Microwave processing CaO-Al203-SiO2 Glass Using Sol-Gel Technique

1996 ◽  
Vol 430 ◽  
Author(s):  
Y. Zhou ◽  
O. Van der Biest ◽  
C. Groffils ◽  
P. J. Luypaert

AbstractGels in the CaO-A12O3-SiO2 (CAS) system were successfully converted into glass in a single mode, tuneable, cylindrical microwave applicator, operating at 2.45 GHz in the TM012 mode. Transparent glasses were formed as a result of the direct microwave heating of homogeneous CAS gels to well above their melting temperature (1170°C). The effect of processing parameters, such as incident power level, sample mass and location, and thermal insulation has been investigated. The excellent coupling of the CAS gel with microwave can be understood from the structural evolution during sol-gel processing.

2010 ◽  
Vol 438 ◽  
pp. 65-72 ◽  
Author(s):  
Andreas Mehner ◽  
Ju An Dong ◽  
Timo Hoja ◽  
Torsten Prenzel ◽  
Yildirim Mutlugünes ◽  
...  

The demand for high precision optical elements as micro lens arrays for displays increases continually. Economic mass production of such optical elements is done by replication with high precision optical molds. A new approach for manufacturing such molds was realized by diamond machinable and wear resistant sol-gel coatings. Crack free silica based hybrid coatings from base catalyzed sols from tetraethylorthosilicate (TEOS: Si(OC2H5)4) and methyltriethoxysilane (MTES: Si(CH3)(OC2H5)3) precursors were deposited onto pre-machined steel molds by spin coating process followed by a heat treatment at temperatures up to 800°C. Crack-free multilayer coatings with a total thickness of up to 18 µm were achieved. Micro-machining of these coatings was accomplished by high precision fly cutting with diamond tools. Molds with micro-structured coatings were successfully tested for injection molding of PMMA optical components. The wear resistance of the coatings was successfully tested by injection molding of 1000 PMMA lenses. Hardness and elastic modulus of the coatings were measured by nano indentation. The chemical composition was measured by X-ray photo electron spectroscopy (XPS) as a function of the sol-gel processing parameters.


1997 ◽  
Vol 49 (2) ◽  
pp. 129-134 ◽  
Author(s):  
D. Haranath ◽  
G.M. Pajonk ◽  
P.B. Wagh ◽  
A. Venkateswara Rao

2021 ◽  
Author(s):  
Jayanta Ray ◽  
Leena Bhowmik

Herein we describe the synthesis and in-depth characterization of chemically blended hybrid glasses in which polymer molecules are uniformly distributed and covalently bonded to inorganic matrices. This approach uses a monomer with double bonds, which are hydrosilylated with triethoxy silane and co-condensed with silicon tetraalkoxide to afford a molecular composite of SiO2 glass and the polymer. The generated coposites were characterized using SEM, TGA and XRD as well as a host of stability tests. They showed increased stability and uniform distribution of the blend. <br>


2010 ◽  
Vol 148-149 ◽  
pp. 1016-1020
Author(s):  
Li Ren Han ◽  
Wei Guo Fu ◽  
Xiang Yun Deng ◽  
Xiao Fen Guan ◽  
Zhong Wen Tan ◽  
...  

(Ba0.7Ca0.3)TiO3 (BCT) powders and ceramics have been prepared by sol-gel technique. Structural evolution of the BCT dry gels are investigated by thermal gravimetric analysis–differential scanning calorimetry. It is found that BCT crystallites can be formed before 800 . Well-sintered samples are synthesized at 1260 for 2h. The crystal structure of the BCT powders is studied by XRD and ferroelectric properties of the ceramics are characterized by TF analyzer 2000. The Curie temperature Tc of the BCT ceramics is at about 125 . The maximum dielectric constant (εr) reaches about 4851 at 125 and hysteresis loops are measured with the temperature range from 25 to 150 .


Cerâmica ◽  
2019 ◽  
Vol 65 (suppl 1) ◽  
pp. 17-21 ◽  
Author(s):  
D. G. da Silva ◽  
W. L. Vasconcelos

1988 ◽  
Vol 132 ◽  
Author(s):  
Deanne P. Yamato ◽  
Abraham L. andis ◽  
Teh S. Kuan

ABSTRACTThe sol-gel technique was used to fabricate α-Fe/mullite composite materials with iron concentrations ranging from 20–60 wt.% Fe. Microscopy studies showed the microstructure to consist of particulate α-Fe dispersed uniformly throughout a mullite matrix. Iron particle size, estimated by TEM, ranged from 20–500 nm. The materials exhibited ferromagnetic hysteresis with saturation magnetization Ms values as high as 115 EMU/g.


2012 ◽  
Author(s):  
Ahmad Sharmi Abdullah ◽  
Amirjan Nawabjan ◽  
Norazan Mohd Kassim ◽  
Mohd Haniff Ibrahim ◽  
Mohamad Zahid Abdul Malek

Pandu gelombang optik jalur berasaskan bahan–bahan sol–gel organik–bukan organic (hybrid) direka, disimulasi dan dibentuk. Bahan–bahan sol–gel hybrid tersebut disediakan daripada vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) dan tetrabutoxytitanate (TTBu) malalui kaedah pemprosesan sol–gel. Pandu gelombang optik tersebut telah dibentuk di atas lapisan quartz menggunakan kaedah penyalutan berputar, lithografi langsung, dan goresan kimia basah. Beberapa lapisan sol telah dibentuk demi mendapatkan struktur pandu gelombang dengan ketebalan yang sesuai untuk laluan mod cahaya sebagaimana diperolehi daripada simulasi. Kebolehan pandu gelombang untuk memandu cahaya pada panjang gelombang 1550 nm telah dicirikan mengunakan kaedah direct end–face fiber butt–coupling. Struktur fizikal pandu gelombang tersebut telah diperhatikan melalui mikroskop berkuasa tinggi. Keputusan yang diperolehi menunjukkan bahawa bahan yang dicadangkan boleh digunakan dalam aplikasi pemanduan gelombang optik pada panjang gelombang 1550 nm. Simulasi menunjukkan bahawa pandu gelombang jalur satu mod dapat direalisasikan jika ketebalan dan kelebaran pandu gelombang tersebut berada pada suatu julat nilai tertentu. Julat nilai tersebut dapat diperolehi melalui pengawalan parameter–parameter penyalutan berputar dan pembentukan mikro. Kualiti keratan rentas yang baik juga diperhatikan telah diperolehi melalui kaedah pembelahan semulajadi. Kata kunci: Pemprosesan sol–gel; bahan organik–bukan organic; pandu gelombang jalur Ridge optical waveguides based on organic–inorganic (hybrid) sol–gel materials were designed, simulated and fabricated. The hybrid sol–gel materials were synthesized from vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBu) precursors by means of sol–gel processing technique. The optical waveguides were fabricated on quartz substrate using spin coating, direct photolithography, and wet chemical etching techniques. Multiple layers of sol were deposited so as to obtain waveguide structure with suitable thickness for mode propagation such as acquired from the simulation. Waveguiding ability of the ridge optical waveguides at 1550 nm wavelength was characterized using direct end–face fiber butt–coupling method. Physical structure of the waveguides was observed through high power microscope. Observation showed that the proposed material possesses the ability for waveguiding application at the wavelength of 1550 nm. Simulation showed that a single mode ridge optical waveguide could be realized provided that the structure thickness and width are within certain range. The range is attainable through proper control of spin coating and micropatterning parameters. Acceptable end–face quality resulted from natural cleaving process was also discovered. Key words: Sol–gel processing; organic–inorganic material; ridge optical waveguide


2005 ◽  
Vol 15 (20) ◽  
pp. 2020 ◽  
Author(s):  
Venkata Krishnan ◽  
Gregorio Bottaro ◽  
Silvia Gross ◽  
Lidia Armelao ◽  
Eugenio Tondello ◽  
...  

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