Multiple use of pan concentrate from placer deposits directly in technical process without prealltoment of pure components could become one of promising directions in the field of receiving wide ...range of multicomponent metal and ceramic powdered materials. In this paper as the object of comparative examination, we present the hemimethylated plating made of exploited experimentative flux cored wires based on industrial Ni-Cr-B-Si system powder modified with rare-earth elements of concentrated complex from Tomtor mineral assets Republic of Sakha (Yakutia). The structure of received plating is heterogeneous and has oxidation coating as boundaries. According to the data of the phase shift analysis plating predominantly consist of Fe-Ni austenitic alloy phases with the Cr, Si carbide and Cr boride precipitation strengthening, plating generally consist of Al2O3, Cr2O3 и Fe2O3 oxide. The research of the plating ultimate composition testifies the equable allocation of main and alloying elements, local location of some elements in the structure of the plating. Microhardness of flux cored wire plating substantially depends on composition and fabricated structure. It has been established that the introduction of rare earth elements provided the formation of strengthening phase with the high hardness of plating resulting in wear resistance increase.
A low-temperature test bench is developed for studying the low-temperature wear of frictional pairs based on powder coatings. The tribological properties of frictional pairs at low temperature are ...analyzed. Their wear is studied. The temperature variation of a frictional pair in cold startup of a mechanism is determined. Laws describing coating and counterbody wear are derived.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The ultimate values of the porosity of basalt–plastic composites in the process of degradation under ambient conditions are estimated. The estimative calculations take into account the layered ...structure of the composites with cylindrical and planar symmetry. The obtained results are compared with the experimental data measured for the open porosity of basalt–plastic composites in climatic tests under northern conditions.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
For the development of new compositions of modified powder mixtures a comprehensive analysis of the technical characteristics of powder additives is required. The specific surfaces of nanosized ...powders of "Tarkosil" silicone dioxide were determined by the experimental method. Therefore, at present, the estimating relationships of sizes, particles shapes and specific surface area of nanosized powder is relevant scientific and practical task. And the particles shape was evaluated by the values of these surfaces. Using the method of small-angle scattering the functions of distribution of the modifying powders particles on their sizes were estimated, and the average values of particles size of "Tarkosil" powder were specified The particle shape of the modifying powders has been estimated according to the specific surface values. The particle shapes of T50 powders are close to isometric (a ball, a cube); particle shapes of T150 powders correspond to a tetrahedron, the particle size T80 and T110 corresponds to the intermediate value of the specific surface area.
The unique physical and chemical characteristics of rare earth elements make them attractive for use in a number of existing and innovative production lines. The use of complex concentrates of ...various deposits to obtain new materials is a promising area of modern materials science. The article presents the results of studies of electroarc metallization coatings of flux-cored wires with modifying additives. As additives, a complex concentrate of rare-earth metals from the deposits of the Republic of Sakha (Yakutia) and other modifying powders were used to obtain hardening phases. To determine the optimal composition of the modifying additives, various compositions of cored wires were made. An analysis of the structure of coatings showed a uniform distribution of the main elements of the cored wire, as well as a local distribution of unmelted particles of the modifying additives. The levels of open porosity and microhardness of the phase components of the coatings are determined. The prospects of using complex concentrate with rare-earth elements from deposits of the Republic of Sakha (Yakutia) as modifying additives for coatings with enhanced performance properties is shown.
Abstract Background Walking down slopes and/or over uneven terrain is problematic for unilateral trans-tibial amputees. Accordingly, ‘ankle’ devices have been added to some dynamic-response feet. ...This study determined whether use of a microprocessor controlled passive-articulating hydraulic ankle–foot device improved the gait biomechanics of ramp descent in comparison to conventional ankle–foot mechanisms. Methods Nine active unilateral trans-tibial amputees repeatedly walked down a 5° ramp, using a hydraulic ankle–foot with microprocessor active or inactive or using a comparable foot with rubber ball-joint (elastic) ‘ankle’ device. When inactive the hydraulic unit's resistances were those deemed to be optimum for level-ground walking, and when active, the plantar- and dorsi-flexion resistances switched to a ramp-descent mode. Residual limb kinematics, joints moments/powers and prosthetic foot power absorption/return were compared across ankle types using ANOVA. Findings Foot-flat was attained fastest with the elastic foot and second fastest with the active hydraulic foot ( P < 0.001). Prosthetic shank single-support mean rotation velocity (p = 0.006), and the flexion ( P < 0.001) and negative work done at the residual knee ( P = 0.08) were reduced, and negative work done by the ankle–foot increased ( P < 0.001) when using the active hydraulic compared to the other two ankle types. Interpretation The greater negative ‘ankle’ work done when using the active hydraulic compared to other two ankle types, explains why there was a corresponding reduction in flexion and negative work at the residual knee. These findings suggest that use of a microprocessor controlled hydraulic foot will reduce the biomechanical compensations used to walk down slopes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The porosity of basalt–plastic composite materials formed during climatic tests is studied. The statistical model of porosity formation during climatic tests of basalt–plastic composite materials ...with cylindrical and plane symmetry is developed based on the Markov chain theory.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A bench for wear testing of powder coatings and metal counterbodies has been developed and manufactured under conditions of low climatic ambient temperatures. Thermophysical measurements of the ...operation of the “powder coating–counterbody” friction unit in cold conditions have been carried out. Wear tests were carried out during sliding friction of modified powder coatings at low climatic temperatures. Corundum additives Al
2
O
3
and ultrafine spinels CoAl
2
O
4
and CuAl
2
O
4
were used as modifying additives for wear-resistant powder coatings. For friction, counterbodies were used—pads made of ordinary and hardened ShKh15 grade steel.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The formation of open porosity in rebar made of basalt fiber-reinforced polymer composite (BFRP) is investigated during exposure tests in northern climates. A statistical model is proposed for pore ...formation in BFRP rebar.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A statistical model of porosity formation during climatic tests of a composite material with basalt reinforcing fibers is proposed based on an analysis of experimental data.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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