Dry pressing ceramic powders esp. high-purity alumina - using powder particles coated with polyisobutylene soln

The polyisobutylene (PIB) has an average mol. wt. obtd. by viscosity measurements of 95,000-5,000,000 (pref. 1.3.106), and is used either as a 1-10, pref. 2-6 wt.% soln. in an organic solvent, or an aq. dispersion, to coat the ceramic powder, which is then granulated to particle size 0.1-1.5mm (pref. 0.2-0.5mm), pressed to shape at 100-1500kp/cm2 and fired in air to remove the PIB. The powder which can be coated include BeO, BeTiO3, steatite, cordierite, silicate, titanate, ferrite, spinel, carbide, boride, nitride, silicide, sulphide, cermet, garnet, porcelain, refractories, or other ceramic powders. Pref. solvents for the PIB are toluene, benzene, isoctane, CCl4. The cold flow of the PIB helps pressing of ceramics for electronic use.