Materials Science Forum Vol. 1031

Abstract: A method of forming arbitrarily shaped microchannels on substrates of brittle dielectric materials, such as optical glasses and optical crystals, is considered. This method makes it possible to ensure the identity of microchannel edges over the entire perimeter

Abstract: Experiments proved that the arc voltage influences its spatial form and electrode metal transfer behavior characteristics during twin electrode GMAW with a single power source. Two specific arc forms were revealed for two corresponding types of metal transfer. The V-shaped arc exists on the melt drop common to the two consumable wires at voltage rate 24-27 V. The columnar shaped arc is formed due to voltage increase up to 34-36 V, which results in increased mobility of the cathode spot in the weld pool surface. As a result, the arc travels between the ends of two electrode wires, and the metal is transferred in drops of small size. It was demonstrated that for the common drop formation the gas mixture of 82% Ar+18% CO₂ is preferable to pure argon. It decreases the surface tension on the boundary between the melted electrode metal and the vapor-gas mixture, resulting in the increased volume of the common drop. It was found that a consistent common arc from two electrode wires decreases dilution is made up 43%, which is 1,65 times more and improves the deposited metal formation quality.

Abstract: This article is devoted to the study of the filtration coefficient depending on the loads applied to the material. In filtration theory, it is classical to solve problems with a constant filtration coefficient. Moreover, due to the conditionality of the filtration coefficient value by various physical and chemical processes, both in the solid fraction and in the liquid, its value is usually determined empirically. However, it is obvious that depending on the loads applied to the material, the pore space and filtration coefficient will change. This is especially true when using various filter materials, such as concrete. The latter, depending on the brand, can absorb the liquid quite well. Therefore, assuming that the pore space is a collection of capillary tubes, the paper shows the relationship between the filtration coefficient and the average pore diameter of the material. The dependence of the material filtration coefficient on the first invariant of the stress tensor arising in the medium is found. The change in the filtration coefficient of a concrete slab at different points is shown when a force load is applied to its upper surface.

Abstract: To solve the problem of obtaining an effective composite abrasive material that allows preserving the focusing tube and increasing the cutting capabilities of the water jet, the authors obtained theoretical dependences that establish the relationship between the strength of the abrasive-polymer compound and its production modes

Abstract: The purpose of this work is to experimentally prove the possibility of modifying the surface of a material by exposure to a long-lived plasma formation (DPO). Under this action, the surface of the material experiences heat shock, since the contact time is about 100 ms. The paper deals with the usage of autonomous long-lasting plasm formations (DPO). The tasks of thermal processing, coating, thermal shock tests metallic and non-metallic materials are introduced in the given paper. Large stored energy (till 10 kJ) and high brightness temperature (4 500 K) at sufficient time of influence can determine the range of technological problems, where long-lasting plasma formations have advantages in comparison with plasmatrons. This paper presents the results of the tests of the thermal shock by the concentrated flow of electromagnetic energy, saved by long-lasting plasm formation.

Abstract: This work is devoted to the study on the possibility of applying the method of analyzing the particle size of hydroxyapatite at various stages of synthesis. A series of hydroxyapatite powders obtained by chemical deposition using microwave radiation is considered. Determination of the size of hydroxyapatite nanorods is carried out on the basis of data on the density and specific surface area. The specific surface area is analyzed by the sorption method. Determination of the ratio "length / diameter" of nanorods is based on the analysis of images obtained by scanning electron microscopy.

Abstract: The need to create highly accurate pressure sensors that capable operate under extreme conditions in aviation, rocket and space equipment increases and becomes more relevant. The unique properties of diamond make it a promising material for microelectronic sensors. Sensitive elements of pressure sensors were developed where a resilient element is formed from silicon but resistance strain gauges are formed from a boron-doped polycrystalline diamond film.

Abstract: The article presents a method for eliminating the crystallization of thermal nodes and shrinkage defects in the form of micro-friable cavities. The method of soldering on castings from steel grades VNL-1 and VNL-6 using 5VA powder solder has been investigated. Also, the optimal soldering modes were determined, the effects of soldering modes on the properties of the base material and the soldered joint were studied, the corrosion resistance was investigated, the corrosion resistance of the soldered joints in corrosive environments. The conducted studies of sealing by soldering cast parts with microdefects lead to the following results: increased corrosion resistance; ensuring increased tightness; improving the presentation; elimination of surface microdefects.

Abstract: The article deals with the mechanism of transition of silicon to aluminate solutions in the process of leaching aluminum sinters in the production of alumina from nepheline. It was found that features of the transition in silica aluminate solutions by leaching cakes of various types relate to the structure of two-calcium silicate, and the dependence of reactions in the aluminate solution, its temperature and composition. A pattern has been established that determines the relationship between the SiO₂/Al₂O₃ ratio in the list and the concentration of silica in aluminate solutions after leaching.

Abstract: The exploration of the depths of the sea is an activity that is important for many branches of science; it is associated with the work of people and technology in extremely difficult external conditions, which, in their extremeness, are comparable, perhaps, only with the conquest of space. At the present stage, deep-sea surveys are carried out using various instruments, including manned ones. These machines do not belong to the class of military large-tonnage submarines, but to the so-called Bubble Subs. The hull, which is a translucent thick-walled spherical shell is the main characteristic feature of this type of underwater vehicle. The presented work lists the main problems faced by researchers in the strength analysis of such PMMA hulls. In particular, the issue of the significant difference between the results of calculations in cases where the material is considered as physically linear and as physically non-linear is disclosed in detail. In addition, the obtained numerical results are compared with the experimental data.