Tape casting

Abstract: Slurry formulations and processing parameters of the water-based tape casting of ceramic powders are reviewed. Additives include binders, like cellulose ethers, vinyl or acrylic-type polymers; plasticizers, like glycols; and dispersants, like ammonium salts of poly(acrylic acids). Mostly alumina powders have been employed. Hydrophobing of ceramic powders permits the aqueous processing even of water-reactive powders, like aluminium nitride. Non-toxicity and non-inflammability of water-based systems represent an alternative to organic solvent-based ones. Aqueous slurries are, on the other hand, complex multiphase systems, very sensitive to process variations. Statistical design of experiments was used for the improvement of the process.

Abstract: Chapter 1. Ceramic Membranes and Membrane Processes. 1.1 Introduction. 1.2 Membrane Processes. 1.2.1 Gas separation. 1.2.2 Pervaporation. 1.2.3 Reverse osmosis and nanofiltration. 1.2.4 Ultrafiltration and microfiltration. 1.2.5. Dialysis. 1.2.6 Electrodialysis. 1.2.7 Membrane contactor. 1.2.8 Membrane reactors. References. Chapter 2. Preparation of Ceramic Membranes. 2.1 Introduction. 2.2 Slip casting. 2.3 Tape casting. 2.4 Pressing. 2.5 Extrusion. 2.6 Sol-gel process. 2.7 Dip-coating. 2.8 Chemical vapour deposition (CVD). 2.9 Preparation of hollow fibre ceramic membranes. 2.9.1 Preparation of spinning suspension. 2.9.2 Spinning of ceramic hollow fibre precursors. 2.9.3 Sintering. 2.9.4 Example 1: Preparation of porous Al2O3 hollow fibre membranes. 2.9.5 Example 2: Preparation of TiO2/Al2O3 composite hollow fibre membranes. 2.9.6 Example 3: Preparation of dense perovskite hollow fibre membranes. Appendix 2.1: Surface forces. References. Chapter 3. Characterisation of Ceramic Membranes. 3.1 Introduction. 3.2 Morphology of membrane surfaces and cross sections. 3.3 Porous ceramic membranes. 3.3.1 Gas adsorption/desorption isotherms. 3.3.2 Permporometry. 3.3.3 Mercury porosimetry. 3.3.4 Thermoporometry. 3.3.5 Liquid displacement techniques. (a) Bubble point method. (b) Liquid displacement method. 3.3.6 Permeation method. (a) Liquid permeation. (b) Gas permeation. 3.3.7 Measurements of solute rejection. 3.4 Dense ceramic membranes. 3.4.1 Leakage test. 3.4.2 Permeation measurements. 3.4.3 XRD. 3.4.4 Mechanical strength. Notation. References. Chapter 4. Transport and Separation of Gases in Porous Ceramic Membranes. 4.1 Introduction. 4.2 Performance indicators of gas separation membranes. 4.3 Ceramic membranes for gas separation. 4.4 Transport Mechanisms. 4.4.1 Knudsen and slip flow. 4.4.2 Viscous flow. 4.4.3 Surface flow. 4.4.4 Capillary condensation. 4.4.5 Configurational or micropore diffusion. 4.4.6 Simultaneous occurrence of different mechanism. 4.5 Modification of porous ceramic membranes for gas separation. 4.6 Resistance model for gas transport in composite membranes. 4.6.1 Effect of support layers. 4.6.2 Effect of non-zeolitic pores. 4.6.3 Effect of coating. 4.7 System design. 4.7.1 Operating Schemes. (a) Perfect mixing. (b) Cross flow. (c ) Parallel plug flow. 4.7.2 Design equations for membrane processes in gas separation. (a) Perfect mixing. (b) Cross flow. (c) Cocurrent flow. (d) Countercurrent flow. Notation. References. Chapter 5. Ceramic Hollow Fibre Membrane Contactors for Treatment of Gases/Vapours. 5.1 Introduction. 5.2 General review. 5.3 Operating modes and mass transfer coefficients. 5.3.1 Nonwetted mode. 5.3.2 Wetted mode. 5.3.3 Mass transfer coefficients determined from experiments. 5.4 Mass transfer in hollow fibre contactors. 5.4.1 Mass transfer in hollow fibre lumen. 5.4.2 Mass transfer across membrane. 5.4.3 Mass transfer in shell side of a contactor. 5.4.4 Nonwetted, wetted, and partially wetted conditions in a hollow fibre contactor. 5.5 Effect of chemical reaction. 5.5.1 Instantaneous reaction. 5.5.2 Fast reaction. 5.6 Design equations. Notation. References. Appendix A. Chapter 6. Mixed Conducting Ceramic Membranes for Oxygen Separation. 6.1 Introduction. 6.2 Fundamentals of mixed conducting ceramic materials. 6.2.1 Structure of peroviskite-type of materials. 6.2.2 Doping strategies. 6.2.3 Properties of materials. 6.3 Current status in oxygen permeable membranes. 6.3.1 Pervoskite-type oxides. Sr(Co,Fe)O3-d (SCFO). La(Co,Fe)O3-d (LCFO). LaGaO3(LGO). 6.3.2 Non-perovskite-type oxides. 6.3.3 Summary of ceramic oxygen permeable materials. 6.4 Dual phase membranes. 6.5 Oxygen transport. 6.5.1 Transport mechanism. 6.5.2 Transport equations. 6.5.3 Transport analysis. 6.6 Air separation. 6.6.1 Design equations. Cocurrent flow. Countercurrent flow. 6.6.2 Performance analysis. Effect of operating pressures and temperatures. Effect of flow patterns. Effect of feed flow rate. Effect of membrane area. Comparison with experimental data. Production of oxygen using hollow fibre modules. 6.7 Further development-challenges and prospects. Notation. References. Chapter 7. Mixed Conducting Ceramic Membranes for Hydrogen Permeation. 7.1 Introduction. 7.2 Proton and electron (hole) conducting materials and membranes. 7.2.1 Pervoskite-type oxides. 7.2.2 Non-pervoskite-type oxides. 7.3 Dual phase membranes. 7.4 Proton transport. 7.4.1 Transport mechanism. 7.4.2 Transport equations for mixed proton-hole conducting membranes. 7.4.3 Transport analysis. Effect of membrane thickness. Effect of temperature. Effect of partial pressure of oxygen. Comparison with experimental data. 7.5 Applications of proton conducting ceramic membranes. 7.5.1 Hydrogen production. 7.5.2 Dehydrogenation reactions. Notation. References. Chapter 8. Ceramic Membrane Reactors. 8.1 Introduction. 8.2 Membranes as product separators. 8.2.1 Microporous membrane reactors. 8.2.2 Dense ceramic membrane reactors. 8.2.2.1 Experimental investigation of a dense ceramic membrane reactor for methane coupling reaction. 8.3 Membranes as a reactant distributor. 8.3.1 Porous membrane reactors. 8.3.1.1 Techniques in modification of membrane pores. 8.3.1.2 Applications of porous ceramic membrane reactors. 8.3.1.3 Analysis of membrane reactors for elimination of DO from water. 8.3.2 Dense ceramic membranes. 8.3.2.1 Configurations of the dense ceramic membrane reactors. 8.3.2.2 Applications of the dense ceramic membrane reactors. 8.3.2.3 Experimental investigation of a dense membrane reactor for oxidative methane coupling (OMC). Notation. References.

Abstract: Ceramic three dimensional parts have been fabricated by a Stereolithography (SL) process using a ceramic slurry containing alumina powder, UV curable monomer, diluent, photoinitiator and dispersant, subsequent removal of organic components and sintering. The SL process consists of fabricating parts with complex shapes layer by layer by laser polymerization of a ceramic/resin mixture. The effects of each component on the rheology of the ceramic suspension were investigated. Both, the addition of dispersant and diluent to the curable monomer and the increase in temperature decrease the viscosity down to suitable values for tape casting of the layers and for SL. The homogeneous and stable high ceramic concentration suspensions (53 vol%) exhibited a shear thinning behavior, which is favorable for casting the layers. Adequate cured depth (above 200 μm) and width were obtained even at high scanning speeds with an argon ionized laser.

Abstract: Freeze casting is a promising technique to fabricate porous materials with complex pore shapes and component geometries. This review is aimed to elaborate the fundamental principles of the porous microstructure evolution and critical factors that influence the fundamental physics involved in freeze casting of particulate suspensions. The discussion separately analyses homogeneous and directional freeze casting for both aqueous and non-aqueous systems. The effects of additives, freezing conditions, suspension solids loading and particle size on pore shape, size and morphology evolution are discussed. Special techniques based on modified freeze casting, such as freeze tape casting, double sided freeze casting and field directed freeze casting, are also included.