Ceramic tile processing, drying

At the time of writing, two pilot scale machines and two production machines have been in operation. The production machines contain cylinders of diameter 1.5 m and width 700 mm, with an output of some 250 kg/h drawn strip, or approximately 500 m per day. These machines have been used for the production of thin ceramic tiles. The processing time from slip to fabricated t11e amounts to 2-3 h, and the complete Installation requires no more than two persons for operation. Energy consumption Is around 30 kMh/tonne In wet processing and 45 kWh/tonne in drying and firing. 

Figure 7.26 Compaction behavior of KBr powder and spray-dried granules of alumina and clay tile as a function of punch pressure. From J. S. Reed, Principles of Ceramics Processing, 2nd ed. Copyright 1995 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

In the wet process a slip carrying the ceramic powder is laid down, by screenprinting for example, onto a temporary carrier such as a glass tile. The process can be repeated to build up the required thickness of the dielectric onto which the electrodes are screen-printed. The next dielectric layer is then laid down and the process repeated. The mutlilayer structure is diced as described above, and the individual chips removed from the tile for the subsequent stages, as for the dry process. 

Spray drying [B.48, B.97] is used in the manufacture of granulated press powders for tiles and electronic parts. It also plays an important role in the industrial production and development of high-performance (advanced) ceramics because of the ability of this process to meet size distribution requirements and give granules with a smooth surface and spherical shape, all resulting in excellent flowability, which is important for the subsequent forming step. Another reason for the widespread use of spray dryers in the ceramic industry is the fact that they can handle abrasive feedstocks without problems. 

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