• Title, Summary, Keyword: Sol-gel

Search Result 2,433, Processing Time 0.046 seconds

Properties of Nano-Hybrid Coating Films Synthesized from Colloidal Silica-Silane (콜로이달 실리카와 실란으로부터 합성된 나노하이브리드 코팅 박막의 특성)

  • Na, Moon-Kyong;Ahn, Myeong-Sang;Kang, Dong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.232-233
    • /
    • 2006
  • In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

  • PDF

Improved Immobilized Enzyme Systems Using Spherical Micro Silica Sol-Gel Enzyme Beads

  • Lee, Chang-Won;Yi, Song-Se;Kim, Ju-Han;Lee, Yoon-Sik;Kim, Byung-Gee
    • Biotechnology and Bioprocess Engineering:BBE
    • /
    • v.11 no.4
    • /
    • pp.277-281
    • /
    • 2006
  • Spherical micro silica sol-gel immobilized enzyme beads were prepared in an emulsion system using cyclohexanone and Triton-X 114. The beads were used for the in situ immobilization of transaminase, trypsin, and lipase. Immobilization during the sol to gel phase transition was investigated to determine the effect of the emulsifying solvents, surfactants, and mixing process on the formation of spherical micro sol-gel enzyme beads and their catalytic activity. The different combinations of sol-gel precursors affected both activity and the stability of the enzymes, which suggests that each enzyme has a unique preference for the silica gel matrix dependent upon the characteristics of the precursors. The resulting enzyme-entrapped micronsized beads were characterized and utilized for several enzyme reaction cycles. These results indicated improved stability compared to the conventional crushed form silica sol-gel immobilized enzyme systems.

Development of Hybrid Sol-Gel Coating to Prevent Corrosion of Magnesium Alloys (마그네슘 합금의 방청을 위한 하이브리드 졸-겔 코팅제의 개발)

  • Lee, Dong Uk;Kim, Young Hoon;Moon, Myung Jun
    • Corrosion Science and Technology
    • /
    • v.17 no.1
    • /
    • pp.30-36
    • /
    • 2018
  • The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density ($I_{corr}$). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.

Preparation conditions of YBCO Superconducting Sol-Gel Powder (YBCO 초전도 분말의 졸겔 제작법에 관한 조건 연구)

  • Cho, Yong-Joon;Soh, Dea-Wha;Jeon, Yong-Woo;Park, Jeong-Cheul
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.555-558
    • /
    • 2004
  • In this paper, the variable producing conditions of YBCO superconducting powder by use of sol-gel method was investigated. YBCO superconducting powder which was prepared by sol-gel method was shown the characteristic gel formation, particle size and its properties under variable preparation conditions, such as pH, drying and processing time, and powder heat treatment, etc.

  • PDF

Sol-Gel법으로 제조한 $TiO_2$ 박막의 전기적 특성

  • 이병수;이덕출
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.110-110
    • /
    • 2000
  • Sol-Gel법은 산화물 전구체(precursor) 상태인 Sol상태로부터 가수분해, 중, 축합반응을 거쳐 최종적으로 Gel 산화물을 합성하는 방법이며 기존의 세라믹스를 합성할 수 있고 고순도의 균질한 화합물을 용이하게 얻을 수 있는 특징이 있다. 최근 전자부품이 소형, 경량화되는 추세에 따라 전자 세라믹스분야에서도 박막화가 대두되고 있는 가운데 Sol-Gel법은 dipping, spining 및 spray 법등을 이용하여 박막의 제작이 가능하며 CVD, PVD, sputtering 법등과 같은 박막제작에 비하여 장비가 복잡하지 않으면서 제작기법이 간단한 이점을 가지고 있다. 소재면에서 볼 때 TiO2 물질은 물리적, 화학적으로 안정하고 굴절율, 착샐율 및 반사율 등이 우수한 재료로서 세라믹스 콘센서, 압전소자, 습도센서와 가스센서분야등에 있어서 중요한 위치를 점하고 있어서 연구자들에게 많은 관심을 가지게 하였다. 본 연구에서는 Sol-Gel법에 의해 TiO2 Sol을 합성한 후 dipping 법으로 박막을 제작하고 박막의 전기전도 특성 및 습도센서소재로의 개발을 위해 습도감지특성에 주목하였고 경시변화로 인해 생성된 Gel powder의 물성에 대해서도 검토하였다.

  • PDF

Comparison of Tribological Characteristics of ZnO Coatings Prepared by Sputtering and Sol-gel Methods

  • Lin, Li-Yu;Kim, Dae-Eun
    • KSTLE International Journal
    • /
    • v.10 no.1_2
    • /
    • pp.23-26
    • /
    • 2009
  • In this work the tribological characteristics were compared between ZnO coatings on glass substrate prepared by sputtering and sol-gel methods. In order to assess the effects of processing method on the tribological characteristics, the friction and wear properties of the coatings were measured by using a reciprocating type of micro-tribotester. The sputtered ZnO coatings were prepared on a glass substrate at room temperature, $150^{\circ}$, and $300^{\circ}$. The ZnO coatings prepared by sol-gel method were heat-treated in air atmosphere at $550^{\circ}$ for one hour. The crystal structure and surface morphology of the coatings were measured by X-ray diffraction (XRD) and Atomic Force Microscope (AFM), respectively. The experimental results showed that overall the sputtered coatings exhibited better friction and wear properties than coatings prepared by sol-gel method. The sputtered coating grown at room temperature had a relatively low friction coefficient of 0.14 and superior wear resistance compared with the other coatings. Nevertheless, sol-gel method of coating ZnO on glass is beneficial for economical coating of a large surface area.

Properties of $TiO_2-V_2O_5$ Ceramics Prepared by Sol-Gel Method (솔젤법으로 제작한 $TiO_2-V_2O_5$ 세라믹스의 물성)

  • You, Do-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.56 no.7
    • /
    • pp.1255-1260
    • /
    • 2007
  • [ $TiO_2-V_2O_5$ ] sol was prepared using sol-gel method. Sol changed to gel with hydrolysis and polymerization. DTA properties of gel powder had endothermic reaction due to evaporation of propanol about $80^{\circ}C$, had exothermic reaction due to combustion of propanol about $230^{\circ}C$ and had exothermic reaction due to combustion of alkyl group about $350^{\circ}C$. Crystalline properties of gel powder retained amorphous phase at $50^{\circ}C$, retained anatase phase from $400^{\circ}C\;to\;600^{\circ}C$ and had all rutile phase over $700^{\circ}C$ at 0.01mole $V_2O_5$ additive. The capacitance of thin films increased with increasing heat treatment temperature and thin films had best properties at $700^{\circ}C$. The capacitance of thin films increased a lot with decreasing measurement frequency.

Intramolecular Excimer Formation Processes of 1,3-Dipyrenylpropane in Silicate Sol-Gel

  • Gwon, Mi Su;Lee, Yun Hui;An, Byeong Tae;Lee, Min Yeong
    • Bulletin of the Korean Chemical Society
    • /
    • v.17 no.2
    • /
    • pp.158-162
    • /
    • 1996
  • The steady-state emission and fluorescence lifetimes of 1,3-dipyrenylpropane were measured in silicate sol-gel and xerogel matrices. In sol solution, the fluorescence emission spectra of monomer and excimer resemble those in hydrocarbon solvents. In gel and xerogel condition, however, the fluorescence spectra exhibit significant change, largely confirming the intramolecular motions in gel pores are influenced by microviscosity. The rate constants for intramolecular excimer formation were obtained from the measured fluorescence lifetimes and the rate processes for excimer forming in silicate sol-gel are described by a simple kinetic scheme.

  • PDF

Preparation and Characteristics of PLT(28) Thin Film Using Sol-Gel Method (Sol-Gel 법을 이용한 PLT(28) 박막의 제작과 특성)

  • Kang, Seong-Jun;Joung, Yang-Hee;Yoo, Jae-Hung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • v.9 no.2
    • /
    • pp.865-868
    • /
    • 2005
  • We fabricated the $Pb_{0.72}La_{0.28}TiO_3 (PLT(28))$ thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of 100% perovskite phase by drying at 350$^{\circ}C$ after each coating and final annealing at 650$^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the Pt/Ti/SiO$_2$/Si substrate and its dielectric constant and leakage current density were measured as 936 and 1.1${\mu}$A/cm$^2$, respectively

  • PDF

Preparation and Characteristics of PLT(28) Thin Film Using Sol-Gel Method (Sol-Gel 법을 이용한 PLT(28) 박막의 제작과 특성)

  • Kang Seong Jun;Joung Yang Hee;Yoo Jae-hung
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.9 no.7
    • /
    • pp.1491-1496
    • /
    • 2005
  • We fabricated the $Pb_{0.72}La_{0.28}TiO_3$ (PLT(28)) thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of $100\%$ perovskite phase by drying at $350^{\circ}C$ after each coating and final annealing at $650^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the $Pt/Ti/SiO_2/Si$ substrate and its dielectric constant and leakage current density were measured as 936 and $1.1{\mu}A/cm^2$, respectively.