Materials Science Forum Vol. 946

Abstract: The purpose of the work is the obtaining of magnesium silicate ceramic proppants, based on ultrabasic overburden rocks of Kempirsai deposits of chromite ores (Kazakhstan). The chemical and mineralogical composition of ultrabasic overburden rock was studied by chemical, microscopic and X-ray diffraction analyzes. It is established that the main mineral of ultrabasic overburden rocks is serpentine, present in the form of fibrous chrysotile and lamellar antigorite. In the impurities are iron oxides and hydroxides, chrome spinel, carbonates, quartz. Assessment of the use of overburden rocks as a raw material for the production of ceramic proppants was carried out. The sintering interval of overburden rocks was determined at 1280-1300 °C. The sintering firing optimum temperature of ceramics, based on this type of raw material is 1300 °C. It is established that to harden the structure of magnesium silicate ceramic it is necessary to activate the raw material thermally at a temperature of 1000 °C. The influence of binder type on the properties of magnesium silicate proppants, based on the Kempirsai serpentinites was studied. Magnesium silicate proppants, based on ultrabasic overburden rocks, were obtained with the following properties: apparent density – 1.6 g/cm³, strength resistance (52 MPa) – 14%, sphericity and roundness – 0.8; chemical resistance (hydrochloric acid) – 98%, static strength of the fraction 16/20 - 72–118 N/granule. The field of application is oil and gas production, metallurgy and ceramic industries.

Abstract: The complex approach based on the combination of methods of equilibrium thermodynamics and x-ray electron spectroscopy for layer-by-layer analysis of the composition of surface layers of amorphous alloys is described on the example of Fe-Si-B-Nb-Cu alloy.

Abstract: Titanium dioxide has a special feature: anatase, to rutile transformation which was considered in our investigations. It is especially important to keep anatase form of titanium dioxide for photocatalytic materials, different ceramics with tribo-chemical properties, self-cleaning coatings and self-sterilizing coatings. For that only one of the titanium dioxide forms is more suitable – anatase, which is more active but not stable, because it transforms to rutile during the time or with the temperature increase loses its activity. Different methods of stabilising anatase have been considered in the paper. Several doping agents have been determined and it was chosen fluorine ion to modify titanium dioxide. Stabilization of anatase is achieved by preparing the reaction mixture by a sol-gel method with hydrofluoric acid. It has shown thermodynamic data, results of experiment, temperatures of anatase to rutile transformation of non-doped and doped titanium dioxide, its X-Ray diffraction and TGA. It is proved that titanium dioxide doped by fluorine ion keeps anatase form till the temperature is more than 1000 °C.

Abstract: In the presented article the possibility analysis of highly entropic oxide phases composition and structure formation was performed. Moreover, the studies devoted to the production of substituted single crystals with the M-type hexa-ferrite structure were carried out. The experiments were conducted to studying the possibility of obtaining oxide high-entropy crystalline solid solutions with the M-type hexa-ferrites structure. As the result of the crystallized samples investigation, the microcrystalline highly entropic Ba (Fe,Mn,Ni,Ti,Al)₁₂O₁₉ and (Ba,Pb,Sr)(Fe,Mn,Ti,Ni,Al)₁₂O₁₉ phases appearing was detected. Based on the obtained data, it is possible to consider that the poly-substituted crystals growth with M-type hexa-ferrite structure. The structural stabilization is promoted by high values of the configurational entropy of the crystal matrix components mixing.

Abstract: In domestic practice development of the production technology of rail grinding wheels has outstripped the development of technology for the production of zirconium electro-corundum; the electrocorundum meets the requirements of non-thermal metal treatment. Among the artificial abrasives the leading place belongs to corundum and corundum based alloys (zirconium electrocorundum). At the moment the domestic factories of the abrasive industry are producing zirconium electrocorundum of the pre-eutectic composition (containing about 25% of zirconium dioxide) for rough grinding applied for the rough processing of the rolled products. The zirconium electrocorundum for the final non-thermal metal treatment is not produced by domestic factories; there are no technical requirements for such a material. This work was targeted to develop compositions and parameters for melting of prototypes for the industrial scale production of zirconium electrocorundum with specified and controlled properties. The grain of zirconium electrocorundum in the grinding wheels used in rail grinding trains has specific properties. According to the principles of non-thermal material processing, the structural and phase state of the grinding grain should provide high strength and durability under normal conditions, and at the same time it should tend to shear during the thermal exposure. The design of domestic electrocorundum for rail grinding with properties which are not inferior in comparison with the imported analogues is a strategic issue.

Abstract: Widely used in thermal production quenching surroundings, gas atmospheres and working mixtures for shot peening are considered. Features of materials at their use are presented and recommendations for more effective application are given. The change of quenching surroundings cooling capacity on the water-soluble polymer basis after an annual operation is shown. Hardening oils during operation are exposed to oxidation and viscosity index change, what affects on the quenched products properties. For endothermic atmospheres that are used in the parts chemical-thermal treatment the composition improvements are required. Working mixtures for shot peening must have a certain composition, properties and sizes, depending on the tasks to be solved.

Abstract: Magnetostatic shields, based on Ni-Fe alloys, were obtained via electrochemistry method with different thickness of partial magnetic layers. The experimental researches of the magnetic properties and magnetostatic shielding effectiveness of the single-layer and malty-layer cylindrical sample of the shields, based on the electrodeposited Ni₈₀Fe₂₀ and Ni₅₀Fe₅₀ alloy, are carried out. It has been shown that the shields of gradient type (200 μm Ni₅₀Fe₅₀+200 μm Ni₈₀Fe₂₀ and 100 μm Ni₅₀Fe₅₀+300 μm Ni₈₀Fe₂₀), containing layers with different values of saturation induction (B_s), have a higher shielding efficiency than shields of symmetric type (400 μm Ni₅₀Fe₅₀ and 400 μm Ni₈₀Fe₂₀). Maximum efficiency of magnetostatic shielding has been noted for 200 μm Ni₅₀Fe₅₀+ 200 μm Ni₈₀Fe₂₀ sample. It opens wide prospects for practical application for protection of the microelectronics devices against permanent magnetic fields.

Abstract: The paper considers theoretical aspects of the kinetics of austenite → ferrite transformation in an Fe–9 %Cr alloy, a common model of diffusionless transformation. In previous studies it was shown that this transformation under isothermal conditions shows a behaviour typical for nucleation site saturation, including the change of the Avrami exponent n (determined as the slow of transformation curve on double logarithmic scale) from 4 to 1. Activation energies determined in two ways: by the ‘nose’ temperature of the normal C-curve and by the slope of the C-curve re-drawn on a reverse temperature scale are unexpectedly similar (272–315 kJ/mole) and not temperature-dependent. But the complete TTT diagrams calculated using these values determined directly from experimental data and the precise formula of Cahn’s solution of grain face nucleated transformation problem do not provide good agreement with experiment in the whole temperature range. This may mean that the theory of site saturation needs some correction.

Abstract: In connection with the need to improve the quality characteristics of metal products, metallurgists are faced with the task of finding new effective methods for secondary steel processing. It is known that the use of simple, two-component materials does not significantly improve the quality of the metal. Complex modifiers with alkaline-earth elements are increasingly used for the modifying processing of steel. These modifiers allow to influence both the metal structure and the shape, phase composition and physical properties of nonmetallic inclusions. At the same time, it is known that barium and strontium practically do not dissolve in steel and are removed from the alloy in the extremely short time. The ability of barium and strontium alloys to deoxidize and desulphurize is low because of the large atomic mass of these elements. The modifying effect of alkaline-earth elements on the properties of steel is undeniable. This effect can be explained by the ability of barium and strontium to affect the magnitude of inter-phase tension in the event of contact with the phase boundary. The purpose of this work was to generalize the industrial experience of using multicomponent alloys with alkaline-earth elements for modifying of steel. Data on the effects of alloys with alkaline-earth elements on the properties of metals are given, as well as technological features of the use of complex alloys with alkaline-earth metals in steelmaking. Thus, it is noted that in conditions of large-scale steelmaking, a very important factor is the limited time in time of the modifying effect of alloys with alkaline-earth metals, which dictates the necessity of transferring the process of modification directly to casting.

Abstract: The description of the basic material for the printboards production is given, its basic physical properties are formulated, the features of machining are shown and the range of problems that arise in this case is determined. We specified common mistakes that could lead to mass marriage in the manufacture of printboard assemblies. The structure and composition of base materials for the production of clad dielectric materials are described in this paper. An equation for calculating the maximum shear stress for a composite material is given. It is shown that nesting and, as a consequence, an increased content of glass fibers through a chain of interrelated factors affects the quality and reliability of the printboard operation and the entire product as a whole. In addition, the dense laying of fibers increases the cutting tool wear significantly. The article provides the technique of the base material choice depending on the distribution structure of glassfiber filaments on which the labor productivity, the quality, the cutter power and the manufacturing cost of the printboards depends.