Research of the plastic strength of alumina mass for molding corundum ceramics by extrusion depending on them humidity

One of the characteristics that makes it possible to evaluate the plasticity and formability of ceramic masses is the plastic strength of structure — the ultimate shear stress that the plastic mass can withstand under static stress. The dependence researches of the plastic strength of alumina masses from alumina MARTOXID and CT 3000 brands on a flour binder on their humidity and keeping time were carried out. The determination of the plastic strength of the masses was carried out on a KP-3 conical plastometer, for which purpose a cone with an apex angle of 30о was used (mass of the cone together with rod is 0.8056 kg). The optimum humidity of alumina masses for the molding of corundum ceramics by extrusion from alumina MARTOXID brand is 19 % and from alumina CT 3000 brand is 20 % were established. In depending on technological needs and capabilities were set that, the keeping time of alumina masses with the optimum humidity can be 1—7 days. The samples of corundum ceramics received by extrusion from the alumina mass of alumina MARTOXID and CT 3000 brands with optimum humidity after firing at 1580 оC are characterized by low open porosity and correspond to high refractories corundum high-density products requirements (open porosity no more 0.8 %).