National University of Science and Technology MISiS, Moscow, Russia:

A. A. Sokorev, Senior Lecturer, Department of Foundry and Artistic Processing of Materials, e-mail: RCstuff@ya.ru
S. S. Mishurov, Leading Engineer, Metal Forming Department, e-mail: mishurovs@mail.ru
A. P. Dolbachev, Engineer, Metal Forming Department

Moscow State Technological University “STANKIN”, Moscow, Russia:

E. A. Naumova, Associate Professor

As a result of the present research, the mechanism of step-by-step sintering of multicomponent composites was revealed on the example of industrial waste IM-2201 during thermal cycling, which consists in the formation of a refractory mullite structure in the first cycle of the process from the continuous liquid phase of fusible inclusions and its transformation into a composite structure of mullite, corundum and chromium oxide at higher temperatures at subsequent cycles. The step-by-step sintering is accompanied by a consistent reduction of shrinkage in each cycle and is associated with the successive removal of impurities and relaxation of structure defects. Also, the fractional nature of the particle size distribution of the components included in the industrial waste IM-2201 containing 4 pronounced fractions with an average particle size of 18 μm (Al₂O₃), 6 μm (Cr₂O₃), 3 μm (SiO₂) and 1.4 μm (RO, R₂O) was experimentally established. The number of fractions, their hardness and fire resistance increase with increasing particle size, which explains the step-by-step mechanism of sintering. Also, the use of refractory clays with ultrafine particles obtained as a result of mechanochemical activation in the compositions of refractory solutions, contributes to the compaction of the structure and increase the physicochemical properties. The results of the conducted dilatometric studies allow us to speak about the effectiveness of the proposed industrial waste in a number of high-temperature casting processes. At the moment, active tests of IM-2201 as a refractory filler of ceramic LVM-forms are carried out, along with the regeneration and re-use of traditional fillers: corundum, disten-sillimanite concentrate, marshalite.
The paper was prepared as part of Agreement No. 11.7172.2017/8.9 “Studies on synthesis of aluminum- and iron-based structural and functional materials, functionally graded coatings of a new generation and development of new approaches to their diagnostics”.

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