Net shape ceramic microcomponents by modified sol-gel casting

Development of ceramic microcomponents can open up the current silicon-based MEMS (micro-electromechanical systems) technology to new applications, especially for use in high temperature, chemically reactive environments. We report a study of sol-gel technologies applied to the fabrication of microcomponents. Organic/inorganic hybrid materials, particularly silica-based hybrids, were developed by sol-gel processing. A weak silica network was made possible by using acid catalyst, low functionality organic precursor in the sol preparation. Since the weak network has a high tendency to collapse, the result is a denser material. Incorporation of organic ligands modifies the surface chemistry of gel network so that a greater drying stress was developed and a denser hybrid structure was achieved without high temperature treatment. In addition, the incorporation of organic ligands prevented formation of cracks. Nanoscale oxide particles were dispersed and incorporated into the gel network by surface condensation. The incorporation of titania nanoparticles into sols greatly reduced the volume shrinkage of gels and enhanced the mechanical strength of the components. In this work, silica sol was also applied to coat metallic microcomponents and a thin uniform coating was formed.