• Journal of Ceramic Processing Research
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• v.23 no.2
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• pp.199-207
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• 2022

A rapid cooling (quenching) step has been introduced in fabrication of TiO₂ photoelectrodes for dye-sensitized solar cells (DSSCs). The quenching process, studied at a fixed sintering temperature, decreased particle size but increased surface roughness without any substantial change in the crystal structure or oxidation state of TiO₂ films. Therefore, the change in the DSSC performance induced by the quenching was related closely to the microstructural and morphological changes in the TiO₂ films. Smaller particle size and the rough surface of TiO₂ films facilitated dye adsorption and increased the number of active reaction sites. In particular, the enlarged number of active reaction sites produced by the quenching process promoted the charge transfer reaction at the TiO₂-dye-electrolyte interface, resulting in overall performance improvement of DSSCs. The conversion efficiency of the furnace cooled- and quenched-TiO₂ films at 500 ℃ were 4.588% and 5.797%, respectively.

• Journal of Photoscience
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• v.4 no.3
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• pp.97-103
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• 1997

The effect of temperature on the fluorescence quenching of 2-(4-Methoxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazole (MPNO1), 2-(4-Methoxyphenyl)-5-(2-naphthyl)-1,3,4-oxadiazote(MPNO2), by aniline, and 2-Phenylindole (2-PI) by CCk, in toluene by steady state method and in benzene by time-resolved method have been carried out in the temperature range 30 - 70$\circ$C. The Stem-Volmer (S-V) plots, I$_0$/I against quencher concentration [Q] at different temperanares show positive deviations. The fluorescence lifetimes determined at different temperatures show no systematic variations and the variations being within the experimental error, the average values of lifetimes $ $\tau$ (t) are taken for further calculations. Rate constants such as Stem-Volmer quenching constants K$_sv}$, quenching rate parameters k$_q$ and k'$_q$, static quenching constant V and kinetic distance r are determined using the modified Stem-Volmer equation and sphere of action static quenching model. In order to see whether the reactions are diffusion limited, equations k$_q$ = e$^{-Eq/RT}$ and k'$_q$ = e$^{-Eq/RT}$ are used to determine the values of E$_q$ and E'$_q$, the activation energies for collisional quenching and the values of E$_q$ are 14.53. 17.28 and 16.20 kJ mole$^{-1}$ for MPNO1, MPNO2 and 2-PI respectively and the values of E'$_q$ are 14.62 and 17.73 for MPNO1 and MPNO2 respectively. From the magnitudes of various quantities it has been concluded that the reactions are diffusion limited and the observed positive deviations in the S-V plot are due to static and dynamic quenching.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.3
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• pp.206-214
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• 1999

The effect of cooling rate on carbide precipitation during quenching of austenitic manganese steel was investigated by optical microscopy, image analyzer and numerical analysis. A computer program based on the finite difference method for analyzing heat treatment processes was developed in order to evaluate cooling rates and the possibility of carbide precipitation during quenching. The area ratio of carbide precipitated in the austenite matrix was measured by the image analyzer, and used to determine the critical point of carbide precipitation. Temperature-dependent critical cooling rates at the critical points were calculated using the present simulation program, The calculated results showed a good agreement with the experimental ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.51-54
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• 2001

This Paper is described basic principles of arc quenching in Molded Case Circuit Breaker. We analyzed magnetic blowout forces acting on the arc in contact system when circuit breakers interrupt fault currents in different three models by 3-D FEM(Finite Element Method). The interrupting time simulated is compared with that of short circuit tests. The results of this study derive valid of the simulation method and present the techniques to improve arc quenching performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.419-423
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• 1989

The laboratory quench method used in this study is based on plunging a silver cylinder heated to 800.deg. C in to mineral oil and vegetable at given temperature. Experimental apparatus and measuring method followed Korean Industrial Standard. Colling curves at the boundary of the cylinder measured by a silver-alumel thermocouple is recorded throughout the quenching period. Using the cooling curves, the coolingability of the quenching oils at various temperatures were compared and discussed.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.259-260
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• 2001

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1529-1540
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• 1993

The quenching of steels by water is one of the imprtant problems in the applications of heat treatment, but the fundamental researches by way of theoretical approaches have not been satisfactorily improbed yet. This study aimed at measuring the exact subcooled transient boiling curve for cylindrical specimens and at conducting the analytical researches into the prediction of cooling curves, including the latent heat of phase transformation of steel. Experiments of quenching were made with cylindrical specimens of carbon steel S45C of diameters from 12 to 30 mm and with Cu specimens of 12 mm diameter respectively. The internal temperature of specimens during the quenching process was measured by C-A sheathed thermocouple. The heat fluxes were numerically calculated by the numerical method of inverse heat conduction problem, using the measured inner temperature of specimen as a boundary condition. In case of ${\Delta}T_{sub}=80K$, $q_{s}$ is as follows $q_{s}=2.02{\times}10^{5}{\Delta}T_{set}^{0.05}:{\Delta}T_{set}\le500K.$ And the numerical analysis of unsteady heat conduction during the quenching process was made and the cooling curves were calculated by TDMA method.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.504-510
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• 1996

Low-density polyethylene(LDPE)/Linear low-density polyethylene(LLDPE) blends were prepared by the compositional quenching process, a new morphology control method. The blends were characterized in terms of melting and crystallization behavior and mechanical properties. The results were compared with those of mechanically blended and solution blended samples. From DSC experiments, it was found that the melting temperatures and crystallization temperatures of the blends were dependent on the blending methods. In thermal property, LDPE/LLDPE blends prepared by compositional quenching process were similar to the blends prepared by solution blending but different from the blends prepared by mechanical blending. This result is explained to be due to the domain size dispersed in the matrix. The elongation-at-break and tensile strength of the samples blended by compositional quenching showed similar to those of the samples blended by solution blending method but larger than those of samples prepared by mechanical blending. Also, the Young's modulus showed the same trends as elongation-at-break. The tensile strength of the blends prepared by compositional quenching was not as high as the samples prepared by the other two blending methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.362-363
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• 2008

Well-defined o-$LiMnO_2$ cathode materials were synthesized using LiOH and $Mn_3O_4$ starting materials at $1050^{\circ}C$ in an argon flow by quenching method. The synthesized $LiMnO_2$ particles with crystalline phases were identified with X-ray diffraction (XRD, Dmax/1200, Rigaku). XRD results, demonstrated that the compound $LiMnO_2$ can be indexed to a single-phase material having the orthorhombic structure. In this paper, we analyzed the electrochemical performance of $LiMnO_2$/Li using solid polymer electrolyte and liquid electrolyte.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1665-1667
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• 2003

Recently, a breaking capacity increases with breaking method using gas pressure from ablation materials in low voltage circuit breakers. In this paper, we investigated arc quenching materials with spectroscopic method. Especially, Hydrogen spectrum was investigated because its dielectric characteristics are better than other gases. We selected two arc quenching materials, UP and PA6, that use in circuit breakers. They had hydrogen spectrums, but PA6 was better than UP in the qualitative aspect.