This paper describes some fundamental principles, specific features, and the technological capabilities of a new method of quenching steel surface by turning without separation of chips. The underlying process of this method is a deformational cutting (DC), which is based on the undercutting and deformation of surface layers that remain attached to the workpiece. The energy released in the area of DC is used to heat the undercut layer up to the temperatures of structural and phase transformation of workpiece material. This type of process results into a hardened structure formed at the surface which consists of inclined thin undercut layers tightly packed and stuck together and form a single solid body. The resulting hardened structures achieved in steels workpieces are presented in the paper. The samples hardened by DC showed a higher wear resistance compared to samples with traditional quenching. This paper also describes an estimation of the thermo-physical parameters of the DC process.
The paper considers the dependence of the load on displacement during uniaxial compression of spruce wood samples with an adjustable deformation rate (1 mm/min); the water content in the samples was equal to 6.4%. The study focuses on the analysis of criteria for brittle destruction of wood and its transition to a plastic state. The concept of virtual material transformation (CoViMT) forms the basis of the research. At the idea level, this concept is a variant of the well-known equivalent material concept (EMC). An integral criterion for brittle fracture was developed. Comparison with experimental data showed that the integral criterion and the known differential criterion lead to mismatched points of brittle fracture and transition of wood to the plastic state. Therefore, it is possible to determine the boundaries of the region of plastic states with the help of these criteria. Experiments confirmed the adequacy of the criteria when compressing wood with 6.4% and 18.0% moisture content. However, the volume of studies of the problem touched upon is small, so further research is necessary to better understand the stages of deformation of wood of different species.
In the present study, we report the development of a new type of anodic aluminium oxide membranes. Nanoporous alumina films have been fabricated by galvanostatic two-step anodizing technique. For the 1stgroup of samples at both stages was used water solution of oxalic acid as an electrolyte; and for the 2ndgroup at the 2ndstage was used a special multicomponent electrolyte. Using atomic force microscopy, it was found that a method of barrier layer thinning “from above” in combination with chemical removal of metal enables permeable anisotropic alumina membranes fabrication.
The aim of the work is determination of production temperature and salt regimes for an industrial threevessel vacuum evaporation unit for concentrating magnesium chloride solution, included within technology for artificial carnallite preparation. A scheme is provided, and a unit developed and manufactured for this purpose is described. Experimental data are provided that were obtained during magnesium chloride solution concentration within a single-tube evaporation unit with a descending film (unit) under different regimes. A distribution device is selected for provision of stable film flow over the inner surface of a heatexchange tube. The possibility is confirmed by experiment for the first time of using equipment with a descending film for concentrating actual magnesium chloride solution. Data are obtained for the limiting salt content within the concentrated solution providing operation of the unit in a crystallization-free regime.The Russkii Magnii company entered into construction of a plant for preparation of magnesium metal. One of the semi-finished products of magnesium production is synthetic carnallite. For the production process of magnesium chloride solution, obtained during salt-acid leaching of serpentinite, before supply for synthesis of artificial carnallite it is concentrated in a three-vessel vacuum-evaporation unit (VEU) fitted with evaporation equipment with a descending film.Magnesium chloride solution is a complex multicomponent system of the following chemical composition, wt.%: MgCl 2 -20.06; CaCl 2 -0.42; NaCl -1.2; KCl -1.39. The composition of concentrated solution (in wt.%) is: MgCl 2 -34.5; CaCl 2 -0.72; NaCl -2.08; KCl -2.4. During concentration by a factor of 1.72-1.73, salt crystals do not separate from the solution.Experience of industrial operation of a VEU shows that under actual production conditions quite broad deviations of compositions from regulated values are possible for the solutions being processed, which leads to over-evaporation of solutions and separation of crystals on the heat-transfer surfaces of heating pipes and other internal surfaces of the evaporation equipment in the form of solid incrustations. In addition, presence within a solution of calcium and silicon compounds under
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