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Abstract

The paper presents the results of numerical simulation of processes aimed at production of nanostructures with the use of oil emulsions in water. The appropriate molecular models of water and oil, as well as the model of the substance which would sediment at the water – oil interface, are looked for. Such substance, after suitable solidification, would become the main component of the produced material. For the described simulations, the Molecular Dynamics method has been used throughout this paper.
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Abstract

The production process of prosthetic restorations runs in two stages. In the first stage, the prosthetic foundation is produced of metal alloys. In the second stage, a facing material is applied on the produced element. In both stages, the wettability is significantly important, as well as the free surface energy relating to it. The quality of the obtained cast depends on the surface phenomena occurring between the metal alloy and the material of which the casting mould is made. The performed examinations also point to a relation between the ceramics joint and the base, depending on the wetting angle. The aim of the presented paper was to examine influence of the composition of a Ti(C,N)-type coating on bases made of the Ni-Cr prosthetic alloy on the wettability and the surface free energy. The test material were disks made of the Ni-Cr alloy with the diameter of 8 mm. The disks were divided into five groups, which were covered with Ti(C,N) coatings, with different amounts of C and N in the layer. In order to determine the surface free energy (����), the wetting angle was measured. Two measure liquids were applied: distilled water and diiodomethane. The obtained results of the measurements of the water-wetting angles suggest that together with the increase of the ratio of nitrogen to carbon in the Ti(C,N) coating, the surface hydrophobicity increases as well. In all the samples, one can see a large difference between the energy values of the polar and the apolar components. The high values of the polar components and the low values of the apolar ones make it possible to conclude that these surfaces exhibit a greater affinity to the polar groups than to the apolar ones. On the basis of the analysis of the surface free energy, one can state that covering the alloy with Ti(C,N)-type coatings should not decrease the adhesion of the ceramics to the alloy, whereas TiC coatings should lead to the latter’s improvement. Due to their hydrophilicity, TiC coatings should decrease the adhesion of bacteria to the surface and hinder the formation of a bacterial biofilm.
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Abstract

The aim of this article is to present the design procedure for determining modification coefficients of toothed wheels of involutes planetary gear train with internal conjunction of teeth. It is possible to obtain a higher load-carrying capacity which depends also on correction coefficients. For example, we take into consideration a concept of planetary gears in which the teeth can be corrected, which allows better fatigue and contact surface strength. Two cases are considered when the namely zero center distance (without corrections) of the central and satellite wheels is the same or not, in relation to the zero center distance between the satellite and the sun wheel. Geometrical dimensions are described with regard to the technological teeth correction scope, and inequality restriction conditions are determined with respect to the ISO standards recommendations and the literature. The procedure can be applied to any other planetary gears with another kinematic connection of wheels.
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