Effet de Mgo sur la microstructyre et les propriétés d'un composite zircone /muliite

Abstract

Abstract: Mullite (3Al2O3.2SiO2) is widely appreciated for its exceptional properties, including high thermal stability, low dilation and thermal conductivity coefficients, high flue resistance, and good chemical stability. In addition, mullite has a high mechanical resistance to heat, a melting temperature above 1830°C, a high hardness (from 10 to 15 GPa), and an average thermal shock resistance. These characteristics make mullite a material of choice for applications requiring reliable performance at high temperatures. However, mulliteis characterized by limited toughness tenacity, which restricts some of its applications. To remedy this, an effective reinforcement technique is to incorporate zirconium particles (ZrO2) into the mullite matrix. This incorporation exploits the phase transformation mechanism of zirconium, moving from the monoclinic phase to the tetragonal phase, which significantly improves the mechanical properties of mullite. Research continues to focus on improving the properties of mullit and mullit composites, exploring various synthesis processes and materials combinations to optimize its performance and durability in demanding environment.

In this regard, we used aluminum scraps as a source of α aluminum and Algerian kaolin to develop a mullit-zirconedispersoid composite. First, we studied the starting powder (kaolin and aluminum scrap) to better understand phase transformations. Finally, the Mullite-Zircon composite was prepared from aluminum scories, kaolin and zircon. To improve sample densification, we added MgO and TiO2 and studied the impact of each oxide on the properties of the compounds. We have used several characterization methods to verify the results of the elaboration. The data obtained confirms that the addition of MgO and TiO2 to compounds improves their density, decreases their withdrawal, strengthens their mechanical and thermal properties, and reduces their fragility.