A method for preparing a multilayer thin film thermocouple on a metal substrate surface based on full inkjet printing

Abstract

The application relates to a kind of metal substrate surface multilayer film thermocouple preparation methods based on full inkjet printing, belonging to the field of thin film thermocouple, comprising: respectively preparing Ni-Cr2O3 transition layer nanoparticle ink, Al2O3 insulating layer nanoparticle ink and ITO-In2O3 functional layer nanoparticle ink;Using Ni-Cr2O3 transition layer nanoparticle ink to carry out inkjet printing and sintering on the surface of pretreated nickel-based superalloy substrate, obtain transition layer;Using Al2O3 insulating layer nanoparticle ink to carry out inkjet printing and sintering on the surface of transition layer, obtain insulating layer;ITO-In2O3 functional layer nanoparticle ink is used to carry out inkjet printing and sintering on the surface of insulating layer, obtain functional layer.The application does not need mask, photoetching and multi-device process switching, realizes the low cost, high efficiency, designable full inkjet printing preparation of multilayer thin film thermocouple on the surface of metal substrate.

Description

Technical Field

[0001] This invention belongs to the field of thin-film thermocouple technology, specifically relating to a method for preparing multilayer thin-film thermocouples on a metal substrate surface based on inkjet printing. Background Technology

[0002] With the continuous improvement of aero-engine performance, turbine blade surface temperature measurement technology requires higher precision, faster response, and stronger adaptability to complex operating conditions. Existing armored thermocouples offer high temperature measurement accuracy, but installation requires slotting, drilling, or welding, which can easily damage the blade structure and alter local flow and heat transfer conditions. Temperature-sensing paint and liquid crystal displays typically only provide instantaneous or peak temperatures and are limited by rotating components and observation conditions. Non-contact methods such as infrared thermometry are susceptible to material emissivity, high-temperature background radiation, and complex combustion gas environments. In contrast, thin-film thermocouples can be directly constructed on the turbine blade surface, with a thickness of only tens of micrometers, resulting in minimal flow field disturbance and advantages such as fast response, good conformability, and real-time temperature signal output. Metal-substrate thin-film thermocouples typically consist of a transition layer, an insulating layer, a functional layer, and a protective layer. The transition layer facilitates the transition of thermal expansion coefficients from metal to ceramic materials, the insulating layer isolates conductive interference from the metal substrate, and the functional layer forms the temperature sensing junction and generates thermoelectric potential.

[0003] Researchers have conducted extensive studies on the fabrication of multilayer thin-film thermocouples, with key issues including the selection of deposition methods for different functional layers and the integrated fabrication of multilayer structures. Currently, the fabrication methods for multilayer thin-film thermocouples mainly include magnetron sputtering, electron beam evaporation, physical vapor deposition, screen printing, or a combination of these processes. Vacuum deposition methods such as magnetron sputtering, electron beam evaporation, and physical vapor deposition produce films with good uniformity, controllable thickness, and dense layers, but they are costly, have long fabrication cycles, low material utilization, and require masks or photolithography for patterning. On complex curved metal substrates, problems such as mask adhesion difficulties, pattern misalignment, and deposition shadows can easily occur. While screen printing is low-cost and simple to operate, it has limitations in pattern accuracy and film thickness control, making it difficult to meet the requirements for fine, low-disturbance, and multi-point array fabrication of thin-film thermocouples. In contrast, inkjet printing technology offers advantages such as digitalization, non-contact operation, mask-free operation, high material utilization, and customizable patterns. It can directly deposit functional inks along pre-defined paths, making it more suitable for the rapid fabrication and arraying of multilayer thin-film thermocouples on metal substrates. However, the material composition, ink properties, printing parameters, and sintering parameters of each functional layer directly affect the film uniformity, interfacial bonding, insulation performance, and thermoelectric output stability. Existing research on inkjet-printed thin-film thermocouples largely focuses on printing thermoelectric functional layers or local electrode layers, while transition layers and insulating layers still rely on traditional processes such as magnetron sputtering, screen printing, coating, and conductive paste bonding. Although these methods incorporate inkjet printing, they still require multiple devices and processes, resulting in complex interlayer positioning, insufficient process compatibility, poor interface consistency, and low batch production efficiency. This fails to fully leverage the advantages of inkjet printing in continuous multi-material deposition, digital pattern construction, and low-cost end-to-end manufacturing. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating multilayer thin-film thermocouples on metal substrates based on inkjet printing, thereby addressing the problems of poor process compatibility, poor interface consistency, high fabrication cost, and low fabrication efficiency in existing inkjet printing methods for fabricating thin-film thermocouples. This invention achieves rapid fabrication and precise deposition of multilayer thin-film thermocouples on metal substrates, eliminating the need for the vacuum environment and complex multilayer mask design required by traditional methods.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] This invention provides a method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing, comprising the following steps:

[0007] Ni-Cr2O3 transition layer nanoparticle ink, Al2O3 insulating layer nanoparticle ink, and ITO-In2O3 functional layer nanoparticle ink were prepared respectively. Ni-Cr2O3 transition layer nanoparticle ink was used to inkjet print and sinter on the surface of a pretreated nickel-based superalloy substrate to obtain a transition layer. Al2O3 insulating layer nanoparticle ink was used to inkjet print and sinter on the surface of the transition layer to obtain an insulating layer. ITO-In2O3 functional layer nanoparticle ink was used to inkjet print and sinter on the surface of the insulating layer to obtain a functional layer.

[0008] As a preferred embodiment, the preparation method of the Ni-Cr2O3 transition layer nanoparticle ink is as follows: Ni nanoparticles and Cr2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, wherein the mass fraction of solute for both Ni nanoparticles and Cr2O3 nanoparticles is 5 to 8%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the transition layer nanoparticle ink.

[0009] As a preferred embodiment, the Al2O3 insulating layer nanoparticle ink is prepared as follows: Al2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, wherein the mass fraction of the solute in the Al2O3 nanoparticles is 2 to 4%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the insulating layer nanoparticle ink.

[0010] As a preferred embodiment, the preparation method of the ITO-In2O3 functional layer nanoparticle ink is as follows: ITO nanoparticles and In2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, wherein the mass fraction of solute for both ITO nanoparticles and In2O3 nanoparticles is 10 to 20%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the functional layer nanoparticle ink.

[0011] As a preferred embodiment, the pretreatment method of the nickel-based superalloy substrate is as follows: first, it is polished, then ultrasonically cleaned with ethanol and deionized water for 15-30 minutes respectively, then the drying oven temperature is set to 120-150℃ and dried for 20-30 minutes to remove residual organic solvents on the surface, and finally the surface of the nickel-based superalloy substrate is hydrophilically treated with surfactant for 3-5 minutes.

[0012] In a preferred embodiment, the transition layer serves as an adhesive layer between the multilayer thin-film thermocouple and the nickel-based superalloy substrate, as well as a transition layer for the coefficient of thermal expansion. Its preparation method is as follows:

[0013] Ni-Cr2O3 transition layer nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was started: the horizontal dot spacing was 0.03~0.04 mm; the vertical dot spacing was 0.03~0.04 mm; the printing speed was 10~20 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

[0014] In a preferred embodiment, the insulating layer serves as an electrical signal blocking layer between the multilayer thin-film thermocouple and the nickel-based high-temperature alloy substrate, and its preparation method is as follows:

[0015] Al2O3 insulating nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was started: the horizontal dot spacing was 0.03~0.04 mm; the vertical dot spacing was 0.03~0.04 mm; the printing speed was 3~5 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

[0016] In a preferred embodiment, the functional layer serves as the thermoelectric characteristic output layer of a multilayer thin-film thermocouple, used to realize the temperature measurement function of the thin-film thermocouple. Its preparation method is as follows:

[0017] ITO-In2O3 functional layer nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was performed: the horizontal dot spacing was 0.04~0.06 mm; the vertical dot spacing was 0.04~0.06 mm; the printing speed was 5~10 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

[0018] In a preferred embodiment, the parameters of the voltage waveform are:

[0019] Positive voltage 60-70 V, negative voltage 90-110 V, reference voltage 0-10 V, positive voltage rise time 5-15 ms, positive voltage duration 25-30 ms, positive voltage fall time 25-30 ms, negative voltage duration 20-25 ms, negative voltage rise time 10-15 ms.

[0020] In a preferred embodiment, the printed patterns in the transition layer, insulating layer, and functional layer are identical.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a method for fabricating multilayer thin-film thermocouples on metal substrates using inkjet printing. By designing the material ratios of the transition layer, insulating layer, and functional layer, and controlling the dispersibility, wettability, and printability of the functional inks in each layer, combined with layer-by-layer inkjet printing and step-by-step sintering processes, continuous deposition and integrated forming of multilayer thin-film thermocouples on metal substrates are achieved. The transition layer facilitates the transition of thermal expansion coefficients between the metal substrate and the ceramic film, the insulating layer blocks conductive interference from the metal substrate, and the functional layer forms temperature-sensing junctions and outputs thermoelectric potential signals. This invention achieves low-cost, high-efficiency, and designable inkjet printing fabrication of multilayer thin-film thermocouples on metal substrates.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. This invention utilizes inkjet printing direct-write deposition technology to prepare multilayer thin-film thermocouples on the surface of a metal substrate. It eliminates the need for masking, photolithography, and multiple equipment process switching, thereby shortening the preparation time, improving preparation efficiency, increasing material utilization and pattern alignment accuracy, and reducing preparation costs.

[0025] 2. This invention improves the bonding strength of the film-substrate interface through the co-oxidation of metal nanoparticles and metal substrate. The material ratio combination of the bottom metal (Ni) and the surface metal oxide (Cr2O3) transition layer reduces the preparation requirements of traditional single-layer transition films that require vacuum segregation and high-temperature oxidation.

[0026] 3. The multilayer thin film thermocouple on the metal substrate surface prepared by this invention has reliable thermoelectric output capability and high repeatability, and has low preparation cost and high preparation efficiency. It has potential for application in multiple scenarios and has a wide range of experimental and industrial applications.

[0027] 4. This invention can be extended to the deposition of sensors or electrical devices on other metal substrates, possessing portability and convenience. It is a universal solution for strong metal substrate-thin film interface bonding and high insulation. This invention can be applied to the fabrication of thin-film sensors on other metal substrates. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a multilayer thin film thermocouple on a metal substrate surface prepared by the method for preparing a multilayer thin film thermocouple on a metal substrate surface based on inkjet printing provided by the present invention.

[0029] Figure 2 This is a cross-sectional SEM image of the multilayer thin-film thermocouple on the metal substrate surface prepared in this invention.

[0030] Figure 3 This is a physical image of the multilayer thin-film thermocouple on the metal substrate surface prepared according to the present invention.

[0031] Figure 4 The thermoelectric output characteristic curve of the multilayer thin film thermocouple on the metal substrate obtained by the present invention is shown. Detailed Implementation

[0032] The present invention provides a method for preparing multilayer thin film thermocouples on a metal substrate based on inkjet printing, which mainly consists of the following steps: preparation of nanoparticle ink, inkjet printing and sintering of transition layer, inkjet printing and sintering of insulating layer, and inkjet printing and sintering of functional layer.

[0033] Specifically, the implementation process of the nanoparticle ink formulation steps is as follows:

[0034] (1) First, prepare the transition layer nanoparticle ink: disperse Ni nanoparticles and Cr2O3 nanoparticles in a binary organic solvent, wherein the mass fraction of solute of Ni nanoparticles is 5~8% and the mass fraction of solute of Cr2O3 nanoparticles is 5~8%; disperse the resulting ink at a power of 160~200W for 2~4 hours, and keep it in a water bath at a temperature of 10~20℃ to reduce solvent evaporation; filter the ink with a 0.45μm PTFE filter membrane and a needle filter to obtain the transition layer nanoparticle ink.

[0035] Preferably, the binary organic solvent can be a mixture of ethylene glycol and isopropanol, wherein the mass ratio of ethylene glycol to isopropanol is c.

[0036] (2) Then prepare the insulating layer nanoparticle ink: disperse Al2O3 nanoparticles in a binary organic solvent, wherein the mass fraction of solute of Al2O3 nanoparticles is 2~4%; disperse the obtained ink at a power of 160~200W for 2~4 hours, and keep it in a water bath at a temperature of 10~20℃ to reduce solvent evaporation; filter the ink with a 0.45μm PTFE filter membrane and a needle filter to obtain the insulating layer nanoparticle ink.

[0037] Preferably, the binary organic solvent can be a mixture of ethylene glycol and isopropanol, wherein the mass ratio of ethylene glycol to isopropanol is 7:3 to 5:5.

[0038] (3) Finally, prepare the functional layer nanoparticle ink: Disperse ITO nanoparticles and In2O3 nanoparticles in a binary organic solvent. The mass fraction of solute for ITO nanoparticles is 10-20%, and the mass fraction of solute for In2O3 nanoparticles is 10-20%. Disperse the resulting ink at a power of 160-200W for 2-4 hours. Keep the water bath at a temperature of 10-20℃ to reduce solvent evaporation. Filter the ink with a 0.45μm PTFE filter membrane and a needle filter to obtain the functional layer nanoparticle ink.

[0039] Preferably, the binary organic solvent can be a mixture of ethylene glycol and isopropanol, wherein the mass ratio of ethylene glycol to isopropanol is 7:3 to 5:5.

[0040] This invention provides a functional ink with a uniform, stable, and non-settling system through a nanoparticle ink formulation process. This ink is used to stably generate droplets for inkjet printing, ensuring inkjet printing quality and consistency.

[0041] Specifically, the implementation process of the transition layer inkjet printing and sintering steps is as follows:

[0042] (1) Before inkjet printing, polish the nickel-based high-temperature alloy substrate, then use ethanol and deionized water to ultrasonically clean for 15~30 min respectively, then set the drying oven temperature to 120~150℃ and dry for 20~30 min to remove residual organic solvents on the surface, and finally use surfactant to hydrophilically treat the surface of the nickel-based high-temperature alloy substrate for 3~5 min.

[0043] (2) Inkjet printing;

[0044] 1) Add transition layer nanoparticle ink to inkjet printer and output stable droplets by setting the voltage waveform of inkjet printer.

[0045] Preferably, the voltage waveform is as follows:

[0046] Positive voltage 60-70 V, negative voltage 90-110 V, reference voltage 0-10 V, positive voltage rise time 5-15 ms, positive voltage duration 25-30 ms, positive voltage fall time 25-30 ms, negative voltage duration 20-25 ms, negative voltage rise time 10-15 ms.

[0047] 2) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 140~155℃.

[0048] 3) Set the following printing parameters and print pattern using the software:

[0049] The horizontal dot spacing for printing is 0.03~0.04 mm;

[0050] The vertical dot spacing for printing is 0.03~0.04 mm;

[0051] The printing speed is 10~20 mm / s;

[0052] The printed pattern is preferably rectangular, and the size of the printed pattern is determined by the arrangement requirements of the thin-film thermocouple measuring points.

[0053] 4) Start inkjet printing by following the settings in steps 1) to 3) above.

[0054] (3) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 5~10℃ / min, the holding time is 30~60min, and the sintering temperature is 600~900℃.

[0055] The transition layer film prepared by the present invention through the transition layer inkjet printing and sintering steps can be used as an adhesive layer between a multilayer thin film thermocouple and a nickel-based high-temperature alloy substrate, as well as a transition layer for the coefficient of thermal expansion.

[0056] Specifically, the implementation process of the inkjet printing and sintering steps for the insulating layer is as follows:

[0057] (1) Find the starting point of the transition layer film by using a vertical positioning camera, and perform inkjet printing at the same position to obtain the insulating layer film.

[0058] (2) Inkjet printing;

[0059] 1) Add insulating nanoparticle ink to the inkjet printer and output stable droplets by setting the voltage waveform of the inkjet printer.

[0060] Preferably, the voltage waveform is as follows:

[0061] Positive voltage 60-70 V, negative voltage 90-110 V, reference voltage 0-10 V, positive voltage rise time 5-15 ms, positive voltage duration 25-30 ms, positive voltage fall time 25-30 ms, negative voltage duration 20-25 ms, negative voltage rise time 10-15 ms.

[0062] 2) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 140~155℃.

[0063] 3) Set the following printing parameters and print pattern using the software:

[0064] The horizontal dot spacing for printing is 0.03~0.04 mm;

[0065] The vertical dot spacing for printing is 0.03~0.04 mm;

[0066] The printing speed is 3~5 mm / s;

[0067] The printed pattern and its dimensions are the same as those in the transition layer film.

[0068] 4) Start inkjet printing by following the settings in steps 1) to 3) above.

[0069] (3) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 5~10℃ / min, the holding time is 30~60min, and the sintering temperature is 600~900℃.

[0070] The insulating film prepared by this invention through inkjet printing and sintering can serve as an electrical signal blocking layer between a multilayer thin-film thermocouple and a nickel-based high-temperature alloy substrate. The dimensional parameters of the insulating film can be freely customized without affecting the film resistance test results.

[0071] Specifically, the implementation process of the functional layer inkjet printing and sintering steps is as follows:

[0072] (1) The insulating film can only be used for inkjet printing of the functional layer after sintering.

[0073] (2) Inkjet printing;

[0074] 1) Add functional layer nanoparticle ink to the inkjet printer and output stable droplets by setting the voltage waveform of the inkjet printer.

[0075] Preferably, the voltage waveform is as follows:

[0076] Positive voltage 60-70 V, negative voltage 90-110 V, reference voltage 0-10 V, positive voltage rise time 5-15 ms, positive voltage duration 25-30 ms, positive voltage fall time 25-30 ms, negative voltage duration 20-25 ms, negative voltage rise time 10-15 ms.

[0077] 2) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 140~155℃.

[0078] 3) Set the following printing parameters and print pattern using the software:

[0079] The horizontal dot spacing for printing is 0.04~0.06 mm;

[0080] The vertical dot spacing for printing is 0.04~0.06 mm;

[0081] The printing speed is 5~10 mm / s;

[0082] The printed pattern and its dimensions are the same as those in the transition layer film.

[0083] 4) Start inkjet printing by following the settings in steps 1) to 3) above.

[0084] (3) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 5~10℃ / min, the holding time is 30~60min, and the sintering temperature is 600~900℃.

[0085] The functional layer film prepared by the present invention through the functional layer inkjet printing and sintering steps can be used as the thermoelectric characteristic output layer of a multilayer thin film thermocouple to realize the temperature measurement function of the thin film thermocouple.

[0086] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0087] Example 1

[0088] This embodiment provides a method for fabricating multilayer thin-film thermocouples on a metal substrate based on inkjet printing. The specific implementation process is as follows:

[0089] (1) Ni nanoparticles and Cr2O3 nanoparticles were dispersed in a mixed solvent of ethylene glycol and isopropanol (mass ratio of ethylene glycol to isopropanol was 7:3), with the mass fraction of solute for Ni nanoparticles being 6% and the mass fraction of solute for Cr2O3 nanoparticles being 6%. The resulting ink was dispersed at 180 W for 3 hours and kept in a water bath at 15 °C to reduce solvent evaporation. The ink was filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain a transition layer nanoparticle ink.

[0090] (2) Disperse Al2O3 nanoparticles in a mixed solvent of ethylene glycol and isopropanol (mass ratio of ethylene glycol to isopropanol is 1:1), wherein the mass fraction of solute of Al2O3 nanoparticles is 3%; disperse the resulting ink at 180W power for 3 hours and keep it in a water bath at 15℃ to reduce solvent evaporation; filter the ink with a 0.45μm PTFE filter membrane and a needle filter to obtain insulating layer nanoparticle ink.

[0091] (3) ITO nanoparticles and In2O3 nanoparticles were dispersed in a mixed solvent of ethylene glycol and isopropanol (mass ratio of ethylene glycol to isopropanol was 1:1), with the solute mass fraction of ITO nanoparticles being 15% and the solute mass fraction of In2O3 nanoparticles being 15%. The resulting ink was dispersed at 180W for 3 hours and kept in a water bath at 15℃ to reduce solvent evaporation. The ink was filtered using a 0.45μm PTFE filter membrane and a needle filter to obtain functional layer nanoparticle ink.

[0092] (4) Before inkjet printing, the nickel-based high-temperature alloy substrate is polished, and then ultrasonically cleaned with ethanol and deionized water for 20 min. Then, the drying oven is set to 120℃ and dried for 25 min to remove residual organic solvents on the surface. Finally, the surface of the nickel-based high-temperature alloy substrate is hydrophilic treated with surfactant for 3 min.

[0093] (5) Inkjet printing and sintering of the transition layer;

[0094] 1) Add the transition layer nanoparticle ink to the inkjet printer and output stable droplets by setting the voltage waveform of the inkjet printer (positive voltage 65 V, negative voltage 100 V, reference voltage 5 V, positive voltage rise time 10 ms, positive voltage duration 25 ms, positive voltage fall time 25 ms, negative voltage duration 20 ms, negative voltage rise time 10 ms).

[0095] 2) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 150°C.

[0096] 3) Set the following printing parameters and print pattern using the software:

[0097] The horizontal dot spacing for printing is 0.03 mm;

[0098] The vertical dot spacing is 0.03 mm.

[0099] The printing speed is 15 mm / s;

[0100] The printed pattern is preferably rectangular, and the size of the printed pattern is determined by the requirements for the arrangement of the thin-film thermocouple measuring points.

[0101] 4) Start inkjet printing by following the settings in steps 1) to 3) above.

[0102] 5) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 6℃ / min, the holding time is 45 min, and the sintering temperature is 750℃.

[0103] (6) Inkjet printing and sintering of the insulating layer;

[0104] 1) Locate the starting point of the transition layer film using a vertical positioning camera, and perform inkjet printing at the same location to obtain the insulating layer film;

[0105] 2) Add the insulating layer nanoparticle ink to the inkjet printer and output stable droplets by setting the voltage waveform of the inkjet printer (positive voltage 65 V, negative voltage 100 V, reference voltage 5 V, positive voltage rise time 10 ms, positive voltage duration 25 ms, positive voltage fall time 25 ms, negative voltage duration 20 ms, negative voltage rise time 10 ms).

[0106] 3) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 150°C.

[0107] 4) Set the following printing parameters and print pattern using the software:

[0108] The horizontal dot spacing for printing is 0.03 mm;

[0109] The vertical dot spacing is 0.03 mm.

[0110] The printing speed is 4 mm / s;

[0111] The printed pattern and its dimensions are the same as those in the transition layer film.

[0112] 5) Start inkjet printing by following the settings in steps 2) to 4) above.

[0113] 6) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 6℃ / min, the holding time is 45 min, and the sintering temperature is 750℃.

[0114] (7) Functional layer inkjet printing and sintering;

[0115] 1) Add functional layer nanoparticle ink to the inkjet printer and output stable droplets by setting the voltage waveform of the inkjet printer (positive voltage 65 V, negative voltage 100 V, reference voltage 5 V, positive voltage rise time 10 ms, positive voltage duration 25 ms, positive voltage fall time 25 ms, negative voltage duration 20 ms, negative voltage rise time 10 ms).

[0116] 2) Use a heating table to heat the nickel-based superalloy substrate at a temperature of 150°C.

[0117] 3) Set the following printing parameters and print pattern using the software:

[0118] The horizontal dot spacing for printing is 0.05 mm;

[0119] The vertical dot spacing is 0.05 mm.

[0120] The printing speed is 7 mm / s;

[0121] The printed pattern and its dimensions are the same as those in the transition layer film.

[0122] 4) Start inkjet printing by following the settings in steps 1) to 3) above.

[0123] 5) The inkjet-printed nickel-based high-temperature alloy substrate is placed in a muffle furnace for heating and sintering. The heating rate is 6℃ / min, the holding time is 45 min, and the sintering temperature is 750℃.

[0124] Finally, the structure of a multilayer thin-film thermocouple on a metal substrate surface based on inkjet printing prepared in this embodiment is as follows: Figure 1As shown, it mainly consists of a nickel-based superalloy substrate, a transition layer, an insulating layer, a functional layer, and a protective layer. This invention simplifies the traditional transition layer (NiCrAlY) requiring vacuum segregation and air oxidation into a bottom metal (Ni)-surface metal oxide (Cr2O3) transition layer to achieve a transition in the coefficient of thermal expansion from the metal substrate to the ceramic bonding layer. Through inkjet printing and sintering of the insulating layer (Al2O3), a multilayer thin-film thermocouple with high insulation on the metal substrate surface is prepared. Through inkjet printing and sintering of the functional layer (ITO-In2O3), a fully inkjet-printed multilayer thin-film thermocouple on the metal substrate surface is prepared. Cross-sectional observation and elemental analysis of the prepared multilayer thin films are performed. The elemental scanning results of Ni, Al, In, and Sn in the multilayer thin films are shown below. Figure 2 As shown; a multilayer thin-film thermocouple sample was inkjet printed on a nickel-based alloy substrate. The fabricated thin-film thermocouple circuit and thermocouple temperature sensing node are shown in the figure. Figure 3 As shown; quasi-static thermoelectric output tests were performed on the multilayer thin-film thermocouples on the prepared metal substrate surface. The thin-film thermocouples accurately and stably output within the test temperature range, with a temperature measurement range up to 700℃. At this sintering temperature, the Seebeck coefficient of the thin-film thermocouples reached 90 μV / ℃. The output results of the thin-film thermocouples are shown in the figure. Figure 4 As shown, this demonstrates that the multilayer thin-film thermocouple on the metal substrate surface prepared by the present invention has reliable thermoelectric output capability and high repeatability.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing, characterized in that, Includes the following steps: Ni-Cr2O3 transition layer nanoparticle ink, Al2O3 insulating layer nanoparticle ink, and ITO-In2O3 functional layer nanoparticle ink were prepared respectively. Ni-Cr2O3 transition layer nanoparticle ink was used to inkjet print and sinter on the surface of a pretreated nickel-based superalloy substrate to obtain a transition layer. Al2O3 insulating layer nanoparticle ink was used to inkjet print and sinter on the surface of the transition layer to obtain an insulating layer. ITO-In2O3 functional layer nanoparticle ink was used to inkjet print and sinter on the surface of the insulating layer to obtain a functional layer.

2. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The preparation method of the Ni-Cr2O3 transition layer nanoparticle ink is as follows: Ni nanoparticles and Cr2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, with the mass fraction of solute for both Ni nanoparticles and Cr2O3 nanoparticles being 5 to 8%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the transition layer nanoparticle ink.

3. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The preparation method of the Al2O3 insulating layer nanoparticle ink is as follows: Al2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, wherein the mass fraction of the solute in the Al2O3 nanoparticles is 2 to 4%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the insulating layer nanoparticle ink.

4. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The preparation method of the ITO-In2O3 functional layer nanoparticle ink is as follows: ITO nanoparticles and In2O3 nanoparticles are dispersed in a binary organic solvent composed of ethylene glycol and isopropanol in a mass ratio of 7:3 to 5:5, with the mass fraction of solute for both ITO nanoparticles and In2O3 nanoparticles being 10 to 20%; the resulting ink is dispersed at a power of 160 to 200 W for 2 to 4 hours, and the water bath temperature is maintained at 10 to 20°C; the ink is filtered using a 0.45 μm PTFE filter membrane and a needle filter to obtain the functional layer nanoparticle ink.

5. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The pretreatment method for the nickel-based superalloy substrate is as follows: first, it is polished, then ultrasonically cleaned with ethanol and deionized water for 15-30 minutes, then dried in a drying oven at 120-150°C for 20-30 minutes to remove residual organic solvents on the surface, and finally hydrophilic treatment of the nickel-based superalloy substrate surface with a surfactant for 3-5 minutes.

6. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The transition layer serves as an adhesive layer between the multilayer thin-film thermocouple and the nickel-based high-temperature alloy substrate, as well as a transition layer for the coefficient of thermal expansion. Its preparation method is as follows: Ni-Cr2O3 transition layer nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was started: the horizontal dot spacing was 0.03~0.04 mm; the vertical dot spacing was 0.03~0.04 mm; the printing speed was 10~20 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

7. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The insulating layer serves as an electrical signal blocking layer between the multilayer thin-film thermocouple and the nickel-based high-temperature alloy substrate, and its preparation method is as follows: Al2O3 insulating nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was started: the horizontal dot spacing was 0.03~0.04 mm; the vertical dot spacing was 0.03~0.04 mm; the printing speed was 3~5 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

8. The method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to claim 1, characterized in that, The functional layer serves as the thermoelectric characteristic output layer of the multilayer thin-film thermocouple, used to realize the temperature measurement function of the thin-film thermocouple. Its fabrication method is as follows: ITO-In2O3 functional layer nanoparticle ink was added to an inkjet printer, and the voltage waveform of the inkjet printer was set to output stable droplets. The nickel-based superalloy substrate was heated to a temperature of 140~155℃. After setting the printing parameters and printing pattern, inkjet printing was performed: the horizontal dot spacing was 0.04~0.06 mm; the vertical dot spacing was 0.04~0.06 mm; the printing speed was 5~10 mm / s; the inkjet-printed nickel-based superalloy substrate was placed in a muffle furnace for heating and sintering at a heating rate of 5~10℃ / min, a holding time of 30~60min, and a sintering temperature of 600~900℃.

9. A method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to any one of claims 6-8, characterized in that, The parameters of the voltage waveform are: Positive voltage 60-70 V, negative voltage 90-110 V, reference voltage 0-10 V, positive voltage rise time 5-15 ms, positive voltage duration 25-30 ms, positive voltage fall time 25-30 ms, negative voltage duration 20-25 ms, negative voltage rise time 10-15 ms.

10. A method for preparing a multilayer thin-film thermocouple on a metal substrate based on inkjet printing according to any one of claims 6-8, characterized in that, The printed patterns in the transition layer, insulating layer, and functional layer are identical.

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