• Title, Summary, Keyword: chemical composition

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Effect of Chemical Composition on the Microstructure and Tensile Property in TRIP-assisted Multiphase Steels (TRIP형 복합조직강의 미세조직 및 인장성질에 미치는 화학조성의 영향)

  • Lee, K.Y.;Jang, W.Y.;Kang, J.W.
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.3
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    • pp.127-133
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    • 2003
  • The effect of chemical composition on the microstructural change and tensile property in TRIP-assisted steels with different chemical composition was investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be identified as two types; a granular type in a steel containing higher Si and a film type in a steel having higher C. For the case of higher C-containing steel with a tensile strength of 860 MPa and a total elongation of 38%, film-typed retained austenite could be observed between lath bainitic ferrite. Actually, metastable retained austenite was a requisite for the good formability, which means that chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steels. With respect to tensile property, the steels containing suitable Si and Mn, respectively, showed a typical TRIP effect in stress-strain curve, while a steel containing higher Mn content exhibited the similar behavior shown in dual phase steel.

Effect of Chemical Composition on Tensile Property in TRIP-assisted Multiphase Steel for Automobile Structure (차량구조용 변태유기소성(TRIP)형 복합조직강의 인장성질에 미치는 화학조성의 영향)

  • Lee, Ki-Yeol;Bang, Il-Hwan;Ma, Ah-Ram;Kim, Young-Sun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.106-113
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    • 2007
  • The effect of chemical composition on the microstructural change and tensile property in TRIP-assisted steels with different chemical composition was investigated by using SEM, TEM, XRD and UTM. As a result of microscopic observation, the morphology of retained austenite could be identified as two types : a granular type in a steel containing higher sillicon and a film type in a steel having higher carbon. For the case of higher carbon-containing steel with a tensile strength of 860 MPa and a total elongation of 38%, film-typed retained austenite could be observed between lath bainitic ferrite. Actually, metastable retained austenite was a requisite for the good formability, which means that chemical composition plays a significant role in the microstructure and tensile property of TRIP-assisted steels. With respect to tensile property, the steels containing suitable silicon and manganese, respectively, showed a typical TRIP effect in stress-strain curve, while a steel containing higher manganese content exhibited the assimilar behavior shown in dual phase steel.

A Study on the Optimum Chemical Composition of Insert Metal for Liquid Phase Diffuse Bonding (액상확산접합용 인서트금속의 화학조성 최적화에 관한 연구)

  • 김대업;정승부;강정윤
    • Journal of Welding and Joining
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    • v.18 no.5
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    • pp.90-97
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    • 2000
  • Effect of alloy elements on joinability of insert metal for liquid phase diffusion bonding of heat resistant alloys was investigated in this study. Also, optimum chemical composition of insert metal was explained using interpolation method. The insert metals utilized was commercial Ni-base amorphous foils and newly developed Ni-base filler metals with B, Si and Cr in this study. Melting point and critical interlayer width(CIW) decreased with increasing additional amount of B, Si and Cr, melting point lowering element of the insert metal. Optimized chemical composition of insert metals could be estimated by interpolation method. The optimum amount of B, Si, Cr addition into the insert metal were found to be about 3%, 4% and 3%, respectively. The measured characteristic values, melting point, microhardness in the bonded interlayer and CIW of the insert metals were the almost identical to ones of the calculated results by interpolation method.

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The Effect of Chemical Composition on a Hardenability of Steel (강의 화학조성이 경화능에 미치는 영향)

  • Shin, Seung Ho;Chae, Jae Ho
    • Journal of the Korean Society for Heat Treatment
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    • v.2 no.4
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    • pp.40-46
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    • 1989
  • The hardenability of steel is related to its chemical composition. About this relationship, multiple regression analysis of hardenability data was proposed to explain the effect of chemical composition on a hardenability of steel. To establish the formula for calculation hardenability, given hardenability curve(U.S.S. Atlas) were quantitatively analyzed by multiple regression analysis program of computer. The established hardenability model was applied to predict the hardenability of commercial steel fair well. The effect of chemical composition was also expressed quantitatively.

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Effect of Stress on Current-Voltage Characteristics of ZnO Based Ceramics

  • Jung Ju-Yong;Kim Yeong-Cheol;Seo Hwa-Il;Chung Dong-Teak;Kim Young-Jung;Min Joon-Won
    • Journal of the Semiconductor & Display Technology
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    • v.4 no.4
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    • pp.1-4
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    • 2005
  • The chemical composition and uniaxial compressive stress are varied to observe their effect on the current-voltage characteristics of ZnO based ceramics. The variation of chemical composition produces two kinds of ceramics showing ohmic and nonohmic current-voltage characteristics. The current at a fixed voltage increased with the increase of the compressive stress for both ohmic and nonohmic ceramics. Ceramics showing nonohmic behavior exhibit better reversible return of current-voltage curve when the applied compressive stress is removed from the ceramics than those showing ohmic behavior do. We found an appropriate chemical composition showing linear relation between current and stress at a fixed voltage. The ceramic materials with an appropriate chemical composition can be used as a potential sensing material in pressure sensors.

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Compositional Analysis of Naphtha by FT-Raman Spectroscopy

  • 구민식;정호일
    • Bulletin of the Korean Chemical Society
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    • v.20 no.2
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    • pp.159-162
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    • 1999
  • Three different chemical compositions of total paraffin, total naphthene, total aromatic content in naphtha have been successfully analyzed using FT-Raman spectroscopy. Partial least squares (PLS) regression has been utilized to develop calibration models for each composition from Raman spectral bands. The PLS calibration results showed Blood correlation with those of gas chromatography (GC). Using PLS regression, the spectral information related to each composition has been successfully extracted from highly overlapped Raman spectra of naphtha.

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Chemical Durability of Simulated Waste Glasses (모의 폐기물유리의 화학적 내구성)

  • 현상훈;송원선
    • Journal of the Korean Ceramic Society
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    • v.26 no.4
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    • pp.521-531
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    • 1989
  • The dependence of the chemical durability of simulated waste glasses containing the simplified waste similar to the SRP waste on compositions of host glasses, amounts of waste loading, and kinds of leachants has been investigated as a basic study on the waste immobilization through vitrification. The maximum limit of the amount of waste loading for glassforming with the host sodium borosilicate glasses selected in this study was 50wt%. The chemical durability of waste glasses whose host glass belonged to the immiscible composition region was much higher than that of waste glasses whose host glass belonged to the miscible composition region. The former waste glass showed lower chemical durability in deionized and silicate waters than in brine, while the latter glass showed the lowest chemical durability in deionized and silicate waters than in brine, while the latter glass showed the lowest chemical durability in silicate water. It was also observed that the total leaching rates in brine were noticeably small in comparison with those in other solutions. The composition of the host borosilicate glass which was suitable for the treatment of the waste through vitrification was found to be 25 Na2O-5B2O3-70SiO2(wt.%).

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A Study on Chemical Composition of Dustfall Samples in Cheju Area - 1. Chemical composition and deposition (제주지역 강하 먼지의 조성에 관하여 - 1. 화학적 조성 및 침적량)

  • 이기호;허철구;송문호;박용이
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.1
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    • pp.13-22
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    • 1999
  • This study is carried out to investigate the chemical composition of atmospheric deposition in Cheju Island, Korea. For this purpose, dustfall matter samples are collected by dust jar from August, 1995 to July, 1996 at five sampling sites and total suspended particulate matters (TSP) and rain are also collected at one site from October, 1995 to July, 1996. All the samples collected are analyzed, and then the information of the 19 chemical species and deposition amount of each species is obtained. These data are used to determine the regional trends in dustfall chemistry and deposition, and compare the characteristics of chemical compositions between dustfall, TSP and rainwater.

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Dynamics of shearing force and its correlations with chemical compositions and in vitro dry matter digestibility of stylo (Stylosanthes guianensis) stem

  • Zi, Xuejuan;Li, Mao;Zhou, Hanlin;Tang, Jun;Cai, Yimin
    • Asian-Australasian Journal of Animal Sciences
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    • v.30 no.12
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    • pp.1718-1723
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    • 2017
  • Objective: The study explored the dynamics of shearing force and its correlation with chemical compositions and in vitro dry matter digestibility (IVDMD) of stylo. Methods: The shearing force, diameter, linear density, chemical composition, and IVDMD of different height stylo stem were investigated. Linear regression analysis was done to determine the relationships between the shearing force and cut height, diameter, chemical composition, or IVDMD. Results: The results showed that shearing force of stylo stem increased with plant height increasing and the crude protein (CP) content and IVDMD decreased but fiber content increased over time, resulting in decreased forage value. In addition, tall stem had greater shearing force than short stem. Moreover, shearing force is positively correlated with stem diameter, linear density and fiber fraction, but negatively correlated with CP content and IVDMD. Conclusion: Overall, shearing force is an indicator more direct, easier and faster to measure than chemical composition and digestibility for evaluation of forage nutritive value related to animal performance. Therefore, it can be used to evaluate the nutritive value of stylo.

Synthesis and Characterization of Fe-Co/mesoHZSM-5 : Effect of Desilication Agent and Iron-cobalt Composition

  • Jimmy, Jimmy;Roesyadi, Achmad;Suprapto, Suprapto;Kurniawansyah, Firman
    • Korean Chemical Engineering Research
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    • v.58 no.1
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    • pp.163-169
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    • 2020
  • Synthesis of Fe-Co/meso-HZSM5 catalyst, intended to be applied in Fischer-Tropsch (FT) reaction was investigated. The study emphasized the effect of desilication agents, NaOH and KOH, on the catalyst materials properties. Impregnation composition of active metal (Fe and Co) was also examined. HZSM-5, converted from ammonium ZSM-5 through calcination, was treated with NaOH and KOH for desilication, followed by impregnation with 10% metal loading. Fe composition in the initial mixture was varied at 10-50% from total composition. After impregnation, reduction was applied by flowing hydrogen gas at 400 ℃ for 10 hours. The use of KOH solution induced greater mesoporous volumes; however, it had a detrimental effect on zeolite crystal structure. NaOH solutions, on the other hand, increased mesopore area as high as 100%, indicated from surface area increase from 266.28 m2/g of HZSM-5, to 526.03 m2/g of NaOH-desilicated HZSM-5. In addition, the application of NaOH solution increased pore volume from 0.14 cc/g to 0.486 cc/g. Further, more Fe-Co alloys and less oxide of iron (Fe2O3) as well cobalt (Co3O4) had been commonly observed in the produced catalysts. The largest Fe-Co alloys could be found in 50Fe-50Co/HZSM-5