Direct casting technique

The reader will learn abont the origins of attractive forces between particles and how to overcome these forces, yielding a dispersed system. Furthermore, it is shown how these interparticle forces relate to the flow behavior of the slurry system, and finally, how this knowledge can be applied to current direct casting techniques. 

These qualitative differences in suspension properties based on the attractive or repulsive nature of the interparticle forces have been utilized in the optimization of colloidal processing concepts and have led to the development of the direct casting techniques which will be described in more detail below. 

The greatest difficulty in the application of the direct casting technique is to find an adequate mould material which should have the following properties when coming into contact with the Zerodur melt at a temperature of about 1400 °C ... 

Slip casting of metal powders closely follows ceramic slip casting techniques (see Ceramics). SHp, which is a viscous Hquid containing finely divided metal particles in a stable suspension, is poured into a plaster-of-Paris mold of the shape desired. As the Hquid is absorbed by the mold, the metal particles are carried to the wall and deposited there. This occurs equally in all directions and equally for metal particles of all sizes which gives a uniformly thick layer of powder deposited at the mold wall. 

Modern casting techniques allow the production of massive steel rolls, which can subsequently be milled directly into plates for the car industry. Exact proportions of carbon and special additives make steel a "high-tech" material. 

Once the structural support layers have been fabricated by extrusion or EPD for tubular cells or by tape casting or powder pressing for planar cells, the subsequent cell layers must be deposited to complete the cell. A wide variety of fabrication methods have been utilized for this purpose, with the choice of method or methods depending on the cell geometry (tubular or planar, and overall size) materials to be deposited and support layer material, both in terms of compatibility of the process with the layer to be deposited and with the previously deposited layers, and desired microstructure of the layer being deposited. In general, the methods can be classified into two very broad categories wet-ceramic techniques and direct-deposition techniques. 

Ability to form and maintain strong bond with propellant, resist any delamination, cracking or interface separation due to self-stressing. The ability to bond itself with the propellant directly on application by casting technique without any barrier coat is considered an added attribute. 

In order to align the molecules in one direction fi om the solution, we devised a zone-casting technique whose principle is based on observations performed during the solvent evaporation of a drop-cast solution [22]. One can observe that the deposited material is mainly oriented in the direction of the solvent evaporation. Theoretically, at adequate conditions it should be possible to obtain from simple drop-casting a homogeneous film with a radial alignment of the superstructure. However, this is quite difficult, since the concentration... 

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