Experimental impact study of ultra‑fine metal powders on technical characteristics and physical properties of foundry sodium silicate sand cores

The results of the experimental impact study for the mass fractions of ultra‑fine metal powders added into compositions of core mixtures on technical characteristics and physical properties of the foundry sodium silicate sand cores under influence of high temperatures during production of metal castings are presented and discussed. The dependences for technical characteristics and physical properties of the cores on the mass fractions of ultra‑fine powders based on aluminum, steel, and bronze are established. The significant reserves for improving a knocking‑out ability of the cores based on promising compositions for cast iron by adding ultra‑fine powders of aluminum or bronze into core mixtures are revealed. It is established that the best knockingout ability of the cores in combination with a low outgassing rate and a high gas permeability can be achieved by combining 15.0 wt. % crushed seashell and 0.5–1.0 wt. % aluminum powder. The boundaries for reasonable use of a recycled mixture in preparation of a core mixture are determined.