Shaping and Flat Ceramics

Tape casting results from the relative movement between the doctor blade and the support or carrier (Fig. 5.14). There are two possibilities the doctor blade moves and the carrier is fixed, or the doctor blade is fixed and the Ccirrier moves [24]. 

In laboratory operations, batch casting with a mobile doctor blade and stationary carrier are used. Plate glciss is usually used as a carrier. Tape drying can take place on the support by electric heaters placed imder the support. If only partial drying occurs, the tape, with or without the support, is placed in an oven to complete the dr5dng. Tapes of 0.5 m wide, 2 m long and 1-2 mm thick can be obtained. 

Large productions are based on continuous casting machines where the doctor blade is stationary. A moving carrier, such as an endless stainless-steel or plastic-film belt, moves under the fixed doctor blade. In this case, the carrier width is 1 m and the length can reach 40 m. The tape is dried by passing through a tunnel where solvents are evaporated. Dried tape can be removed from the carrier and rolled for storage at the end of the carrier. 

5 — CERAMIC PROCESSING TECHNIQUES OF SUPPORT SYSTEMS FOR MEMBRANES SYNTHESIS 

The second step is slow, because of the need for heat to evaporate the solvent. The third step is necessary to avoid a high concentration of solvent at the surface of the slurry and the formation of a skin on the upper surface of the tape. The drying temperature is limited by the boiling point of the solvent if the formation of bubbles is to be avoided. 

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