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For the manufacture of metal parts of complex shape, the most promising method is casting according to smelted or burnt models. As a smelted material, a complex composition of wax with other organic compounds is used, characterized by high constancy of physico-chemical and mechanical properties, since the accuracy of multiple reproduction of critical parts, for example, the blades of a turbojet engine, depends on it. The wax model is necessary for growing a ceramic shell around it, the accuracy of which is crucial for obtaining a high-quality casting. Since the surface of the wax model is hydrophobic, and the ceramic suspension applied to the model is created on a water basis, a critical factor in the shell manufacturing technology is the ideal wettability of the model surface by the suspension applied to it. Improvement of wettability can be achieved not only by introducing special surfactants into the aqueous phase, but also by changing the properties of the wax surface itself, i.e. giving it the properties of hydrophilicity.
The paper presents a method of physical modification of the wax model surface, which consists in applying a thin layer of ceramic powder on it, which is well wetted with aqueous ceramic suspensions.
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The volumes of large-tonnage mineral waste generation cause serious concern from the side of environmental supervision. Most of the mineral waste is a valuable secondary raw material, but the lack of integrated technologies for their processing significantly slows down their processing. As part of the work, an assessment was made of the possibility of joint processing of quartz-leucoxene concentrate (waste from the oil production process) and brucite-containing waste from the production of refractories. Joint pyrometallurgical processing of two waste products made it possible to obtain magnesium titanium, a valuable product for various industries. Hydrometallurgical processing of magnesium titanate made it possible to obtain a complex magnesium-titanium-containing coagulant, which showed extremely high efficiency in the process of treating wastewater with a high pH level (concrete mixing unit). The use of a complex reagent, in addition to increasing the cleaning efficiency (reducing residual concentrations of pollutants), made it possible to reduce reagent costs and intensify the processes of sedimentation and filtration of coagulation sludge (simplification of the instrumental scheme).
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The article presents the results of a study of the influence of humidity, oxygen on the formation of the structure and strength properties of products based on magnesium oxide and organic binder SFPR-054. It has been established that carrying out the polymerization process at a temperature of 25 ?C without access to air increases the strength of the samples by about 5 times compared to samples polymerized in dry form at a temperature of 300 ?C. The obtained results suggest that the increase in the structural and mechanical properties of products based on magnesium oxide will be facilitated by the moistening of the mixture, the settling of the pressed product and the polymerization process in an oxygen-free environment or in an atmosphere of water vapor.
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The paper considers the issue of the possible use of stainless steel grade 20Cr23Ni18 and its foreign analogue AISI 310S, instead of steel 12Cr18Ni10T, as a material for the manufacture of a shaping die in the production of glass insulators from electrovacuum glass grade G93-3M, widely used in the radio-electronic industry as cases for magnetic contacts.
It is shown that at working temperatures there is a chemical interaction between both steels and glass of grade G93-3M, which leads to a deterioration in the quality of products due to the appearance of a large number of gas bubbles in it.
It has also been shown that due to additional heat treatment it is possible to reduce the consequences of this chemical interaction, thereby increasing the quality of the resulting product.
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The characteristics of glass-ceramic materials obtained using thermal plasma have been studied. The effect of TPP ash on the properties of glass-ceramic materials should be taken into account. Samples with a mass content of ash of 70 % were obtained. They have the following characteristics: compressive strength 530 MPa, flexural strength 110 MPa, density 3000 kg/m3.
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The possibility of obtaining complex-shaped mechanical engineering products based on reaction-sintered silicon carbide using two methods - mechanical processing of polymerized blanks before sintering and hot slip molding under pressure, has been studied. The obtained silicon carbide ceramic materials are characterized by a low density of about 3.04…3.07 g/cm3, a porosity of ? 1 % and a bending strength of 320…360 MPa. Materials based on silicon carbide modified with boron carbide have a density of 2.72 g/cm3, a porosity of about 1 % and a bending strength of 280 MPa.
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Ceramovermiculite thermal insulation on a wollastonite bundle was obtained from chalk, diatomite and expanded vermiculite by the method of solid-phase synthesis of components. The influence of the granulometric composition of expanded vermiculite, as well as the composition of the charge on the phase composition, physical, mechanical and thermophysical properties of ceramic materials has been studied. The main crystalline phase of ceramic samples is biotite and wollastonite. The developed ceramovermiculite thermal insulation has an apparent density from 310 to 510 kg/m3 and can be operated at temperatures up to 1050 °C inclusive. The developed materials can be used as refractory thermal insulation of industrial furnaces, equipment, etc.
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The paper presents the results of a study of the processes of glass formation during the production of a frit by the method of induction heating. According to X-ray phase analysis, the resulting frit is completely amorphous. The frit meets the standard requirements for a 45 mm flow and a thermal expansion coefficient of 120?10–7 K–1. The enamel coating has a high chemical resistance to acids and alkalis. A comparative analysis of frit synthesis in a laboratory electric furnace using an induction heating device showed that the duration of frit induction heating is halved, energy consumption is reduced by 23 %, and the process efficiency is increased four times on average.
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A method is proposed for processing the reverse side of silicon transistor structures before the metal deposition process and obtaining contact to the collector of the transistor being formed. The parameters of the surface roughness of the silicon surface treated with carbide–silicon sand are studied in order to improve the adhesive properties before spraying the contact to the collector region of the transistor.
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Purpose of this work is to establish the features in the microstructure and thermoelectric properties of composites consisting of Bi2Te2.7Se0.3-based matrix and a Fe filler. The composition with a filler content of 0.3 wt. % Fe has a higher thermolectric figure of merit as compared to the Bi2Te2.7Se0.3 matrix. For this composition, the maximum value of ZT reaches ~0.75, while for Bi2Te2.7Se0.3 ZT does not exceed ~0.63. Thus, in the composite of the Bi2Te2.7Se0.3 + Fe system, the thermoelectric figure of merit can be increased by about 20 %.
