ИССЛЕДОВАНИЕ СКОРОСТИ И ОСОБЕННОСТЕЙ КОРРОЗИИ ОБРАЗЦОВ ИЗ НАНОСТРУКТУРИРОВАННОГО АЛЮМИНИЕВОГО СПЛАВА В СЕРОВОДОРОДСОДЕРЖАЩЕЙ СРЕДЕ

The study determines corrosion rate and covers corrosion damage specifics of AK4-1 aluminum alloy samples in the NACE hydrogen sulfide solution. The alloy was studied in an ultrafine state as compared to the coarse-grained state obtained after standard T6 treatment (hardening + ageing). The alloy was nanostructured by equal-channel angular pressing (ECAP). It was shown that the alloy corrosion rate after ECAP was 1,9 times higher than after T6 treatment. Thus, general corrosion occurred in the alloy after ECAP, while in the T6 state pit corrosion occurred in the alloy in addition to general corrosion. The corrosive effect had a greater impact on surface roughness of samples made of AK4-1 alloy after ECAP as compared to samples after T6 treatment.Определяли скорость коррозии и исследовали особенности коррозионного повреждения в сероводородсодержащем растворе NACE образцов из алюминиевого сплава АК4-1. Сплав изучали в ультрамелкозернистом состоянии в сравнении с крупнозернистым состоянием, полученным после стандартной обработки Т6 (закалка + старение). Наноструктурирование сплава проводили путем равноканального углового прессования (РКУП). Показано, что скорость коррозии сплава после РКУП в 1,9 раза выше, чем после обработки Т6. При этом в сплаве после РКУП имеет место общая коррозия, а в сплаве в состоянии Т6 помимо общей коррозии наблюдается и язвенная. Коррозионное воздействие оказывает большее влияние на параметры шероховатости поверхности образцов из сплава АК4-1 после РКУП по сравнению с образцами после обработки Т6

Synthesis of macrocyclic tris-cis-tris-trans- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane in carbonic acid solution

The possibility to synthesize stereoregular tris-cis-tris-trans- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane (tris-cis-tris-trans-[PhSi(O)OH]12) in an inorganic liquid medium – aqueous carbonic acid solution – was shown. The interaction of polyhedral phenylcoppersodiumsiloxane, {[(C6H5Si(O)O−]12(Cu2+)4(Na+)4}*(L)m (L = Bun OH, H2O), with carbonic acid can be considered as a new ‘green’ method to obtain functional organosiloxane macrocycles. In contrast to the known methods, no organic solvents were used during the reaction. The identification of the structure of the end compound was performed by means of NMR and Infrared spectroscopy as well as X-ray crystallography

Fracture toughness at cryogenic temperatures of ultrafine-grained Ti-6Al-4V alloy processed by ECAP

This research is focused on a study of the relationship between mechanical behavior, microstructure and fracture toughness of a Ti-6Al-4V alloy in both coarse-grained (CG) and ultrafine-grained (UFG) conditions. The UFG state with a primary alpha-phase grain size, but with different orientations with respect to the testing direction, was produced by equal-channel angular pressing (ECAP) after thermo-mechanical treatment. Fracture toughness and mechanicaltesting were conducted at a temperature of 196 °C. A duplex UFG structure formation in the Ti-6Al-4V alloy led to an enhancement of yield stress and a decrease in the fracture toughness at -196 °C by comparison with the CG alloy. The lowest values of fracture toughness were observed in a sample in which there were elongated grains lying parallel to the loading direction during testing compared to the situation where the grains were perpendicular to this direction.The reasons for the reduction in fracture toughness in the UFG Ti alloy are discussed

Synthesis of macrocyclic tris<i>-cis-</i>tris<i>-trans</i>- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane in carbonic acid solution

<p>The possibility to synthesize stereoregular tris-<i>cis</i>-tris-<i>trans</i>- dodeca[(phenyl)(hydroxy)]cyclododecasiloxane (tris-<i>cis</i>-tris-<i>trans</i>-[PhSi(O)OH]12) in an inorganic liquid medium – aqueous carbonic acid solution – was shown. The interaction of polyhedral phenylcoppersodiumsiloxane, {[(C₆H₅Si(O)O⁻]₁₂(Cu₂⁺)₄(Na⁺)₄}*(L)<i>_m</i> (L = Bu<i>ⁿ</i>OH, H₂O), with carbonic acid can be considered as a new ‘green’ method to obtain functional organosiloxane macrocycles. In contrast to the known methods, no organic solvents were used during the reaction. The identification of the structure of the end compound was performed by means of NMR and Infrared spectroscopy as well as X-ray crystallography.</p