• 제목/요약/키워드: Phase Composition

검색결과 2,048건 처리시간 0.026초

AlN-SiO2-Al2O3계로부터 AlN-Polytypes의 제조 (Synthesis of AlN-SiO2-Al2O3 System)

  • 박용갑;장병국
    • 한국세라믹학회지
    • /
    • 제26권1호
    • /
    • pp.31-36
    • /
    • 1989
  • In order to synthesize AlN-polytypes from AlN-SiO2-Al2O3 system, composition A (AlN/SiO2/Al2O3=1/0.3/0.05, mole ratio) and composition B(AlN-SiO2-Al2O3=1/0.2/0.05, mole ratio) were used. AlN-polytypes were produced by nitriding the mixture at 175$0^{\circ}C$~190$0^{\circ}C$ under N2 atmosphere. For lower reaction temperature, 15R phase was produced and in the case of higher reaction temperature, AlN phase was only produced. As each composition was heated at 185$0^{\circ}C$ in N2 atmosphere, produced main phases were 15R phase for composition A and 21R phase for composition B respectively. The fracture surfaces of produced reactants showed porous skeleton structure.

  • PDF

Effect of Phase Stability on the Microstructure Development of α-SiAlON Ceramics

  • Kim, Joosun;Lee, Hae-Weon;Chen, I-Wei
    • 한국분말재료학회지
    • /
    • 제10권2호
    • /
    • pp.118-122
    • /
    • 2003
  • Alpha-SiAlON ceramics having various compositions and modifying cations were investigated with respect to their phase stability, transformation kinetics. and resulting microstructures. Each composition was heat treated at 150$0^{\circ}C$ for 1h and measured the $\alpha$-SiAlON transformation. The phase-boundary composition in the single-phase $\alpha$-SiAlON region showed sluggish transformation from $\alpha$-$Si_3N_4$ to $\alpha$-SiAlON compared to the phase-center composition in the diagram. Using the different rare earth modifying cations, dependence of transformation kinetics on the phase stability in a fixed composition was also explained. By changing size of the stable u-phase region with exchanging cations, systematic change in transformation was observed. Transformation rate of $\alpha$-SiAlON at low temperature has an important role on controlling the final microstructure. Less transformation gives more chances to develop elongated grain in the microstructure.

잉여 없는 웹 서비스 조합을 위한 2단계 탐색 알고리즘 (Two-phase Search Algorithm for Web Services Composition Redundanty)

  • 김현지;권준호;이대욱;이석호
    • 한국정보과학회논문지:데이타베이스
    • /
    • 제36권2호
    • /
    • pp.123-138
    • /
    • 2009
  • 최근 웹 서비스 관련 기술들이 많은 관심을 받고 있다. 그 중 하나인 웹 서비스 컴포지션에 대한 연구도 활발히 진행되고 있다. 웹 서비스 컴포지션은 기존에 존재하던 웹 서비스들을 조합하여 마치 하나의 서비스처럼 보여 주는 것이다. 웹 서비스 컴포지션을 사용하면 기존에 존재하지 않던 웹 서비스의 기능도 제공할 수 있으며 사용자에게 더 많은 질의 결과를 줄 수도 있다. 기존의 많은 웹 서비스 컴포지션 관련 연구들은 전향 혹은 후향 체인 방식을 사용하였다. 그러나 전향 체인 방식이나 후향 체인 방식은 질의와 상관없는 방향을 탐색하는 경우가 많기 때문에 많은 시간이 걸린다는 단점이 있다. 전향과 후향을 모두 사용하여 2단계로 컴포지션을 찾는 방식도 있으나, 이 방식은 컴포지션에 포함되지 않아도 되는 웹 서비스를 포함한 결과를 낸다는 문제점이 있다. 본 논문에서는 전향 단계와 후향 단계를 거쳐 웹 서비스 컴포지션을 찾는 2단계 웹 서비스 컴포지션 탐색 방법을 제안하였다. 전향 단계에서는 미리 구축한 연결 인덱스를 사용하여 좀 더 빠르게 후보 컴포지션을 찾는다. 후향 단계에서는 토큰을 사용하여 후보 컴포지션을 잉여 웹 서비스가 포함되지 않은 컴포지션으로 분해한다. 실험을 통해 2단계 웹 서비스 컴포지션이 기존의 한 방향으로 진행하는 방식보다 더 효율적이라는 것을 보였다. 또한 기존의 2단계 방식보다 더 많은 컴포지션 결과를 사용자에게 돌려주면서도 실행 시간 면에서 기존의 2단계 방식에 필적한다는 것을 보였다.

알루미나 조성에 따른 고강도 자기 애자의 특성 연구 (Study on Characteristics of Porcelain Insulators for High Strength with Alumina Composition)

  • 조한구;한세원;박기호;최연규
    • 한국전기전자재료학회논문지
    • /
    • 제17권3호
    • /
    • pp.353-359
    • /
    • 2004
  • In this study. porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about l7wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and B which have the Cristobalite phase. In dielectrics test on porcelain samples with below l7wt% alumina composition, it was found that the amount of glass phase(SiO$_2$) have an main effect to decrease the dielectric loss(tan$\delta$), and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro tracks analysis, HRB were measured, then the intensity of HRB increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

Mobile Phase Compositions for Ceramide III by Normal Phase High Performance Liquid Chromatography

  • Hong, Seung-Pyo;Lee, Chong-Ho;Kim, Se-Kyung;Yun, Hyun-Shik;Lee, Jung-Heon;Row, Kyung-Ho
    • Biotechnology and Bioprocess Engineering:BBE
    • /
    • 제9권1호
    • /
    • pp.47-51
    • /
    • 2004
  • Ceramide III was prepared by the cultivation of Saccharomyces cerevisiae. Ceramide III was partitioned from the cell extracts by solvent extraction and analyzed by Normal Phase High Performance Liquid Chromatography (NP-HPLC) using Evaporative Light Scattering Detector (ELSD). We experimentally determined the mobile phase composition to separate ceramide III with NP-HPLC. Three binary mobile phases of n-hexane/ethanol, n-hexane/lsoprophyl Alcohol(IPA) and n-hexane/n-butanol and one ternary mobile phase of n-hexane/IPA/methanol were demonstrated. For the binary mobile phase of n-hexane/ethanol, the first mobile phase composition, 95/5(v/v), was step-increased to 72/23(v/v) at 3 min. In the binary mobile phase, the retention time of ceramide III was 7.87min, while it was 4.11 min respectively in the ternary system, where the mobile phase composition of n-hexane/IPA/methanol, 85/7/8(v/v/v), was step-increased to 75/10/15(v/v/v) at 3 min. However, in the ternary mobile phase, the more peak area of ceramide III was observed.

동테이프 위의 Bi-계 초전도 후막에서 전구체분말 조성의 영향 (The Effect of the precursor powder composition for Bi-system superconducting thick films on Cu tapes)

  • 한상철;성태현;한영희;이준성;김상준
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
    • /
    • pp.65-68
    • /
    • 1999
  • A well oriented Bi2212 superconductor thick films were fabricated by screen printing with a Cu-free Bi-Sr-Ca-O mixture powder on a copper plate and heat-treating at 820-88$0^{\circ}C$ for several minute in air. During the heat-treatment, the printing layer partially melted by reaction between the Cu-free precursor and CuO of the oxidizing copper plate. In the partial melting state, it is believed that the solid phase is Bi-free phase and Cu-rich phase and the composition of the liquid is around Bi : Sr : Ca : Cu = 2 : 2 : 0 : 1. Following the partial melting, the Bi2212 superconducting phase is formed at Bi-free phase/liquid interface by nucleation and grows. With decreasing the Bi composition in the precursor powder, the critical temperature(T$_{c}$) of the fabricated Bi2212 thick film increased to about 79 K.K.

  • PDF

송전용 자기재 현수애자의 고강도 특성 연구 (A Study on the High Strength of porcelain insulators for transmission line)

  • 조한구;한세원;박기호;최연규;이동일;최인혁;김태영
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
    • /
    • pp.85-88
    • /
    • 2003
  • In this study, porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about 17wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and 8 which have the Cristobalite phase. In dielectrics test on porcelain samples with below 17wt% alumina composition, it was found that the amount of glass phase$(SiO_2)$have an main effect to decrease the dielectric loss$(tan{\delta})$, and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro cracks analysis, HRS were measured, then the intensity of HRS increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

  • PDF

InGaN/GaN 양자우물의 SA-MOVPE에서 표면확산을 고려한 박막성장 해석 (Analysis of Film Growth in InGaN/GaN Quantum Wells Selective Area Metalorganic Vapor Phase Epitaxy including Surface Diffusion)

  • 임익태;윤석범
    • 반도체디스플레이기술학회지
    • /
    • 제10권3호
    • /
    • pp.29-33
    • /
    • 2011
  • Film growth rate and composition variation are numerically analyzed during the selective area growth of InGaN on the GaN triangular stripe microfacet in this study. Both the vapor phase diffusion and the surface diffusion are considered to determine the In composition on the InGaN surface. To obtain the In composition on the surface, flux of In atoms due to the surface diffusion is added to the concentration determined from the Laplace equation which is governing the gas phase diffusion. The solution model is validated by comparing the growth rates from the analyses to the experimental results of GaN and InN films. The In composition and resulting wave length are increased when the surface diffusion is considered. The In content is also increased according to the increasing mask width. The effect of mask width to the In content and wave length is increasing in the case of a small open region.

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

  • 김대업;정승부;강정윤
    • Journal of Welding and Joining
    • /
    • 제18권5호
    • /
    • pp.90-97
    • /
    • 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.

  • PDF

EPMA quantification on the chemical composition of retained austenite in a Fe-Mn-Si-C-based multi-phase steel

  • Yoon‑Uk Heo;Chang‑Gon Jeong;Soo‑Hyun Kim;Gun‑Young Yoon;T. T. T. Trang;Youngyun Woo;Eun Yoo Yoon;Young‑Seon Lee
    • Applied Microscopy
    • /
    • 제52권
    • /
    • pp.14.1-14.10
    • /
    • 2022
  • An electron probe X-ray microanalyzer (EPMA) is an essential tool for studying chemical composition distribution in the microstructure. Quantifying chemical composition using standard specimens is commonly used to determine the composition of individual phases. However, the local difference in chemical composition in the standard specimens brings the deviation of the quantified composition from the actual one. This study introduces how to overcome the error of quantification in EPMA in the practical aspect. The obtained results are applied to evaluate the chemical com position of retained austenite in multi-phase steel. Film-type austenite shows higher carbon content than blocky-type one. The measured carbon contents of the retained austenite show good coherency with the calculated value from the X-ray diffraction.