Development of Nanoceramics; Application to Diffusion Bonding

摘要

Nanoceramics are experiencing a rapid development in recent years. Nanoceramics exhibit superplasticity at homologous temperatures lower than the deformation temperature of their coarser-grained counterparts, because of the enhanced diffusion. The phenomenon of low-temperature-superplasticity is of technological importance owing to its cost effectiveness of near-net-shape forming preparation. The enhanced diffusion in nanoceramics should lend itself nicely to the process of diffusion bonding, then, the superplastic nanoceramics can be used as interlayers in diffusion bonding. As the first step, we performed diffusion bonding of conventional Y_2O_3 stabilized tetragonal ZrO_2 (Y-TZP, d = 300 nm) by using an interlayer of nano Y-TZP (d = 60 nm), which was fabricated by hot isostatic pressing (HIP). The joining was accomplished by uniaxially applying a compressive load (50 MPa) at temperature of 1423 K, which was 300 K lower than the sintering temperature of the conventional Y-TZP.