Preparation and Characterization of Alumina-Silica and Alumina-Silica-Magnesia Nano-composites from Industrial Wastes for Advanced Applications

Abstract

Mullite is an important material in both conventional and high technology applications. The largest use of mullite based products is in refractories for steel industry. Meanwhile, cordierite represents a valuable ceramic material which has interesting properties. The main uses for cordierite are including the electro-technical porcelains, thermally stable ceramic masses or supports for catalysts. This thesis consists of four main chapters, literature survey, experimental, results and discussions as well as summary and conclusions chapter. The present study is concerning the processing of advanced ceramics such as mullite and cordierite ceramics from pure chemicals and different industrial wastes via co-precipitation method. Additionally, the effect of synthesis conditions on crystallization of both mullite and cordierite nanopowders has been studied. Moreover, effects of different processing conditions on the physical, thermal, mechanical and electrical properties of mullite and cordierite ceramics have been also investigated. On the other hand, the influence of metal ions incorporation on the physical, thermal, mechanical and electrical properties of mullite and cordierite ceramics have been also studied. In nutshell, the results can be summarized as follows:

1. Chemical treatment of industrial wastes (i) Processing of Al industrial wastes The optimum conditions for production of water soluble sodium aluminate (NaAlO2) from Al dross (Egyptian Aluminum Company) using soda ash sintering process are 1000°C annealing temperature, 1.4 molar ratio, 3 h annealing time, 700 rpm stirring speed, 10 L/S ratio and 120 mesh (100%) particle size. The maximum Al extraction efficiency was about 49.3%.

(ii) Processing of Si industrial wastes a. Silica fume The optimum conditions for production of water soluble sodium silicate (Na2SiO3) from silica fume (Ferro-silicon Alloys Industry) using alkali leaching process with sodium hydroxide are 100°C reaction temperature, 3 molar ratio, 4 h reaction time, 700 rpm stirring speed, 10 L/S ratio and 10 micron (100%) particle size. The maximum Si extraction efficiency was about 99.8%. b. Acidic silica wastes The optimum conditions for processing of washed silica wastes (Egyptian Alum Industries) using soda ash sintering process are 700°C annealing temperature, 3 molar ratio, 4 h annealing time, 700 rpm stirring speed, 10 L/S ratio and 180 micron (100%) particle size. The maximum Si extraction efficiency was about 17.1%.