Polymetallic Alkoxides - Precursors for Ceramics

1988 ◽  
Vol 121 ◽  
Author(s):  
Ram C. Mehrotra
Keyword(s):  
Molecular Level ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Metal Alkoxides ◽  
Mixed Solution ◽  
Oxide Ceramics ◽  
Chemical Bonds ◽  
Initial Cost ◽  
Hydrolysis Process ◽  
Sol Gel Process

ABSTRACTBeginning with the work of Dislich, metal alkoxides have been increasingly used for the preparation of oxide-ceramics by the ‘sol-gel’ process. In spite of higher initial cost of alkoxides, their main advantages are (i)homoge-neous mixing at molecular level in the initial solution; (ii)ease of hydrolysis; and (iii) lower sintering temperatures.Although the formation of new chemical bonds between different alkoxides employed in the starting mixed solution has been envisaged, the actual isolation of a large variety of polymetallic alkoxides in our laboratories has given an entirely new turn to the expectations (e.g., preparation of spinel from magnesium bis-tetraalkoxyaluminates) from this process. Some such possibilities are being presented for synthesis of novel ceramic materials.Reactions of polymetallic alkoxides with water, alcohols andβ-diketones would be discussed to throw light on their hydrolysis process in the presence of other alcohols and chelating ligands.

Hybrid Nanocomposites Based on Metal Oxides and Polysiloxanes with Controlled Morphology

2007 ◽  
Vol 1007 ◽  
Author(s):  
Sorin Ivanovici ◽  
Christoph Rill ◽  
Claudia Feldgitscher ◽  
Guido Kickelbick
Keyword(s):  
Metal Oxides ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
Hybrid Nanoparticles ◽  
Spectroscopic Methods ◽  
Metal Alkoxides ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Ft Ir ◽  
Controlled Morphology

ABSTRACTHybrid materials based on polysiloxanes and metal oxides (SiO2, TiO2, ZrO2) were prepared by hydrosilation of allyl acetoacetate (AAA) modified metal alkoxides (M(OR)4; M = Ti, Zr; R = ethyl, isopropyl) or vinyl triethoxysilane with poly(dimethylsiloxane-co-hydrosiloxane) (PDMS-co-PMHS). The obtained compounds acted as single-source precursors in the sol-gel process. Various spectroscopic methods showed the complete functionalization of the polysiloxane chains with the complexes. When alcohols were used as solvents in the sol-gel process, hybrid nanoparticles were obtained, as observed by dynamic light scattering (DLS) measurements, transmission electron microscopy (TEM), and spectroscopic methods such as NMR and FT-IR.

Study on the Synthesis of Nano-Crystalline Mg2SiO4 Powders by Aqueous Sol-Gel Process

2013 ◽  
Vol 538 ◽  
pp. 142-145 ◽  
Author(s):  
X.F. Chen ◽  
J. Li ◽  
T.T. Feng ◽  
Y.S. Jiang ◽  
X.H. Zhang ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Sol Gel ◽  
Magnesium Nitrate ◽  
Metal Alkoxides ◽  
X Ray Diffraction ◽  
Calcination Process ◽  
X Ray ◽  
Nano Crystalline ◽  
Sol Gel Process ◽  
Scanning Electron

The forsterite-structure Mg2SiO4 was successfully synthesized by the aqueous sol-gel method using Si sols dioxide and magnesium nitrate as starting materials instead of expensive organic solvent and metal alkoxides. The as-prepared nanopowders were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscope (SEM), respectively. The results showed that the calcination process of gel consisted of a series of oxidation and combustion reactions, accompanied by significantly exothermal effects. Highly reactive nanosized Mg2SiO4 powders were successfully obtained at 850 °C with particle size of 60~80 nm.

Some Comments on the Production of Medium Sized Spherical Particles by Anion and Water Extraction Variant of Sol-Gel Process

1994 ◽  
Vol 372 ◽  
Author(s):  
A. Deptula ◽  
W. Łstoke;ada ◽  
T. Olczak ◽  
A. Chmielewski
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Extraction Process ◽  
Spherical Particles ◽  
Drastic Reduction ◽  
Sol Gel Process ◽  
Emulsion Drops ◽  
Clustering Effect ◽  
Non Destructive

AbstractMedium sized spherical particles (with diameters below 100 μm) of ceramic materials (Al203 and Al203 +8%TiO2) were produced in the following steps: (1) preparation of concentrated hydroxide sols of cations by extraction of anions using Primene JMT, (2) formation of sol emulsion in 2-ethylhexanol-1 containing various amounts of surfactants (EH), (3) gelation of emulsion drops by extraction of water with partially dehydrated EH, (4) non-destructive thermal treatment. Principal properties of the sol depend on the temperature of the extraction process. For preparation of lowanionic sols a two step extraction process, separated by digestion of the aqueous phase at boiling point, was necessary. It was found that the parameters of emulsion formation as well as the properties of the sols significantly influence the particle size distribution. It was concluded that lowering of the sol- EH interracial tension by the surfactant does not influence the process. On the contrary the “anti-clustering” effect of surfactants is essential for preparation of perfect spherical powders. The thermal decomposition of gels to oxides is determinant for densities, specific surface area and carbon content. Medium sized spherical powders are free flowing. The compactibility and sinterability of those powders are poor. However drastic reduction of particle size by milling (connected with their transformation to irregular shape) significantly improves the sinterability.

The Effects of Aluminum Alkoxides on the Synthesis of Composite Powders of Alumina and Titania

1989 ◽  
Vol 155 ◽  
Author(s):  
Michael T. Harris ◽  
Charles H. Byers ◽  
Ronald R. Brunson
Keyword(s):  
Sol Gel ◽  
Particle Morphology ◽  
Ceramic Materials ◽  
Metal Alkoxide ◽  
Oxide Ceramic ◽  
Powder Synthesis ◽  
Composite Powders ◽  
Sol Gel Process ◽  
Hydrolysis Of ◽  
Uniform Composition

ABSTRACTThe synthesis of mixed oxide ceramic powders that consist of very fine (submicron)-monodisperse particles with uniform composition is desirable in the improvement of existing ceramics and the development of new ceramic materials. Metal alkoxide hydrolysis is a very attractive method for the synthesis of ultrapure composite powders at low temperatures by the sol-gel process.The present study investigates the effects of the hydrolysis of aluminum alkoxides and the condensation products on the growth kinetics and morphology of composite particles containing alumina and titania. Alkoxides of titanium and aluminum are employed; therefore, powders of high purity are produced. Since various solvents are used as media for powder synthesis, the effect of the solvent on particle morphology will also be discussed.

On-Line Spectroscopic Studies of Group iv Alkoxides and their Interactions with Polymerizable Organic Additives During the Sol-Gel Process

1998 ◽  
Vol 519 ◽  
Author(s):  
R. Cinier ◽  
J. Guilment ◽  
O. Poncelet ◽  
S. Truchet ◽  
D. Wettling
Keyword(s):  
Sol Gel ◽  
Nir Spectroscopy ◽  
Relevant Information ◽  
Spectroscopic Studies ◽  
Organic Additives ◽  
Hydrolysis Process ◽  
Sol Gel Process ◽  
On Line ◽  
Versatile Technique ◽  
Ir And Raman

AbstractThe monitoring of different reactions such as the stabilization of the alkoxides with polymerizable organic additives, the building of the inorganic network during the hydrolysis process, and in a same manner, the polymerization of the organic additives, can be of great importance for the development of hybrid materials with improved processability.NIR spectroscopy is a very versatile technique but lacks of specificity. IR and Raman give more interpretative results but are not always easy to run on a process. We used both techniques along with chemometric tools to extract relevant information from our processes. Then 2D correlation allowed to benefit from the specificity of IR and Raman to develop robust NIR methods able to be used on line to control the different steps of the sol-gel process.The hydrolysis of mixed species of titanium containing chloro, isopropoxo and methacrylato ligands will be discussed in terms of mechanism occuring during the sol-gel process.

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.

Sign in / Sign up

Export Citation Format

Share Document