Elaboration and Characterization of Mullite Refractory Products from Moroccan Andalusite

Abstract

Enrichment of schist mined in Morocco resulted in an extract essentially made of andalusite, quartz and muscovite, which was investigated with the aim to synthesize mullite refractory materials. X-ray diffraction analysis was used to assess phase transformations upon heating at different temperatures. Mullite formation starts as early as 1200℃ and seems almost total at 1450℃. This process correlates with a weak shrinkage (3.5% at 1450℃) and the formation of an important glass phase. Green compacts obtained by unidirectional pressing the extract powder were heated under air in the temperature range 1200℃ - 1600℃. Chemical and mechanical properties of these materials were investigated and correlated with their microstructure

Synthesis of Al6Si2O13-BaAl2Si2O8-ZrO2-based composites and their wettability by molten Al and an Al-Si alloy

“…It is known that mullite is a promising candidate for advanced ceramic applications due to its high melting point (1840 1C), low-thermal expansion (5 Â 10 À 6 K À 1 in the temperature range 20-800 1C), good thermal shock resistance, high creep resistance (dε/dt4 10 À 10 s À 1 at 1200 1C), flexural strength (above 360 MPa) [34], chemical stability [35] and high refractoriness [36].…”

Phase Evolution, Microstructure, and Mechanical Properties of Alumina–Mullite–Zirconia Composites Prepared by Iranian Andalusite

“…The low density of the A10‐1650‐1 h and A10‐1650‐3 h samples may relate to the high amount of SiO 2 phase caused by a greater amount of andalusite. The heavy fall in porosity was the result of the glassy phase formation, which filled the open voids . This trend showed that, at the sintering temperature of 1650°C where the reaction sintering was carried out continuously by the addition of andalusite, the decomposition of zircon would be completed (constant porosity).…”

“…During the process, mullite precipitates and the excess silica creates a liquid phase, which is then reacted again with the alumina matrix and produces the mullite phase . The liquid phase, which is formed by reactions between the free silica, alumina, and alkaline, in accordance with the ternary SiO 2 ‐Al 2 O 3 ‐R 2 O system, is responsible for densification of the compacts and improvement of the sintering state . The formation of the liquid phase leads to the accerelation of mullitization and also reacts with alumina to form secondary mullite.…”

Hybrid Membranes Based on Clay-Polymer for Removing Methylene Blue from Water

“…It confirms that mullite does not contain any foreign inclusions. 29 The tested sample shows the Al/Si ratio to be ≈ 0.84 as shown in Table 2. It is less than the stoichiometric composition of mullite (Al/Si 3:1).…”