• Title/Summary/Keyword: 승온시간

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Improvement of Oxidative Resistance for C/C Composite Coated (졸-겔법으로 알루미나를 도포한 탄소/탄소 복합재의 산화 억제효과)

  • Ju, Hyeok-Jong;Choe, Don-Muk;Kim, Yeong-Guk;Gwon, Ho-Gil
    • Korean Journal of Materials Research
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    • v.3 no.4
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    • pp.372-380
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    • 1993
  • In order to improve the oxidative resistance of carbon/carbon composites, aluminium-isopropoxide and aluminium-tri-sec-butoxide sol were coated on the surface of 2D--carbon/carbon composiles and the effects uf coating were investigated. The effects of oxidative resistance were dominant in the case of catalyst/alkoxide mole ratio, 0.07, and $H_2O$/alkoxide mole ratio, 100. Through the dynamic TGA analysis with the heating rate of 20%/min, oxidative initiation tempera~ ture was enhanced about $80^{\circ}C$. The oxidative resistance effects of alkoxide sol were improved according to the times of coating. Also the 20% weight loss time of coated samples by TGA analysis was 20% better than that of un~ coated samples. The thickness of 1^{st} coated layer was about 3${\mu}$m and that of $2^{nd}$ and $3^{nd}$ coated layers was about respectively 4~5${\mu}$m and the weight loss were increased with the increasing of thermal shock test times.

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Studies on Simultaneous Analysis of Organophosphorus Pesticide Residues in Crops by Gas-Liquid Chromatography (II). Separation of Pesticides by Capillary Column (기체-액체 크로마토그래피에 의한 농작물 중 유기인제 잔류농약의 동시 분석에 관한 연구 (제 2 보). 모세관 컬럼에 의한 분리)

  • Kim, Taek-Jae;Eo, Yun-Woo;Kim, Young-Sang
    • Journal of the Korean Chemical Society
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    • v.31 no.3
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    • pp.236-243
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    • 1987
  • The optimum resolution condition of 11 organophosphorus pesticides by gas-liquid chromatography was studied using a capillary column. The injection modes and types of vaporization tubes were evaluated in relation to pesticide analysis. The best reproducibility of peak heights of pesticides was obtained by the split mode with the vaporization tube packed with quartz wool. A 25m SE-30 capillary column provided better resolution than SE-54 column for their optimum resolution. The column at $200^{\circ}C$ initially was heated by $5^{\circ}C/min\;to\;230^{\circ}C$ followed by $10^{\circ}C/min\;to\;270^{\circ}C$ and the temperatures were held constant for 5 minutes at $230^{\circ}C\;and\;270^{\circ}C$, respectively. The relative standard deviations of their retention times were less than 0.19%.

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Pyrolytic Reaction Characteristics of a Mixed Fuel of Municipal Solid Wastes and Low-grade Anthracite (도시생활폐기물과 저품위 무연탄 혼합연료의 열분해 반응특성)

  • Oh, Kwang-Joong;Lee, Hyung-Don;Seo, Jong-Beom;Jeon, Soo-Bin;Cho, Sang-Won
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.11
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    • pp.1046-1053
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    • 2010
  • The objective of this study was to investigate the pyrolytic reaction characteristics of a mixed fuel of municipal solid wastes and low-grade anthracite. The reaction variables are pyrolysis condition of mixing ratio, reaction temperature, temperature increase rate. As a result, the optimum mixing ratio was 20 wt.% low-grade anthracite in MSW, which maintains for the low heating value over 3,500 kcal/kg on pyrolysis. The most high reaction velocity constant was shown at $700^{\circ}C$. Also, under the all experimental condition, the reaction velocity constant increased linearly as temperature rate increase, but pyrolysis has to be considered electric power cost and yield of char at lower temperature rate.

Thixoforming Characteristics of Metal Matrix Composites (Phase identification of $SiC_p/AZ91HP$ Mg composite) (금속기 복합재료의 틱소포밍 특성 ($SiC_p/AZ91HP$ Mg 복합재료의 상분석을 중심으로))

  • Lee, Jung-Il;Kim, Young-Jig
    • Applied Microscopy
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    • v.29 no.3
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    • pp.281-289
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    • 1999
  • The stirred and thixoformed $SiC_p/AZ91HP$ Mg composites are studied on the basis of microstructural analysis using transmission electron microscopy (TEM). The products of interfacial reaction are identified as $Mg_2Si$, MgO and $Mg_{17}Al_{12}$ phases and the crystallized phases are found to be orthorhmbic $Al_6Mn$ and decagonal T phases. It is shown that $Mg_2Si$ and $Mg_{17}Al_{12}$ phases are found at the surface of $SiC_p$ and $Al_6Mn$ is found near interface and crystallized on the matrix. Phase identification is carried out by crystallographic work based on primitive cell volume, zero order Laue zone (ZOLZ) patterns and single convergent beam electron diffraction (CBED) patterns containing higher order Laue zone ring from a nanosized region.

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Study on Cure Behavior of Low Temperature and Fast Cure Epoxy with Mercaptan Hardener (Mercaptan 경화제에 의한 저온속경화 에폭시의 경화거동에 관한 연구)

  • Eom, Se Yeon;Seo, Sang Bum;Lee, Kee Yoon
    • Polymer(Korea)
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    • v.37 no.2
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    • pp.240-248
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    • 2013
  • The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener, -SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at $90^{\circ}C$ or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below $80^{\circ}C$ and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.

Effect of $MoO_3$ addition on the permeability of Mn-Zn ferrites ($MoO_3$ 첨가가 Mn-Zn Ferrites의 투자율에 미치는 영향)

  • 장정수;한영호;신명승
    • Journal of the Korean Magnetics Society
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    • v.11 no.1
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    • pp.26-31
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    • 2001
  • The effect of MoO$_3$ addition on the permeability of Mn-Zn ferrites was studied. 600 ppm, 800 ppm and 1,000 ppm of MoO$_3$ were added to the main composition after calcination. Ferrite cores were sintered at 135$0^{\circ}C$ for 3hrs, followed by cooling according to the equilibrium oxygen concentration. The initial permeability was about 8,000 with heating rate 5$^{\circ}C$/min for 3hrs without MoO$_3$ addition. When 600 ppm and 800 ppm of MoO$_3$ were added, the initial permeabilities, 13,200 and 13,550 were obtained, respectively. However, the sample with 1,000 ppm MoO$_3$ showed lower permeabilities because of abnormal grain growth. At the heating rate 1$0^{\circ}C$/min, the ferrite cores with 1,000 ppm MoO$_3$ demonstrated the highest initial permeability greater than 15,000, without exaggerated grain growth.

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Thermal Degradation Behavior of Biomass Depending on Torrefaction Temperatures and Heating Rates (반탄화 온도와 승온속도에 의한 바이오매스 열분해 거동)

  • Gong, Sung-Ho;Ahn, Byoung-Jun;Lee, Soo-Min;Lee, Jae-Jung;Lee, Young-Kyu;Lee, Jae-Won
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.5
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    • pp.685-694
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    • 2016
  • In this study, the thermal degradation behavior of biomass during torrefaction was studied by thermogravimetric and byproduct gas analysis. Torrefaction temperature, time, and heating rate were $220{\sim}300^{\circ}C$, 110 min, and $10{\sim}30^{\circ}C/min$, respectively. The degradation rate of yellow poplar was 8.01~8.81% at $220^{\circ}C$ and 71.86~77.38% at $300^{\circ}C$ depending on heating rate. The degradation rate significantly increased at temperature over $240^{\circ}C$. On the other hand, degradation rate of larch was relatively low as 49.58~54.15% at $300^{\circ}C$. The activation energy of yellow poplar was 87.32~91.24 kJ/mol; these values did not significantly change with heating rate. The activation energy of larch was 83.85~91.60 kJ/mol. The major components of the gas generated during torrefaction were derived from hemicellulose. The component types and concentrations increased with torrefaction severity. High concentrations of furfural and acetic acid were detected during torrefaction of yellow poplar.

Oxidative Dehydrogenation of n-Butenes over BiFe0.65MoP0.1 Oxide Catalysts Prepared with Various Synthesis Method (다양한 합성 방법으로 제조된 BiFe0.65MoP0.1 산화물 촉매 상에서 n-부텐의 산화탈수소화 반응)

  • Park, Jung-Hyun;Shin, Chae-Ho
    • Korean Chemical Engineering Research
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    • v.53 no.3
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    • pp.391-396
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    • 2015
  • To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, $BiFe_{0.65}MoP_{0.1}$ oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $NH_3/1$-butene-temperature programmed desorption ($NH_3/1$-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, $BiFe_{0.65}MoP_{0.1}$ oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of $NH_3$-TPD, the catalytic activity is closely related to the acidity of the $BiFe_{0.65}MoP_{0.1}$-x oxide catalyst and acidity of the $BiFe_{0.65}MoP_{0.1}$ oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (< $200^{\circ}C$) and the desorbing temperature of strongly adsorbed intermediates (> $200^{\circ}C$).

Process Development for Production of Ultramarine Blue from Kaolin (고령토로부터 군청안료 제조)

  • Choi, Young-Yoon;Lee, Hoo-In;Kim, Byung-Su;Kim, Sang-Bae
    • Journal of the Mineralogical Society of Korea
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    • v.22 no.2
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    • pp.107-114
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    • 2009
  • In present study, an alternative process for manufacturing ultra marine blue by using kaolin, sulfur, sodium carbonate, silica, and rosin was investigated. From the experiments, it was found in the reductive calcination process that the temperature variation with the bed height of input materials is relatively high due to the inadequate thermal conductivity of them. It was also found that the color of the ultramarine blue manufactured is sensitive for the shape of the input materials and the calcinations conditions, and specially the heating rate is very important to form ultramarine. For manufacturing green ultramarine by using sulfur, sodium carbonate, silicon, and pine resin, an optimum condition was investigated to be the heating rate region below $0.6^{\circ}C/min$, the reaction temperature of $850^{\circ}C$ and the reaction time of 4 hr. At the oxidative calcination process to manufacture ultra marine blue from green ultramarine, the optimum flow rate of air is $500{\sim}550\;{\ell}/kg$ (green ultramarine) and the reaction temperature is $500{\sim}550^{\circ}C$.

Minimum Ignition Temperature of Zn-Al Dust Mixture Layer (Zn-Al혼합물 퇴적분체의 최소발화온도)

  • Han, Ou-Sup;Lee, Su-Hee
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2012.04a
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    • pp.345-348
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    • 2012
  • 본 연구는 Zn-Al혼합물 분진의 화재폭발사고예방을 위한 안전자료 확보를 목적으로 최소발화온도를 실험적으로 조사하였다. Zn-Al혼합물의 최소발화온도 측정은 퇴적두께 10 mm, 직경 100 mm의 원형 형태로 퇴적된 시료를 대상으로 가열판의 승온속도 $20^{\circ}C/min$의 조건에서 실시하였다. 그 결과, $280^{\circ}C$에서 Zn-Al혼합물 분체는 가열 후 1000 s부터 발열을 통하여 급격히 온도가 상승하여 발화 여부 판단기준이 되는 $450^{\circ}C$를 넘어 $600^{\circ}C$에 다다르며 시간과 함께 감소하였으며 임계 최소발화온도는 $280^{\circ}C$로 나타났다. 퇴적Zn-Al혼합물 분체의 최소발화온도는 문헌에 제시된 Al에 비하여는 낮은 것으로 나타났다.

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