Journal of Engineering Sciences / Журнал інженерних наук

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    Fabrication, mechanical characterization, and ranking of shell ash reinforced Al-7075-based hybrid composites
    (Sumy State University, 2023) Kumar, E.V. Ratna G.; Kumar, Senthil K.; Babu, Ranga J.A.
    In the research article, the fabrication of Al-7075-based hybrid composites was done by stir casting technique with the addition of a mixture of crab shell ash (CSA), oyster shell ash (OSA), and snail shell ash (SSA). The mixtures of CSA, OSA, and SSA (MCOSA), CSA and OSA (MCOA), CSA and SSA (MCSA), as well as OSA and SSA (MOSA) with weight percentages in a range of 1–3% were added to the base material. The specimens were prepared according to the ASTM standards and tested for mechanical properties. The hardness, as well as impact, flexural, and tensile strengths of the composites, were increased as the amount of reinforcement to the base metal was increased, and compressive strength was decreased. The greatest tensile strength, tensile modulus, and compressive strength values were observed for the composite designated with AlOSA3. The maximum flexural strength and hardness values were observed for the compositions AlOS21 and AlCO12, respectively. Two techniques (TOPSIS and VIKOR) were successfully applied to the mechanical attributes of composites. The ranking results of both methods were compared. The ranking results for TOPSIS and VIKOR were the same for the index value 0.25. The composites filled with aquatic waste fillers can be used for automotive applications concerning their enhanced mechanical properties compared to the Al-7075 metal alloy properties.
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    Investigation on the rheological properties of polydimethylsiloxane
    (Sumy State University, 2022) Javanbakht, T.
    This paper focuses on studying the rheological properties of polydimethylsiloxane (PDMS). This polymer has been used to fabricate membranes and filters in engineering. The analysis of the rheological properties of this polymer is required for a further investigation of its mechanical behavior. In this study, the rheological behavior of PDMS is reported at different temperatures. This polymer showed steady shear viscosity during a short duration. However, this behavior changed with time and increased more with increasing temperature. The impact of the temperature increase was also observed when the shear viscosity of PDMS increased with shear strain. The increase of torque with shear strain and time was observed at different temperatures. Shear stress increased linearly with the shear rate at 20 °C and 40 °C. As expected, the deformation of the polymer required less shear stress with the increase of temperature. However, the change of shear stress with the shear rate at 60 °C was not linear, and the slope of the curve increased more at high shear rates. The results of this investigation can provide the required information for a better fabrication of membranes and filters with this polymer.
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    Potentials of date-seed/snail shells as a carburizer for enhanced mechanical properties of mild-steel
    (Sumy State University, 2021) Kolawole, M.Y.; Awoyemi, E.A.; Abiona, O.M.
    The suitability of date-seed/snail shells as a carburizer for enhanced mechanical properties of mild-steel using the packed carburization technique was investigated in this work. Standard tensile, impact and hardness test samples prepared from mild-steel were subjected to pack-carburization process using mixtures of date-seed and snail shell in the ratio 60:40 respectively at 800, 900, and 1 000 °C for 3 hours. The carburized samples were quenched in water at room temperature and further tempered at 300 °C for 30 minutes for residual stress relief of the quenching effect. The mechanical properties and optical microstructure of carburized specimen were performed. Results indicated an enhanced mechanical property of the carburized mild-steel using date-steel/snail shell as a carburizer compared to un-carburized same steel material. The tensile strength and hardness increased with increasing carburizing temperature, though with an associated decrease in ductility. The peak hardness (32.82 HRB) and tensile strength (521 MPa) with equivalent 31.28 and 51.45 percentage increments respectively were obtained at carburizing temperature of 1 000 °C. Hence, using date-seed/snail shell powder as a carburizer can enhance the mechanical properties of mild-steel.
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    Influence of heat treatment technologies on the structure and properties of the corrosion-resistant martensitic steel type AISI 420
    (Sumy State University, 2020) Lupyr, O.; Говорун, Тетяна Павлівна; Говорун, Татьяна Павловна; Hovorun, Tetiana Pavlivna; Vorobiov, S.; Burlaka А., А.; Khvostenko, R.
    One of the methods for increasing the complexity of chromium steel properties of martensitic class AISI 420 is the use of an optimal heat treatment mode. The steel of martensitic class AISI 420 has high resistance in atmospheric conditions (except for the sea atmosphere), in the river, and tap water. It is widely used in power engineering, in cracking units with a long service life at temperatures up to 500 °C, for furnace parts. Additionally, it is used in the following fields: the production of turbine blades, working in conditions of high temperatures and parts of increased plasticity, subject to shock loads, for products exposed to atmospheric precipitation, solutions of organic salts and other slightly aggressive environments; production of fasteners; production of parts for compressor machines operating with inert gas; production of parts operating at low temperatures in corrosive environments; production of parts for aviation purposes. It is shown that the optimal mode of heat treatment for a maximum hardness of 40 HRC is quenching at a temperature of 980 °C with cooling in oil and tempering at a temperature of 200 °C with air cooling. With an increase in the tempering temperature from 200 °C to 450–500°C, the impact strength does not change much. Tempering at higher temperatures leads to the intense weakening of the steel. Simultaneously, a decrease in the impact strength is observed, the minimum value is reached at a tempering temperature of 550 °C. With an increase in the tempering temperature to 700 °C, the impact toughness increases, but the steel’s hardness sharply decreases at such temperatures.
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    Influence effect of electric action on the micro structure of steel in crystallization
    (Sumy State University, 2017) Zhbanova, O.M.
    The dependence of physical and mechanical properties of manganese steel grade 110H13L on the effect of electrical activity during crystallization of the casting is considered. Treatment of the melt by electric current increases the speed of dissolution of metallic impurities and other components in the melt many times, providing not only finely crystalline structure, but also improving the homogeneity of metal casting. Improvement of mechanical properties is a consequence of crushing those which constitute microstructure. Processing by electric current does a beneficial effect on the process of crystallization of metal melts during casting, which significantly improves the structure of the ingot and its mechanical properties.