Phase Formation and Structure of Mullite-Alumina-Zirconia and Spinel-Enstatite Ceramics Developed from Synthetic and Mineral raw materials

摘要

New dense and porous ceramics are developed using two formulation approaches. These are ceramics with remarkable content of mullite, corundum and ZrO_2 - tetragonal and monoclinic in crystalline phase and porous (average size of pores up to 150-350μm) spinel-enstatite/forsterite ceramics. To promote the phase development by high-temperature synthesis of these ceramics the mineral raw materials - illite clay and illite clay together with dolomite are used. Bulk density for mullite (corundum) - zirconia ceramics is increased by equal addition of illite clay (8.2 wt.%) as well as ZrO_2 and especially ZrO_2 +Y_2O_3 to starting mullite mixtures. Contrary the addition of different kind and amount of illite clay together with dolomite trends to formation of spinel - enstatite (forsterite) ceramics and decrease the bulk density to the value up to 0.35 g/cm~3. The XRD results indicate that ZrO_2 monoclinic/tetragonal incorporation in mullite (corundum) structure realizes through the liquid phase. Development of the spinel MgAl_2O_4 and enstatite MgSiO_3 crystalline phases along with the sufficient amount of glassy phase in microstructure and even distributed pores are proper for spinel-enstatite (forsterite) ceramic samples.