ИСТИНА

The present paper addresses an alumina-based ceramic material for milling bodies and a method for obtaining thereof. Starting materials were commercially available alumina and an eutectic additive in CaO-ZnO-Al2O3-SiO2 system that was obtained by solid-state reaction. Sinterability of experimental batches was studied at 1350–1550 °C, and the limiting stage of the process was shown to be diffusion mass transfer through liquid phase. Samples fired at 1500 °C demonstrated excellent mechanical properties and highest degree of structure perfection (see Figure). Matrix phase was formed with corundum crystals with mean size of 4–6 μm, the additive segregated as a secondary crystalline phase on grain boundaries. Glassy phase content didn’t exceed 1,5 % vol., and closed porosity was below 2 %. Mean density of such samples with alumina content of 87-95 % wt. reached 3.63 g/cm3, and mean bending strength of 360 MPa. Wear tests in electrofused corundum milling showed weight loss below 0.01 %/h, which is 10 to 15 times less as compared with commercially available uralite milling bodies.