Tape-casted transparent alumina ceramic wafers

Abstract

Ceramic wafers of alumina (Al 2 O 3 ) 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 lm. The tapes displayed a post-sintering thickness of 150-660 lm. 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 Al 2 O 3 wafers with a thickness of 660 lm was found to be 72% at a wave length of 5 lm and 26% at a wave length of 600 nm.

Chemical stability of KNbO3, NaNbO3, and K0.5Na0.5NbO3 in aqueous medium

“…To overcome those matters, wet fabrication routes have drifted towards to aqueous processing in recent years. [20][21][22][23][24][25][26][27] Understanding the surface chemistry of ceramic powders is a critical step for utilization of aqueous processing. Like most oxide systems, some perovskite structures are also thermodynamically unstable in aqueous medium.…”

Near-net-shape processed ZnS ceramics by aqueous casting and pressureless sintering

“…In the current study, research on aqueous slip casting of ZnS ceramics was performed, using nano-sized ZnS powder synthesized in a laboratory-scale according to our previous study [4]. Organic dispersant of an alternative copolymer of isobutylene and maleic anhydride, with its commercial name as ISOBAM [19], was introduced for the stable dispersion of ZnS nano powder. Cold isostatic pressing (CIP), followed by pressureless sintering were performed before obtaining final ceramic products.…”

Investigation of room‐temperature super‐stabilized suspension casting system mechanism

“…Typically, several polymeric components (a monomer, dispersant, cross‐linker, and/or an activator/initiator) are used to create an in situ macromolecular cross‐linked gel network around the dispersed ceramic particles to hold the particles in place during formation to ensure a dense, pore‐free microstructure . Traditional systems include acrylics, which are known toxins, cellulose ethers, and polyvinyl alcohols, all of which add cost . Some natural organic polymer systems have been investigated, including systems based on starch, gelatin, protein, and agarose, due to their lower environmental toxicity and cost .…”

“…Recently, a novel casting system using a water‐soluble, alternating block co‐polymer of isobutylene and maleic anhydride (see Figure ) (trade name: ISOBAM [#104, Kuraray America, Elastomer BU]) has gained interest. It is particularly advantageous because it uses one organic component that purportedly acts as both a binder and a dispersant, while producing dense green bodies with homogenous microstructures at high solids loading (up to 55 vol%), low added organic content (~0.1%‐1%), and low shrinkage and cracking …”