Hydration-induced thermal behavior of crystalline and amorphous dispersed alumina

Vainer, Boris G.; Володин, А. М.; Shepelin, Artem V.

doi:10.1016/j.tca.2021.179066

Cited by 5 publications

(4 citation statements)

References 40 publications

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“…However, experimental studies of η-Al 2 O 3 and γ- Al 2 O 3 dispersed in aqueous media having different pH indicate oxide chemical activity and transformation to hydroxide phases [ 18 , 19 , 20 , 21 , 22 ]. This transition takes place in both the liquid aqueous phase and in a humid atmosphere [ 19 , 23 ]. The literature shows that, in the presence of water, hydroxides demonstrate a higher thermodynamic stability than alumina, supported by both experiment and thermodynamic calculations [ 18 , 19 , 22 ].…”

Section: Discussionmentioning

confidence: 99%

“…The literature shows that, in the presence of water, hydroxides demonstrate a higher thermodynamic stability than alumina, supported by both experiment and thermodynamic calculations [ 18 , 19 , 22 ]. The reaction of alumina particles with water might result in different products such as bayerite β-Al(OH) 3 , gibbsite α-Al(OH) 3 , or boehmite AlOOH, depending on temperature, pH of the aqueous phase, and type of oxide [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. For example, at room temperature and low pH the gibbsite phase prevailed, while a high pH facilitated bayerite formation [ 18 , 19 , 20 , 21 , 22 ].…”

Section: Discussionmentioning

confidence: 99%

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Evolution of Superhydrophilic Aluminum Alloy Properties in Contact with Water during Cyclic Variation in Temperature

et al. 2022

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Hydrophilic or superhydrophilic materials in some cases are considered to be potentially icephobic due to a low ice-adhesion strength to such materials. Here, the evolution of the properties of a superhydrophilic aluminum alloy with hierarchical roughness, fabricated by laser processing, was studied in contact with water during prolonged cyclic variation in temperature. It was shown that the chemical interaction of rough alumina with water molecules caused the substitution of the surface oxide by polymorphic crystalline gibbsite or bayerite phases while preserving hierarchical roughness. Due to such substitution, mechanical durability was notably compromised. Thus, in contrast to the superhydrophobic laser-processed samples, the superhydrophilic samples targeted on the exploitation in an open atmosphere as a material with anti-icing properties cannot be considered as the industrially attractive way to combat icing.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Evolution of Superhydrophilic Aluminum Alloy Properties in Contact with Water during Cyclic Variation in Temperature

et al. 2022

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“…This result is associated with a structural collapse and decrease in the amount of surface electron-acceptor or electron-donor sites. However, as stated by [37], in spite of the high scientific interest in these nanoparticles, little is known yet about the physicochemical properties of their several morphological variations, which remain largely unexplored until now. Table 1 also summarizes the phase of the alumina nanoparticles used in different experimental studies.…”

Section: Referencementioning

confidence: 99%

Aqueous Theta-Phase Aluminum Oxide Nanofluid for Energy Applications: Experimental Study on Thermal Conductivity

Zacarías,

de Vega,

García-Hernando

et al. 2024

Applied Sciences

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The use of nanofluids in energy systems allows for increasing efficiency and developing more economic systems. Alumina-water is one of the most common nanofluids used but little information is available about the aqueous theta-phase aluminum oxide. Given the lack of thermal conductivity data for this nanofluid, in this research, this property is experimentally evaluated. Nanofluid is prepared using the two-step method, employing a magnetic stirrer and a sonication bath. A high-precision sensor is employed for measuring thermal conductivity, using the method of transient hot wire. The thermal conductivity measurements for the base fluid (water) are compared with data provided by NIST. Nanoparticle mass fraction in the nanofluid is increased from 1 to 10% and the temperature from 22.1 to 59.3 °C. Three sonication times (1.5, 4 and 16.5 h) are used. A strong dependence between the thermal conductivity and the temperature and nanoparticles concentration has been found, while the sonication time has a negligible influence on the thermal conductivity in the range of times tested. A correlation to obtain the thermal conductivity of the water-based nanofluid using theta-phase aluminum oxide has been developed, including nanoparticle volume concentration and temperature. An excellent agreement is obtained between predicted and experimental data.

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“…The main operating tool of this method is the high-performance focal plane array (FPA)-based infrared thermography (IRT)(Pron and Bissieux 2004, Vainer 2008) derived from an earlier-generation infrared (thermal) imaging(Weis et al 1973, Ring 1998, Deng et al 2015. Currently, FPA-based IRT is effectively used in biomedical(Gorbach et al 2003, Vainer 2005, Santa Cruz et al 2009, Lahiri et al 2012, Yavuz et al 2014, Lasanen et al 2015, Moreira et al 2017, physicochemical(Mutschler et al 2019, Vainer 2020, Vainer et al 2021, and many other applications. A modern FPA-based infrared camera TKVr-IFP/SVIT (frame rate 100 frames per second, temperature sensitivity 0.03 °C) equipped with a cooled infrared detector was exploited in our studies.SEIRT is based on the dynamic (about 100 fps and more) thermographic recording of the temperature changes caused by the phase transition heat release/absorption during the physical adsorption/desorption of…”

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confidence: 99%

Radial artery pulse wave velocity: a new characterization technique and the instabilities associated with the respiratory phase and breath-holding

Vainer¹

2023

Physiol. Meas.

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Objective. Pulse wave velocity (PWV) is a key diagnostic parameter of the cardiovascular system state. However, the approaches aimed at the PWV characterization often suffer from inevitable drawbacks. The statistical results demonstrating how closely the PWV in the radial artery (RA) and the respiration phase correlate, as well as the RA PWV evolution during breath-holding (BH), have not been presented in the literature yet. The aims of this study are: a) to propose a simple robust technique for measuring RA PWV, b) to reveal the phase relation between the RA PWV and spontaneous breathing, c) to disclose the BH influence on the RA PWV. Approach. The high-resolution remote breathing monitoring method, Sorption-Enhanced Infrared Thermography (SEIRT), and the described new technique aimed at measuring RA PWV, were used synchronously, and their measurement data were processed simultaneously. Main Results. Spontaneous breathing leaves a synchronous "trace" on the RA PWV. The close linear correlation of the respiration phase and the phase of concomitant RA PWV changes is statistically confirmed in 5 tested persons (Pearson's r is of the order of 0.5-0.8, P<0.05). The BH appreciably affects the RA PWV. A phenomenon showing that the RA PWV is not indifferent to hypoxia is observed for the first time. Significance. The proposed technique for the RA PWV characterization has high prospects in biomedical diagnostics. The presented pilot study deserves attention in the context of mutual respiratory and cardiovascular systems interplay. It may also be useful in cases where the peripheral pulse wave propagation helps assess the respiratory function.

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Hydration-induced thermal behavior of crystalline and amorphous dispersed alumina

Cited by 5 publications

References 40 publications

Evolution of Superhydrophilic Aluminum Alloy Properties in Contact with Water during Cyclic Variation in Temperature

Evolution of Superhydrophilic Aluminum Alloy Properties in Contact with Water during Cyclic Variation in Temperature

Aqueous Theta-Phase Aluminum Oxide Nanofluid for Energy Applications: Experimental Study on Thermal Conductivity

Radial artery pulse wave velocity: a new characterization technique and the instabilities associated with the respiratory phase and breath-holding

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