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

Abstract

New dense and porous ceramics are developed using two formulation approaches. These are ceramics with remarkable content of mullite, corundum and ZrO2 - 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 ZrO2 and especially ZrO2 +Y2O3 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/cm3. The XRD results indicate that ZrO2 monoclinic/tetragonal incorporation in mullite (corundum) structure realizes through the liquid phase. Development of the spinel MgAl2O4 and enstatite MgSiO3 crystalline phases along with the sufficient amount of glassy phase in microstructure and even distributed pores are proper for spinel-enstatite (forsterite) ceramic samples.

Comparative study of illite clay and illite-based geopolymer products

“…Their grain-size is various, content of clay minerals are dominated by illite (75-80%) with admixture of chlorite. The Quaternary clay of Latvia is useful for various kinds of traditional ceramic production such as bricks, building blocks, roof tiles as well as sorbents and precursors for promoting of sinterability of new Published under licence by IOP Publishing Ltd ceramic products [5]. The aim of this study was to synthesize geopolymer product from illite clays of Latvia under alkaline and alkaline/thermal activation.…”

Blīva augsttemperatūras mullīta-ZrO2 keramika

“…ir izteikti mullīta prizmatisko un pseidoprizmatisko kristālu vienmērīgi, blīvi sakopojumi. Atsevišķu kristālu izmēri ir aptuveni 850 nm, bet graudu sakopojumu izmēri ir 1-7 μm.Illītu māla piedevas ietekme uz mullīta mikrostruktūras veidošanos[9]-[11] pie adekvātiem malšanas apstākļiem ir nedaudz atšķirīga. Piemēram, keramikas parauga, kas saķepināts 1300 °C temperatūrā no 24 h malta pulvera ar mālu piedevu, mikrostruktūra (7. b att.)…”