• Resources Recycling
• /
• v.29 no.1
• /
• pp.35-42
• /
• 2020

Even asbestos-containing waste (ACW) are highly harmful to humans, it continues being produced due to the massive disposal of asbestos-containing products. A development of asbestos detoxification and recycling technologies is required. Heat treatment using microwave is the most efficient method for ACW detoxification. However, microwave heat treatment method has the limitation that asbestos does not absorb microwave at room temperature. That is why, in this study, ACW was detoxified by microwave heat treatment adding the ACW between SiC plates, which are inorganic heating elements that absorb microwaves at room temperature. In order to improove the heat transfer, ACW was crushed and pulverized and then heated using microwave. Microwave heat treatment temperature and time variables were adjusted to investigate the detoxification properties according to heat treatment conditions. After heat treatment, treated ACW was analyzed for detoxification properties through crystal structure and microstructure analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microwave heat treatment method using SiC plate can be heated up to the target temperature within a short time. Finally, complete asbestos detoxification was confirmed from the crystal structure and the microstructure when the microwave heat treatment was performed at 1,200℃ for at over 60 minutes and at 1,300℃ for at over 10 minutes.

• Journal of the Korean Society for Heat Treatment
• /
• v.35 no.6
• /
• pp.327-336
• /
• 2022

In this study, a model for automatically recognizing several steel parts through a camera before charging materials was developed under the assumption that the temperature distribution in the pre-air atmosphere was known. For model development, datasets were collected in random environments and factories. In this study, the YOLO-v5 model, which is a YOLO model with strengths in real-time detection in the field of object detection, was used, and the disadvantages of taking a lot of time to collect images and learning models was solved through the transfer learning methods. The performance evaluation results of the derived model showed excellent performance of 0.927 based on mAP 0.5. The derived model will be applied to the model development study, which uses the model to accurately recognize the material and then match it with the temperature distribution in the atmosphere to determine whether the material layout is suitable before charging materials.

• Journal of the Korean Society for Heat Treatment
• /
• v.36 no.6
• /
• pp.359-366
• /
• 2023

Changes in microstructure and mechanical properties of Mg-1.0Al-1.0Zn-0.2Mn-0.5Ca (AZMX1100) alloy sheet manufactured by normal casting and twin roll casting process, were studied according to process and heat treatment. Non-uniform microstructure was observed in the initial sheet produced through both processes, and in particular, tilted dendrites and shifted central segregation were observed in the twin roll casting sheet. It was homogenized through hot rolling and heat treatment, and heat treated at 350℃ and 400℃ to compare the effect of heat treatment temperature. Both sheets were homogenized by the hot rolling process, and the grain size increased as the heat treatment temperature and time increased. It was confirmed that the grain size, deviation, and distribution of the second phase were finer and more homogenized in the TRC sheet. Accordingly, mechanical properties such as hardness, formability, and tensile strength also showed better values. However, unlike other previously reported AZMX alloy systems, it showed low formability (Erichsen value), which was judged by the influence of Al2Ca present in the microstructure.

• The Journal of Natural Sciences
• /
• v.11 no.1
• /
• pp.151-157
• /
• 1999

The study was investigated the improved printing effect of heat transfer ability for the cotton fabric treated with disperse dyes. Some important factors were studied to determine the most optimal conditions such as concentration of dye, treated time and temperature, after treatment and before treatment using swelling agent, and molecular weight of dye. The fastness to laundering and light for heat transfer printing was measured.The optimal conditions of heat transfer printing for cotton fabric treated with disperse dye were concentration of 5% owf, treated temperature of $200^{\circ}C$, treated time of 3 minute. The diffusion of disperse dyes inside cotton fabric was accelerated as a result of swelling agent such as glycerin, ethylene glycol, tetramethylene glycol, propylene glycol using in this study. The effects of heat transfer printing were increased that the increasement of before treatment time for swelling agent, decrease of molecular weight of dye.

• Journal of the Korean Society for Heat Treatment
• /
• v.33 no.6
• /
• pp.277-283
• /
• 2020

Cu-Co-Si based alloy has a strengthening mechanism for Co₂Si intermetallic compounds deposited on the copper matrix after aging treatment and the solution treatment has a key influence on the strength and electrical conductivity of the final products. In this paper, the Cu-1.6%Co-0.38%Si alloy was fixed at the time and the solution treatment temperature was set at a temperature in the range of 800 to 950℃, and the change in mechanical properties was observed by fixing the temperature at 950℃ and changing the time. The microstructure was observed using an electron microscope and an optical microscope, and the changes in hardness, electrical conductivity, and bending workability after aging treatment were investigated. When the solution treatment time is less than 20 seconds, the solution treatment is not sufficient and the formation of precipitates contributing to the increase in hardness decreases and the hardness decreases after the aging treatment, and in more than 50 seconds, the hardness decreases due to the coarsening of the grains and the bending workability got worse.

• Journal of the Korean Society for Heat Treatment
• /
• v.29 no.5
• /
• pp.220-226
• /
• 2016

The mechanical properties of Ti-6Al-4V can be improved by microstructural control through the heat treatment in ${\alpha}+{\beta}$ region. The heat treatment was carried out with a variety of heat treatment temperatures and holding times to find the optimized heat treatment conditions and it was analyzed by linking the microstructural characteristics and mechanical properties. The part of ${\beta}$ phase with $10{\pm}2wt%$ vanadium was transformed into ${\alpha}^{{\prime}{\prime}}$ martensite phase after quenched, so the hardness and tensile properties were decreased below $900^{\circ}C$. The higher the heat treatment temperature is, the smaller is the vanadium-rich region, which leads to transformation into hcp ${\alpha}^{\prime}$ martensite above $900^{\circ}C$. The hardness and tensile properties were improved due to the hard ${\alpha}^{\prime}$ martensite. As the holding times were longer, the hardness and tensile properties decreased below $900^{\circ}C$ because of the softening effect by the grain growth. When varying the holding times above $900^{\circ}C$, the change of mechanical properties was slight because the softening effect of grain growth and the strengthening effect of ${\alpha}^{\prime}$ phase were counteractive. Therefore, the best conditions of heat treatment, which is in the range of $920{\sim}960^{\circ}C$, 40 min, WQ, can effectively improve the mechanical properties of Ti-6Al-4V.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.6
• /
• pp.526-533
• /
• 2006

The prediction of heat-up time of an LCD glass plate in LCD glass pre-treatment process has been implemented in the present study. Firstly, the analytical solution for one-dimensional radiation heat transfer from IR heaters to a LCD glass plate is obtained. When the surface temperature of the IR heaters is set at 473 K, the heat-up time of LCD glass to averaged temperature of 383K is 28 seconds. In addition, a three dimensional full CFD analysis using STAR-CD is implemented in an effort to consider the effect of 3-D heat loss through the furnace walls. From the results of the 3-D CFB analysis, the heat-up time increases up to 32.5 seconds under the same conditions. When the IR heater temperature in creases up to 573 K, the heat-up time decreases to 12 seconds for the one-dimensional analytical solution and to 13.5 seconds for the 3-D CFD analysis, respectively.

• Journal of the Korean Wood Science and Technology
• /
• v.42 no.1
• /
• pp.13-19
• /
• 2014

Three heat-treatment schedules were applied to $90{\times}90mm$ dimension square lumber of Pinus koraiensis, one of major domestic species, and their colors and physical properties were investigated for obtaining an optimum schedule. Each square lumber was heat-treated three times. The temperatures of $170^{\circ}C$ and $190^{\circ}C$, and the time of 9 hours and 13 hours were used for the first heat-treatment. The schedule of $190^{\circ}C$ and 7 hours were used for the next two heat-treatments. The averages of brightness $L^*$ decreased linearly as the heat-treatment repeated and its standard deviations also decreased slightly. While the averages of color difference ${\Delta}E^*$ increased linearly as the heat-treatment repeated and its standard deviations also increased slightly. The average compressive strength of the heat-treated specimen was higher than that of the control by 9%, which deviates from previous reports. ASE and WPG of the heat-treated specimens were measured to confirm that heat-treatment improved dimensional stability significantly.

• Korean Journal of Poultry Science
• /
• v.15 no.1
• /
• pp.39-44
• /
• 1988

This study was undertaken to find out the effect of heating time and temperature, pH and NaCl concentration on heat sensitivity of egg albumen during heat treatment. Sharp increase of the turbidity and rapid decrease of the foaming power were observed when egg albumen was heated at above $60^{\circ}C$. Egg albumen became opaque when it was heated at $60^{\circ}C$ for above 13 minutes or at $65^{\circ}C$ for above 5 minutes. The turbidity was markedly increased at below pH 7 and the foaming power was largely decreased at around pH 4.0 by the heat treatment ($60^{\circ}C$, 5 min). The foam stability was slightly decreased at alkaline pH range by the heat treatment (60t, 5 min). The addition of NaCl up to 0.3M decreased the turbidity. There was no effect of NaCl addition on the foaming power, but the foam stability was decreased by the addition of NaCl at above 0.2M before and after the heat treatment ($60^{\circ}C$, 5 min).

• Journal of the Korean Society for Heat Treatment
• /
• v.12 no.4
• /
• pp.287-293
• /
• 1999

Effect of heat-treatment on the microstructure and recrystallization behavior of pure Zr was studied. The specimens were prepared under the various annealing temperatures from $400^{\circ}C$ to $800^{\circ}C$ and times from 300 to 5000 minutes after vacuum arc remelting. The recrystallization behavior was observed by a polarized optical microscope, TEM and micro-vickers hardness tester. With increasing the annealing time, the temperature region of hardness drop moved to the lower temperature region due to the recovery and recrystallization behaviors at the lower temperature. The recrystallization of cold-worked pure Zr was completed between 450 and $600^{\circ}C$. The size of recrystallized grain increased at $700^{\circ}C$ for 600min. Activation energy(Q) of pure Zr measured by the time for constant fraction technique was 78 KJ/mol.