Hydraulic Pressing and Tape Casting of Advanced Ceramics a Comparison Alfred Kaiser, LAEIS GmbH Josef Kraus, SAMA MASCHINENBAU GmbH Roel van Loo, ALPHA CERAMICS GmbH 32 nd International Conference and Exhibition on Advanced Ceramics & Composites Jan 27 Feb 01, 2008, Daytona Beach
Table of Content 1. Introduction of Team 2. Shaping of Advanced Ceramics 3. Experimental 4. Comparison Hydraulic Pressing vs. Tape Casting 5. Firing Technology 6. Summary
Introduction of Team SACMI Group: turnover > 1 billion more than 3500 employees main activities: ceramics beverage & packages plastics food processing SACMI Group companies active in ceramic process technology:
Introduction of Team Cutting-edge technical ceramic production process synergy, from raw material preparation to shaping and firing with precision quality control at every stage of production Outstanding R&D facilities to assist with material development and process optimization Scope of supply covering a wide range of various types of machinery for complete plants and production lines Best technical and economical solution for a given task
Shaping of Advanced Ceramics Selection of shaping technologies: Isostatic pressing (cold & hot) Slip Pressure casting Extrusion Injection moulding Thin film technology Uniaxial hydraulic pressing Tape Casting
Experimental / Hydraulic Pressing material: Almatis CT 3000 (Al 2 O 3 ; 99,7 %) spray dried powder binder content < 2 % LAEIS press ALPHA 800 closed steel mould; 193 mm dia; volumetric filling specific pressure 50-150 MPa pressing under vacuum cycle time approx. 20 s
Experimental / Tape Casting material: Almatis CT 3000 (Al 2 O 3 ; 99,7 %) slip; 58 % solid content organic content 18,7 % machine: SAMA FGT 250 casting height: 0.08-3.0 mm useful width: 250 mm casting track length: 3200 mm casting speed: 20-350 mm/min
Experimental / Drying + Firing temperature [ C] 1800 1600 1400 1200 1000 800 600 400 200 0 0 100 200 300 400 500 600 700 time [min] top-hat kiln; gas-tight; electrically heated; normal atmosphere conditions; firing in stack thermal treatment: pre-drying at 120 C 1 h holding time at 300 C (debindering) firing cycle 11 h cold to cold (not optimized) T max = 1600 C; 1 h
Experimental Results (Examples) shaping technique specific pressure green thickness green density firing Tmax / holding time fired density MPa mm g/cm³ C / h g/cm³ pressing 50 8.55 2.24 1550 / 8 pressing 100 8.40 2.28 1550 / 8 > 3.8 pressing 150 8.30 2.32 1550 / 8 pressing 100 1,01 2.24 1550 / 8 3.824 pressing 100 4,65 2.29 1600 / 1 3.924 tape casting --- 2.26 2.26 1600 / 1 3.77
Hydraulic Pressing / Tape Casting product properties hydraulic pressing tape casting green / fired density density distribution dimensional accuracy conture sharpness green strength surface quality reproducibility ++ ++ ++ ++ ++ (rigid) ++ ++ -- +- - - ++ (flexible) + ++
Hydraulic Pressing / Tape Casting process characteristics hydraulic pressing tape casting material requirements binder content drying necessary large specimen product thickness geometry complexity process scrap process flexibility powder low no yes (3 dimensions) flexible (~ 0.5 - > 10 mm) high no higher slip (water / solvent) high yes / debindering yes (2 dimensions) flexible (< 0.1-3 mm) low yes lower
Hydraulic Pressing / Tape Casting general hydraulic pressing tape casting invest costs mould costs production capacity range of available machines higher higher high higher lower none lower lower useful for advanced ceramics production +++ +++
TC Firing Technology Selection kiln type operation mode design capacity fuel type max. temperature special features pusher-type kiln continuous medium gas, electricity 1600 C gas-tight design possible roller kiln continuous low, medium, high gas, electricity 1600 C gas-tight design possible top-hat kiln batch low, medium electricity 1600 C gas-tight shuttle kiln batch medium gas, electricity 1800 C large volumes up to 30 m³ all kiln types to be equipped with thermal post combustion if required
Summary uniaxial hydraulic pressing and tape casting are useful technologies for shaping of advanced ceramics with low thickness each technology provides special advantages and restrictions combination with adequate firing technologies allows production of advanced ceramic products fulfilling utmost quality requirements Team offers a unique opportunity to provide optimal solutions for an economical production, taking various technologies into consideration
Acknowledgements Thanks to: R. Kremer (Alpha Ceramics GmbH, Aachen) K. Müller (LAEIS GmbH, Wecker) for the experimental and analytical work
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