I. N. Ulyanov Chuvash State University (Cheboksary, Russia):

I. E. Illarionov, Dr. Eng., Prof, Head of the Chair “Materials science and metallurgical processes”, e-mail: tmilp@rambler.ru
Sh. V. Sadetdinov, Dr. Chem., Prof., Chair “Materials science and metallurgical processes”, e-mail: avgustaf@list.ru
O. V. Moiseeva, Lecturer, Chair “Materials science and metallurgical processes”, e-mail: MoiceevaLit@mail.ru

Zelenodolsk Designing and Engineering Office (Zelenodolsk, Russia):
E. N. Zhirkov, General Director

For the manufacture of foundry molds and cores, aluminum and magnesium phosphate compounds are used as binders. However, molding and core mixtures prepared with their use as binders do not possess sufficient technological properties, and complex binders, additionally containing boric, borophosphoric and borophosphorous acids, are proposed to improve them. The formation of complex compounds of borophosphoric acid (H₃BO₃ · H₃PO₄ composition) and borophosphorous acid (H₃BO₃ · H₃PO₃ composition) was established by studying the H₃BO₃ – H₃PO₄ – H₂O and H₃BO₃ – H₃PO₃ – H₂O systems at 50 °C by physicochemical analysis. Mixtures were prepared by mixing aluminum, magnesium and complex borophosphate binders separately in an amount of 9 % (wt.) with 4% (wt.) kaolin clay and 87% (wt.) quartz sand. A comparative analysis and evaluation of technological properties of the mixtures showed that the modification of phosphate binders with boric, borophosphoric and borophosphorous acids can increase the robustness and compressive strength of the mixture, reduce crumbling, and also improve knocking-out. Data are presented on the effect of boric, borophosphoric, borophosphorous acid and time on the strength of the magnesium phosphate mixture and the knocking-out quality of experimental mixtures. According to the results obtained, the best technological characteristics have mixtures of compositions containing borophosphorous acid as a modifier.

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