Electrophoretic deposition of alumina,yttria, yttrium aluminium garnet and lutetium aluminium garnet

The electrophoretic deposition (EPD) method has been adapted for the deposition of ceramic green bodies from aqueous nanodispersions of alumina, yttria, yttrium aluminium garnet and lutetium aluminium garnet. These materials have been selected, since they are promising candidates for optically transparent ceramics. Films as well as cylindrical bodies have been successfully prepared by application of pulsed direct current (pDC) EPD. To guarantee constant deposition yield during pDC, a variant with variable pulse widths and pulse heights has been developed. The obtained green bodies were studied by surface area analysis, scanning electron microscopy, optical transmittance measurements, determination of pycnometric density and sintering behaviour. The effect of colloid-chemical dispersion properties on green and sintered ceramics is discussed as well. The green ceramics received are nanoporous and dense, providing excellent properties for further processing under mild conditions to optical materials. For comparison, EPD-formed green bodies were either processed directly to ceramic bodies or after additional compacting by hot-pressing in a piston-cylinder apparatus.