Search Results (55)

Efficient thermal management is critical for the performance, safety, and longevity of lithium-ion batteries, particularly in new energy vehicles. This paper presents the development and application of a NiCr/NiSi thin-film thermocouple fabricated via magnetron sputtering on a polyimide substrate, aiming to provide high-precision, fast-response internal temperature measurements for lithium-ion battery systems. The thermocouple demonstrates a Seebeck coefficient of approximately 40.95 μV/°C and a repeatability error of only 0.45%, making it highly suitable for capturing transient thermal events. The main innovation of this work lies in the comprehensive integration of simulation and experimental validation to optimize the thermocouple’s performance for lithium-ion battery applications. This includes static calibration, external short-circuit, and puncture tests, which collectively confirm the thermocouple’s reliability and accuracy. Additionally, the study explores the impact of ambient temperature variations on internal battery temperatures, revealing a nearly linear increase in internal temperature with rising ambient conditions. The findings offer valuable insights for improving battery thermal management systems, establishing early warning thresholds for thermal runaway, and enhancing the overall safety of lithium-ion battery applications. Full article

This study presents the calibration methodology of NiCr-NiSi thin-film thermocouples and evaluates their application in real-time temperature monitoring and characterization of fuel cell thermal behavior. Experimental results reveal that the Seebeck coefficients of the NiCr-NiSi thin films remain stable after multiple calibration cycles, indicating good reliability and repeatability. Furthermore, the thermocouples demonstrate an ultrafast response time of less than 15 microseconds and reach thermal equilibrium within 200 microseconds under transient thermal inputs. These characteristics enable accurate and rapid temperature measurement of fuel cell plates up to 100 °C, which is critical for maintaining the safe and efficient operation of fuel cells. Full article

Based on the COMSOL simulation software (v.6.1), this paper systematically investigates the influence law of runner length on the velocity and pressure distribution of cathode and anode gas runners in proton exchange membrane fuel cells (PEMFCs), and experimentally verifies the measurement effect of thin-film thermocouples on the operating temperature of PEMFCs. The simulation results show that the maximum pressure of the cathode and anode increases nonlinearly with the increase in the runner length, while the velocity distribution remains stable; the shortening of the runners significantly reduces the friction loss along the flow path and optimizes the matching of the permeability of the porous medium. In addition, the NiCr/NiSi thin-film thermocouple prepared by magnetron sputtering exhibits high accuracy (Seebeck coefficient of 41.56 μV/°C) in static calibration and successfully captures the dynamic response characteristics of temperature in PEMFC operation. This study provides a theoretical basis and experimental support for the optimization of fuel cell flow channel design and temperature monitoring technology. Full article

In the new energy electric drive system, the thermal stability of IGBT, a core power device, significantly impacts the system’s overall performance. Accurate IGBT temperature measurement is crucial, but traditional methods face limitations in IGBT’s compact working space. Thin-film thermocouples, with their thin and light features, offer a new solution. In this study, Ni 90% Cr 10% and Ni 97% Si 3% thin-film thermocouples were prepared on polyimide substrates via magnetron sputtering. After calibration, the Seebeck coefficient of the thin-film thermocouple temperature sensors reached 40.23 μV/°C, and the repeatability error stabilized at about 0.3% as the temperature rose, showing good stability. Researchers studied factors affecting IGBT temperature. Thin-film thermocouples can accurately monitor IGBT module surface temperature under different conditions. Compared to K-type wire thermocouples, they measure slightly higher temperatures. As the control signal’s switching frequency increases, IGBT temperature first rises then falls; as the duty cycle increases, the temperature keeps rising. This is consistent with RAC’s junction temperature prediction theory, validating the feasibility of thin-film thermocouples for IGBT chip temperature measurement. Thin-film thermocouples have great application potential in power device temperature measurement and may be a key research direction, supporting the optimization and upgrading of new energy electric drive systems. Full article

To enhance the safety of lithium ternary battery cases in new energy vehicles, this study designed a temperature monitoring and fault warning system based on NiCr/NiSi thin-film thermocouples. The system integrates six modules—sensor, amplifier, data acquisition, microprocessor (using the KPCA nonlinear dimensionality reduction algorithm), communication and monitoring, and alarm control—to monitor temperature, voltage, and humidity changes in real time. Multi-level warning thresholds are established (e.g., Level 1: initial temperature 35–55 °C rising to 42–65 °C after 10 min; initial voltage 400–425 V dropping to 398–375 V after 10 min). Experimental results demonstrate that the NiCr/NiSi thermocouple exhibits high sensitivity (average Seebeck coefficient: 41.42 μV/°C) and low repeatability error (1.04%), with a dense and uniform surface structure (roughness: 3.2–5.75 nm). The warning logic, triggered in four levels based on dynamic temperature and voltage changes, achieves an 80% accuracy rate and a low false/missed alarm rate of 4%. Long-term operation tests show stable monitoring deviations (±0.2 °C for temperature and ±0.02 V for voltage over 24 h). The system also adapts to varying humidity environments, with peak sensitivity (41.3 μV/°C) at 60% RH. This research provides a highly reliable solution for battery safety management in new energy vehicles. Full article

High-temperature thin-film thermocouples (TFTCs) have gained significant attention in the aerospace and energy industries due to their compact size and millisecond response time. Although previous studies have reduced the size of TFTCs to the millimeter scale, the heat flow field has continued to limit temperature measurement accuracy. To address this issue, this study used an electrohydrodynamic printing process to fabricate tungsten-rhenium TFTCs with a thickness at the micrometer scale. In the static test, the tungsten-rhenium TFTCs showed good performance with a measurement accuracy better than 1.2%, repeatability better than 0.99%, and a drift rate of 0.72%/h. In dynamic tests, the response time was 1.2 ms. Additionally, during flame gun heating tests, the response time and temperature measurement accuracy exceeded those of the standard thermocouple. Full article

Thin-film thermocouple is widely used in temperature measurement because of its high temperature measurement accuracy and small size. In order to calibrate the temperature accurately with thin-film thermocouple, NiCr/NiSi thin-film thermocouple was prepared by magnetron sputtering according to the Seebeck effect. Through static calibration experiments, the Seebeck coefficient of K-wire thermocouple was found to be 39.23 μV/°C, while that of the NiCr/NiSi thin-film thermocouple was 38.89 μV/°C. Further experiments showed a Seebeck coefficient of 39.092 μV/°C for the NiCr/NiSi thin-film thermocouple, which verifies that the prepared thin-film thermocouple has good consistency and repeatability. Through the temperature measurement experiment of automobile engines, the highest stable working temperature of the engine is 107.9 °C, which further verifies that the prepared NiCr/NiSi thin-film thermocouple can have a sensitive dynamic response to temperature and high temperature measurement accuracy. Finally, the causes of experimental errors, the application prospect and existing problems of thin-film thermocouples are analyzed. Full article

A new CuNi/TiB₂ thin-film thermocouple was fabricated using magnetron sputtering. A 400 nm thick CuNi interior layer was deposited on a dielectric substrate initiatory, and then covered by an 800 nm thick TiB₂ layer. The tests revealed that the TiB₂ layer had a dense and columnar cross-section. The measured hardness and elastic modulus of the TiB₂ layer were ~20.5 and 315.9 GPa, respectively. No cracking or delamination occurred at the CuNi/TiB₂ interface. The work functions of the TiB₂ and the CuNi layers were calculated to be 4.406 and 4.726 eV, respectively. The difference in work functions between the TiB₂ and the CuNi was ~0.3 eV. The CuNi/TiB₂ thin-film sensor exhibited a high Seebeck coefficient of 38.07 μV/°C with excellent linearity. The maximum service temperature of the thin-film sensor was evaluated to be ~400 °C. A further increase in temperature degraded the Seebeck coefficient due to oxidation of the TiB₂ layer. Full article

In the process of using thin-film thermocouples for contact measurement of the reaction temperature in proton exchange membrane fuel cells (PEMFC), the impact of thin-film thermocouple volume on the system’s reaction temperature field variation, reaction efficiency, and the lifespan of thermocouples under these conditions is not thoroughly studied. Using magnetron sputtering technology, NiCr/NiSi thin-film thermocouples (NiCr/NiSi TFTCs) with different junction sizes were fabricated on the proton exchange membrane (PEM). These NiCr/NiSi TFTCs exhibit excellent compactness, with thickness and planar dimensions in the micrometer range. When PEMFCs are equipped with built-in NiCr/NiSi TFTCs of different hot junction sizes, the time required for the system to reach a steady state varies with the size of the hot junction, with smaller hot junction sizes reaching a steady state more quickly. In a 500-h continuous operation test, the failure rates of NiCr/NiSi TFTCs also vary based on the hot junction size. Both smaller and larger hot junction sizes have relatively higher failure rates, whereas medium-sized junctions have a lower failure rate. These extensive and repetitive comparative experiments provide significant reference value for the size design of TFTCs operating inside PEMFCs, promoting both industrial production and scientific research. Full article

In the assembly process of aerospace parts, drilling is essential for carbon fiber-reinforced materials. However, due to the extreme thermal sensitivity of these composites, continuous drilling often leads to irreparable defects such as hole wall burns and exit delamination caused by concentrated cutting heat, resulting in the scrapping of parts. To address this issue, this paper explores the impact of temperature characteristics on drilling quality, providing guidance for optimizing the composite drilling process. A simulation model for single and continuous drilling was established to analyze the temperature distribution on the tool surface during drilling. A drilling temperature measurement system based on thin-film thermocouple technology was developed, enabling real-time online temperature monitoring. Continuous drilling experiments were conducted, analyzing the correlation between maximum drilling temperature and hole quality. Results show that temperatures from −25.75 °C to −9.75 °C and from 182 °C to 200.75 °C cause significant exit damage, while optimal hole quality is achieved between −1.25 °C and 168 °C. Full article

Conformal thin film sensing represents a cutting-edge technology capable of precisely measuring complex surface temperature fields under extreme conditions. However, fabricating high-temperature-resistant conformal thin film thermocouple arrays remains challenging. This study reports a method for manufacturing conformal thin film thermocouple arrays on metal spherical surfaces using a printable paste composed of silicates and Ag. Specifically, the use of silicate glass phases enhances the high-temperature performance of the silver printable paste, enabling the silver ink coatings to withstand temperatures up to 947 °C and survive over 25 h at 900 °C. The thermocouples, connected to Pt thin films, exhibited a Seebeck coefficient of approximately 17 μV/°C. As a proof of concept, an array of six Ag/Pt thin film thermocouples was successfully fabricated on a metal spherical surface. Compared to traditional wire-type thermocouples, the conformal thin film thermocouple arrays more accurately reflect temperature variations at different points on a spherical surface. The Ag/Pt conformal thin film thermocouple arrays hold promise for monitoring temperature fields in harsh environments, such as aerospace and nuclear energy applications. Full article

The detection and real-time monitoring of temperature parameters are important, and indium oxide-based thin film thermocouples can be integrated on the surface of heaters because they operate normally under harsh conditions and provide accurate online temperature monitoring. The higher stability and appropriate optical and electrical properties of In₂O₃ make it very suitable as an electrode material for thermocouple sensors. This work demonstrates that copper doping can alter the optical and electrical properties of In₂O₃ films and regulate the output performance of thermocouples. Copper-doped In₂O₃ thin films were prepared using the magnetron co-sputtering method. The doping concentration of Cu was controlled using direct current (DC) power. An In₂O₃/Pt thermocouple sensor was prepared, and the optoelectronic and thermocouple properties were adjusted by changing the copper doping content. The thickness valve of the thin film sample was 300 nm. The results of the X-ray diffraction suggested that the structure of the doped In₂O₃ thin films was cubic. The results of the energy-dispersive X-ray analysis revealed that Cu was doped into the In₂O₃ thin films. All deposited films were n-type semiconductor materials according to Hall effect testing. The 4.09 at% Cu-doped thin films possessed the highest resistivity (30.2 × 10⁻³ Ω·cm), a larger carrier concentration (3.72 × 10²⁰ cm⁻³), and the lowest carrier mobility (0.56 cm²V⁻¹s⁻¹). The optical band gap decreased from 3.76 to 2.71 eV with an increase in the doping concentration, and the transmittance of the film significantly reduced. When the DC power was increased, the variation range of Seebeck coefficient for the In₂O₃/Pt thermocouple was 152.1–170.5 μV/°C, and the range of thermal output value was 91.4–102.4 mV. Full article

Ni90%Cr10% and Ni97%Si3% thin-film thermocouples (TFTCs) were fabricated on a silicon substrate using magnetron sputtering technology. Static calibration yielded a Seebeck coefficient of 23.00 μV/°C. During staged temperature elevation of the TFTCs while continuously monitoring their thermoelectric output, a rapid decline in thermoelectric potential was observed upon the hot junction reaching 600 °C; the device had failed. Through three cycles of repetitive static calibration tests ranging from room temperature to 500 °C, it was observed that the thermoelectric performance of the TFTCs deteriorated as the testing progressed. Utilizing the same methodology, Ni-Cr and Ni-Si thin films corresponding to the positive and negative electrodes of the TFTCs were prepared. Their resistivity after undergoing various temperature annealing treatments was measured. Additionally, their surfaces were characterized using Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The causes behind the decline in thermoelectric performance at elevated temperatures were analyzed from both chemical composition and microstructural perspectives. Full article

Thin-film sensors are regarded as advanced technologies for in situ condition monitoring of components operating in harsh environments, such as aerospace engines. Nevertheless, these sensors encounter challenges due to the high-temperature oxidation of materials and intricate manufacturing processes. This paper presents a simple method to fabricate high temperature-resistant oxidized SiCN precursor and La(Ca)CrO₃ composite thin film temperature sensors by screen printing and air annealing. The developed sensor demonstrates a broad temperature response ranging from 200 °C to 1100 °C with negative temperature coefficients (NTC). It exhibits exceptional resistance to high-temperature oxidation and maintains performance stability. Notably, the sensor’s resistance changes by 3% after exposure to an 1100 °C air environment for 1 h. This oxidation resistance improvement surpasses the currently reported SiCN precursor thin-film sensors. Additionally, the sensor’s temperature coefficient of resistance (TCR) can reach up to −7900 ppm/°C at 200 °C. This strategy is expected to be used for other high-temperature thin-film sensors such as strain gauges, heat flux sensors, and thermocouples. There is great potential for applications in high-temperature field monitoring. Full article

Traditional contact heat flux sensors suffer from a lack of dynamic performance, and existing non-contact optical heat measurement equipment fails to detect convective heat transfer effectively. This limitation precludes the effective testing of composite heat flux in explosive fields. This study introduces an ultra-responsive atomic layer thermopile (ALTP) heat flux sensor, developed and employed for the first time, to evaluate the transient heat flux associated with thermobaric explosions. Measurements reveal that the ALTP sensor’s temporal resolution surpasses that of the thermal resistance thin film heat flux sensor (TFHF), attaining a spectral response time of 10 μs under pulsed laser irradiation. Beyond these radiation-based tests, the present work also conducted novel simulation analyses of high-temperature jet impacts using COMSOL software. Static simulation discovered that fluid velocity significantly influences ALTP’s sensitivity, resulting in an error of 71%. Conversely, dynamic simulation demonstrated that an increase in fluid velocity reduces the ALTP’s time constant, whereas other factors such as fluid temperature exert minimal impact on its dynamic characteristics. This confirms that the simulation model compensates for the cost and accuracy deficiencies of convection heating tests. It also provides a new way to analyze the error of explosive heat flux measurement caused by sensitivity fluctuation and insufficient dynamic performance. In thermobaric explosive trials, the maximum heat fluxes recorded were 202 kW/m² in semi-enclosed environments and 526 kW/m² in open environments. A distinctive double-wave phenomenon was evident in the test curve. By a fast-response thermocouple, the study was able to differentiate between radiation and convective heat flux in the explosion field. The findings substantiate that the ALTP sensor amalgamates the benefits of optical thermal measurement tools with those of traditional contact heat flux sensors, thereby facilitating composite heat flux measurements in the challenging conditions of an explosive field. Full article