SILICONE-COATED ALUMINA POWDERS BY THE EMULSION TECHNIQUE

Alumina powders were prepared using an emulsion technique to chemicall y bond silanol-terminated poly dimethylsiloxane (PDMS or silicone) to the surface of alumina powders. Stable aqueous emulsions of silicone w ere prepared using Tween-80 surfactant. Transmission optical microscop y was used to measure the oil-droplet and coated-particle sizes. Fouri er transform-infrared spectroscopy was used to quantify bonding betwee n the silicone and the Al2O3. Coated powders were dry-pressed, and PDM S was compared to paraffin for dry-pressing behaviour and green streng th. Densification studies were made on powders. X-ray diffraction and scanning electron microscopy were used to characterize the sintered ce ramic.