Hollow Mullite Ceramic Microspheres by Water Extraction of Emulsified Aqueous Droplets

1994 ◽  
Vol 346 ◽  
Author(s):  
Guoxu Liu ◽  
David L. Wilcox
Keyword(s):  
Sol Gel ◽  
Model Material ◽  
Water Extraction ◽  
Microelectronic Packaging ◽  
Droplet Dispersion ◽  
Mullite Ceramic ◽  
Sol Gel Process ◽  
Potential Applications ◽  
Important Processing ◽  
Aqueous Droplet

ABSTRACTThis paper describes a novel colloidal route for the preparation of hollow mullite ceramic microspheres with sizes in the range of 10 μm. An emulsion technique was combined with a water extraction sol-gel process, to form an aqueous droplet dispersion and gel the resulting droplets by extracting water with a dehydrating liquid. The liquid-filled gelled microcapsules were then dried and fired to form hollow ceramic microspheres. Important processing variables controlling the microspherc morphology were determined and a formation mechanism was proposed. Due to its potential applications in microelectronic packaging, mullite was selected as the model material for the present work, but the synthesis technique may be used for making other single or multiphase ceramic compositions

Mechanical Behavior of Bioactive Glass-Polyvinyl Alcohol Hybrid Foams Obtained by the Sol-Gel Process

2005 ◽  
Vol 284-286 ◽  
pp. 757-760 ◽  
Author(s):  
Marivalda Pereira ◽  
Showan N. Nazhat ◽  
Julian R. Jones ◽  
Larry L. Hench
Keyword(s):  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Mechanical Behavior ◽  
Sol Gel ◽  
Precursor Solution ◽  
High Porosity ◽  
Soft Tissue Regeneration ◽  
Sol Gel Process ◽  
Potential Applications ◽  
Hybrid Foams

The possibility of enhancing mechanical properties by incorporation of polymeric components to sol-gel derived materials is extremely attractive to prepare macroporous scaffolds, leading to materials with potential applications in both hard and soft tissue regeneration. In this work bioactive glass-polyvinyl alcohol hybrids were developed and their mechanical behavior was evaluated. Hybrids were synthesized by adding polyvinyl alcohol to a sol-gel precursor solution, which was then foamed with the addition of a surfactant and vigorous agitation. The foams were cast, aged and dried at 40°C. A cleaning step to decrease the acidic character of the obtained hybrids was undertaken by immersion in a NH4OH solution. The mechanical behavior of the hybrids was evaluated in compression using both stress and strain control tests. Hybrid foams had a high porosity varying from 60-90% and the macropore diameter ranged from 10 to 600 µm. The modal macropore diameter varied with the inorganic phase composition and with the polymer content in the hybrid. The strain at fracture of the as prepared hybrid foams was substantially greater than pure gel-glass foams. The cleaned hybrids presented a slightly higher strength and lower deformation than the as prepared foams.

Needle-Like Mullite Ceramic Prepared by Sol-Gel Process

2011 ◽  
Vol 233-235 ◽  
pp. 2640-2643 ◽  
Author(s):  
Fu Sheng Song
Keyword(s):  
Powder Diffraction ◽  
Solid Phase ◽  
Raw Materials ◽  
Sol Gel ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Mullite Ceramic ◽  
X Ray ◽  
Sol Gel Process ◽  
Ceramic Blocks

Using tetraethoxysilane, aluminum nitrate and aluminum fluoride as raw materials, the precursor of mullite was prepared by sol-gel process. When the precursor sintered at 1200°C, mullite ceramic was obtained. Differential thermal analysis, X-ray powder diffraction and scanning electron microscope were used to characterize the dried mullite gel and ceramic blocks. The results suggest mullite is synthesized by solid-phase reaction mechanism. X-ray powder diffraction indicates mullite is the main crystals phase in the ceramic specimen. SEM micrograph shows the mullite grains in the shape of short rod with length of 20 um when sintered at 1200 °C for 2 h and the grains grown up to acicular with length of more than 50 um when the treating time under 1200 °C achieved to 4 h.

scholarly journals Sol-Gel Coatings for Electrochromic Devices

1992 ◽  
Vol 276 ◽  
Author(s):  
M. A. Macedo ◽  
L. H. Dall'Antonia ◽  
M. A. Aegerter
Keyword(s):  
Heat Treatment ◽  
Sol Gel ◽  
Radiant Energy ◽  
Electrochromic Devices ◽  
Smart Windows ◽  
Ito Glass ◽  
Sol Gel Process ◽  
Ion Storage ◽  
Potential Applications ◽  
Transmission And Reflection

ABSTRACTAll solid state electrochromic smart windows with the configuration glass/ITO/WO3/electrolyte/TiO2-CeO2/ITO/glass have been realized. These devices have potential applications in architectural and automotive fields to regulate the transmission and reflection of the radiant energy. The ion storage electrode TiO2–CeO2 have been realized by sol-gel process and its electrochemical properties are studied as a function of various parameters (thickness, heat treatment, etc.). The electrochemical and optical performances of two cells are reported.

Preparation of Superconducting YBa2Cu3O7−x Compounds By Water Extraction Variant Of Sol-Gel Process

1990 ◽  
Vol 180 ◽  
Author(s):  
A. Deptula ◽  
W. Lada ◽  
T. Olczak ◽  
T. zoltowski ◽  
A. Di Bartolomeo
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Ammonium Hydroxide ◽  
Water Extraction ◽  
Spherical Particles ◽  
Acidic Solutions ◽  
Sol Gel Process

ABSTRACTThe starting sols were prepared by addition of ammonium hydroxide to acidic solutions of Y-Ba-Cu acetates or by dissolving solid Ba9CO9 or CuCO9.CuCOH)2H2O in acetates of the remaining components. The sols were then gelled to spherical particles with diameter below 50μm by extracting water with 2-ethyl-l-hexanol or to shard by evaporation of water. After thermal treatment of both powders amorphous and then crystalline YBa2Cu,9O7−x were obtained. Formation of these compounds is strongly improved by aging the gel at 200°C. Green and sintered pellets exhibit excellent superconductivity properties.

Preparation of BSCCO Precursors by Water Extraction Variant of Sol-Gel Process

1992 ◽  
Vol 271 ◽  
Author(s):  
A. Deptula ◽  
W. Lada ◽  
T. Olczak ◽  
A. Di Bartolomeo
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Water Extraction ◽  
Sol Gel Process ◽  
Emulsion Drops ◽  
Preparation Step

ABSTRACTThe starling acetate sols of molar compositions of Bi:Pb:Sr:Ca:Cu=I-2:O:2:l: 2, 11–2:0:2:2:3 and 111–1.6:0.4:2:2:3 were prepared by NH4OH addition at various rates, followed by evaporation. Sols were gelled by further evaporation to shard or to microspheres (diameter below 100 μm) by water extraction from the sol emulsion drops formed in 2-ethyl-l-hexanol. The gels were converted to BSCCO phases by thermal treatment. The processes were characterized by XRD and IR examinations. The influence of the sol preparation step connected with formation of polynuclear cations on the following stages of the process was examined.

Preparation and Characterization of Silica-Coated ZnSe Nanowires with Thermal Stability and Photoluminescence

2007 ◽  
Vol 7 (12) ◽  
pp. 4494-4500 ◽  
Author(s):  
Shenglin Xiong ◽  
Baojuan Xi ◽  
Weizhi Wang ◽  
Hongyang Zhou ◽  
Shuyuan Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Volume Ratio ◽  
Silica Coating ◽  
Sol Gel Process ◽  
High Resolution Tem ◽  
Potential Applications ◽  
Znse Nanowires

Silica-coated ZnSe nanowires with well-controlled the thickness of sheath in the range of 10–60 nm have been synthesized through a simple sol–gel process. The thickness of silica coating could be controlled through altering reaction parameters such as volume ratio of TEOS and ammonia. XRD, high-resolution TEM, X-ray photoelectron spectroscopy (XPS), Raman spectra, thermogravimetric analysis (TGA), and photoluminescence (PL) spectra were used to characterize the core/sheath nanostructures. Room-temperature PL measurements indicate these silica-coated ZnSe nanowires remarkably improve the PL intensity. Meanwhile, the thermal stability has been enhanced greatly, which is useful for their potential applications in advanced semiconductor devices.

scholarly journals Bismuth titanate nanoparticles dispersed polyacrylates

2004 ◽  
Vol 19 (8) ◽  
pp. 2343-2348 ◽  
Author(s):  
Wei-Fang Su ◽  
Jiann-Fong Lee ◽  
Ming-Yao Chen ◽  
Ron-Ming Ho
Keyword(s):  
Optical Waveguides ◽  
Bismuth Titanate ◽  
High Dielectric Constant ◽  
Coefficient Of Thermal Expansion ◽  
Sol Gel ◽  
Polymer Composition ◽  
Sol Gel Process ◽  
Potential Applications ◽  
High Dielectric

We successfully dispersed amorphous bismuth titanate nanoparticles (<50 nm)in situ in poly-hydroxy ethyl methacrylate via a sol-gel process. Since less than 20% of the polymer composition is bismuth titanate by weight, the material exhibits high refractive indices (>1.6) and good optical transparency (>90% transmittance from 530 to 800 nm). Furthermore, this highly cross-linked material has an improved thermal stability and a lower coefficient of thermal expansion than that of neat polymers. The material also displays a high dielectric constant (>10) without ferroelectricity. Thus the material has potential applications in optical lenses, optical waveguides, and capacitors.

Preparation and Characterization of ZrO2 Coating by Sol-Gel on Mullite Short Fiber

2013 ◽  
Vol 591 ◽  
pp. 66-69
Author(s):  
Ying Na Zhao ◽  
Meng Zhang ◽  
Jiang Ren ◽  
Xiong Feng Zeng
Keyword(s):  
Heat Treatment ◽  
Ph Value ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Short Fiber ◽  
Material Strength ◽  
Mullite Ceramic ◽  
Mullite Fiber ◽  
Sol Gel Process

The modified mullite fiber was used to toughen the mullite ceramic, which can effectively overcome the brittleness of ceramic materials and improve the material strength and toughness. Using 8ZrOCl2•H2O as precursor, anhydrous ethanol as solvent, H2O2 as hydrolysis promoter and NH3·H2O as precipitant, the stable and transparent zirconium sol could be obtained by sol-gel process, which coated mullite short fiber. The results showed that the stable and transparent ZrO2 sol was obtained when pH value was 3.8~4.8 and reaction temperature was at 25°C. XRD results indicated that monoclinic ZrO2 particles grew up and formed after heat-treatment at 700°C. The coating ZrO2 film combined with mullite fiber homogeneously and closely, and the film thickness was about 1 μm.

Synthesis and Electro-Optical Properties of Potassium Titanyl Phosphate thin Films by Sol-Gel Method

1997 ◽  
Vol 495 ◽  
Author(s):  
Jianping Zhang ◽  
Burtrand I. Lee ◽  
Feiling Wang ◽  
Melvin A. Leitheiser
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Sol Gel ◽  
Structural Evolution ◽  
Optical Devices ◽  
Potassium Titanyl Phosphate ◽  
Sol Gel Process ◽  
Potential Applications ◽  
Ft Ir

ABSTRACTPotassium titanyl phosphate, KTiOPO4 (KTP), thin films were prepared by sol-gel process. The structural evolution of KTP thin films was investigated by means of DTA/TGA, XRD, and FT-IR. The electro-optical results show that KTP thin films have a refractive index of 1.8 and large quadratic electro-optical coefficient of R=2.50643*10−16 and have potential applications for electro-optical devices.

Sintering of ZrO2 ‐ CeO2 Spherical Powders Prepared by a Water Extraction Variant of the Sol‐Gel Process

1993 ◽  
Vol 140 (8) ◽  
pp. 2294-2297 ◽  
Author(s):  
A. Deptula ◽  
M. Carewska ◽  
T. Olczak ◽  
W. Lada ◽  
F. Croce
Keyword(s):  
Sol Gel ◽  
Water Extraction ◽  
Sol Gel Process
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