Effects of MgO additive derived from different precursors on the slurry viscosity and sintering properties of easy-sintered α-Al2O3

Commercial easy-sintered Al2O3 is typically added with several hundred ppm MgO to facilitate sintering and suppress abnormal grain growth. However, such MgO addition increases slurry viscosity owing to hydration, complicating aqueous Al2O3 processing. Because the surface properties of Al2O3 can be tailored by adjusting processing parameters, this study investigated the effects of various MgO-precursors MgCO3, Mg(NO3)2, Mg (OH)2, and MgO on the rheological and sintering properties of alpha-Al2O3 containing 0-3000 ppm MgO. The results revealed that the slurry viscosity, sintered density, and microstructure were significantly influenced by the precursor amount and type, with 1200 ppm MgO addition using Mg(OH)2 followed by sintering at 1650 degrees C for 2 h demonstrating optimal sintering properties. The observed variations in rheological and sintering behavior depending on the precursors were attributed to differences in Mg2+ ion distribution and surface chemistry, as evidenced by energy-dispersive X-ray spectrometry and Fourier-transform infrared analysis, respectively.