter the precursor to form a temperature-sensitive film. During the laser action, silicon carbide acts as a photothermal converter to achieve laser-heat conversion. The precursor film is densified under the condition of rapid temperature increase to form a conductive path. At the same time, the instantaneous ultra-high temperature induces partial oxidation of silicon carbide and titanium boride to generate silicon borate, which envelops the titanium boride conductive path, effectively isolating further oxygen intrusion and achieving improved oxidation resistance at high temperatures.

[0078] Step 6: Hand-coat 02H-1805 silver-palladium slurry on both ends of the sensitive film as a connecting layer; embed a platinum wire with a diameter of 0.2mm into a D3*1mm alumina ceramic sheet with a 0.25mm diameter slot; press the alumina ceramic embedded with platinum wire on the connecting layer, press a 50g weight on the ceramic, and dry the entire device at 130 degrees Celsius for 1 hour to solidify the connecting layer, so that electrical conduction is formed between the sensitive film and the lead wire;

[0079] Step 7: Apply a small amount of precursor ink on the connection layer of step 6, and heat and dry it on a heating table (80 degrees Celsius) for 10 minutes.

[0080] Step 8: Prepare the control film. In addition to the different mass ratios of titanium boride and silicon carbide in step 2 (the control group is 10:0, 10:1, 10:4, and 10:6), the laser processing energy density is different (0 J / mm 2 , 2.58J / mm 2 , 9.04J / mm 2 ), the rest of the steps are the same.

[0081] In this example, the thickness and pattern of the sensitive film, the connection layer, and the connection protection layer can be adjusted as needed. Preferably, the thickness of the sensitive film is 10-50 microns, the thickness of the connection layer is 10-30 microns, and the thickness of the connection protection layer is 20-100 microns.

[0082] According to a specific embodiment of the present invention, the preparation process is as follows Figure 2 shown.

[0083] Test platform such as Figure 3 The test platform includes a tube furnace, a commercial K-type thermocouple, a Keysight data collector, a laptop computer, etc. The signals of the prototype and the commercial K-type thermocouple are read by the Keysight data collector and transmitted to the computer for visualization.

[0084] Two examples of the temperature sensitive film in the thermal resistance type high temperature resistant film temperature sensor of the present invention are shaped as follows: Figure 4 As shown in the figure, C1 is a high temperature substrate and C2 is a sensitive film. This further demonstrates the patterning capability of the laser manufacturing in the present invention, such as Figure 5 shown.

[0085] The scanning electron microscope (SEM) image of the thermal resistance high temperature resistant thin film temperature sensor of this example is as follows: Figure 6 As shown in the figure, the SEM shows that the sensitive films prepared with different laser energy densities have different morphologies before and after being subjected to long-term high temperature. Figure 6 The microscopic image shows that 6.46J / mm 2 The surface morphology of the sensitive film prepared by laser energy density is still very good after high temperature, without defects such as cracks, holes, and cracks. However, too low laser energy density will lead to obvious surface oxidation, and too high will lead to surface cracking. The preferred laser energy density is 4-7J / mm 2 532nm green light.

[0086] The Raman characterization of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Figure 7 As shown, the upper curve is before the high temperature test, and the lower curve is after the high temperature test. The Raman characterization shows that before and after the high temperature, the main substance of the film is TiB2, which is the component of the conductive path of the film. The substance has almost no change before and after the high temperature, proving that the film has high temperature stability.

[0087] The XPS characterization of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Figure 8 As shown, the XPS characterization shows that the B element in the film exists in the form of [BO4] rather than in the form of [BO3] of boron oxide, indicating the formation of boric acid silicon.

[0088] The FTIR characterization of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig. 9 As shown, the FTIR characterization shows the various bonds present in the film, among which 920.8 cm -1 and 783.4cm-1 All of them prove the existence of silicon borate.

[0089] The square resistance contour diagram of the control group film in this example after high temperature test is as follows Fig.10 As shown in the contour diagram, the film prepared by the ink without silicon carbide addition is insulated after high temperature and completely oxidized and fails because an effective boric acid silicon protective phase cannot be formed in such a film.

[0090] The thermal performance of the sensitive layer of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig.11 As shown, the sensitivity can be fitted according to the Steinhart-Hart equation. The fitting formula is specifically:

[0091] 1 / T=0.00125+1.1023×10 -4 lnR+1.73711×10 -6 (lnR) 3 In the fitting formula, T is the temperature to be detected, in Kelvin, and R is the output resistance of the thermal resistance type high temperature resistant thin film temperature sensor of this example, in ohm.

[0092] The temperature test hysteresis curve of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows: Fig.12 As shown in the figure, the hysteresis curve is divided into 100-800 degrees Celsius heating and 800-100 degrees Celsius cooling, with a total of 6 cycles, and has excellent stability. The resistance fluctuates in the first heating process because the borosilicate flows to fill the pores in the film after laser processing.

[0093] The temperature cycle detection curve of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows: Fig.13 As shown, the temperature cycle is divided into a temperature increase of 100-800 degrees Celsius and a temperature decrease of 800-100 degrees Celsius, which is cycled four to five times in total.

[0094] The high temperature stability of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig.14 As shown, the high temperature stability test is to place the sensor at 800 degrees Celsius for more than 20 hours without failure.

[0095] The temperature step test of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig.15 As shown, the temperature step test is to place the sensor at 0-800 degrees Celsius for 30 minutes at intervals of 100 degrees Celsius to test stability.

[0096] The temperature-sensitive properties of the connection layer, substrate, and original ink of the thermal resistance high-temperature resistant thin film temperature sensor in this example are as follows: Fig.16As shown, the temperature-sensitive property of the connecting layer in the example is negligible compared with the sensitive film, and the substrate and the original ink in the example can be considered as insulating.

[0097] The adhesion test of the sensitive film of the thermal resistance type high temperature resistant thin film temperature sensor in this example is as follows Fig.17 As shown, the resistance of the sensitive film hardly changes after the 3M tape is peeled off 30 times and ultrasonically damaged for 10 minutes.

[0098] The transient response test of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig.18 As shown, the sensor can respond quickly under a flame torch.

[0099] The wear and vibration resistance test of the thermal resistance high temperature resistant thin film temperature sensor in this example is as follows Fig.19 As shown, the sensor has almost no change in resistance under sandpaper wear and vibration.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-packaged high-temperature resistant thin film temperature sensor manufactured in situ by laser, characterized in that: The sensor comprises a high-temperature substrate (1), a sensitive film (2), a connecting layer (3), a connecting protective layer (4) and a lead wire (5). The sensitive film (2) is prepared on the high-temperature substrate (1) and is a titanium boride conductive path protected by glass phase borosilicate anti-oxidation formed by laser sintering and induced passivation of titanium boride-based precursor ink. The connecting layer (3) is arranged on the sensitive film (2) for connecting the lead wire (5). The connecting protective layer (4) covers the connecting layer (3) for suppressing fracture failure caused by the difference in thermal expansion between the connecting layer (3) and the sensitive film (2). The lead wire (5) is located between the connecting layer (3) and the connecting protective layer (4) for leading out the electrical signal of the sensitive film (2). The sensor is a thermal resistance temperature sensor.

2. The high temperature resistant thin film temperature sensor according to claim 1, characterized in that: The precursor ink consists of titanium boride powder, silicon carbide powder, isopropyl alcohol, glycerol and polyvinyl pyrrolidone.

3. The high temperature resistant thin film temperature sensor according to claim 1, characterized in that: The thickness of the sensitive film is 1 to 100 microns.

4. The high temperature resistant thin film temperature sensor according to claim 1, characterized in that: The high temperature substrate is an insulating material, including but not limited to alumina ceramics and silicon carbide ceramics; the connecting layer is a high temperature resistant conductive paste, including but not limited to silver paste and silver palladium paste; the lead wire is a high temperature resistant conductive wire, including but not limited to platinum wire.

5. The high temperature resistant thin film temperature sensor according to claim 1, characterized in that: The connection protection layer is prepared by using the precursor ink.

6. A method for preparing a high temperature resistant thin film temperature sensor according to any one of claims 1 to 5, characterized in that: The preparation steps include: Step 1: preparing precursor ink; Step 2: high temperature substrate pretreatment; Step 3: Precursor film preparation; Step 4: Prepare sensitive film by laser sintering; Step 5: Apply the connection layer and fix the lead wire to make it well connected with the sensitive film; Step 6: Prepare a connection protection layer by drop coating the precursor ink on the connection layer of the sample obtained in step 5.

7. The method for preparing a high temperature resistant thin film temperature sensor according to claim 6, characterized in that: The precursor ink described in step 1 is composed of titanium boride powder, silicon carbide powder, isopropanol, glycerol and polyvinyl pyrrolidone, and is prepared by adding titanium boride powder and silicon carbide powder in batches to a functional solvent obtained by mixing isopropanol, glycerol and polyvinyl pyrrolidone, and ultrasonically dispersing the mixture; wherein the amount ratio of titanium boride powder, silicon carbide powder, polyvinyl pyrrolidone, glycerol and isopropanol is: 2.8-3.2g: 0.4-0.8g: 0.4-0.5g: 0.2-0.4g: 4-6mL, the particle size of titanium boride powder is 1-3μm, and the particle size of silicon carbide is 0.5-0.7μm.

8. The method for preparing a high temperature resistant thin film temperature sensor according to claim 6, characterized in that: The high-temperature substrate pretreatment described in step 2 is ultrasonic alcohol cleaning, ultrasonic water cleaning, and drying. The precursor film preparation method described in step 3 is to evenly cover the precursor ink on the surface of the high-temperature substrate by any coating method, and obtain a uniform precursor film after drying on a heating table.

9. The method for preparing a high temperature resistant thin film temperature sensor according to claim 6, characterized in that: The laser sintering method for preparing the sensitive film described in step 4 is to use laser integration technology to utilize the photothermal effect and photochemical reaction of the laser to sinter the precursor ink coating on a high-temperature substrate according to a designed pattern, induce passivation to form a glassy phase boric acid silicon encapsulated titanium boride, and obtain a temperature-sensitive film.

10. The method for preparing a high temperature resistant thin film temperature sensor according to claim 6, characterized in that: The fixing of the lead wires in step 5 is to coat the precursor ink on the required position of the sensitive film, press the lead wires by covering them with alumina ceramics and keep them at 80-150 degrees Celsius for 1 hour, so that the connection layer is cured to achieve electrical conduction between the sensitive film and the lead wires.

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