Degradace vlastností montmorillonitických jílů interakcí jádrových pojiv

Abstract

Currently, about two thirds of all iron alloy castings are produced using molds with the green sand systems (GSS) with cores usually bound through organic binders. After pouring, separation of core sands from the green sand mixture is very difficult. The core sand concentration increases due to circulation of green sand mixture in a closed circulation system. Furthermore, in some foundries, core sands have been added to green sand systems as a replacement for new sands. The goal of this research is to analyze the following question: “How are the green sand systems influenced by core sands?” This influence is analyzed with respect to selected technological features and degree of green sand system re-bonding. In studies, which were published, there is no consistent view on influence of core sand on the GSS. In order to simulate the effect of core sands on the technological properties of green sands, the most commonly used technologies of core production (PUR COLD - BOX, HOT - BOX, CRONING and RESOL - CO2) were applied. Concentration of core sands added to the GSS, was up to 50 %. Influence of core sand was examined through evaluation of basic technological features (compactibility, wet tensile strength, green compression strength, splitting strength, cone jolt toughness, wear resistance and moisture), physical-chemical properties (pH, conductivity and loss of ignition). Also, the ratio of active bentonite using the Methylene blue test, EDX analysis, granulometry and the DTA / TG analysis was determined.