TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Components: The ceramic fibers (a1) and ceramic powder (b1) are optionally of the same material and comprise alumina or zirconia. The gas seal (s1) is formed by a tape casting process.Preferred Process: The tape-forming step involves tape casting, pressure rolling, slurry coating, shear compaction or cold pressing (preferably tape casting). The slurry further comprises a plasticizer and a dispersant.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The liquid is a non-aqueous liquid of aliphatic or aromatic hydrocarbon (preferably toluene, ketone or alcohol, especially ketone or alcohol). The dispersant is phosphate ester.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The organic binder is polyvinyl butyral.The plasticizer is polyethylene glycol, dibutyl phthalate and/or benzyl butyl phthalate. EXAMPLE - Tape cast seal was formed by mixing Saffil HA (RTM; alumina fiber) (15 wt.%) with alumina powder (85 wt.%) on ceramic basis. A tape-casting slurry was formed using methyl ethyl ketone (66.6 wt.%) and absolute anhydrous ethanol (33.3 wt.%), and using polyethylene glycol 400 and dibutyl phthalate as the plasticizer. Butvar B76 (RTM) was used as polyvinyl butyral binder and Emphos PS236 (RTM) was used as phosphate ester dispersant. A bottle with 9.5 mm diameter alumina grinding media (1500 g), was used to disperse the alumina powder. The powder, solvent and dispersant were added first and then ball milled for 2 hours at approximately 100 rpm. The plasticizer and binder were added and ball milled for an additional 2 - 6 hours. The fiber was then added to the mixture. In other trial, a mixer was used to disperse the fibers. The slurry was poured into the mixer first and the fiber was added over 0.5 - 1 hour. The slurry formulations were tape cast on to silicone coated Mylar (RTM) at viscosity of 20191 cp at 25degreesC, casting speed of 1 cm/sec with doctor blade opening 1.3 mm. Trials were performed without degassing and with degassing for 30 minutes at a vacuum of 65 - 70 kPa. Cast was dried for 4 hours. The green density was 2.78 g/cm3; the fired density was 2.51 g/cm3; the green porosity was 29.9%; fired porosity was 36.7%; average shrinkage was -0.05% and -1.17%. Dip-impregnated seals were tested with air at 750degreesC at 0.5 psi under different compressive forces. The seal was pre-compressed with a force of 1338 psi prior to installation in the test jig. The leak rates decreased nearly linearly as compressive force on the seal increased to 250 psi. The leak rate of dip-impregnated seal was 0.15 ml/min/inch at 750degreesC under 50 psi compressive force, much higher than that of tape cast seal (less than 0.1 ml/min/inch). The tape cast seal showed good thermal cycling capability in terms of measured leak rate data after a number of thermal cycles.