• 열처리공학회지
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• 제13권1호
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• pp.42-50
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• 2000

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.531-535
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• 2013

철 이온을 담지시킨 BEA 제올라이트에서 $N_2O$가 분해되는 반응을 조사하여 열처리 온도가 촉매의 활성에 미치는 영향을 고찰하였다. $N_2O$ 분해 반응 실험 결과, Fe/BEA 촉매에 대한 열처리 온도가 증가함에 따라 $N_2O$ 분해 활성이 현저히 줄어들었다. 열처리 온도의 증가에 따른 Fe/BEA 촉매의 입자모양 및 크기의 변화는 크지 않았지만, 열처리 온도 증가에 따라 비표면적이 크게 줄어들었다. 또한 열처리온도가 증가함에 따라 ${\beta}$ 구조의 결정성이 크게 낮아지는 것을 확인하였고, 열처리 온도가 높아질수록 SiO 구조는 증가하거나 크게 변화가 없는 반면, Fe가 골격구조와 결합된 구조는 감소하는 것으로 판단되었다. 이와 같은 결과로 열처리 온도의 증가에 따라 알루미늄과 Fe가 결합된 ${\beta}$ 구조가 붕괴되어 $N_2O$ 분해활성이 크게 저하되는 것으로 사료된다.

• Carbon letters
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• 제11권2호
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• pp.131-136
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• 2010

Propellant waste was impregnated on the surface of activated carbon fiber and heat-treated at different temperature to introduce newly developed functional groups on the ACF surface. Functional groups of nitrogen and oxygen such as pyridine, pyridone, pyrrol, lacton and carboxyl were newly introduced on the surface of modified activated carbon fiber. The porosity, specific surface area, and morphology of those modified ACFs were changed as increasing the heat-treated temperature from 200 to $500^{\circ}C$. The optimum heat-treatment temperature was suggested to $500^{\circ}C$, because lower temperature given rise to the decrease of specific surface area and higher temperature resulted in the decrease of weight loss. Propellant waste can be used as an useful surface modifier to porous carbons.

• 열처리공학회지
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• 제11권4호
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• pp.315-323
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• 1998

This study has been conducted to develope the combined heat treating technique of gas carburising - gas nitriding and gas carburising to improve the hot working performance of type H3 hot work tool steel. Case depth and carbrides coarsening were increased with increasing carburising temperature and time, respectively. Surface hardness showed decreasing tendency with increasing 2nd tempering temperature after carburising treatment. After carburising, 2nd treatment at 500 to 600 was chosen according to a hardness demand of final product. High temperature tempering resistance showed more excellent quality during such carburising-nitriding or carburising than complex treatment as after conventional hardening.

• 동아시아식생활학회지
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• 제14권3호
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• pp.283-287
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• 2004

To investigate the effects of preheating treatment on the properties of salt-preserved cucumber, cucumber were heated in the warm water to 40, 60, and 75$^{\circ}C$ for 15 min. Thereafter, cucumbers were cooled and the ratios of cucumbers: water was adjusted to 1:1.2(w/w) and salt was added to have final salt concentration of 12%. The group which was heated to 6$0^{\circ}C$ showed the highest scores on hardness followed by 4$0^{\circ}C$, no-heat, and 75$^{\circ}C$ treated groups after 60 days of salt-preservation. The yellowness on the surface of cucumber peels was getting intense as temperature was increased during heat treatment, which resulted in the most intense yellowness in no-heat and 4$0^{\circ}C$ treated groups. The intensities of greeness and redness of the groups also differed according to different temperature applied during heat treatments. Regardless of heat treatment, no difference in the absorbance of isopropyl alcohol extracts were found. Activities of pectinesterase were the highest in 6$0^{\circ}C$ treated group followed by 4$0^{\circ}C$, 75$^{\circ}C$, and no-heat treated group until 60 days of preservation, while activities of polygalacturonase in 4$0^{\circ}C$ and 6$0^{\circ}C$ treated groups were lower.

• 열처리공학회지
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• 제34권5호
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• pp.226-232
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• 2021

The relationship between precipitation and coefficient of thermal expansion of Al-6%Si-0.4%Mg-0.9%Cu-(Ti) alloy (in wt.%) after various heat treatments were studied by the thermodynamic analyzer (TMA) and differential scanning calorimetry (DSC). Solution heat treatment of the alloy was carried out at 535℃ for 6 h followed by water quenching, and the samples were artificially aged in the air at 180℃ and 220℃ for 5 h. The coefficient of thermal expansion (CTE) curve showed some residual strain and decreased with increasing aging temperature. The CTE curves changed sharply in the temperature range of 200℃ to 400℃, and the corresponding peak shifted for the aged samples due to the change in the precipitation behavior of the secondary phase. These transformation peaks in the aged sample are related to the volume of the precipitation of the Si phase as determined by DSC analysis. The change in CTE is mainly caused by the precipitation of the Si phase in the Al-Si alloy, and the size of the change occurs simultaneously with the size of the precipitate.

• 한국재료학회지
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• 제33권4호
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• pp.142-150
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• 2023

AZO/Cu/AZO thin films were deposited on glass by RF magnetron sputtering. The specimens showed the preferred orientation of (0002) AZO and (111) Cu. The Cu crystal sizes increased from about 3.7 nm to about 8.5 nm with increasing Cu thickness, and from about 6.3 nm to about 9.5 nm with increasing heat treatment temperatures. The sizes of AZO crystals were almost independent of the Cu thickness, and increased slightly with heat treatment temperature. The residual stress of AZO after heat treatment also increased compressively from -4.6 GPa to -5.6 GPa with increasing heat treatment temperature. The increase in crystal size resulted from grain growth, and the increase in stress resulted from the decrease in defects that accompanied grain growth, and the thermal stress during cooling from heat treatment temperature to room temperature. From the PL spectra, the decrease in defects during heat treatment resulted in the increased intensity. The electrical resistivities of the 4 nm Cu film were 5.9×10^-4 Ω·cm and about 1.0×10^-4 Ω·cm for thicker Cu films. The resistivity decreased as the temperature of heat treatment increased. As the Cu thickness increased, an increase in carrier concentration resulted, as the fraction of AZO/Cu/AZO metal film increased. And the increase in carrier concentration with increasing heat treatment temperature might result from the diffusion of Cu ions into AZO. Transmittance decreased with increasing Cu thicknesses, and reached a maximum near the 500 nm wavelength after being heat treated at 200 ℃.

• 한국결정성장학회지
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• 제30권1호
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• pp.12-16
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• 2020

RF 마그네트론 스퍼터링법으로 투명 PI 기판 위에 상온 증착된 ITO(indium tin oxide) 박막을 여러 온도(50, 100, 150 그리고 200℃)에서 열처리하였다. 열처리 온도에 따른 ITO 박막의 전기적, 광학적 특성과 결정성의 변화를 조사하였다. 상온 증착된 ITO 박막은 비정질 구조를 가지며 열처리 온도가 증가할수록 결정성과 결정립 크기가 증가하였다. 이러한 구조적 변화와 더불어 전하 캐리어 농도와 이동도가 증가함으로써 비저항은 열처리 온도가 50℃에서 200℃로 증가함에 따라 2.93 × 10^-3 Ω·cm에서 1.21 × 10^-4 Ω·cm로 감소하였다. ITO가 증착된 PI 기판의 투과도는 열처리함으로써 감소하였다. 50~150℃ 온도에서는 81 % 이상이었고 200℃에서는 78 %로 상당히 감소하였다.

• 열처리공학회지
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• 제14권1호
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• pp.27-34
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• 2001

The effects of pre-heat treatment(Q/T) on microstructure and hardness of STD11 and STD61 tool steel nitrided by micro-pulse plasma were investigated. The quenching temperature for obtaining matrix hardness of STD11 and STD61 steel on range of HRC 50 to HRC 60 desired for machine parts is about $1070^{\circ}C$ and $1020^{\circ}C$ respectively. The hardness of STD11 and STD61 quenched at the temperature was HRC 63 and HRC 56 respectively. The nitrided case depth of STD11 and STD61 nitrided at $550^{\circ}C$ for 5 hours was independent of pre-heat treatment condition and the depth was approximately $100{\mu}m$. However, hardness and compactness of nitrided layer on Q/T treated specimen were higher than the annealed specimen. The case depth increased linearly with the increase of nitriding temperature, however, the hardness of nitrided layer decreased with the increase of temperature. Phase mixture of ${\gamma}-Fe_4N$ and ${\varepsilon}-Fe_{2-3}N$ was detected by XRD analysis in the nitrided layer formed at the optimum nitriding condition. The optimum nitriding temperature was approximately $490^{\circ}C$ which was $10^{\circ}C$ lower than the tempering temperature for preventing softening behavior of STD11 and STD61 matrix during nitriding process and the surface hardness of nitrided layer obtained by optimum pre-heat treatment condition was about Hv1400.

• 한국주조공학회지
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• 제40권2호
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• pp.16-24
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• 2020

The effect of a heat treatment on the microstructure and mechanical properties of Inconel 713C alloy vacuum investment castings were investigated. The microstructure of the as-cast state was observed, showing well-developed dendrite structures and distributed carbide particles and solidified massive precipitates in the grain or grain boundary during solidification, in this case the γ′ phase and MC particles. During a heat treatment, the γ phase matrix was reinforced by solid solution elements, carbide particles from the film morphology precipitated along the grain boundary, and many micro-precipitates of second γ′ phases 0.2 ㎛~2 ㎛ in size were newly formed in the γ phase matrix according to SEM-EDS analysis results. The tensile strength at a high temperature (850℃) decreased slightly becoming comparable with the room-temperature result, while the hardness value of the specimen after the vacuum heat treatment increased by approximately 19%, becoming similar to that of the as-cast condition. However, the impact values at room temperature and low temperature (-196℃) were approximated; this alloy was mostly not affected by an impact at a low temperature. In the observations of the fracture surface morphologies of the specimens after the tensile tests, the fractures at room temperature were a mix of brittle and ductile fractures, and an intergranular fracture in the inter-dendrite structure and some dimples in the matrix were observed, whereas the fractures at high temperatures were ductile fractures, with many dimples arising due to precipitation. It was found that a reinforced matrix and precipitates of carbide and the γ′ phase due to the heat treatment had significant effects, contributing greatly to the excellent mechanical properties.