Showing papers on "Sodium silicate published in 1991"

Structural differences and phase separation in alkali silicate glasses

Abstract: Reasonable and significant structural differences between potassium silicate glass and sodium silicate glass can be revealed by molecular dynamics computer simulations.The differences in their immiscibility behavior reflect these structural differences. The simulation results are consistent with the experimental observations of many researchers that the variation in the number of nonbridging oxygens per silicon decreases in the order Li>Na>K. The distribution of the silicon species with various numbers of nonbridging oxygens is a reflection of the degree of homogeneity in the distribution of the modifier cation and nonbridging oxygen clusters. Nanoscale inhomogeneity seems to be an inherent nature of alkali silicate glasses.

Local structure around Er in silica and sodium silicate glasses

Abstract: Extended X-ray absorption fine structure (EXAFS) and photoluminescence (PL) measurements have been performed on three different Er-doped glasses: silica and sodium silicate doped with Er in the molten phase, and silica doped by MeV ion implantation. All samples show a luminescent transition centered around a wavelength of λ = 1.54 μ m, corresponding to an intra-4f transition of Er 3+ . EXAFS data show that the Er ions have about six O first neighbors, at a distance of 2.26 A in all systems. Both silica glasses show a second-neighbor ErSi shell at 3.11 A which is not seen in the sodium silicate glass. This difference is reflected in a difference in the PL spectra. The ErO shell in the silica glass shows 0.01 A 2 more disorder than that in the Na-loaded material. These findings are rationalized in terms of the network-modifying effect of Na. Both EXAFS and PL show no significant differences between silica samples prepared in the molten phase or by implantation. At an Er concentration of ∼1 at.%, no direct ErEr bonds are observed.

Microstructural evaluation of simulated sodium silicate glasses

Abstract: A molecular dynamics study of sodium trisilicate and sodium disilicate glasses has been performed in order to evaluate structural details of these systems. The total potential energy is a function of both two-body and three-body interactions in order to account for the partially covalent nature of silica bonding. The simulations reproduce the bulk structural features observed in XRD and EXAFS experiments. The simulations show that the connectivity of the silica network, as in the classical picture, although the distribution of non-bridging oxygen is not as uniform as generally assumed. This feature is supported byu recent NMR studies in which Q-species indicate a significant degree of disorder in the arrangement of non-bridging oxygen. Channels are observed in the simulated glasses at both compositions and are associated with lower order Q n species.

Phonon sideband spectra and local structure around Eu3+ ions in sodium silicate glasses

Abstract: The local structure around Eu3+ ions in sodium silicate glasses was investigated by the phonon sideband associated with 5D2 ← 7F0 transition of Eu3+. Since the shapes of the electronic transition were asymmetric due to the Stark splitting of 5D2 level, the spectra were analyzed by assuming the superposition of the Gaussian distributions of phonon energy and coordination of non-bridging oxygen of the Qn (n = 3, 2, 1) unit in silicate glass. The phonon energy almost corresponded to those of the stretching vibrations of Qn units by Raman spectra. The type and fraction of the Qn units coordinating Eu3+ varied with alkaline content. The compositional variations of Qn units were similar to those determined by NMR for undoped alkaline silicate glasses. It is shown that the local structure around Eu3+ is affected by the composition of matrix glass and the phonon sideband analysis can become a powerful technique to estimate the local distribution of Qn in silicate glasses.

Preparation of amorphous silica-alumina particles by acid-treating spherical P-type zeolite particles crystallized from a sodium aluminosilicate gel

Abstract: The invention is a process for preparing amorphous silica alumina spherical particles by mixing sodium silicate or silicic acid gel with sodium aluminate and sodium hydroxide in an aqueous solution to form a gel, homogenizing the formed gel, crystallizing this intermediate product at 85° C. to 200° under atmospheric pressure or under hydrothermal conditions to form spherical zeolite particles with an x-ray diffraction pattern inherent to P-type zeolites and with a notched surface, treating the zeolite particles with acid to remove the sodium, thereby rendering the particles amorphous.

Microwave susceptor incorporating a coating material having a silicate binder and an active constituent

Abstract: A microwave susceptor which includes a dielectric substrate and a dry layer of microwave active coating material overlaying at least a portion of the substrate is provided The coating material includes a silicate binder and an active constituent and the weight ratio of the silicate to active is about 98:2 or less (ie less silicate) The dry layer is electrically continuous and has a surface concentration of active constituent of about 1 gram per square meter or greater Sodium silicate is preferred as the binder and graphite is preferred as the active constituent In addition additives such as saccharides, glycerine and plasticizers can be added to inhibit thermal shut down and to increase the flexibility of the dry layer The susceptor can exhibit moderate heat performance or even high heating performance if desired A susceptor baking cup, a baking system including a dome shaped cover which can be used to form an enclosure, and a container for frying are all possible uses for this microwave active coating material

Method for preparing acid resistant calcium carbonate pigments

Abstract: A method for preparing an acid resistant calcium carbonate pigment. An aqueous slurry of particulate calcium carbonate is provided at a pH of from about 11.0 to 12.0 and having from 2 to 5 g/l of excess calcium hydroxide. The slurry temperature is brought to the range of about 75° to 80° C., and sodium silicate solution is slowly mixed therewith to provide on a solid dry weight ratio from about 5 to 10% sodium silicate to calcium carbonate. Gaseous carbon dioxide is added to bring the slurry pH to the range of about 10.2 to 10.7, and the slurry is cooled to about 25° to 30° C. Finally zinc chloride is added to the cooled slurry to bring the pH to within the range of 7.5 to 8.0.

Sodium ash reactions during combustion of pulverised coal

Abstract: Reactions of sodium with mineral silicates contribute to the formation of fireside deposits during the combustion of some high sodium coals. A systematic experimental study of the reactions between sodium with inherent silica and kaolin during pulverised coal combustion was undertaken in order to examine the mechanisms of the reactions. The experiments were conducted in a drop tube furnace with coal samples which had been specially prepared to control the concentrations, the size and the distribution of the inorganic constituents, which included silica, kaolin, sodium chloride, sodium acetate, and gaseous SO2 to simulate organic sulfur. The rate of formation of sodium silicate was found to increase with temperature but the extent of formation was limited by the progressive agglomeration and coalescence of the ash which reduced the surface area available for reaction. The extent of interaction between the sodium and silica/silicates was reduced by the presence of chlorine and sulphur and this effect was greater with kaolin than with quartz. At gas temperatures of 1200–1400°C, sodium was volatilised from the coal before significant reactions occurred with the silica. At 1000°C the sodium was not fully released prior to the commencement of the silicate formation reaction.

Silicate bonded unsintered ceramics of Bayer process waste

Abstract: Sodium silicates are investigated to enhance the strengths of Bayer process muds and develop structural ceramics without sintering. With an impregnation of sodium silicate from 2% to 10% concentration in red mud, the fracture toughness is enhanced from 0.2 to 0.9 MPa $$\sqrt {\rm{m}} $$ . Compression strengths of 25.1 MPa (3628 psi) have been attained with red mud at 10% silicate concentration. Similar enhancements by a factor of 4 to 5 have been obtained for modulus of rupture and Brinell hardness number. It is shown that these properties do not deteriorate in acidic and neutral environment in water, implying stability to weathering conditions. SEM investigations reveal elongated crystal formation, possibly of aluminum and iron silicates in the aggregate. These crystals act like whiskers enhancing the strength. The process is applicable for development of low-cost construction components.

Method for preventing the adverse effects of swell in sulfate bearing, expansive clay soils

Abstract: A method is shown for stabilizing sulfate bearing soils in which a silica compound is incorporated into the soils with the soils being further stabilized by the application of lime. The silica compound can be either an amorphous, flume silica, a crystalline silica, a silica gel, sodium silicate, potassium silicate or combination thereof. The silica compound and lime can be incorporated into the soils in a single step.

Permeability of acrylate, urethane, and silicate grouted sands with chemicals

Abstract: A laboratory study is conducted to evaluate the' long‐term resistance to percolation of grouted sands, using chemicals that represent the more common industrial waste effluents. Such performance data is necessary if grouts are to be considered for sealing off hazardous waste sites. Six different grouts are tested: acrylate, urethane, Pene‐grout, sodium silicate, glyoxal‐modified sodium silicate, and sodium aluminate‐modified sodium silicate. Water, eight chemicals, and two real‐site wastes are used as permeants. The acrylate grout exhibits very low permeability with water, has excellent resistance to the paint and refinery wastes and sodium hydroxide, and performs satisfactorily with cupric sulfate, ethylene glycol, and xylene. The urethane grout has low permeability with water, remains relatively impervious with acetone, aniline, ethylene glycol, methanol, paint and refinery wastes, and performs marginally well with cupric sulfate and hydrochloric acid. The Pene‐grout has moderately low permeability with...

High performance coarse particle size sams pigments for paint and plastics applications

Abstract: High performance synthetic sodium aluminosilicate compositions, and the method of making the same by the hydrothermal reaction of certain delaminated kaolin clays with select sodium silicate reagents, result in enhanced performance flatting agents for paint systems and anti-block agents for plastic film applications.

Corrosion-inhibiting cleaning systems for aluminum surfaces, particularly aluminum aircraft surfaces

Abstract: An alkaline blast cleaning system for aluminum surfaces which avoids discoloring or tarnishing of the aluminum surfaces, is comprised of an alkali metal bicarbonate having a particle size of from about 50 to about 1,000 and an aqueous solution of sodium silicate, the sodium silicate having an SiO2:Na2O ratio of from about 2.44 to about 3.22:1 and being present in the aqueous solution in a corrosion inhibiting concentration of from about 100 to about 1,000 ppm, the pH of the solution ranging from about 8.1 to about 8.3.

Production of crystalline lamellar sodium silicate

Abstract: PURPOSE: To produce a mainly 5 type crystalline lamellar sodium silicate exhibiting a high ion exchange ability by feeding a sodium silicate solution having a specific SiO 2 /Na 2 O molar ratio into a heating zone maintained in a crystallization temperature range. CONSTITUTION: A solution of industrially produced sodium silicate is adjusted to a SiO 2 /Na 2 O molar ratio of 1.9-3.2 and, if necessary, mixed with the oxide of aluminum or boron. The solution is fed directly as such into a heating zone (e.g. a rotary kiln provided with a scraper) maintained in a crystallization temperature range of 680-830°C. The time of the crystallization is an important condition factor, usually 1-3hr. The sodium silicate solidified by the heating treatment is slowly transferred into the heating system in a foamed bulk state, and crystallized in the process. The product is pulverized to provide the subject crystal having a composition of Na 2 Si 2 O 5 and containing 6 type crystals and a small amount of α type crystals. COPYRIGHT: (C)1992,JPO&Japio

Production of modified disodium silicate

Abstract: PURPOSE: To obtain in high productivity low-hygroscopic Na 2 Si 2 O 5 with high ion exchange ability by adding a specified amount of aluminum and/or boron component(s) to a sodium silicate solution of specified composition followed by baking. CONSTITUTION: A solution of sodium silicate with the molar ratio SiO 2 /Na 2 O being 1.9-3.2 is incorporated with 0.5-2mol%, based on the Si, of an aluminum and/or boron component(s) followed by homogenization. The resulting solution is then baked and crystallized through such a process as to introduce it into a heating zone held at a state of crystallization temperature range, thus obtaining the objective modified disodium silicate. The aluminum source to be added is pref. sodium aluminate or soluble aluminate, while the boron source, pref. boric acid or borax. The present modified disodium silicate can be suitably used as e.g. a raw material for builders to be used in synthetic detergents. COPYRIGHT: (C)1992,JPO&Japio

Silicate bonding of inorganic materials

Abstract: The room-temperature setting process in compacts of various silicate and non-silicate mineral particles bonded with sodium silicate was found to be markedly accelerated by treatment with the acidic gases CO2, S02 and H2S, but was unaffected by neutral or alkaline gases. Strength development increases with gassing time up to a maximum value which depends on the Si to Na ratio of the sodium silicate, the nature of the mineral matter and the gas used. Longer gassing times are needed to achieve ultimate strength with sodium silicates of higher pH and gases of lower solubility in water. The chemical species formed by reaction of CO2, S02 and H2S with sodium silicate were investigated by IR spectroscopy, X-ray diffraction and 29-Si solid state NMR spectroscopy.

Consolidation inhibition method of sodium hydrogen carbonate

Abstract: PURPOSE:To inhibit consolidation progress of sodium hydrogen carbonate having sodium carbonate component on the surface for a long period of time, to ensure fluidity in use and to enable long-term storage. CONSTITUTION:Sodium hydrogen carbonate containing sodium carbonate on the surface is sealed by a packaging material having water vapor permeability of day specified in JIS-Z0208 or blended with 0.5-1wt.% of a consolidation inhibitor composed of calcium stearate, magnesium stearate, calcium carbonate, magnesium carbonate, calcium phosphate, sodium silicate, kaolin, talc, silicon dioxide or a higher aliphatic acid to inhibit the consolidation.

Production of heat insulating material

Abstract: PURPOSE: To readily and efficiently produce a heat insulating material of any shape in ultra-fine silica-based heat insulating material by using synthetic hydrous silicic acid of ultra-fine particles and molding the synthetic hydrous silicic acid by press molding using a mold. CONSTITUTION: Synthetic hydrous silicic acid of ultra-fine particles is produced by a wet method of reacting sodium silicate with sulfuric acid. The synthetic hydrous silicic acid of ultra-fine particles is blended with an infrared light screening material of ultra-fine particles and reinforcing heat-resistant inorganic fibers, the prepared mixture is packed into a mold and press molded. The synthetic hydrous silicic acid of ultra-fine particles requires to have ≤100g/L bulk density and ≥100m 2 /g specific surface area. By this method, a high-performance heat insulating material having approximately the same heat insulating performance as that of a heat insulating material comprising aerogel can be produced more readily than a conventional method without restriction of molding shape. COPYRIGHT: (C)1993,JPO&Japio

Synthesis of a manganese dioxide-silica hydrous composite and its properties as a sorbtion material for strontium

Abstract: This paper reports on hydrous manganese dioxide prepared by precipitation of MnO{sub 2} from potassium permanganate with H{sub 2}O{sub 2}. The reaction was carried out in the presence of SiO{sub 2} as sodium silicate. Afterward the precipitate was dewatered, washed, and dried. The resultant materials were tested for strontium sorption as a function of MnO{sub 2}:SiO{sub 2} content and as a function of drying temperature. A product containing 17% SiO{sub 2} in the initial solution was shown to be the best for Sr adsorption. The mechanical strength, density, capacity, and water stability of the exchangers were determined. Their properties were compared with a grade of MnO{sub 2} available commercially. Addition of SiO{sub 2} had several advantages.

Efflorescence of soluble silicate coatings

Abstract: Efflorescence of soluble silicate coatings has a serious effect on the properties of the coatings. Efflorescence results in the formation of a whitish powder on the surface of the coating, and causes the silicate material to become brittle and lose adhesion. This efflorescence occurs due to a reaction between CO2 in the atmosphere and the silicate material. This paper examines the rate of efflorescence of different types of soluble silicates, i.e. sodium silicate, potassium silicate, and lithium silicate. Also, the effect of silica: metal oxide molar ratio, and the effect of humidity on the rate of efflorescence are studied. The results indicate that the mechanism of efflorescence is a reaction between CO2 in the atmosphere and OH− in the silicate coating which is catalysed by the presence of water. Lithium silicate has a significantly lower rate of efflorescence than either sodium or potassium silicate. This is believed to be due to the stronger association between Li+ and OH− than either Na+ or K+ and OH−.

Interaction of sodium, sulfur, and silica during coal combustion

Abstract: The interaction of sodium, sulfur, and silica at conditions typical in a pulverized coal furnace was investigated by using both model mixtures and a synthetic coal. The model mixtures consisted of selected inorganic constituents that were well mixed in proportions typically found in low-rank coal. The synthetic coal consisted of a furfuryl alcohol polymer with appropriate amounts of sodium, sulfur, and silica to duplicate the characteristics of low-rank coal

Core removal from molded products

Abstract: A method of removing a core from a molded product in which the core is formed of a particulate inert material, such as sand, bound together by a cured binder of a water soluble carbohydrate alone or mixed with a silicate is disclosed. The silicate is preferably an alkali earth metal silicate, preferably sodium silicate, and the carbohydrate is preferably a saccharide or starch. The binder is cured by heat. The core and molded product are exposed to water, preferably heated water in a bath or steam, to rapidly disintegrate the core and remove it from the molded product.

Ceramic coating material for a microfuse

Abstract: A ceramic coating for a subminiature fuse includes sodium silicate and silicon dioxide applied over a subminiature fuse wire in slurry form. The coating gives the fuse arc quenching properties.

Synergistic combination of sodium silicate and orthophosphate for controlling carbon steel corrosion

Abstract: An orthophosphate salt and sodium silicate, when used in a 3:1 ratio by weight, and in a concentration of 0.1 to 100 mg/L, are found to have a synergistic effect in controlling the corrosion of carbon steel in an aqueous system, e.g., a municipal water supply system. The synergistic combination is also useful in reducing lead solubility and leaching, and in stabilizing soluble iron and manganese and their reaction products.

Electrolysis cell and refractory material therefor

Abstract: Aluminum electrolysis cell having a refractory lining, said lining being produced by calcining red mud obtained as a byproduct of the Bayer process of producing alumina, grinding the calcined product to form particles of -4 Tyler mesh, mixing the ground product with a binder (e.g. colloidal silica, colloidal alumina, sodium silicate or sodium aluminate) and sufficient water to produce a formable mixture. The mixture is formed into a shaped product, fired and used, for example, as a monolithic lining, to form the internal surface of the aluminum electrolysis production cell.

Process for producing a pourable, phosphate-free de-aerating preparation

Abstract: The process results in pourable de-aerating granulates which contain (a) 7.5 to 18 wt. % of a water-insoluble de-aerating agent from the organo-polysiloxane class containing finely divided silica and its mixtures with paraffin oil and/or paraffin wax, (b) 0.2 to 3 wt. % of a mixture of sodium carboxymethyl cellulose and a non-ionic cellulose ether in the proportion by weight of 80:20 to 40:60, (c) 70 to 90 wt. % of a phosphate-free vehicle salt mixture consisting of sodium silicate, sodium carbonate and sodium sulphate, and (d) water to 100 %. The granulation process involves soaking 2 to 8 wt. % of the aqueous solution containing the cellulose ether mixture (b) at a temperature of 15 to 60° until the viscosity of the solution is at least 60 % of that which is measured with the complete soaking of the cellulose ether solution, dispersing the de-aerator (a) in this solution and spray drying the homogenised dispersion after the addition of the vehicle salts and, where appropriate, water.

Grouting liquid composition for stabilizing soil, etc., and stabilization and reinforcement of soil using the same

Abstract: PURPOSE:To provide a grouting liquid composition useful for the consolidation and stabilization of an unstable part of a rock-bed, ground, artificial construction, etc., and to provide a stabilization, reinforcement and water-stopping process using the grouting composition. CONSTITUTION:The objective grouting liquid composition is composed of (A) an aqueous solution of sodium silicate and (B) a hydrophilic urethane prepolymer containing oxyethylene chain. A ground or an artificial construction can be stabilized and reinforced by injecting and solidifying the grouting composition. Since the hydrophilic urethane prepolymer (B) has high compatibility with the aqueous solution of sodium silicate (A) and high affinity to rock-bed, ground and artificial construction, the composition has improved penetration property into the rock-bed, etc., the strength of the consolidated composite is increased and the safety of the application work is improved.