Processing of high temperature alumina/aluminum titanate ceramic composites from clean sources

Abstract

Producing new technological materials with high performance from clean sources has become a global requirement. Alumina/aluminum titanate (Al2O3/Al2TiO5) composites are high-temperature portentous materials used in various advanced applications. In this work, different Al2O3/Al2TiO5 composites were obtained with high thermal and mechanical properties for high-temperature applications by a low-cost process. The targeted composites were produced from calcined alumina and, rutile ore extracted from the Egyptian black sands by pressureless sintering at a temperature of 1650 °C/2 h. Rutile was added to alumina with a different content (0–40 wt%) to promote its sinterability and thermo-mechanical response. Evaluation of the produced composites in terms of phase composition, densification, microstructural features, mechanical and thermal properties was investigated. The results indicated that the addition of small amounts of rutile (10 and 20 wt%) succeeded in forming a stable Al2O3/Al2TiO5 composite structure. However, higher content of rutile led to the formation of Al2TiO5 rich matrix composites. Moreover, highly dense composites with harmonic microstructure and enhanced mechanical strength were attained by increasing the rutile content. The composite with only 10 wt% rutile addition gave the highest density of 3.6 g/cm3 and the highest cold crushing strength and modulus of rupture values of 488.73 MPa and 106.19 MPa, respectively. Notably, the addition of rutile has a substantial effect on promoting the thermal properties and thermal stability of the obtained composites up to a high temperature of 1400 °C. The present study shows that addition of rutile ore to alumina is one economical way of improving the densification and thermal expansion of Al2O3 for high temperature applications. Using a clean source such as rutile ore that contains some thermal stabilizers as Fe2O3, Al2O3, SiO2, ZrO2, and MgO instead of pure TiO2 has played a noticeable role in improving the reaction sintering and resulting in a highly qualified material. Thus, sintered Al2O3/Al2TiO5 composites can be considered as a promising high-temperature material for advanced applications.