Papers by Keyword: Vermiculite

Abstract: To extinguish flammable polar liquids, it is proposed to use a multicomponent fire extinguishing system consisting of one or two layers of wetted lightweight bulk materials. It has been established that wetting bulk materials leads to a significant increase in the following components of fire extinguishing action: cooling, insulation, and dilution. In addition, the introduction of water into the fire extinguishing system leads to a decrease in the concentration of vapors of polar flammable liquids above the fire extinguishing layer of bulk materials due to their absorption by water. Crushed foam glass with a granule size of 10-15 mm was selected as a bulk material for the formation of the base layer of the fire extinguishing system. To improve the insulating properties of the base layer, it is proposed to apply swollen perlite with a granule size of 1.0-1.4 mm or swollen lamellar vermiculite with a scale size of 1 × 2.5 mm to its surface. Such sizes of perlite and vermiculite particles enable them to fill the cavities between the granules of the foam glass base layer, which leads to an increase in the insulating properties of the fire extinguishing system. The following were experimentally determined: bulk density, buoyancy in methanol, ethanol, propanol-2, and acetone, moisture retention of bulk materials, and the fraction of material that spilled through the foam glass layer. The fire extinguishing capacity of the proposed fire extinguishing systems based on bulk materials in the case of extinguishing polar flammable liquids was experimentally determined. The systems based on bulk materials have a combined fire extinguishing effect by the following mechanisms of combustion termination: cooling, insulation, and dilution. It is concluded that the advantages of the proposed system in comparison with existing fire extinguishing agents for polar flammable liquids are substantiated.

Abstract: To extinguish flammable liquids, it is suggested to use a multi-component fire extinguishing system consisting of two layers. The first layer is designed to ensure the buoyancy of the fire extinguishing system. It is suggested to use crushed foam glass as the material of this layer. As the material of the upper layer, it is suggested to use light dispersed materials with increased thermal insulation properties. As such materials, the use of exfoliated perlite and vermiculite is justified. To increase the insulating and cooling properties of the fire extinguishing system, wetting of the upper layer with water is used. Bulk density, buoyancy in heptane and moisture retention of crushed foam glass, expanded perlite and vermiculite were experimentally determined. The insulating properties of binary layers of foam glass + perlite and foam glass + vermiculite were studied. The heights of the layers of dry and wet bulk materials necessary for extinguishing heptane were determined experimentally. A conclusion was made about the advantages of the proposed fire extinguishing system based on light bulk materials compared to the existing fire extinguishing means.

Abstract: This work is devoted to studying the impact of carbon fibers with vermiculite and ultrafine polytetrafluoroethylene on the structure and properties of polytetrafluoroethylene. The mechanical and tribological characteristics of composites based on PTFE was compared depending on the content of carbon fibers. The yield strength and compressive strength improvement with increase of contents carbon fibers of the PTFE was showed. The method of X-ray analysis showed that with by introducing of complex fillers in the PTFE leads to the increasing the degree of crystallinity. PTFE-based composites reinforced complex fillers have shown a significant improvement in wear resistance compared to initial polymer. The study of the worn surface using scanning electron microscopy and IR spectroscopy to describe the tribological behavior of PTFE-based composites was carried out. Using IR spectroscopy, it was revealed that in the process of friction on the worn surface of PTFE-based composites products of tribo-oxidation are formed. It has been established that in the friction process of polymer composite materials, secondary structures are formed on the friction surface of the material, which protects the material from abrasion.

Abstract: The possibility of obtaining the vermiculite fire treatment at low temperature (burnt vermiculite) is considered in the article. The vermiculite structure features are investigated to reduce the subsequent burn temperature. By X-ray diffraction analysis it is established that the pre-treatment by a salt solution causes a change in the elementary cell of the vermiculite crystalline grid. It allows to receive the extended vermiculite under the lower burn temperature than in case of the ordinary non-treated vermiculite. To show the creation possibility of the building materials with burnt vermiculite the concrete unit weight and strength with gypsum and cement binder are studied. It is determined that the mentioned concrete strength is higher compared to concrete with ordinary vermiculite at the same density of these concretes. The thermal insulation properties are also significantly higher. The light concrete with vermiculite aggregate is used as the thermal-shield enclosing structures in building and structure constructions. The decrease of the vermiculite burn temperature will contribute to reducing the energy intensity of construction as a whole.

Abstract: The results of research on the development of heat-resistant cement composites using volcanic pumice and expanded vermiculite are presented. Compositions of heat-resistant cement composites are proposed that significantly reduce Portland cement consumption and simultaneously improve their heat-resistant properties. The use of basalt fibers in composites makes it possible to increase their strength, crack resistance and heat-resistant properties due to the perception of tensile temperature stresses. Part of the expensive vermiculite can be replaced by pumice without significantly increasing the average density of the composite, while their strength characteristics increase.

Abstract: The paper describes the tribotechnical properties of thin-film coatings obtained by the tribotechnical modification of 40X grade steel with different organic and inorganic tribotechnical materials (natural inorganic and artificial polymers), as well as with composite materials based on vermiculite. Comparative tribotechnical investigations revealed that composites possess better tribotechnical properties than single-component materials. The most promising materials for the tribotechnical modification of steel friction surfaces are vermiculite-based nanostructured composites that provide minimal friction coefficient and high wear resistance under the conditions of boundary friction. The tribotechnical properties of polymagnesiumphenylsiloxane are a little worse than that of the materials based on vermiculite. Polymagnesiumphenylsiloxane and nanostructured composites based on vermiculite can be used as additives to motor oils and solid lubricants, as well as for the modification of friction surfaces during manufacturing or reconditioning of machine parts to increase their durability.

Abstract: The article describes the aspects of fire protection of high-rise buildings. Various methods of protection of unique buildings from fire and explosion in the world practice were considered. For example, using the innovative fire-resistant materials on load-bearing structures, their characteristics and rationing, progressive collapse. The comparative analysis of various types of fire-resistant plaster by such parameters as the chemical composition, fire resistance, durability, density, thickness of the layer was made. Perspectives of development of fireproof plaster compositions were projected.

Abstract: The catalytic cracking of sunflower oil over vermiculite clay was studied in a thermal analysis system, the process being accompanied by thermogravimetry. The vermiculite was chemically modified by acid leaching and characterized by techniques of XRD, FTIR, SEM and TG. The catalytic test was performed in a thermal analysis system with heating up to 900 °C, with proportion oil/clay = 100. The results of thermogravimetry showed that in the presence of the catalyst, the thermograms present a single mass loss. The test was also performed with the molecular sieve Al-MCM-41 with proportion Si/Al = 25 and 75, with similar results to those presented by vermiculite.

Abstract: Vermiculite has a structure consisting of layered silicates surfaces interspersed with layers of water. When the expansion occurs intra lamellar clay water is removed. This paper aims to characterize the Vermiculite clay of Santa Luzia, Paraíba (Brazil) in their natural form, and after thermogravimetric treatments by classic X-ray diffraction analysis, thermal analysis and scanning electron microscopy. The results show that the method of expansion, using the technique of microwave energy is possible, however, the expansion factor is lower when compared to the indirect heating by the thermal expansion of the clay.

Abstract: Kovdor (Karelia) deposite vermiculites modified by acid of different concentrations and chitosan were studied using positron annihilation lifetime spectroscopy, measuring apparent density, dye adsorption, nitrogen adsorption by BET and porometry. It has been shown that after acidizing vermiculite density changes comparing to the samples’ density depending on the acid concentration. The density increases with the increasing acid concentration. Internal volume of the micropores and the value of maximum sorption of brilliant green change directly proportional to the density of the modified vermiculite.