A detailed characterization of BaMgAl10O17:Eu phosphor as a thermal history sensor for harsh environments

Abstract

Knowledge of component temperatures in gas turbines is essential for the design of thermal management systems and to maintain the lifetime of highly loaded parts as the firing temperature increases in pursuit of improved thermal efficiency. When on-line methods such as pyrometers and thermocouples are not suitable, a thermal history sensor can be used to record the maximum temperatures and read them out after operation. Currently, temperature sensitive paints are applied to obtain temperature profiles in gas turbine components but they present some limitations. A new method based on irreversible changes in the optical properties of thermographic phosphors can potentially overcome some of these difficulties. In particular, a sensor based on the oxidation of europium based phosphors has shown great potential. In this work the temperature sensing capabilities of the phosphor BaMgAl10O17:Eu are investigated in the temperature range from 700 °C to 1200 °C, and suitable measurands defined. The influence of practical factors comprising excitation fluence, exposure time, dopant concentration, cooling down time and atmosphere composition, on measurement accuracy and sensitivity are also reported

Broadening the Spectral Response of Perovskite Photodetector to the Solar-Blind Ultraviolet Region through Phosphor Encapsulation

“…Under 277 nm UV radiation, BaMgAl 10 O 17 :Eu shows a blue emission spectrum (blue solid line in Figure a) due to the 5D → 4F transition of Eu 2+ . It exhibits a broad band from 400 to 600 nm with a peak excitation at 458 nm. , The corresponding excitation spectrum of BaMgAl 10 O 17 :Eu (blue dashed line in Figure a) shows a broad excitation band from 235 to 400 nm with a maximum excitation at 314 nm and a shoulder at 277 nm. When irradiated at 276 nm UV light, CeMgAl 11 O 19 :Tb shows a green emission spectrum (green solid line in Figure b) with four strong fluorescence emissions peaking at 486, 541, 584, and 621 nm, owing to the 5 D 4 → 7 F J (J = 6, 5, 4, and 3) of Tb 3+ .…”

Accelerated thermal profiling of gas turbine components using luminescent thermal history paints

“…The changes can be measured by analysing the luminescent behaviour and correlated to temperature. The technology is capable of measuring temperatures between 150°C and 1,400°C (Rabhiou et al, 2010(Rabhiou et al, , 2011Yáñez-González et al, 2015). The doped ceramic material can either be applied directly through atmospheric plasma spraying (APS) or mixed with a binder into a non-toxic paint to generate a durable coating.…”

Novel erbia-yttria co-doped zirconia fluorescent thermal history sensor

“…Many physico-chemical changes can indeed have a significant impact on the energy level distribution of activators and on the probability of occurrence of radiative electronic transitions, thus affecting spectral (emission wavelength and intensity) and temporal (decay time) luminescence properties. Currently, four main temperature-driven mechanisms have been identified which, providing that they are achieved under controlled conditions (temperature and exposure time), can serve to determine thermal history: (i) phase transformations [9,10,23], (ii) diffusion of activator or sensitizer/quencher species [12,24], (iii) oxidation of activator ions [16][17][18][19] and (iv) crystallization of the host matrix [11-15, 25, 26]. The latter mechanism is of particular interest in the case of inorganic phosphors produced by a sol-gel process or many similar soft chemistry routes, since an amorphous or incomplete crystallized state is generally obtained due to the relatively low temperatures involved during their fabrication, typically lower than 873-1073 K [27][28][29].…”

“…One of the solutions under investigation over the last few years is the implementation of photoluminescent markers, whose luminescence emission properties are subjected to permanent evolutions with temperature and duration of exposure as a result of thermally activated microstructural or chemical changes occurring within the material [9][10][11][12][13][14][15][16][17][18][19]. With appropriate calibration, the changes observed in at least one luminescence characteristic can therefore be correlated back to the temperature to which the material has been subjected during a previous thermal event under controlled conditions.…”