Seeding effect: impact and consequences on the characteristics of sol-gel derived α-Al2O3

Alumina (α-Al2O3) -an advanced ceramic with high mechanical strength, chemical stability and biocompatibility- can be effectively produced via the sol-gel technique. Seeding approach can be an alternative way to further improve the properties of sol-gel derived α-Al2O3 by promoting nucleation and growth. This work concentrates on the chemical/physical, microstructural, and mechanical characteristics of the sol-gel derived and seeded α-Al2O3 powders, and pellets. Seeding was applied by using commercial α-Al2O3 powders with wt.0%, 3%, 6%, and 10% of the precursor. As the seeding agent amount increased, bulk density values of the pellets also increased. However, the highest bulk density increase was observed for the samples heat treated at 1300 °C. Likewise, the compression strength enhanced but the best results were determined for the samples heat treated at 1300 °C. As the heat treatment temperature increased, heterogeneous grain growth occurred depending on the formation of large pores, and this situation reduced the compression strength.