Synthesis and processing of nano scaled ceramic powders and composite coatings using sol-gel and related techniques

摘要

Nanoscaled particles are of interest from various reasons for different types of materials, since many material properties change dramatically when dimensions are re-duced to the nanometer scale. An impressive example is the significant decrease of the sintering temperature of ceramic powders (1), allowing new ceramic coatings and cofiring techniques. The decrease of processing temperatures is also used for the preparation of high purity SiO_2 glasses from dispersed Aerosil powders (5) par-ticulate silica gels or by the combined alkoxide-particulate method (6,7), In the case of polycrystalline nano phased metals and metal alloys, where the material properties are determined by grain boundary phases, some interesting physical phenomena as plastic behaviour or extremely high coefficients of diffusion have been reported (8) in the last years.