Alumina-YAG Micro-Nanocomposites: Elaboration and Mechanical Characterization
Annotatsiya
A surface doping of commercial alpha alumina powders was performed to develop Al2O3 - 5 vol.% YAG (Y3Al5O12) composites made by micronic or highly sub-micronic alumina particles and veryne YAG grains, yielded on the alumina surface by in-situ reaction. In fact, the alumina powders were � rstly dispersed in the aqueous suspension by ball-milling for different times as a function of the starting raw material and then an yttrium chloride solution was added as a precursor. After a controlled drying carried out by atomization, the modied powders were treated up to 1500oC, following the phase development by XRD. Using these results, a suitable powder pre- treatment was selected; in particular, aash heating by soaking the powders in a furnace kept in the range 1050-1150oC was se t up to control yttrium-aluminates crystallization and crystallite growth. After that, green bodies were prepared by uniaxial pressing of dried powders as well as by slip-casting of slurries having a proper solid content. Pressureless sintering was optimized by the dilatometric study up to 1500oC for 3 h. Less-conventional sintering routes, such as hot-pressing and spark plasma sintering, were also employed. Themicrostructures obtained by conventional or non- conventional densication routes were compared by SEM characterization. Finally, the sintered materials were submitted to a st andard mechanical characterization (hardness and fracture toughness) in order to dene the relationship between micro-nanostructural features and mechanical behaviour. Keywords: Al2O3, YAG, Nanocomposite