Tape casting defects

In the case of tape casting a membrane on a porous support, the membrane thickness and the quality of the support surface appear to be important issues. It has been found that alumina, but not titania or zirconia, can be tape cast into crack-free membranes on porous supports and any defect on the support surface (e.g., a protrusion or cavity) can yield a deposit layer that is either bare or cracked [Simon et al., 1991]. Alumina membranes have b tape cast on top of tape cast alumina supports. Borosilicate glass, but not silica, membranes have also been tape cast [Winnick, 19 ). 

Figure I Dense LSCT substrate made by aqueous tape casting. Minor defects probably due to entrapped air in green tapes...

In this case the 200 mm thick reinforced concrete cast in situ slab gives a good inherent resistance against gas ingress. This can be enhanced with a 1200 g DPM and a passive xmderfloor venting layer in accordance witii Table 8.1. However, it should be noted that 1200 g DPM will require sealing with tape at all joints and to service penetrations and across any cavities (if present). It will also require independent inspection to confirm that it has been installed correctly and without defects. 

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