Zirconia/alumina functionally gradiented composites by electrophoretic deposition techniques

Continuous variation of composition, and thus of physical property, is characteristic of a functionally gradiented material (FGM). Such composite find applications in extreme thermal shielding, the joining of ceramics to metals, optical/electronic functions, and biomaterial implant development. FGMs have been synthesized by chemical vapor deposition (CVD), plasma spraying, self-propagating high-temperature synthesis, and green forming followed by sintering. An electrophoretic deposition and sintering route was used to prepare YSZ/Al2O3 composites with a compositional gradient. The YSZ content was continuously decreased from the YSZ-rich surface to the Al2O3-rich surface. Microstructural and Vickers hardness (16--24 GPa) evidence tracked the compositional development, and the indentation fracture toughness was found to vary across the section (10--3 MPa·m1/2)