Tape-casted transparent alumina ceramic wafers

Ceramic wafers of alumina (Al2O3) were produced by tape casting of aqueous slurry followed by vacuum sintering. The binder system used to form the tape casting slurry is a copolymer of isobutylene and maleic anhydride, which is environmentally friendly, marketed under the name ISOBAM. The rheological properties of the slurries were studied by varying solid loading and binder addition level. Through the optimization of plasticizer addition, green tapes were casted with excellent plasticity and a thickness of 240–740 µm. The tapes displayed a post-sintering thickness of 150–660 µm. The morphologies, as well as the fracture surface and the as-sintered surface of the powder were examined using a scanning electron microscope (SEM). The in-line transmittance of the transparent unpolished Al2O3wafers with a thickness of 660 µm was found to be 72% at a wave length of 5 µm and 26% at a wave length of 600 nm.