Browsing by Author "Dyadyura, Kostiantyn"

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Expanding Technical and Technological Posibilities in the Production of Parts and Tools Using Bronzes
(MM Science Journal, Czech Republic, 2026) Kimstach, Tetiana V.; Panda, Anton; Dyadyura, Kostiantyn; Uzlov, Kostiantyn I.; Solonenko, Liudmyla I.; Repyakh, Sergey I.
ENG: Among the known standardized bronze grades, there are currently no foundry structural bronzes that would simultaneously combine both non-magnetism and corrosion resistance, in particular, in tap water and seawater. The presence of bronze with such a list of preferential properties will allow not only to expand the boundaries of bronzes as a structural material using, but also to provide prospects for increasing and expanding the technical and technological capabilities of new equipment and technologies in the field of shipbuilding, aircraft construction, instrument making, etc. Today, the only bronze with such a list of properties is aluminum bronze BrA7K2O1.5Mts2, in which, nevertheless, corrosion resistance in comparison with known standardized bronze grades has not yet been studied. All bronzes studied in this work, except for bronze BrO6C6C3, are absolutely stable in warm standing tap water with a cyclic change in temperature from 30 to 50 °С. With the exception of BrA9Zh3L bronze brand, all other bronzes studied in the work are stable in warm standing artificial seawater with a daily change in temperature from 30 to 50 °С and on a ten-point scale have the 4th point of corrosion resistance. The greatest corrosion resistance is possessed by bronze BrA7K2O1.5Mts0.3 with a value of KR = 0.47…0.63. Corrosion in samples of BrA7K2O1.5Mts0.3 bronze, which are after their heat treatment and without heat treatment, is equally continuous. Bronze BrA7K2O1.5Mts0.3 without heat treatment in cold standing artificial seawater is more corrosion-resistant if it is cast in a chill mold. At the same time, in all corrosive environments used in the work, the corrosion resistance of bronze BrA7K2O1.5Mts0.3 is more affected by its heat treatment than by in its chemical composition changing. Further development was received by ideas about the corrosion resistance of non-magnetic structural cast aluminum bronzes in tap water and artificial seawater, taking into account the initial state of the bronzes and the corrosive environment condition. For the first time, in comparison with standardized corrosion-resistant bronze grades, data were obtained on the corrosion rate of “as-cast” and heat-treated non-magnetic bronze BrA7K2O1.5Mts0.3 in warm tap water, warm and cold artificial sea water. This will allow making a well-founded choice of bronzes for the operation of products made of them in the environments and conditions used in this work or close to them. This will save time, financial costs and material resources for developers of new machines, assemblies and units to make a rational or optimal technical decision regarding a rational product material.
Freezing in a Refrigerator of Engineering Products from Sand-Water Mixtures
(MM Science Journal, Czech Republic, 2026) Solonenko, Liudmyla I.; Panda, Anton; Dyadyura, Kostiantyn; Repiakh, Sergey I.; Yakimenko, Dmytro
ENG: The work establishes a number of features regarding the mechanics of freezing wet quartz sands when manufacturing products of limited sizes from them. Products of limited sizes from frozen sand in foundry production are casting models used for manufacturing volumetrically closed and detachable casting molds using the SMS-process method, frozen casting molds and rods, etc. The work used quarry quartz sand of the 1K2O202 brand and tap water. The mass was measured on a VTA-60/6-73-AL-2 scale with an accuracy of ±1 g. The temperature was measured with an alcohol thermometer of the TTZ type and a chromel-copel thermocouple complete with an electronic device of the STC-1000 brand with an accuracy of ±1 С with video recording of temperature changes over time with an interval of 1 s. Drying of sand was carried out in a microwave oven with a magnetron power of 900 W and a microwave radiation frequency of 2.45 MHz. Freezing of wet sand was carried out in a refrigeration chamber with a capacity of 17 kg/day at a temperature of -20 °C. According to the results of the research, it was found that flat products with a thickness of 10 mm, regardless of the water content (up to 12.5% above), under conditions of unidirectional heat removal, cool to 0 °C faster than dry quartz sand. Freezing of wet sand under conditions of multidirectional heat removal from it leads to a significant migration of water in the sand in the direction of gravity, i.e. from the solidification front of wet sand to a surface with a higher temperature, which is in the direction of movement of unfrozen water. Increasing the initial temperature of wet sand contributes to an increase in the rate of its cooling to 0 °C and the time of solidification of water, but increases the total time of solidification of wet sand.