Correlation between microstructure and mechanical properties of fibrous yttria-stabilized zirconia densified by Spark Plasma Sintering

The reactivity of two commercial YSZ fibers (FYSZ-1 and FYSZ-5) was studied by in situ Spark Plasma Sintering (SPS) dilatometry. FYSZ-1 exhibited synthesis residues and higher reactivity with densification 260 degrees C earlier than FYSZ-5. The correlation between a wide range of microstructures and their mechanical properties such as hardness and flexural strength of ceramics from these YSZ fibers was also investigated. No significant difference was observed between the two fibers with hardness ranging from 119 to 1482 Hv for porosity rates between 44.3 and 3 % respectively. Nevertheless, FYSZ-1 demonstrated superior flexural strength to FYSZ-5 across the porosity range attributed to its greater reactivity and its larger proportion of closed porosity. These results were again compared to powders with different form factors, it clearly evidenced that both the morphology and porosity of raw powders and the level of porosity associated are key parameters to optimize the mechanical properties of such materials.