Факультет електромеханіки та електрометалургії (ДМетІ) <br> Дніпровський металургійний інститут (ДМетІ)

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ENG: Faculty of Electromechanics and Electrometallurgy
Dnipro Metallurgical Institute

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    Alumophosphate Binders: Synthesis, Phase composition, Thermal Stability and Application in Foundry Production
    (Elsevier B.V., Netherlands, 2025) Petryk, Ivan; Liutyi, Rostyslav V.; Osypenko, Irina O.; Myslyvchenko, Olexander; Byba, Ievgen; Lukianenko, Ivan
    ENG: Organic binders currently used in the foundry industry are highly toxic. During the pouring of casting molds, many volatile organic compounds are released, the vast majority of which are environmentally harmful. The development of alumophosphate binders will have a positive impact on the environment. The article gives the results of the study of aluminum phosphate binders, which are the result of the chemical reaction of orthophosphoric acid with powdered aluminosilicates. The subjects of the research are the phase and chemical composition, the dynamics of thermal transformations of the binders, as well as the properties of core mixtures for the production of foundry cores. It was found experimentally that as a result of the chemical reaction of powdered pyrophyllite Al2(OH)2[Si4O10] and disten-sillimanite Al2O[SiO4] with orthophosphoric acid after heating to 300 оС, strong and thermally stable binders are formed, which are crystalline and amorphous aluminum orthophosphates. These phases ensure binding of the quartz refractory filler and therefore high strength. Synthesized binders can be used in refractories or core mixtures for foundry production. X-ray phase and differential thermogravimetric analyzes were used to determine the structure and properties of binders. The compositional planning of the experiment with appropriate data processing was applied to determine the working composition of the mixture for foundry cores. The structure of aluminum phosphate binders, which were obtained using refractory fillers common in foundry production, was investigated for the first time. The circumstances for the formation of crystalline phases were analyzed for the first time. It was established that as a result of the reaction of orthophosphoric acid and disten-sillimanite, the larger specific amount of aluminum orthophosphate and the smaller amount of residual quartz is formed, compared to the reaction of acid with pyrophyllite. This ensures the higher strength of the core mixture, which is formed from the binders in which orthophosphoric acid and disten-sillimanite are used. Taking into account the mass ratios for the whole realization of the chemical reaction of the formation of the aluminum phosphate binders, the core mixture on the basis of quartz sand, orthophosphoric acid and disten-sillimanite was developed, which hardens after heating to 300 оС and has a compressive strength of at least 2.0 MPa.