Plasma sprayed nanostructured glass-ceramic matrix composite coatings from the CaO-SiO2-ZrO2 eutectic system

Mechanical properties and wear behaviour of ceramic matrix composites are strongly affected by the size of the crystallites of individual ceramic phases, with optimal performance frequently exhibited in the presence of nanostructured hard phases. Nano-composite coatings are preferentially manufactured starting from nanostructured powders by high velocity-low temperature techniques, such as HVOF, in order to reduce the degree of crystal growth experienced during spraying. For the present investigation, a different approach was attempted. The devitrifiable CaO-ZrO2-SiO2 ternary system was investigated, and amorphous plasma sprayed coatings were deposited onto glass-ceramic substrates normally used for traditional ceramic applications. Subsequently, suitable thermal conditions for the precipitation of homogeneous dispersions of nanosized particles from solid phase eutectic reactions were identified, with the main objective of improving wear resistance of traditional ceramic floor tiles. Preliminary results in terms of coating microstructure and properties are presented