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Increasing of the hardness and wear resistance of the working surfaces of parts made of aluminum and its alloys is achieved by modifying them by the method of micro-arc oxidation in alkalescent electrolytes. This technology consists in the formation of a highly hard and wear-resistant ceramic layer by means of the spark discharges and implies an enormous investment of energy and time. The finished product surface roughness in numerous cases fails to meet the requirements, and demands additional machining. High hardness of the hardened layer, at the same time causes an increased wear of the processing tool. A method in which the technological process is carried out in two stages allows improving energy efficiency of this technology. At the beginning, when using an electrolyte with a high content of liquid glass, a primary oxide layer, consisting predominantly of silicon oxide, is formed. At the next stage of micro arc oxidation, the content of the liquid glass in the electrolyte decreases, which allows the formation of predominantly high rigid aluminum oxide in ceramic layer. This technology can significantly reduce the time of formation of a coating and reduces energy consumption. To reduce the processing tool wear it is proposed to keep the surface of the modified by oxidation workpiece in hydrofluoric acid for 5 - 30 minutes. This operation allows to reduce the hardness of the upper layer, consisting mainly of silicates, without affecting the lower layer, formed mainly of aluminum oxide. As a result, it is possible to receive the required surface micro geometry with less tools wear, less time and energy. There was achieved a reduction of time for getting the finished product by 1.6 - 2.3 times, electricity by 2 - 2.7 times, tool wear by 8.7 - 12 times.

The paper presents a developed a technology for producing a new abrasive material, which is a refractory ceramic matrix made of aluminum oxide with embedded diamond particles. The tests have shown its advantage over traditional diamond-bearing materials when processing high-hardness ceramics. To synthesize a new material with a predetermined set of operational parameters, it is necessary to build a wear model of a friction pair composed of diamond-bearing ceramic material and ceramics. After analyzing the results of other authors’ studies and assessing the morphology of the contacting surfaces, it is assumed that the contact of microroughnesses on the friction surfaces of abrasive diamond-bearing ceramic tools is linearly elastic. The model is built within the framework of the basic wear equation. The composite material surface was modeled by a set of same radius spherical segments; diamond grains were distributed in the material with a given bulk density. The paper uses the concept of an equivalent surface with the power law distributed of microroughnesses tops. A theoretical relationship is obtained between the micro-and macrocharacteristics of the wear process of a composite ceramic friction pair. The authors established theoretically and confirmed experimentally that the grinding productivity increases with an increase in sliding speed, applied load and diamond grain size. The diamond concentration has no significant effect on the workpiece wear. The established dependencies can help to achieve high productivity of diamond ceramic tools.

Main trends in the formation of biotopic complexes of bumblebees in the northern taiga zone are analyzed. It is proposed that Eurasian forest species of bumblebees (Bombus (Th.) schrencki, B. (Mg.) consobrinus, etc.) are coadaptively connected with entomophilous plant species belonging to the synusia of Eurosiberian riverine-mountain meadow tall herbage, with the numbers of species in both biotic groups (pollinating insects and plants) and their abundance being greater in the landscape characterized by a high degree of karstification. In the biotopic bumblebee complex of a large river valley, the relative abundance of forest bumblebee species is 2.5–5.3 times lower than in other complexes, whereas that of meadow species is two orders of magnitude higher due to favorable thermal conditions and a large number of habitats with mesophilic herbage and legumes. Each of the distinct ecogeographic groups of bumblebees and the corresponding synusiae (each comprising entomophilous plants of different taxonomic groups) appear to be coadapted. This is probably a result of the diffuse coevolution of pollinators and plants belonging to the genetically unified biota.

The morphology and electronic properties of InAs quantum dots (QDs) on the GaAs(001) surface has been studied by ultrahigh vacuum scanning tunnelling microscopy/spectroscopy after removal of a preliminary deposited protective As layer. A thermal annealing procedure has been developed, which, applied to a sample with an As cap layer, allows InAs QDs to be opened on the surface of an InAs wetting layer (WL) exhibiting a [2×4] reconstruction of As dimers. Scanning tunnelling spectroscopy measurements on the decapped surface show that I–V characteristics taken with the microscope tip positioned over single InAs QDs have a smaller voltage width for zero conductivity (dI/dV =0) when compared with those taken over the InAs WL, which are essential the same as the I–V characteristics for a clean GaAs surface. This observation seems to indicate a weakening of the surface band bending in the areas beneath InAs QDs. Copyright © 1999 John Wiley & Sons, Ltd.

The results of studying tribotechnical and physicochemical properties of various liquids have proved applicability of a dispersion medium, which is based on organosilicon liquids, for producing new-generation magnetic lubricating oils. The paper gives recommendations for choosing a dispersed magnetic phase. There is an original approach to selecting surfactants for stabilization of a magnetic oil colloidal structure, taking into account their dielectric properties and the effect on friction. The paper describes technological features of the synthesis of lubricating oils based on polyethylsiloxane PES-5 and chlorphenylsiloxane KhS-2-1VV containing nanosized magnetite. It also investigates lubricating properties of magnetic oils based on oligodiethylsiloxane and oligomethyl(chlorophenyl)siloxane under various friction conditions and shows their specific features. It analyzes the influence of various additives and fillers on tribotechnical characteristics of magnetic oils. It also defines a different mechanism of additives effects on frictional contact properties. The results of magnetic oil tests determine the most promising compositions for practical use in tribounits. Finally, there are recommendations on practical application of optimal compositions of magnetic lubricating oils in traditional and perspective tribounits with various operational parameters.

The paper describes the developed basics of the preparation technology of solid ceramic coatings on titanium and its alloys. The coatings have been formed by the method of microplasma surface oxidation in electrolytes of different composition. The authors have determined the modes of wear-resistant coating application on titanium alloy, which have significantly decreased coating porosity and made it possible to increase its wear resistance. They have also carried out physical and mechanical, as well as tribological tests of the materials obtained and formed a database of their actual properties. The paper shows that self-lubricating coatings can be operated for a long time at moderate loads and sliding speeds in friction units without using a lubricant. It also describes a newly developed and improved existing equipment to create coatings and study their tribological properties.