Silica, amorphous* - Wiley Online Library
1.4 Amorphous silicas as by-products of industrial processes (silica fume) Amorphous silicas occur as a by-product of industrial processes in flying ash and filter dust. When quartz is subjected to high temperatures (1500 °C to 2500 °C) during metallurgical or other production processes, grey to bluish fumes are produced.
AMORPHOUS SILICA - Substance Information - …
AMORPHOUS SILICA. Regulatory process names 1 IUPAC names 1 Other names 3 Other identifiers 1 . Print infocard. Substance identity Substance identity. The ‘Substance identity’ section is calculated from substance identification information from all ECHA databases. The substance identifiers displayed in the InfoCard are the best available substance name, EC number, CAS number and/or the ...
Amorphous Silicon - an overview | ScienceDirect …
In amorphous silicon (a-Si) almost every Si atom is tetrahedrally bonded to four nearest neighbor Si atoms—just as in crystalline Si (c-Si). However, as soon as one goes to more distant neighbors, due to slight stretching and twisting of bonds, long-range order is lost. In contrast, crystals are characterized by structural periodicity over a long range. A consequence of this disorder is a presence of a great …
Processing pathway dependence of amorphous …
26.09.2012 · Silicon dioxide silica is the most abundant mineral on earth - predominantly in the form of alpha-crystalline quartz. 1 Man-made silicas, however, tend to be amorphous and often used as nano-structured powders in applications like fillers to control rheological and mechanical behaviors, catalysts, and desiccants. 2 Amorphous silica nanoparticles are prepared by two main routes, high …
What is Precipitated Silica | PPG Silica Products
Sodium silicate solution (water glass) and mineral acid are reacted in an agitated vessel to produce a slurry of amorphous silica particles. The critical physical properties of precipitated silica, such as particle size and porosity, are controlled during this stage of the process by manipulating, among other things, the composition, concentration, and ratio of reactants in the precipitating solution; the speed of agitation; …
MINIREVIEW An overview of the fundamentals of the ...
silica reach the solubility of amorphous silica, as the particles carry negative charge and repel one another (Fig. 1). If salts or other charge species are present (which is inevitable in a biological environment), then the surface charge that causes repulsion between indi-vidual particles is reduced or cancelled, and the parti-cles aggregate to form dense 3D networks (Fig. 1). Note that, in ...
Amorphous Silica | PPG Silica Products
PPG AGILON® Performance Silica Products. A platform of proprietary chemically modified silica that combines product and process, PPG AGILON® performance silica products eliminate the need for silane coupling agents, enabling industrial stone and tire makers to improve product performance, simplify manufacturing processes and reduce emissions.
Tosoh Silica Corporation | Overview of the …
Process of producing synthetic silica Hydrated amorphous silicon dioxide (synthetic silica) is produced when silicate soda reacts with sulfuric acid. The size, bonding, and structural characteristics of the primary particles are strictly controlled for each product grade. Raw material (silicate soda)
Fumed silica - Wikipedia
Fumed silica, also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three-dimensional secondary particles which then agglomerate into tertiary particles. The resulting powder has an extremely low bulk density and high surface area. Its three-dimensional structure results in viscosity-increasing, …
What is Amorphous Silicon? (with picture)
02.06.2020 · As a result, amorphous silicon can be used in thin film processes employed to make a variety of low-voltage devices, such as pocket calculators and watches. Another advantage of utilizing amorphous silicon thin film over crystalline silicon is that the former absorbs up …
INTRODUCTION Properties, Characterisation and Uses
Naturally occurring amorphous silica –refined pozzolanic material –composed mostly of amorphous silica –derived either from hydrothermal alteration of ignimbrite or pumice breccia or from the extraction of precipitated silica from geothermal water – and supplied as either powdered, slurried or pre-wetted compressed filter cake – these varying in solids and moisture contents.
Health hazards due to the inhalation of …
Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic ("thermal" or "fumed") silica, and (3) chemically or physically modified silica.
silicon dioxide; synthetic amorphous silicon ...
Regulatory process names Silica O2Si This entry covers synthetic amorphous silicon dioxide as a nanomaterial in the form of stable aggregated particles of particle size > …
Sonochemical Deposition and Characterization of …
Nanophasic, amorphous clusters of elemental nickel in the size range 10−15 nm have been deposited on submicrospheres of amorphous silica by the sonication of a suspension containing nickel tetracarbonyl and silica submicrospheres in Decalin by a high-intensity ultrasound radiation.
Silicon dioxide film and process for preparation of …
In the process for preparation of the amorphous silicon dioxide film of the invention, the step for subjecting the silicon alkoxide to hydrolysis and condensation polymerization is carried out in the presence of at least one compound (hydrolysis accelerator) selected from the group consisting of hydroxyaldehyde compounds (or hydroxy-ketone compounds), hydroxycarboxylic acid compounds, …
HYDROGENATED AMORPHOUS SILICON ALLOY DEPOSITION …
Conventional Glow Discharge Deposition Processes for Amorphous Silicon-Based Alloys 99 4.1 Plasma-Enhanced stone Vapor Deposition 100 4.2 Plasma Diagnostics 103 4.3 Feed-Gas Analysis 107 Vll . VUl Contents Design of Glow Discharge Deposition Reactors 5.1 Geometry 5.2 Bias Control 5.3 Plasma Confinement 5.4 Hot Walls 5.5 Contamination from Impurities Glow Discharge Deposition …
Silicon Dioxide, Amorphous
SILICON DIOXIDE, AMORPHOUS Prepared at the 84th JECFA and published in FAO JECFA Monographs 20 (2017), superseding tentative specifications prepared at the 80th JECFA (2015) and published in FAO JECFA Monographs 17 (2015). An ADI not specified for silicon dioxide and certain silicates was established at the 29th JECFA (1985).
High activity amorphous silica-alumina catalyst - …
A process of preparing a high amorphous hydrocarbon cracking catalyst which comprises: a. mixing solutions of a soluble aluminum compound and sodium silicate in a weight ratio of Al 2 O 3 to SiO 2 from 0.64 to 1 to 5.7 to 1 b. aging the resulting gel, c. adjusting the pH of the gel to a pH of 5.0 to 10.0 to precipitate excess alumina,