The porous CaP subcoating was formed on the Ti6Al4V titanium alloy substrate by plasma electrolytic oxidation (PEO). Then, upper coatings were formed by radio frequency magnetron sputtering (RFMS) over the PEO subcoating by the sputtering of various CaP powder targets: β-tricalcium phosphate (β-TCP), hydroxyapatite (HA), Mg-substituted β-tricalcium phosphate (Mg-β-TCP) and Mg-substituted hydroxyapatite (Mg-HA), Sr-substituted β-tricalcium phosphate (Sr-β-TCP) and Sr-substituted hydroxyapatite (Sr-HA). The coating surface morphology was studied by scanning electron and atomic force microscopy. The chemical composition was determined by X-ray photoelectron spectroscopy. The phase composition of the coatings was studied by X-ray diffraction analysis. The Young’s modulus of the coatings was studied by nanoindentation test. RF-magnetron sputtering treatment of PEO subcoating resulted in multileveled roughness, increased Ca/P ratio and Young’s modulus and enrichment with Sr and Mg. Sputtering of the upper layer also helped to adjust the coating crystallinity.
In the given paper we consider the impact of wind velocity upon the active shielding gas flow and changes of thermal processes in the MAG welding area. The authors completed numerical simulation of consumable electrode welding under traditional and two-jet gas shielding. It was established that application of two-jet gas shielding for MAG welding increases the hardness of the shielding gas jet and reduces wind-related displacement of thermal fields in the welded item. This ensures more qualitative shielding of the welding area under the windy conditions and uniform heat distribution in the welded item which leads to more homogeneous structure of weld and HAZ metal in comparison to the traditional (one-jet) gas shielding.
A set of various factors and phenomena defines the quality of welded joints. This is especially noticeable for outdoor welding. A numerical simulation of welding processes with consumable electrode with traditional and two-jet gas shielding was carried out to study the influence of wind speed on the movement of the shielding gas (CO2) and the change of thermal processes in the heat affected zone. It is established that the use of two-jet shielding in welding with a consumable electrode leads to an increase in hardness of the shielding gas stream and lower offset of thermal fields in the welded product in the wind direction. It testifies to a better quality of shielding and smaller probable changes in symmetry of structure formation and mechanical properties of the heat affected zone.
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