OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 1 2024 equilibrium temperature and expansion within the solidifi cation sequence appear to have a strong infl uence [39] on the susceptibility to macro- and micro-shrinkage in ductile iron castings. The work [34] states that molten cast iron usually contains double oxide fi lms (bifi lms). These silicate oxide fi lms provide a substrate on which oxysulfi des and graphite nuclei form. The presence of these double silicate fi lms explains the diversity of graphite morphology. Lamellar graphite grows along the fi lms, and spherical graphite grows when these fi lms are destroyed, for example, with the addition of magnesium. It was shown in [10–17, 35–39] that the appearance of the vermicular form of graphite was associated not only with the interaction of silicon with carbon monoxide, but also due to the interaction, in this case, of silicon monoxide with a graphite nucleus. As the temperature of the metal melt decreases, the surface activity of SiO decreases [10–12], its mobility decreases, and at the site of formation it dissolves in graphite, changing its morphology to vermicular [35–39]. In conclusion, we note that the components of the combined modifi er (silicon oxides and carbides) do not dissolve immediately when added to the melt; dissolution occurs slowly, which gives a preliminary inoculation eff ect that slowly fades and remains eff ective for several hours [8, 12–15, 26 , 28, 34–42]. At the same time, the behavior of SiC before modifi cation in gray cast iron melts has not been suffi ciently studied, but it is stated [31, 41, 42] that during the dissolution of SiC in the melt, graphite clusters form around SiC particles as a result of local supersaturation of the melt with Si and C. These graphite clusters, which are thermodynamically metastable over a period of time, play an important role in the pre-modifi cation eff ect of SiC in the melt and promote the formation of graphite and eutectic nucleation. Dissolution of the FeSi compound can also result in the formation of graphite clusters, but due to the higher dissolution rate these clusters remain stable only for short periods of time. Consequently, when SiC is dissolved, more graphite clusters are formed, which last longer than when FeSi is dissolved. The formation of many graphite clusters around the SiC particles reduces the carbon content in the rest of the melt, and therefore austenite nucleation occurs at higher temperatures. The use of modifi ers from silicon production waste to achieve the technological properties of gray cast iron together with other advanced technologies in mechanical engineering and metal processing [43–50] will make it possible to comprehensively solve high-tech, knowledge-intensive problems. Conclusions 1. Studies conducted to assess the modifying eff ect of a combined modifi er obtained from silicon production waste in the smelting of gray cast iron show its high effi ciency compared to classical modifi ers. It is established that the addition of a combined modifi er based on silicon oxide and carbide instead of the standard FeSi modifi er led to an increase in tensile strength and hardness by 35–50%, due to a change in the morphology of graphite from lamellar to vermicular. 2. It is shown that the proposed composition of the combined modifi er induces the nucleation of a large amount of vermicular graphite, and also increases the number of eutectic cells and reduced the tendency to form white cast iron. 3. It is shown that the analysis of compression/expansion eff ects during the crystallization process correlates well with the change in solidifi cation parameters in accordance with the characteristics of the molten cast iron, which depend on the melting procedure and the modifi ers used, the rigidity of the mold and thermal behavior (heat transfer parameters). References 1. Kondrat’ev V.V., Balanovskii A.E., Ivanov N.A., Ershov V.A., Kornyakov M.V. Evaluation of the eff ect of modifi er composition with nanostructured additives on grey cast iron properties. Metallurgist, 2014, vol. 58, pp. 377– 387. DOI: 10.1007/s11015-014-9919-x. 2. Kondrat’evV.V.,MekhninA.O., IvanovN.A., BogdanovYu.V., ErshovV.A. Issledovaniya i razrabotka retseptury nanomodifi tsirovannogo chuguna dlya nippelei anodov alyuminievykh elektrolizerov [Research and development of
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