Purpose. Determining heating rate of granular materials of inorganic origin used for manufacturing foundry molds and rods in the field of ultrahigh frequency radiation, dependence of the heating rate of materials on the magnitude of their relative dielectric permeability, as well as establishing the influence of the chemical composition and structure of inorganic materials on their relative dielectric permeability.Methodology. Investigation was carried out on test material samples weighing 200 grams which were heated by microwave ra diation with frequency of 2.45 GHz at nominal magnetron power of 700 W. Among the tested materials are: silicate block (soda), rutile, normal electrocorundum, zircon concentrate, distenesillimanite concentrate, chamotte, quartz sand, sodium chloride, bgypsum (G4, closed), αgypsum (G22, closed).findings. According to the results of changing the initial temperature of samples, the heating rate of granular materials of inor ganic origin and values of their relative dielectric permeability (e) were calculated. It has been found that investigated the heating rate of industrialgrade materials is in the range from 12 (for closed gypsum grade G22) to 122 °C/min (for silicate block).originality. Values of dielectric permeability indicators of solid granular materialsinsulators of industrial purity with a value of e ≤ 17 have been established for the first time. It has been determined that their heating rate is directly proportional to e value. Moreover, these materials' dielectric permeability depends solely on their chemical composition and can be calculated according to the additivity rule of elementary chemical components included in their composition Practical value. Based on the obtained data, materials appropriated for manufacturing casting modelcore equipment, as well as casting molding and core mixtures working, dried and structured in the field of microwave radiation have been recommended. Using such materials will reduce energy consumption of casting parts production and increase its environmental safety.

Purpose. Kinetics research and description of drying by microwave radiation mechanism development of quartz sand and its mixes with sodium silicate in limited quantity of water steam medium. Methodology. Distilled water, sodium silicate solute and quartz sand have been used in this research. Study has been performed on sand samples weighing 200 g. Mixtures drying and structuring have been performed by microwave radiation with power of 700W with frequency of 2.45 GHz in air and in saturated water weighing 1 g steam medium. Accuracy of temperature measurement is 1, mass is 0.02 g. Realized in this investigation drying kinetics has been specified as specimen weight change dependence and moisture evaporation from this mixture rate vs. drying duration. Dependencies have been built on the results of video recording and corresponding chrono-gravimetric measurements data digitalization. Mixtures during heating by microwave radiation temperature changes registration has been performed with an interval of 1560 s. Samples average heating rate has been estimated by calculation based on results in their temperature change determination during first 2 minutes of heating with microwave radiation. Findings. For the first time, microwave drying kinetics of quartz sand and its mixtures with sodium silicate in limited water medium (structured by SMS-process) has been studied. For the first time, based on SMS-process material balance, analytical dependence has been developed. This dependence application allows sand-sodium-silicate mixture structured by SMS-process maximum mass to calculate when using sodium silicate solute (silicate module 2.83.0) for quartz sand cladding and 1 g of saturated water steam for mixture structuring. It has been established that when mixtures structuring according to SMS-process water extraction from them takes place in three stages at ~100, 100108 and at 125138 . Maximum appropriate heating temperature of sand-sodium-silicate mixture during structuring by SMS-process has been recommended as ~125 . Exceeding of specified temperature leads to hydrated water from mixture releasing in steam form and its condensation on colder working surface of model-rod rigging. Resulting condensate leads to mixture restructuring in contact with equipment places and, accordingly, sharp quality deterioration in prepared molds and rods. For manufactured molds and rods quality stabilization, it has been recommended to pre-dry the quartz sand cladded with sodium silicate solute in microwave field for at least 3 minutes before structuring according to SMS-process. Originality. For the first time, data on drying kinetics has been obtained and quartz sand and its mixtures with sodium silicate in limited water steam medium microwave drying mechanism description has been developed. Influence of number of SMS-process basic parameters on structured quartz sand weight regularities has been established. Practical value. Research results will be useful in terms of ideas expanding about the processes that accompany granular materials drying, as well as in technologies and equipment for drying and structuring fine-grained dielectric materials and their mixtures development, creating new capillary-porous media, etc. under microwave radiation influence.

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At the present, from among the known methods of sand-sodium-silicate mixtures structuring, the least studied, but the most promising, is the method of steam-microwave solidification. Among unexplored elements of steam-microwave solidification method is nature of mixtures destruction. This is especially important for determining the ways to increase the sand-sodium-silicate casting molds and cores strength before pouring and lowering their strength by the time when casting should be knocked out the mold and the core from cast product. Knowledge about mixture destruction nature is also necessary for appropriate technical solutions elaboration concerning sand regeneration. In this regard, the purpose of the present work has to be nature of sand-sodium-silicate mixtures structured by steam-microwave solidification method destruction establishing. Quartz sand cladded with sodium-silicate solute has been used in the present investigation. Mixture (cladded sand) structuring has been carried out by microwave radiation at nominal magnetron power of 700 W and radiation frequency of 2.45 GHz in area of standing waves. To cladded sand structuring, 1 g water portion has been added, which has been placed in bottom of container in which mixture has been microwave treated. To make decision on mixture destruction nature, images of structured mixtures destruction places within one grain (sand grain), which are typical for adhesive and cohesive character of destruction, obtained with scanning electron microscope have been used. It has been found that with sodium-silicate solute for quartz sand cladding mass content from 0.5 to 6 % (by weight) increasing, as well as with mixture processing by the method of steam-microwave solidification duration increasing, mixture compression ultimate strength increases according to dependence closed to exponential. Character of structured mixture destruction, in this case, is not depend on sodium-silicate solute used for quartz sand cladding content, but depends on steam-microwave solidification duration. With its time increasing it changes from adhesive to mix or from adhesive to mixed and cohesive.

Purpose. To establish regularities of changes in sand-sodium-silicate mixtures (SSSM) relative water resistance, structured by steam-microwave solidification method (SMS), on their structuring parameters and sodium silicate solute (SSS) dissolution conditions. Methodology. Technical purity water, SSS with 2.83.0 silicate modulus, quartz sand with 0.23 mm average particle size were used in this work. Studies were carried out on quartz sand samples, which were preliminarily cladded with 0.52.5% (by weight) SSS and structured by SMS method. The fracture time of structured mixtures was evaluated on cubic specimens with 20 mm rib length, which were immersed in water at different temperatures. Findings. Changes in SSSM water resistance in water regularities depending on their manufacturing, use and storage conditions were established. Recommendations for SSSM rods removal from castings in water were developed. Originality. For the first time, it has been established that relative water resistance of the SSSM structured by SMS method decreases along with increase in water temperature in which it is destroyed. Depending on SSS mass used for quartz sand cladding in range 0.52.5%, water resistance dependence on treatment in steam-microwave environment with 27 minutes running time acquires an inversion character with inversion point `3.1 minutes into the processing. For the first time, it has been discovered that in boiling water the relative water resistance of SSSM, structured by SMS-process and having preheating, monotonically increases with preheating temperature rising from 100 to 600 , sharply increases when heated to 600700 and practically becomes absolute after preliminarily preheating to higher temperatures. Practical value. Research results will be useful in concepts of processes accompanying destruction of structured sands with water-soluble binders expanding, as well as in technologies and equipment development designed for SSS rods and mold rests removing from castings.