The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Andrew L. Heyes - One of the best experts on this subject based on the ideXlab platform.
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Thermal History sensing with thermographic phosphors
2013Co-Authors: Andrew L. Heyes, A. Rabhiou, J. P. Feist, Andreas KempfAbstract:The ability to measure temperatures on high Thermal loaded components in gas turbines and similar prime movers is critical during the design phase if the performance of cooling strategies is to be confirmed. Restricted access and the extreme environment mean that on-line temperature measurement is not always possible and that off-line temperature techniques employing Thermal History sensors are sometimes necessary. The authors have developed a new type of sensor based on ceramic phosphors. These show bright narrow band emission that is easily detected and distinguished from the background. Crystallization, phase change and diffusion are all temperature dependent processes that affect the emission characteristics and that, with proper calibration, can be used to form a phosphor based Thermal History sensor. Results from the calibration of crystallization in Y2SiO5:Tb and its application in the form of a temperature indicating paint are reviewed. A new embodiment of the phosphor Thermal History sensor conce...
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Oxidation of divalent rare earth phosphors for Thermal History sensing
Sensors and Actuators B: Chemical, 2013Co-Authors: A. Rabhiou, Andreas Kempf, Andrew L. HeyesAbstract:Abstract Knowledge of component temperatures under the extreme conditions in industrial prime movers is of great practical importance, but very hard to obtain. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for utilising phosphorescent coatings as Thermal History sensors was proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their photoluminescent emission properties in such a way that off-line analysis of the emission at room temperature can reveal the temperature History of the coating. In this paper, an investigation of the Thermally activated oxidation of 2+ ions in phosphors such as BaMgAl10O17:Eu2+, BaMgAl10O17:Eu2+, Mn2+ and SrAl14O25:Eu2+ is reported and used to demonstrate the potential for a phosphorescent Thermal History sensor based on a new physical process. Phosphor powders were annealed at temperatures up to 1400 °C, and characterised using photoluminescence spectroscopy. An intensity ratio temperature measurand was defined and it was shown that the dynamic range of a Thermal History sensor based on SrAl14O25:Eu2+ could provide a dynamic range extending from 600 °C to 1300 °C.
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Phosphorescent Thermal History sensors
Sensors and Actuators A: Physical, 2011Co-Authors: Abderahman Rabhiou, Andreas Kempf, J. P. Feist, Stephen J. Skinner, Andrew L. HeyesAbstract:Abstract The operating temperatures of surfaces in the hot sections of gas turbines are of great practical importance, but are often very hard to measure. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for the utilisation of phosphorescent coatings as Thermal History sensors was proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their photoluminescent properties and are a function of both the temperature and duration of exposure. If care is taken to ensure steady state conditions during exposure, subsequent off-line analysis of emission in the laboratory can reveal the temperature experienced by the coating. In this paper, an investigation of the amorphous-to-crystalline change of Y 2 SiO 5 :Tb is reported and used to provide a proof of concept for a phosphorescent Thermal History sensor. Phosphor powder was calcined at different temperatures and for different periods, and characterised using photoluminescence spectroscopy. A calibration curve was generated and shows that this phosphor is suitable for temperature measurements over a temperature range from 600 ° C to at least 1000 ° C. With more advanced signal processing routines it is anticipated that the dynamic range might be extended to 1400 ° C. Such routines and other materials/physical processes are the subject of on-going research in the area at Imperial College and Southside Thermal Sciences.
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Concept for a Phosphorescent Thermal History Sensor
Volume 3: Controls Diagnostics and Instrumentation; Cycle Innovations; Marine, 2010Co-Authors: A. Rabhiou, J. P. Feist, Andreas Kempf, Stephen J. Skinner, Andrew L. HeyesAbstract:The Thermal History of hot surfaces is of great practical importance, but very hard to measure. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for the utilisation of phosphorescent coatings as Thermal History sensors has been proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their light emission properties. A subsequent off-line analysis of the emission at room temperature can reveal the temperature History of the coating. In this paper, an investigation of the amorphous-to-crystalline change of Y2 SiO5 : Tb is reported and used to provide a proof of concept for a phosphorescent Thermal History sensor. The phosphor powder was calcined at different temperatures, and characterised using photoluminescence spectroscopy. A calibration curve was generated from the measurements and is presented and discussed.Copyright © 2010 by ASME
Shifeng Zhou - One of the best experts on this subject based on the ideXlab platform.
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Visualized Thermal History sensor based on the rare-earth-doped zirconia
Optics letters, 2020Co-Authors: Heng Wang, Qiannan Mao, Bijiao Lan, Shifeng ZhouAbstract:Temperature is one of the most fundamental parameters, and its accurate measurement is critically important for Thermal systems. Despite substantial progress in temperature measuring techniques, design and fabrication of a reliable Thermal History sensor, which can remember Thermal events, still remain a significant challenge. In this Letter, we propose and experimentally demonstrate a new Thermal History sensor based on the rare-earth-activated and yttria-stabilized zirconia (YSZ). This material candidate exhibits strong heat-treatment-dependent upconversion emission color. The structure and optical characterizations indicate that the phenomenon originates from the cooperative effects of multiple physical parameters, including crystallinity, crystal size, and the quantity of residual OH. This allows us to achieve excellent linear relationship between the heat-treatment temperature and the intensity ratio of the green and red emission band over a wide temperature range from 800°C to 1350°C. Thus, the Thermal History information can be directly judged based on the emission color. These results provide a major step forward in expanding the scope of Thermal History sensor materials.
Zhifeng Ren - One of the best experts on this subject based on the ideXlab platform.
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determination of Thermal History by photoluminescence of core shelled quantum dots going through heating events
Particle & Particle Systems Characterization, 2015Co-Authors: Gang Chen, Hui Wang, Yucheng Lan, Nitin Skula, Xiaoyuan Chen, Zhifeng RenAbstract:A kind of novel Thermal History nanosensors are theoretically designed and experimentally demonstrated to permanently record Thermal events. The photoluminescence (PL) spectrum of core-shelled quantum dots (QDs) CdSe/ZnS irreversibly shifts with heating histories (temperature and duration) of Thermal events. The induced PL shift of the QDs CdSe/ZnS is employed to permanently record Thermal histories. We further model a kind of Thermal History nanosensor based on the Thermal-induced phenomena of core-shelled QDs to permanently record Thermal histories at microscale and demonstrate to reconstruct temperature and duration of heating events simultaneously from PL spectra of the QDs. The physical mechanism of the sensors is discussed.
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Determination of Thermal History by Photoluminescence of Core‐Shelled Quantum Dots Going Through Heating Events
Particle & Particle Systems Characterization, 2014Co-Authors: Yucheng Lan, Gang Chen, Hui Wang, Nitin Skula, Xiaoyuan Chen, Zhifeng RenAbstract:A kind of novel Thermal History nanosensors are theoretically designed and experimentally demonstrated to permanently record Thermal events. The photoluminescence (PL) spectrum of core-shelled quantum dots (QDs) CdSe/ZnS irreversibly shifts with heating histories (temperature and duration) of Thermal events. The induced PL shift of the QDs CdSe/ZnS is employed to permanently record Thermal histories. We further model a kind of Thermal History nanosensor based on the Thermal-induced phenomena of core-shelled QDs to permanently record Thermal histories at microscale and demonstrate to reconstruct temperature and duration of heating events simultaneously from PL spectra of the QDs. The physical mechanism of the sensors is discussed.
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Composite-Nanoparticles Thermal History Sensors
2012Co-Authors: Gang Chen, Zhifeng RenAbstract:Abstract : In the three years of this grant, Thermal History dependences of the photoluminescence spectrum of several types of core-shell quantum dots (QDs) were studied as well as structural determination on transmission electron microscopy (TEM). These quantum dots (QDs) were studied in a broad temperature range from room temperature to over 500 degrees Celsius. Photoluminescence (PL) of core/shell CdSe/ZnS QDs in different sizes was used as a tool to examine their interfacial mass diffusion processes due to temperature change. The PL of core/shell CdSe/ZnS QDs in size of 5 nm shows strong dependence on their temperature History. The PL signal could be detected after QD samples were heated up to 500 degrees Celsius in a time frame of seconds. The blue-shift of the PL spectra with increasing temperature and heating time provides an optical route to read out the Thermal History. A quantitative relationship between peak-shift and heating temperature has been established on CdSe QDs. We showed that the heating History can be read out by the combination of two kinds of quantum dots.
Andreas Kempf - One of the best experts on this subject based on the ideXlab platform.
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Thermal History sensing with thermographic phosphors
2013Co-Authors: Andrew L. Heyes, A. Rabhiou, J. P. Feist, Andreas KempfAbstract:The ability to measure temperatures on high Thermal loaded components in gas turbines and similar prime movers is critical during the design phase if the performance of cooling strategies is to be confirmed. Restricted access and the extreme environment mean that on-line temperature measurement is not always possible and that off-line temperature techniques employing Thermal History sensors are sometimes necessary. The authors have developed a new type of sensor based on ceramic phosphors. These show bright narrow band emission that is easily detected and distinguished from the background. Crystallization, phase change and diffusion are all temperature dependent processes that affect the emission characteristics and that, with proper calibration, can be used to form a phosphor based Thermal History sensor. Results from the calibration of crystallization in Y2SiO5:Tb and its application in the form of a temperature indicating paint are reviewed. A new embodiment of the phosphor Thermal History sensor conce...
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Oxidation of divalent rare earth phosphors for Thermal History sensing
Sensors and Actuators B: Chemical, 2013Co-Authors: A. Rabhiou, Andreas Kempf, Andrew L. HeyesAbstract:Abstract Knowledge of component temperatures under the extreme conditions in industrial prime movers is of great practical importance, but very hard to obtain. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for utilising phosphorescent coatings as Thermal History sensors was proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their photoluminescent emission properties in such a way that off-line analysis of the emission at room temperature can reveal the temperature History of the coating. In this paper, an investigation of the Thermally activated oxidation of 2+ ions in phosphors such as BaMgAl10O17:Eu2+, BaMgAl10O17:Eu2+, Mn2+ and SrAl14O25:Eu2+ is reported and used to demonstrate the potential for a phosphorescent Thermal History sensor based on a new physical process. Phosphor powders were annealed at temperatures up to 1400 °C, and characterised using photoluminescence spectroscopy. An intensity ratio temperature measurand was defined and it was shown that the dynamic range of a Thermal History sensor based on SrAl14O25:Eu2+ could provide a dynamic range extending from 600 °C to 1300 °C.
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Phosphorescent Thermal History sensors
Sensors and Actuators A: Physical, 2011Co-Authors: Abderahman Rabhiou, Andreas Kempf, J. P. Feist, Stephen J. Skinner, Andrew L. HeyesAbstract:Abstract The operating temperatures of surfaces in the hot sections of gas turbines are of great practical importance, but are often very hard to measure. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for the utilisation of phosphorescent coatings as Thermal History sensors was proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their photoluminescent properties and are a function of both the temperature and duration of exposure. If care is taken to ensure steady state conditions during exposure, subsequent off-line analysis of emission in the laboratory can reveal the temperature experienced by the coating. In this paper, an investigation of the amorphous-to-crystalline change of Y 2 SiO 5 :Tb is reported and used to provide a proof of concept for a phosphorescent Thermal History sensor. Phosphor powder was calcined at different temperatures and for different periods, and characterised using photoluminescence spectroscopy. A calibration curve was generated and shows that this phosphor is suitable for temperature measurements over a temperature range from 600 ° C to at least 1000 ° C. With more advanced signal processing routines it is anticipated that the dynamic range might be extended to 1400 ° C. Such routines and other materials/physical processes are the subject of on-going research in the area at Imperial College and Southside Thermal Sciences.
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Concept for a Phosphorescent Thermal History Sensor
Volume 3: Controls Diagnostics and Instrumentation; Cycle Innovations; Marine, 2010Co-Authors: A. Rabhiou, J. P. Feist, Andreas Kempf, Stephen J. Skinner, Andrew L. HeyesAbstract:The Thermal History of hot surfaces is of great practical importance, but very hard to measure. Thermal indicating paints offer one possible and practical way, but they have many disadvantages. A novel concept for the utilisation of phosphorescent coatings as Thermal History sensors has been proposed by Feist et al. [1] in 2007. These phosphor coatings undergo irreversible changes when exposed to high temperatures that affect their light emission properties. A subsequent off-line analysis of the emission at room temperature can reveal the temperature History of the coating. In this paper, an investigation of the amorphous-to-crystalline change of Y2 SiO5 : Tb is reported and used to provide a proof of concept for a phosphorescent Thermal History sensor. The phosphor powder was calcined at different temperatures, and characterised using photoluminescence spectroscopy. A calibration curve was generated from the measurements and is presented and discussed.Copyright © 2010 by ASME
Heng Wang - One of the best experts on this subject based on the ideXlab platform.
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Visualized Thermal History sensor based on the rare-earth-doped zirconia
Optics letters, 2020Co-Authors: Heng Wang, Qiannan Mao, Bijiao Lan, Shifeng ZhouAbstract:Temperature is one of the most fundamental parameters, and its accurate measurement is critically important for Thermal systems. Despite substantial progress in temperature measuring techniques, design and fabrication of a reliable Thermal History sensor, which can remember Thermal events, still remain a significant challenge. In this Letter, we propose and experimentally demonstrate a new Thermal History sensor based on the rare-earth-activated and yttria-stabilized zirconia (YSZ). This material candidate exhibits strong heat-treatment-dependent upconversion emission color. The structure and optical characterizations indicate that the phenomenon originates from the cooperative effects of multiple physical parameters, including crystallinity, crystal size, and the quantity of residual OH. This allows us to achieve excellent linear relationship between the heat-treatment temperature and the intensity ratio of the green and red emission band over a wide temperature range from 800°C to 1350°C. Thus, the Thermal History information can be directly judged based on the emission color. These results provide a major step forward in expanding the scope of Thermal History sensor materials.