Dual-wavelength femtosecond laser direct-writing miniaturized precursor ceramic high-temperature thin film sensor

Abstract

The invention discloses a dual-wavelength femtosecond laser direct-writing miniaturized precursor ceramic high-temperature thin film sensor, and relates to the technical field of high-temperature thin film sensor manufacturing. Depositing the precursor functional slurry on the surface of a substrate layer by layer by adopting additive manufacturing processes such as blade coating, direct writing and the like, and performing pyrolysis to form an amorphous ceramic multilayer film; based on a dual-wavelength femtosecond laser micro-nano processing platform, the device comprises 1035nm / 343nm double light sources, a light path transmission system and a motion platform, and the characteristics of femtosecond laser ultrashort pulse and high peak power density are utilized to realize submicron precision graphical processing of a precursor ceramic film. And the area of the high-temperature film sensor unit is reduced from the square millimeter level of the traditional process to the square micron level. The method has the advantages of dual-wavelength laser collaborative processing, multi-layer film compatibility and the like, overcomes the disadvantages of large size and poor forming precision of a traditional additive manufacturing precursor ceramic film sensor, and provides a new normal form for integrated manufacturing of a micro sensor array serving in an extreme environment.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature thin film sensor manufacturing, and in particular to a dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor. Background Art

[0002] In-situ monitoring of the physical parameters of components in extreme service environments is a key technology supporting the health monitoring and optimized design of high-end equipment. High-temperature thin-film sensors, with their ultra-thin form, lightweight design, and non-invasive measurement capabilities, demonstrate significant potential for real-time monitoring of component status in extreme service environments.

[0003] However, the alloy thin film sensors prepared by the currently widely used physical vapor deposition (PVD) technology have obvious performance limitations: on the one hand, the sensitive layer material is limited by the grain boundary oxidation embrittlement effect, and the maximum operating temperature is difficult to exceed 1000°C; on the other hand, the process relies on a high vacuum environment and a complex mask system, which is not only costly but also difficult to achieve high-quality conformal manufacturing on complex curved components.

[0004] Precursor-deposited ceramic (PDC) materials, due to their exceptional high-temperature resistance, excellent mechanical properties, and unique liquid-phase forming capabilities, are considered an ideal option for overcoming existing technological bottlenecks. However, in practical applications, the high-precision, fine-linewidth fabrication of PDC films still faces key technical challenges.

[0005] In order to meet the needs of electrical performance regulation, a large amount of nanofillers needs to be added to the precursor during the preparation of PDC films, which significantly increases the viscosity of the slurry and limits the minimum forming line width (above 300μm) of existing additive manufacturing technologies such as inkjet printing and direct writing. It is difficult to meet the needs of precise monitoring of local failure areas (usually submillimeter level) of hot end components of aircraft engines. Summary of the Invention

[0006] The present invention aims to provide a processing method for dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensors. By combining the advantages of laser processing at different wavelengths, submicron-level precision graphics of multi-layer precursor ceramic films can be achieved, thereby solving the performance limitations and processing accuracy problems of thin film sensors in high-temperature environments in the existing technology and meeting the monitoring needs in extreme service environments.

[0007] Another object of the present invention is to provide a precursor ceramic high-temperature thin film sensor prepared by the processing method.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions.

[0009] The present invention provides a dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor, which comprises, from bottom to top, a substrate, an insulating layer, a sensitive layer, a protective layer, and a thermal resistance layer; the insulating layer covers the surface of the substrate; the sensitive layer is located on the ceramic layer, and the sensitive layer includes a sensitive grid pattern with a characteristic size of ≤4μm, and the sensitive grid pattern is formed by a dual-wavelength femtosecond laser direct writing process; the protective layer covers the non-pad area of ​​the sensitive layer;

[0010] The dual-wavelength femtosecond laser direct writing process includes: using a 1035nm wavelength femtosecond laser to quickly pattern the functional ceramic film layer, with processing parameters such as a spot size of 20μm, a power of 40W, a scanning speed of 1 to 5000mm / s, and a pulse width of less than 300fs; using a 343nm wavelength femtosecond laser to finely control the edge morphology, resistance value, and surface micro-nano periodic structure of the sensitive gate, with processing parameters such as a spot size ≤5μm, a power of 10W, a scanning speed of 1 to 500mm / s, and a pulse width of less than 250fs.

[0011] The insulating layer is formed by high-temperature pyrolysis of a precursor of nano-Al2O3, nano-SiO2, nano-CaO and polysilazane mixed in a ratio of 1:1:1:1; the sensitive layer is formed by high-temperature pyrolysis of a precursor of nano-TiB2 and polysilazane mixed in a ratio of 7:3; and the protective layer is formed by high-temperature pyrolysis of a precursor of nano-SiO2 and polysilazane mixed in a ratio of 6:4.

[0012] The sensor also includes a thermal resistance layer, which is arranged above the sensitive layer and is formed by high-temperature pyrolysis of a precursor of nano-SiO2 and polysilazane mixed in a ratio of 6:4, and is used to regulate the thermal response characteristics of the sensor.

[0013] The width of the heat-affected zone of the sensitive grid is ≤6 μm, and it has a negative temperature coefficient characteristic in the temperature range of 25 to 800° C., and the resistance response shows high consistency in multiple temperature increase-decrease cycles.

[0014] When the sensor is arrayed, the unit area is ≤1mm², and it has a linear voltage response output for both laser heat flux input and flame heat flux input.

[0015] The dual-wavelength femtosecond laser direct writing process uses a dual-wavelength femtosecond laser micro-nano processing platform, which includes: 1035 / 343nm femtosecond laser light sources, a sealed optical path, an industrial camera, a motion platform, and a marble machine. Two different sealed optical paths focus the 1035nm wavelength femtosecond laser and the 343nm wavelength femtosecond laser on the motion platform, respectively. The industrial camera is used to locate the workpiece surface and the processed pattern, while the motion platform controls the movement of the workpiece to map the processed pattern onto the workpiece surface.

[0016] The power range of the 1035nm wavelength femtosecond laser is 0-40W, the pulse width is 300fs-10ps, and the repetition rate is 25kHz-5MHz. After being collimated and expanded by a beam expander, the femtosecond laser is introduced into a simulated galvanometer through several reflectors. The simulated galvanometer controls the movement of the beam within the plane via an XY motion motor. After being guided out of the simulated galvanometer, the beam is focused on the processing plane through a field lens. The spot diameter within the processing plane is 20μm. The power range of the 343nm femtosecond laser source is 0-10W (preferably 10W). It can be obtained by converting 1035nm light through a frequency-doubling crystal. After adjustment by a dedicated UV focusing lens, the spot size is only 5μm.

[0017] The sealed optical path is an independent dual-path system, each of which includes several reflectors, high-pass dichroic mirrors, a shutter controller, and a high-precision focusing lens. The 1035nm and 343nm optical paths are separated by dichroic mirrors to prevent mutual interference. The sealed cavity uses an aluminum alloy frame with an acrylic dust cover, and is equipped with an air pressure balance valve and humidity sensor to maintain a cleanroom environment ≥ ISO Class 6.

[0018] The industrial camera can use a 5-megapixel color CCD camera equipped with a telecentric lens with a positioning accuracy of ≤±3μm. It uses a visual positioning algorithm to collect workpiece surface marking points in real time, generate coordinate compensation data and feed it back to the motion control system to achieve sub-micron precision alignment of the processed graphics.

[0019] The motion platform can adopt a three-axis high-precision electric translation stage (X / Y / Z axis), driven by a linear motor, with a positioning accuracy of ≤±1μm, a repeatability accuracy of ≤±0.5μm, a maximum movement speed of up to 500mm / s, and is equipped with a vacuum adsorption fixture to fix the workpiece; the platform base is a granite or marble machine table with a surface flatness of ≤5μm / m, and air shock-absorbing pads are installed on the bottom to effectively isolate external vibrations with a frequency of ≥10Hz, ensuring that the platform vibration amplitude is ≤±1μm during processing;

[0020] The motion platform integrates a numerical control system, supports CAD import and G-code generation of processing graphics, can adjust parameters such as laser power, scanning speed, pulse frequency in real time, and display processing progress and status through a human-machine interface; the industrial camera, laser light source and motion platform are synchronously controlled through the Ethernet bus to realize a closed-loop process of "positioning-processing-detection", ensuring that the sensitive grid graphics accuracy error is ≤±2%.

[0021] The power, pulse width, and other parameters of the 1035nm and 343nm femtosecond lasers were determined based on extensive experimental and theoretical analysis to balance processing efficiency and precision. During actual processing, parameters such as laser power, scanning speed, and pulse frequency can be adjusted and optimized in real time based on factors such as the specific film material and the complexity of the processed pattern.

[0022] The method for processing a dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor comprises the following steps:

[0023] Step 1: The surface of the structure to be monitored is cleaned with anhydrous ethanol and ultrasonically cleaned respectively. An insulating layer precursor is deposited on the area where the thin film sensor is to be prepared using an additive manufacturing process. After high-temperature pyrolysis, the precursor is converted into a dense ceramic insulating layer.

[0024] Step 2: Using an additive manufacturing process, a sensitive layer precursor is deposited on top of the aforementioned precursor ceramic insulating layer, and after high-temperature pyrolysis, a functional ceramic film layer with physical parameter sensitive characteristics or other functions is obtained.

[0025] Step 3: Use dual-wavelength femtosecond lasers to perform rapid patterning and fine patterning of the functional ceramic film layer. In the rapid patterning stage, a 1035nm wavelength laser is used to quickly pattern the functional ceramic film layer. In the fine patterning stage, a 343nm wavelength laser is used to finely adjust the edge morphology, resistance value, and surface micro-nano periodic structure of the sensitive gate to ensure that the electrical characteristics of the sensitive gate meet the sensor requirements.

[0026] Step 4: depositing a protective layer precursor on the functional ceramic film layer, and obtaining a high-resistivity protective layer with a dense structure after high-temperature pyrolysis, which is used to isolate the functional ceramic film layer from oxygen at high temperatures;

[0027] Step 5: If necessary, deposit other film precursors on the protective ceramic film layer and convert them into specific ceramic film layers using a high-temperature pyrolysis process;

[0028] Step 6: Prepare solder joints on the surface of the sensor completed in step 5 to lead out the electrical signal.

[0029] In step 3, the processing parameters of the 1035 nm wavelength femtosecond laser are: spot size 20 μm, power 40 W, scanning speed 1-5000 mm / s, and pulse width <300 fs.

[0030] In step 3, the processing parameters of the 343 nm wavelength femtosecond laser are: spot size ≤ 5 μm, power 0 to 10 W (preferably 10 W), scanning speed 1 to 500 mm / s, and pulse width < 250 fs.

[0031] A femtosecond laser with a wavelength of 1035 nm is used to quickly pattern the precursor ceramic film, and then a femtosecond laser with a wavelength of 343 nm is used to perform submicron-level shaping and defect repair on the sensitive gate, thereby minimizing the characteristic size of the sensitive gate and optimizing the high-temperature electrical performance.

[0032] The precursor ceramic slurry includes the following components: an insulating layer precursor consisting of a mixture of nano-Al2O3, nano-SiO2, nano-CaO, and polysilazane in a specific ratio; a sensitive layer precursor consisting of a mixture of nano-TiB2 and polysilazane in a specific ratio; and a protective layer precursor consisting of a mixture of nano-SiO2 and polysilazane in a specific ratio. This precursor ceramic slurry is used to prepare a precursor ceramic film.

[0033] In a preferred embodiment, the insulating layer precursor is a mixture of nano-Al2O3, nano-SiO2, nano-CaO and polysilazane in a ratio of 1:1:1:1; the sensitive layer precursor is a mixture of nano-TiB2 and polysilazane in a ratio of 7:3; and the protective layer precursor is a mixture of nano-SiO2 and polysilazane in a ratio of 6:4.

[0034] The present invention provides a precursor ceramic high-temperature thin film sensor prepared by the above processing method. The sensitive grid line width of the sensor is ≤4μm, and its physical parameter sensitivity at high temperature is not significantly different from that of the precursor ceramic thin film sensor prepared by traditional additive manufacturing process.

[0035] The 1035nm wavelength femtosecond laser is collimated, expanded, and introduced into the simulated galvanometer through a reflector. The movement of the beam is controlled by an XY motion motor. After focusing through a field lens, the spot diameter is 20μm. The 343nm femtosecond laser is adjusted to a spot size of 5μm through a UV-specific focusing objective lens.

[0036] The above processing method adopts the aforementioned dual-wavelength femtosecond laser micro-nano processing platform. The platform's sealed cavity maintains a processing environment with a cleanliness level ≥ ISO 6. The industrial camera uses a visual positioning algorithm to achieve sub-micron precision alignment of the processing graphics, and the motion platform controls the movement of the workpiece to map the processing graphics to the workpiece surface.

[0037] The present invention provides a dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor for use in aircraft engine thermal barrier coating surface temperature monitoring, gas turbine blade heat flow monitoring, or high-temperature alloy structure stress monitoring.

[0038] Compared with the prior art, the present invention has outstanding technical effects and advantages:

[0039] 1. Ultra-high processing precision and miniaturization: This invention adopts a 1035nm and 343nm dual-wavelength femtosecond laser direct writing process. It uses a 1035nm laser for rapid patterning and a 343nm laser for fine shaping and defect repair. It achieves a sensor sensitive grid feature size of ≤4μm, reducing the original millimeter-level effective area to the micron level, significantly improving the sensor's integration and space utilization, and meeting the demand for miniaturized monitoring equipment in extreme service environments.

[0040] 2. Excellent High-Temperature Performance: This invention leverages the cold working properties of a femtosecond laser to control the width of the heat-affected zone (HAZ) of the sensitive grid to ≤6μm, significantly reducing thermal damage. Experimental verification demonstrates that the sensor fabricated in this invention exhibits a stable negative temperature coefficient (NTC) within the temperature range of 25–800°C, with highly consistent resistance response over multiple temperature ramps. Its high-temperature sensitivity to physical parameters is comparable to that of products fabricated using conventional processes. Furthermore, it exhibits superior thermal stability and reliability, enabling long-term stable operation in extreme high-temperature environments.

[0041] 3. Dual-wavelength collaborative processing achieves both efficiency and quality: Single-wavelength laser processing struggles to achieve both efficiency and precision, resulting in insufficient precision during high-speed processing and low efficiency during high-precision processing. The dual-wavelength femtosecond laser micro-nanoprocessing platform of this invention utilizes a 1035nm laser with a large spot size and high power to achieve rapid direct writing, significantly improving processing efficiency. The 343nm laser utilizes an extremely small spot size and high power density for fine control, optimizing the electrical properties of the sensitive gate. The synergistic operation of these two lasers ensures both efficient processing and high-precision submicron patterning, resolving the current challenge of balancing efficiency and precision.

[0042] 4. Strong process innovation and universal applicability: Existing thin-film sensor processing techniques struggle to meet the demands of complex structures and diverse functions. This invention utilizes innovative dual-wavelength laser direct writing technology, combined with specially formulated precursor ceramic slurries (e.g., the ratio of insulating layer, sensitive layer, and protective layer precursors). This not only enables high-precision fabrication of key sensor components, but also allows the preparation of thin-film sensors with diverse functional characteristics by adjusting process parameters and slurry composition. These sensors are suitable for monitoring multiple physical parameters, such as temperature and heat flow, and can be fabricated in arrays. This makes them widely applicable to extreme service environments, such as aircraft engines and gas turbines, and demonstrates strong process universality and scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is the minimum sensitive grid line width of the precursor ceramic high-temperature thin film sensor involved in the present invention.

[0044] Figure 2 This is a schematic diagram of the typical structure of a precursor ceramic high-temperature thin film heat flow sensor according to an embodiment of the present invention.

[0045] Figure 3 It is a schematic diagram of the preparation process of the precursor ceramic high-temperature thin film heat flow sensor according to an embodiment of the present invention.

[0046] Figure 4 These are optical microscope images and scanning electron microscope images of the precursor ceramic high-temperature thin film heat flux sensor array according to an embodiment of the present invention.

[0047] Figure 5 This is a temperature-resistance correspondence curve of the precursor ceramic high-temperature thin film temperature sensor in the range of 25-800°C according to an embodiment of the present invention.

[0048] Figure 6 This is a scanning electron microscope image of the heat-affected zone of the sensitive grid of the precursor ceramic high-temperature thin-film thermal flux sensor according to an embodiment of the present invention.

[0049] Figure 7 This is the performance response curve of the precursor ceramic high-temperature thin film heat flux sensor under laser heat flux input in an embodiment of the present invention.

[0050] Figure 8 This is the performance response curve of the precursor ceramic high-temperature thin film heat flux sensor under flame heat flux input in an embodiment of the present invention.

[0051] Figure 9 It is a schematic diagram of the array preparation of the precursor ceramic thin film heat flow sensor implemented in the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following embodiments will be further described in conjunction with the accompanying drawings. It should be understood that what is described herein is only a specific implementation method of the present invention, and the design concept of this aspect is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed to infringe the scope of protection of the present invention. Where not described in detail, conventional methods of those skilled in the art may be used.

[0053] like Figure 1 As shown in the figure, the present invention takes advantage of the advantages of laser processing at different wavelengths: a 1035nm wavelength femtosecond laser is used to perform fast and high-precision direct writing on multi-layer thin films, thereby realizing the formation of sensor sensitive grids with a feature size of ≤4μm; after the initial formation of the thin film, a 343nm wavelength femtosecond laser with an extremely small spot and extremely high power density is used to perform submicron-level high-precision shaping and defect removal on the sensitive grids.

[0054] The embodiment of the present invention provides a dual-wavelength femtosecond laser direct writing method for processing a miniaturized precursor ceramic high-temperature thin film sensor, using a dual-wavelength femtosecond laser micro-nano processing platform, including the following steps:

[0055] (1) Precursor ceramic slurry is deposited layer by layer on the substrate surface by an additive manufacturing process, and a ceramic insulating layer and a sensitive ceramic film layer are sequentially prepared on the substrate surface: the insulating layer precursor is deposited on the substrate surface and pyrolyzed at high temperature to form a ceramic insulating layer; the sensitive layer precursor is deposited on the surface of the ceramic insulating layer and pyrolyzed at high temperature to form a sensitive ceramic film layer;

[0056] (2) Rapid patterning of sensitive ceramic film layers using a 1035 nm wavelength femtosecond laser. Processing parameters include: spot size 20 μm, power 20-40 W, scanning speed 1-5000 mm / s, and pulse width <300 fs.

[0057] (3) Using a 343nm wavelength femtosecond laser to finely shape and repair defects on the pattern obtained in step (2), the processing parameters include: spot size ≤ 5μm, power 5-10W, scanning speed 1-500mm / s, pulse width <250fs; reducing the sensitive gate line width to less than 4μm, and adjusting the edge morphology and resistance value of the sensitive gate to improve the high-temperature stability of the sensitive gate;

[0058] (4) Depositing a protective layer precursor on the surface of the sensitive gate and forming a dense oxygen-isolating protective layer through high-temperature pyrolysis; thereby preventing the sensitive layer from rapid oxidation and electrical performance failure at extremely high temperatures;

[0059] (5) The width of the heat-affected zone is controlled by optimizing laser parameters to ensure that the electrical characteristics of the sensitive grid meet the sensor requirements. Electrode leads are prepared in the pad area of ​​the sensitive layer.

[0060] like Figure 2 As shown, an embodiment of the present invention provides a method for manufacturing a high-precision, fine-linewidth precursor ceramic thin-film sensor array for surfaces of components used in extreme service environments. This thin-film sensor comprises, from bottom to top, a substrate 1, an insulating layer 2, a sensitive layer 3, a protective layer 4, and a thermal resistance layer 5. Laser patterning of the sensitive layer significantly reduces its linewidth while maintaining the same electrical properties as before processing.

[0061] Through additive manufacturing processes such as doctor blade coating and direct writing, the material is deposited layer by layer on the workpiece surface and sintered layer by layer. The choice of specific additive manufacturing process depends on factors such as the area and thickness of the film to be deposited. When the film to be deposited is large and thick, the doctor blade coating process is preferred, as it is simple to operate and highly efficient. When high-precision, complex-patterned films are required, the direct writing process is more advantageous, as it can precisely control the deposition position and shape of the precursor. In addition, the appropriate additive manufacturing process can be selected based on a combination of factors such as the film's material properties and the desired microstructure.

[0062] Figure 3 A schematic diagram of the preparation process of a precursor ceramic high-temperature thin film heat flow sensor according to an embodiment of the present invention is provided. The specific manufacturing process includes the following steps:

[0063] Step 1: Mix nano-Al2O3 powder, nano-SiO2 powder, nano-CaO powder and polysilazane in a ratio of 1:1:1:1, and stir them evenly by magnetic stirring to obtain an insulating layer precursor; mix nano-TiB2 powder and polysilazane in a ratio of 7:3, and stir them evenly by magnetic stirring to obtain a sensitive layer precursor; mix nano-SiO2 powder and polysilazane in a ratio of 6:4, and stir them evenly by magnetic stirring to obtain a protective / thermal resistance layer precursor;

[0064] Step 2: Clean the substrate 1 using ultrasonic cleaning and anhydrous ethanol cleaning to ensure surface quality;

[0065] Step 3: The insulating layer precursor is evenly deposited on the surface of the substrate 1 using a doctor blade process. After being allowed to level for ten minutes, it is pyrolyzed in a tube furnace at 900°C for 1 hour to form a dense Al2O3 / SiO2 / CaO / SiCN insulating layer 2. This insulating layer still has good insulation resistance at high temperatures.

[0066] Step 4: Use a doctor blade coating process to evenly deposit the sensitive layer precursor on top of the insulating layer. After standing for ten minutes to level, it is pyrolyzed in a tube furnace at 800°C for 1 hour to form a dense TiB2 / SiCN sensitive layer 3. This sensitive layer has a stable temperature-resistance relationship in the range of 0-800°C.

[0067] Step 5: Place the substrate 1 covered with the insulating layer 2 and the sensitive layer 3 on the motion platform of the femtosecond laser micro-nano processing platform. First, a high-power (40W) and relatively large spot (20μm) 1035nm wavelength femtosecond laser is used for rapid direct writing to obtain the sensor sensitive gate pattern. Then, a relatively small spot 343nm wavelength femtosecond laser is used to modify and adjust the edge of the sensitive gate. The heat-affected zone width and sensor resistance value are adjusted by optimizing the laser process parameters to obtain a precursor ceramic thin film sensor that meets manufacturing standards.

[0068] Step 6: Deposit the protective layer precursor on the sensor sensitive grid using a direct write process, ensuring that the protective layer precursor covers all sensitive grids (except the pads), and pyrolyze in a tube furnace at 1000°C for 1 hour to form a dense oxygen-isolating SiO2 protective layer 4;

[0069] Step 7: Deposit the thermal resistance layer precursor on the specific sensitive resistor of the sensor using a direct write process, and pyrolyze it in a tube furnace at 1000°C for 1 hour to form a dense thermal resistance layer 5;

[0070] Step 8: Prepare solder joints on the surface of the sensitive gate pad. The solder joints are composed of platinum wire and small alumina discs. They are connected to the sensor pads by high-temperature metal paste. The high-temperature metal paste forms a high-strength connection after high-temperature sintering to ensure reliability in extreme service environments.

[0071] The optical microscope image and scanning electron microscope image of the precursor ceramic high temperature thin film heat flux sensor array of the embodiment of the present invention are as follows: Figure 4 .

[0072] To verify the resistance response characteristics of the sensor of the present invention across different temperature ranges, including stability, repeatability, and temperature-resistance correspondence, the sensor was placed in a precisely temperature-controlled tube furnace. The temperature was programmed to increase from 25°C to 800°C and then decrease from 800°C to 25°C. During testing, the sensor was placed in a precisely temperature-controlled tube furnace, and the temperature was programmed to increase to 800°C at a rate of 10°C / min, then hold at 800°C for 30 minutes and then decrease to room temperature at a rate of 10°C / min. The hot node of a standard K-type thermocouple was placed in the same position as the precursor ceramic thin film temperature sensor. A data acquisition system was used to collect temperature data from the standard K-type thermocouple and resistance data from the sensor. The temperature and resistance data were recorded as the X-axis and Y-axis, respectively, to obtain a temperature-resistance correspondence curve for the precursor ceramic thin film temperature sensor. Figure 5 The temperature-resistance relationship curve of the precursor ceramic high-temperature thin film temperature sensor of the embodiment of the present invention at 25-800°C is given. Figure 5 It can be seen that the resistance value shows a downward trend as the temperature increases, indicating that the precursor ceramic thin film temperature sensor has a negative temperature coefficient characteristic. The cycle curves of the heating stage and the cooling stage (1st run to 7th run) basically coincide, indicating that the sensor shows a high degree of consistency in resistance response during multiple heating-cooling cycles, without obvious fluctuations or deviations, verifying the stability and repeatability of the sensor of the present invention, and the sensor can be reliably used for temperature monitoring. The experimental results fully reflect the high precision and stability of the sensor prepared by the present invention in temperature monitoring. Compared with traditional methods, the present invention effectively controls the thermal effects during the processing through dual-wavelength femtosecond laser processing technology, thereby ensuring the performance reliability of the sensor in a high-temperature environment and meeting the monitoring needs in extreme service environments.

[0073] Figure 6A scanning electron microscope image of the heat-affected zone (HAZ) of the sensitive grid of a high-temperature, thin-film ceramic thermal flux sensor precursor, used in an embodiment of the present invention, is provided. By observing the morphology of the HAZ in the image, the extent and scope of the thermal impact on the material during laser processing can be analyzed. For example, the HAZ width in the image is only 6 μm, and the conductive particles within the HAZ remain intact, with only a small amount of periodic surface structure present on the particle surface. This indicates minimal thermal impact from laser processing, fully demonstrating the advantages of ultrafast laser cold processing.

[0074] Figure 7 The performance response curve of the precursor ceramic high-temperature thin film heat flux sensor under laser heat flux input of the embodiment of the present invention is given. During the test, a high-power continuous laser is used to provide heat flux input. The laser spot diameter is about 10mm. After aligning the laser cursor with the precursor ceramic thin film heat flux sensor, the laser is turned on and the power output is set to 10%, 15%, 20%, and 25% respectively. Each power output is maintained for about 30 seconds. The data acquisition system collects the real-time voltage output of the sensor to obtain the performance response curve of the heat flux sensor. Figure 7 It can be seen that the heat flow sensor of the present invention has a linear voltage response output to the laser heat flow input, and the sensor can be reliably used for heat flow monitoring.

[0075] Experiments show that the sensitivity of the precursor ceramic thin film temperature sensor prepared by dual-wavelength femtosecond laser is not significantly different from that of the device prepared by traditional additive manufacturing ( Figure 5 ), thanks to its extremely small heat-affected zone ( Figure 6 The precursor ceramic thin film heat flow sensor prepared by the process of the present invention has a smaller unit area and can be prepared in an array ( Figure 9 ). Its effect on laser heat flux input ( Figure 7 ) and flame spray gun heat flow input ( Figure 8 ) have good output response.

[0076] This invention provides a submicron-level patterning method for precursor ceramic thin-film sensors. Using a 1035nm wavelength femtosecond laser, a multilayer thin film is rapidly and accurately written, achieving sensor sensitive gate formation with a feature size of ≤4μm. After initial thin-film formation, the sensitive gate is reshaped and repaired with submicron-level precision using the extremely small spot size and high power density of a 343nm wavelength femtosecond laser. This method can reduce the active area of ​​a precursor ceramic thin-film sensor from millimeters to micrometers, while maintaining proper sensor operation even with a significantly reduced sensitive gate line width.

[0077] The above embodiments are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. Dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor, characterized by From bottom to top, it includes a substrate, an insulating layer, a sensitive layer, and a protective layer; the insulating layer covers the surface of the substrate and is formed by high-temperature pyrolysis of a precursor mixed with nano-Al2O3, nano-SiO2, nano-CaO and polysilazane; the sensitive layer is located on the ceramic layer, and the sensitive layer contains a sensitive gate pattern with a characteristic size of ≤4μm, and the sensitive gate pattern is formed by a dual-wavelength femtosecond laser direct writing process; the protective layer covers the non-pad area of ​​the sensitive layer.

2. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 1, characterized in that The insulating layer is formed by high-temperature pyrolysis of a precursor of nano-Al2O3, nano-SiO2, nano-CaO and polysilazane mixed in a ratio of 1:1:1:1; the sensitive layer is formed by high-temperature pyrolysis of a precursor of nano-TiB2 and polysilazane mixed in a ratio of 7:3; and the protective layer is formed by high-temperature pyrolysis of a precursor of nano-SiO2 and polysilazane mixed in a ratio of 6:

4.

3. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 1, characterized in that The dual-wavelength femtosecond laser direct writing process includes: using a 1035nm wavelength femtosecond laser to quickly pattern the sensitive layer, with processing parameters such as a spot size of 20μm, a power of 20-40W, a scanning speed of 1-5000mm / s, and a pulse width of <300fs; and using a 343nm wavelength femtosecond laser to finely shape and repair defects on the sensitive grid, with processing parameters such as a spot size ≤5μm, a power of 5-10W, a scanning speed of 1-500mm / s, and a pulse width of <250fs.

4. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 1, characterized in that The sensor also includes a thermal resistance layer, which is arranged above the sensitive layer and is formed by high-temperature pyrolysis of a precursor of nano-SiO2 and polysilazane mixed in a ratio of 6:4, and is used to regulate the thermal response characteristics of the sensor.

5. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to any one of claims 1 to 4, characterized in that The dual-wavelength femtosecond laser direct writing process adopts a dual-wavelength femtosecond laser micro-nano processing platform, which includes: a 1035 / 343nm wavelength femtosecond laser light source, a sealed optical path, an industrial camera, a motion platform and a marble machine. The 1035nm wavelength femtosecond laser is collimated and expanded by a beam expander and then introduced into a simulated galvanometer through a number of reflectors. The simulated galvanometer controls the movement of the light beam in the plane through an XY motion motor. The light beam is guided out of the simulated galvanometer and focused on the processing plane through a field lens. The 343nm wavelength femtosecond laser light source is obtained by converting 1035nm light through a frequency doubling crystal. After adjustment by a special ultraviolet focusing objective lens, the spot size is 5μm. The sealed optical path is an independent dual-optical path system. Each optical path includes a number of reflectors, a high-pass dichroic mirror, a shutter controller and a focusing lens. Two different sealed optical paths focus the 1035nm wavelength femtosecond laser and the 343nm wavelength femtosecond laser on the motion platform respectively, wherein the 1035nm optical path and the 343nm optical path are The optical path uses a dichroic mirror to achieve wavelength separation to avoid mutual interference; the industrial camera is used to locate the workpiece surface and the processing pattern, while the motion platform controls the movement of the workpiece to map the processing pattern to the workpiece surface.

6. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 5, characterized in that The positioning accuracy of the industrial camera is ≤±3μm. It uses a visual positioning algorithm to collect mark points on the workpiece surface in real time, generate coordinate compensation data and feed it back to the motion control system to achieve sub-micron precision alignment of the processed graphics.

7. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 5, characterized in that The motion platform adopts a three-axis high-precision electric translation stage, driven by a linear motor, with a positioning accuracy of ≤±1μm, a repeat positioning accuracy of ≤±0.5μm, a maximum movement speed of 500mm / s, and is equipped with a vacuum adsorption tooling to fix the workpiece.

8. The dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to claim 5, characterized in that The motion platform integrates a numerical control system, supports CAD import and G-code generation of processing graphics, and real-time adjustment of laser power, scanning speed, and pulse frequency; the industrial camera, 1035 / 343nm wavelength femtosecond laser light source and motion platform are synchronously controlled via an Ethernet bus.

9. A dual-wavelength femtosecond laser direct writing method for miniaturized precursor ceramic high-temperature thin film sensors, characterized in that The following steps are involved: Step 1: The surface of the structure to be monitored is cleaned with anhydrous ethanol and ultrasonically cleaned respectively. An insulating layer precursor is deposited on the area where the thin film sensor is to be prepared using an additive manufacturing process. After high-temperature pyrolysis, the precursor is converted into a dense ceramic insulating layer. Step 2: Using an additive manufacturing process, a sensitive layer precursor is deposited on the aforementioned precursor ceramic insulating layer, and after high-temperature pyrolysis, a functional ceramic film layer with physical parameter sensitive characteristics or other functions is obtained; Step 3: Use dual-wavelength femtosecond lasers to perform rapid patterning and fine patterning of the functional ceramic film layer. In the rapid patterning stage, a 1035nm wavelength laser is used to quickly pattern the functional ceramic film layer. In the fine patterning stage, a 343nm wavelength laser is used to finely adjust the edge morphology, resistance value, and surface micro-nano periodic structure of the sensitive gate to ensure that the electrical characteristics of the sensitive gate meet the sensor requirements. Step 4: depositing a protective layer precursor on the functional ceramic film layer, and obtaining a high-resistivity protective layer with a dense structure after high-temperature pyrolysis, which is used to isolate the functional ceramic film layer from oxygen at high temperatures; Step 5: If necessary, deposit other film precursors on the protective ceramic film layer and convert them into specific ceramic film layers using a high-temperature pyrolysis process; Step 6: Prepare solder joints on the surface of the sensor completed in step 5 to lead out the electrical signal.

10. Use of the dual-wavelength femtosecond laser direct writing miniaturized precursor ceramic high-temperature thin film sensor according to any one of claims 1 to 4 in surface temperature monitoring of thermal barrier coatings on aircraft engines, heat flux monitoring of gas turbine blades, or stress monitoring of high-temperature alloy structures.

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