Tape Casting: Theory and Practice

Описание

CHAPTER 1
Introduction and
History
ince the inception of the modern ceramics era, usually identified S as during or just after World War 11, there have been several
advances in ceramic processing technology. One of the newest and
most prolific of these advances has been the development and
implementation of tape casting as a manufacturing process for the
production of thin sheets of ceramic materials. Glenn Howatt is
universally regarded as the “father” of tape casting since he had the
first publications and patent describing this process.
Tape casting is also known as doctor blading and knife coating, and
under these names the process is well known in many industries,
including paper, plastic, and paint manufacturing. The “doctor” is a
scraping blade for the removal of excess substance from a moving surface being coated. The technique has long been used in the paint
industry to test the covering power of paint formulations. Films of
paint a few mils (< 50 microns) thick are uniformly coated on a standard black-and-white background, and the degree to which the background is hidden is measured optically. Howatt’s patent2 was the
first documented use of this technique to form ceramics. His patent
was for “forming ceramic materials into flat plates, especially useful
in the electric and radio fields.” This is still the principal application
today, although it extends far beyond the uses envisioned in 1952.
The chief advantage of the tape casting process is that it is the best
way to form large-area, thin, flat ceramic or metallic parts. These are
virtually impossible to press and most difficult if not impossible to
extrude. The difficulties are compounded in dry pressing, when the
plate is to be pierced with numerous holes because of the increased
problem of uniform die fill. Punching holes and slots of various sizes
and shapes into unfired tape is relatively easy and essential to the
multilayered ceramic packages being designed and manufactured
today. The thin ceramic sheets are essentially two-dimensional
structures, since they are large in the x and y directions and very thin

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