Environmental Effects in Gel Derived Silicates

1984 ◽  
Vol 32 ◽  
Author(s):  
L.L. Hench
Keyword(s):  
Corrosion Resistance ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Thermal Exposure ◽  
Scientific Basis ◽  
Environmental Stability ◽  
Processing Variables ◽  
End Use ◽  
The Stability ◽  
Gel Processing

Various methods have been developed for producing crystals, powders, coatings and monoliths from gels [1]. The scientific basis for understanding compositional effects, gelation, aging, drying and densification is also advancing rapidly [2]. However, there is as yet relatively little information on the durability, weathering, or corrosion resistance of glasses, glass-ceramics, ceramics, or composites made via the gel route. Data is also sparse on the effects of vacuum, thermal exposure, or mechanical stress on the stability of gel-derived solids. Relationships between sol-gel processing variables and environmental stability are especially lacking at the present time. Since many end-use applications of gel derived materials involve exposure to severe environments, it is essential that the durability of these materials be established during their development.

Gel-derived amorphous cesium-aluminosilicate powders useful for formation of pollucite glass-ceramics

1991 ◽  
Vol 6 (2) ◽  
pp. 217-219 ◽  
Author(s):  
Mari A. Hogan ◽  
Subhash H. Risbud
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Amorphous Powder ◽  
Glass Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Powders ◽  
Gel Processing ◽  
Scanning Electron

Amorphous powders in the Cs2O–Al2O3−SiO2 system were prepared by sol-gel processing. Gels made from TEOS, Al-chelate, and Cs-acetate were dried and calcined to obtain molecularly mixed powders of analyzed compositions in the range useful for conversion to pollucite (CsAlSi2O6) glass-ceramics. X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), and scanning electron microscopy (SEM) were used to characterize the powders. A typical amorphous powder of analyzed chemical composition (in wt.%) = 28.05Cs2O, 37.77SiO2, and 37.96Al2O3 was found to have a glass transition temperature of 945 °C and a glass crystallization temperature of 1026 °C. Preliminary experimental results of densification and crystallization of the amorphous powders show pollucite/mullite phases to be present.

Sol-Gel Processing of Glasses and Glass-Ceramics for Microelectronic Packaging

1991 ◽  
Vol 249 ◽  
Author(s):  
M.A. Sriram ◽  
P.N. Kumta
Keyword(s):  
Dielectric Constant ◽  
Thermal Analyses ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Signal Propagation ◽  
Ceramic Materials ◽  
X Ray Diffraction ◽  
Low Dielectric ◽  
Heat Treated ◽  
Gel Processing

In recent years considerable progress has been made in electronic packaging substrate technology. The future need of miniaturization of devices to increase the signal processing speeds calls for an increase in the device density requiring the substrates to be designed for better thermal, mechanical and electrical efficiency.Fast signal propagation with minimum delay requires the substrate to possess very low dielectric constant. Several glasses and glass-ceramic materials have been identified over the years which show good promise as candidate substrate materials. Among these borophosphate and borophosphosilicate glass-ceramics have been recently identified to have the lowest dielectric constant (3.8). Sol-gel processing has been used to synthesize borosilicate, borophosphosilicate and borophosphate glasses and glass-ceramics using inexpensive boron oxide and phosphorus pentoxide precursors. Preliminary results of the processing of these gels and the effect of volatility of boron alkoxide and its modification on the gel structure are described. X-ray diffraction, Differential thermal analyses and FTIR have been used to characterize the as-prepared and heat treated gels.

Effects of Sol–Gel Processing Variables on the Texture Growth ofLiNbO3Thin Film

1996 ◽  
Vol 35 (Part 1, No. 1A) ◽  
pp. 210-215 ◽  
Author(s):  
Dong Hoon Won ◽  
Nam Hwi Hur ◽  
Kwangsoo No
Keyword(s):  
Sol Gel ◽  
Processing Variables ◽  
Gel Processing

scholarly journals Shielding of metals from the corrosion induced by water and humidity by using scratch resistant and hydrophobic silica coatings

2018 ◽  
Vol 39 (1) ◽  
pp. 23-30
Author(s):  
M. R. Shedam ◽  
S. S. Patil ◽  
Rakesh M. Shedam ◽  
Shridhar N. Mathad
Keyword(s):  
Corrosion Resistance ◽  
Metal Surfaces ◽  
Sol Gel ◽  
Deposition Technique ◽  
Gel Method ◽  
Sol Gel Method ◽  
Practical Applications ◽  
Silica Coatings ◽  
Hydrophobic Silica ◽  
Gel Processing

Abstract The objective of the present paper is to demonstrate the effect of sol-gel derived scratch resistant coatings on different metal surfaces for anticorrosive applications. However, practical applications are limited by problems intrinsic to sol-gel processing or specific of coating/metal systems. Coatings aimed to improve oxidation and wet corrosion resistance have been studied the most. The results published in the literature show that sol-gel coatings may offer good protection against oxidation. More difficult is to achieve a protection against wet corrosion. An important aspect of the application of the sol-gel method for coating metallic objects is also the deposition technique.

Dielectric and structural properties of SiO2-LiFe5O8 glass–ceramics prepared by sol–gel processing

2010 ◽  
Vol 356 (11-17) ◽  
pp. 607-610 ◽  
Author(s):  
M.P.F. Graça ◽  
C.C. Silva ◽  
L.C. Costa ◽  
A.S.B. Sombra ◽  
M.A. Valente
Keyword(s):  
Structural Properties ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Gel Processing

Effects of In Situ Formation of Magnesium Aluminate Spinel on Performance of Modified Sizing Nozzle

2013 ◽  
Vol 750-752 ◽  
pp. 1130-1136
Author(s):  
Guang Liang Yuan ◽  
Qun Hu Xue ◽  
Xiang Li ◽  
Yuan Yang
Keyword(s):  
Corrosion Resistance ◽  
Sol Gel ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Sintering Process ◽  
Stabilized Zirconia ◽  
Composite Powders ◽  
The Stability ◽  
Better Than

The modified sizing nozzle with excellent performances was successfully prepared by using of Mg,Y-PSZ as aggregates, Mg,Y,Ca-PSZ as fines, adding a certain amount of Al2O3-ZrO2 composite powders prepared by sol-gel. Effects of magnesium aluminate spinel in-situ synthesized in modified sizing nozzle on its performances were studied in this experiment. The results show that, the content of cubic zirconia in the sizing nozzle was decreased with the increasing of Al2O3-ZrO2 composite powders; the samples of modified sizing nozzle have no diameter-expanded after 30 hours service. The use effects are obviously better than that of Al2O3-ZrO2 composite powders free. The main reason is that a new bond phase magnesium aluminate spinel was in-situ generated through the reaction between Al2O3 in Al2O3-ZrO2 composite powders and the stabilizer MgO from partially stabilized zirconia in the sintering process at high temperature. The spinels embedded in the substrate of zirconia grow further and fill between zirconia particles. This prevents the stabilizer of CaO further desolventizing and also stop losing the eutectics formed by the reaction with compositions of molten steel. Therefore, the stability of zirconia and the corrosion resistance of the sizing nozzle were improved.

Synthesis and Sintering Comparison of Cordierite Powders

1986 ◽  
Vol 73 ◽  
Author(s):  
J. C. Bernier ◽  
J. L. Rehspringer ◽  
S. Vilminot ◽  
P. Poix
Keyword(s):  
Electronic Properties ◽  
Electronic Packaging ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Theoretical Density ◽  
Drastic Decrease ◽  
Conventional Methods ◽  
Gel Processing ◽  
Inorganic Precursors ◽  
Better Than

ABSTRACTCordierite and cordierite based glass ceramics are promising materials for electronic packaging. Preparations by organic and inorganic precursors along sol-gel processing are reported. Compared with conventional methods, they show a drastic decrease of the sintering temperatures. A process able to giving better than 95% theoretical density ceramic below 1000°C, with good electronic properties is described.

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