• Title/Summary/Keyword: Degree of crystallization

Search Result 109, Processing Time 0.023 seconds

Experimental study on freezing point of saline soft clay after freeze-thaw cycling

  • Wang, Songhe;Wang, Qinze;Qi, Jilin;Liu, Fengyin
    • Geomechanics and Engineering
    • /
    • v.15 no.4
    • /
    • pp.997-1004
    • /
    • 2018
  • The brine leakage is a tough problem in artificial freezing engineering. This paper takes the common soft clay in Wujiang District as the study object, and calcium chloride solutions with six salinity levels were considered. The 'classic' cooling curve method was employed to measure the freezing point of specimens after freeze-thaw. Results indicate that four characteristic stages can be observed including supercooling, abrupt transition, equilibrium and continual freezing, strongly dependent on the variation of unfrozen water content. Two characteristic points were found from the cooling curves, i.e., freezing point and initial crystallization temperature. A critical value for the former exists at which the increment lowers. The higher the saline content approximately linearly, lower the freezing point. In the initial five cycles, the freezing point increases and then stabilizes. Besides, the degree of supercooling was calculated and its correlations with water, salt and freeze-thaw cycles were noted. Finally, an empirical equation was proposed for the relationship of freezing point and three main factors, i.e., water content, saline content and freeze-thaw cycles. Comparison of calculated and measured data proves that it is reliable and may provide guidance for the design and numerical analysis in frozen soil engineering.

Crystallization and Optical Properties of Transparent AZO Thin Films (AZO 투명전극의 결정성과 광학적 특성)

  • Oh, Teresa
    • Journal of the Korean Vacuum Society
    • /
    • v.21 no.4
    • /
    • pp.212-218
    • /
    • 2012
  • The optical properties of AZO thin films prepared by the RF mangnetron sputtering system was studied to research the dependance of chemical properties of substrate. The substrate was the SiOC film deposited by Inductively coupled plasma chemical vapor deposition with various gas flow rate of $O_2$ and Ar (DMDMOS). In accordance with the increase of Ar gas flow rates, the Si-O bond in the SiOC film increased and then progressed the amorphism. The roughness of AZO grown on SiOC film with high degree of amorphism decreased and then improved the flatness of surfaces. Moreover, the ultra violet emission with high intensity was spontaneously induced in the AZO film growed on SiOC film with high degree of amorphism.

The Effect of Methylated Cyclodextrins on the Morphological Change of Poly(3-hydroxybutyrate) with and without the Formation of Inclusion Complex

  • Shin, Kyung-Moo;Dong, Tungalag;Inoue, Yoshio
    • Proceedings of the Polymer Society of Korea Conference
    • /
    • 2006.10a
    • /
    • pp.351-351
    • /
    • 2006
  • The possible interactions between cyclodextrins and biodegradable polyesters were investigated. The hydrophobicity of cyclodextrin could be varied with the methyl substitution of host CD, and the possibility of IC formation and the types of interaction between respective CDs and polyesters were subsequently changed. Further, the effect of cyclodextrins on the morphological change of biodegradable polymer was shown to depend on the degree of IC formation between cyclodextrin and biodegradable polymer as well as on the type of interaction between respective CDs and polyesters. That is, the enhancement and/or the restriction of the crystallization of P(3HB) were observed by the incorporation of various kind of cyclodextrins with different cavity size and hydrophobicity.

  • PDF

Correlation defects of macrostructure with morphology of BGO crystals grown by low thermal gradient Czochralski technique

  • Shlegel, V.N.;Shubin, Yu.V.;Ivannikova, N.V.
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.13 no.1
    • /
    • pp.1-4
    • /
    • 2003
  • In the present work we consider morphological structure of the faces of BGO crystals grown by Czochralski technique under the conditions of low temperature gradient (0.1~1 deg/cm) and interconnection between the morphological features of faces at the crystallization front and the formation of defects within the crystal volume. It is demonstrated that the {112} faces retain stability while the growing surface deviates from the crystallographic (112) plane up to 1 degree. At larger deviation, the region of the stable facet growth passes either to the region of macrosteps or to the region of normal growth. depending on conditions.

Crack-Free Fabrications of Yttria-Stabilized Zirconia Films Using Successive-Ionic-Layer-Adsorption-and-Reaction and Air-Spray Plus Method

  • Taeyoon Kim;Sangmoon Park
    • Korean Journal of Materials Research
    • /
    • v.34 no.2
    • /
    • pp.79-84
    • /
    • 2024
  • Thin films of yttria-stabilized zirconia (YSZ) nanoparticles were prepared using a low-temperature deposition and crystallization process involving successive ionic layer adsorption and reaction (SILAR) or SILAR-Air spray Plus (SILAR-A+) methods, coupled with hydrothermal (175 ℃) and furnace (500 ℃) post-annealing. The annealed YSZ films resulted in crystalline products, and their phases of monoclinic, tetragonal, and cubic were categorized through X-ray diffraction analysis. The morphologies of the as-prepared films, fabricated by SILAR and SILAR-A+ processes, including hydrothermal dehydration and annealing, were characterized by the degree of surface cracking using scanning electron microscopy images. Additionally, the thicknesses of the YSZ thin films were compared by removing diffusion layers such as spectator anions and water accumulated during the air spray plus process. Crack-free YSZ thin films were successfully fabricated on glass substrates using the SILAR-A+ method, followed by hydrothermal and furnace annealing, making them suitable for application in solid oxide fuel cells.

Effect of Ion Damage on the Crystallization of PZT thin films (이온주입이 PZT 박막의 결정화에 미치는 영향)

  • 박응철;이장식;박정호;이병일;주승기
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.5
    • /
    • pp.418-424
    • /
    • 2000
  • Effects of Ar ion damage prior to the phase transformation from pyrochlore to perovskite structure of PZT thin films have been investigated. As the degree of damage increased by increasing the acceleration voltage in the ion mass doping system, the phase transformation temperature decreased such that the temperature could be lowered down to 550$^{\circ}C$ when the film was damaged at 15 kV for 5 minutes. When the film was damaged prior to the heat treatment grain size of the perovskite thin films became less than 300${\AA}$. It turned out that relatively high value of the remanent polarization (about 30${\mu}$C/$\textrm{cm}^2$) as well as improvement of the fatigue characteristics to a large extent is closely related to the fine grain size of thus obtained PZT films.

  • PDF

The Effect of the Structure of the Carbon Fibers on the Structure of the Fiber Intercalated Compounds (탄소섬유의 구조가 섬유층간화합물의 구조에 미치는 영향)

  • 김인기;최상흘;고영신
    • Journal of the Korean Ceramic Society
    • /
    • v.30 no.9
    • /
    • pp.768-774
    • /
    • 1993
  • Sulphuric acid was intercalated in mesophase pitch based graphite fiber (Thornel P100 of Amoco), PAN based graphite fiber (M40 of Thoray) and PAN based carbon fiber (T300 ofThoray, TZ307 of Taekwang in Korea) by 0.4wt% CrO3/H2SO4 solution. The degree of crystallization of fibers increased P100, M40, TZ307, T300 fiber in order and their d002 values were 3.384, 3.424, 3.470, 3.493$\AA$, respectively. After intercalation P100 fiber formed 1 stage compound whose d002 value was 3.994$\AA$(d001=7.988$\AA$). Other fibers showed (002) reflection belonging to their 1 stage comound and prinstine fiber.

  • PDF

Low temperature preparation of $SnO_2$ films by ICP-CVD (ICP-CVD를 이용한 $SnO_2$ 박막 저온 증착)

  • Lee, H.Y.;Lee, J.J.
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • 2007.04a
    • /
    • pp.157-158
    • /
    • 2007
  • Tin oxide films were successfully crystallized without additional heating by inductively coupled plasma assisted chemical vapor deposition (ICP-CVD). The degree of crystallization was affected by the ICP power, hydrogen flow and ion bombardment induced by negative substrate bias. The substrate temperature was increased only up to $150^{\sim}180^{\circ}C$ by plasma heating, which suggests that the formation of $SnO_2$ crystalswas caused by enhanced reactivity of precursors in high density plasma. The hardness of deposited tin oxide films ranged from 5.5 to 11GPa at different hydrogen flow rates.

  • PDF

Mechanical Properties and Microstructure of Dental Heat-Pressable Glass-Ceramics (치과용 열가압 글라스 세라믹스의 기계적 성질과 미세구조)

  • 이해형;이병택
    • Journal of the Korean Ceramic Society
    • /
    • v.41 no.2
    • /
    • pp.143-150
    • /
    • 2004
  • Biaxial flexure strength (ball-on-3-ball) and fracture toughness (indentation microfracture) of heat-pressable glass-ceramics for dental use were investigated in this study. Crystal phase and microstructure of glass-ceramics were analyzed by XRD. SEM, and TEM. Crack propagation in specimens was not effectively arrested by dispersed crystalline particles. However, higher degree of crystallization probably contributes to strengthening of glass-ceramics. Better clinical reliability can be expected from lithium disilicate glass-ceramic because of its significantly higher biaxial flexure strength and fracture toughness.

Electron Beam Effects on Lignin Stabilization during Carbonization

  • Lee, Byoung-Min;Kang, Phil-Hyun;Jeun, Joon-Pyo
    • Journal of Radiation Industry
    • /
    • v.7 no.2_3
    • /
    • pp.167-170
    • /
    • 2013
  • Lignin can be a valuable natural chemical resource. Structurally, lignin is a three-dimensional polymer made up of condensed C-C bonds and some ether linkages, most of which are not readily degraded. In this study, lignin carbonization under various electron beam pretreatment conditions was characterized through a thermogravimetric analysis (TGA), X-ray diffraction (XRD) and Raman spectroscopy. Lignin stabilization was controlled by various doses of electron beam irradiation corresponding to 50, 100, 200, 500 and 1,000 kGy; the carbonization process was performed under a nitrogen gas atmosphere at $1000^{\circ}C$ for 1 h. The TGA results showed that a 1,000 kGy lignin dose increased the residue weight from 39.96% to 45.23%, compared to non-irradiated lignin. This observation is in agreement with the XRD and Raman spectroscopy results, in which the two theta degrees and the degree of crystallization were improved by increasing the electron beam irradiation.