Development of a precursor sol for the electric field assisted sol–gel deposition of yttrium silicate

In this paper we present a synthesis route for an Y2SiO5 sol derived from tetraethoxysilane and yttrium oxo-isopropoxide where the sol particles show a significant particle charge. The dynamic light scattering method was applied to obtain information on the relation between charging and growth of these sol species. The effect of water concentration, pH of the employed water and aging time on hydrolysis and condensation on the amount of charging and the growth mechanism of sol particles were investigated. Synthesis parameters were optimized to allow an electric field assisted deposition of the sol–gel particles from low concentrated sols. Glassy carbon and carbon fibre reinforced carbon composites with a silicon/silicon carbide outer layer (C/C–SiC) were used as substrates for the deposition process.