Obninsk Research and Production Enterprise Tekhnologiya named after
A. G. Romashin, Obninsk, Russia:

D. V. Kharitonov, Dr. Eng., Deputy Director of the Research and Production Complex for Operating Activities, Head of Workshop

N. E. Sher, Process Engineer of the 1^st category, e-mail: kolia1211@yandex.ru

Mendeleev University of Chemical Technology of Russia, Moscow, Russia:
D. O. Lemeshev, Cand. Eng., Associate Prof., Dean of the Faculty of Technology of Inorganic Substances and High-Temperature Materials
D. Yu. Zhukov, Cand. Eng., Associate Prof., Director of the Technological center "Ekokhimproekt"

The technology of obtaining corundum-mullite material for the manufacture of melting crucibles by the method of vibrocasting highly concentrated binder suspensions based on aqueous corundum slip and coarse-grained powders of electrocorundum and mullite into gypsum molds is considered. Corundum slip is prepared by wet grinding white electrocorundum 25A fractions F22, F36 in a ball mill to obtain a suspension with density of 2.7–2.9 g/cm³,conditional viscosity of 20–30 °E, and a content of ~90 % (wt.) of particles up to 10 μm in size. As a filler, a combination of coarse-grained electrocorundum powders with fractions of 0.5–0.6 (16–18 % (wt.)) and 0.125–0.150 (24–26 % (wt.)) mm, as well as electrofused mullite with fractions of 0.4–1.6 (14–16 % (wt.)) and 1.6–3.0 (42–44 % (wt.)) mm. When the filler is mixed with slip in the ratio (61–63):(37–39), % (wt.), a sedimentation-resistant mixture is formed, from which crucibles are formed by vibration casting into plaster molds. Corundum-mullite material after firing at 1550°C has a sufficiently high density (3.0–3.1 g/cm³), compressive strength (140–160 MPa) and a low coefficient of thermal expansion (65∙10^–7 K-1 at 1400 °C). Refractory melting crucibles have a homogeneous structure: material density variation throughout the entire volume of articles does not exceed 3%. The service life of crucibles in the conditions of melting nickel alloys is at least 25 melts.
The researches were carried out using D. Mendeleev Center for collective use of scientific equipment, within the framework of the project No. 075-15-2021-688.

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