SYNTHESIS AND NOVEL APPLICATION OF NANOMATERIALS IN TUNGSTATE, TITAN1A AND SILICON NITRIDE SYSTEMS

摘要

This paper summarizes some recent advances made in synthesis and application of nanomaterials in tungstate, titania and silicon nitride systems. Firstly, the room temperature acidic precipitation and ageing process of tungsten oxide dihydrate grains are presented. Fourier transform infrared spectroscopy studies have shown that structural stability of Freedman type grains can be altered by presence of Li~+ and NH_4~+ ions. Water molecules and OH~- groups present in structure play an important role in ion insertion process during ageing. As regards titania system a mechanochemical coating process is highlighted. Afterwards, a study about silicon nitride ceramics with well known properties as low density, high strength and toughness is presented. As an alternative way to improve the mechanical and thermal properties of silicon nitride matrix, we performed the preparation and examination of nano-crystalline carbon added silicon nitride ceramic matrix composites.