Synthesis of Al2O3 ZrO2 and TiO2 nanoparticles from natural minerals for industrial applications

Abstract

There has been a very few reports in the scientific literature on the use of natural minerals for nanoparticles production, especially the alumina (Al2O3), zirconia (ZrO2) and titania (TiO2) particles. The work described in this thesis is about synthesis of Al2O3, ZrO2 and TiO2 nanoparticles from natural minerals for industrial applications. An economical approach has been developed from inexpensive precursors for the large-scale production of spherical nano- Al2O3, ZrO2 and TiO2 particles with high surface area. All the three production methods were optimised and identified in terms of particle size, surface area, morphology, purity and yield. The Al2O3 and ZrO2 nanoparticles have been optimised for nanostructured surface protective coatings. The optimised TiO2 nanoparticles have been applied for refractory applications. This thesis can be divided into three major parts. The first part describes investigations on the production of Al2O3 nanoparticles from raw bauxite and its application in anticorrosive coating. The second part deals with the synthesis and characterisation of ZrO2 nanoparticles from raw zircon sand for thermal barrier coating. This includes design and construction of nanostructured ZrO2 coating on stainless steel surface for the protection of high temperature oxidation corrosion. The effect of incorporation of nano TiO2 in silica refractory was explored in terms of refractory properties such as bulk density (BD), apparent porosity (AP), cold crushing strength (CCS), refractoriness under load (RUL), creep in compression (CIC) and reversible thermal expansion (RTE). The present study reveals that the addition of nano titania brings about the effective life of silica refractories. A remarkable reduction in thermal expansion of silica brick was achieved with the incorporation of nano TiO2 particles. Further, a decrease in apparent porosity and an increase in bulk density, creep resistance, CCS and RUL were noticed. newline newline newline