Plastic forming of preceramic polymers

The method of plastic forming for the preparation of green bodies from different;ent polymeric precursors is discussed. Experiments on the influence of the pressure, the temperature and the grain size of the powders were carried out with different precursors of the system Si-C-N and the system Si-B-C-N. Optimised conditions led to lower porosities in the pyrolysed ceramic for the specimen prepared by plastic forming (PF) than for the specimen prepared by cold isostatic pressing (CIP) of the preceramic polymer. It was also possible to form dense green bodies from polymers which could not be shaped by CIP. Furthermore, the mechanism of the plastic forming behaviour of the preceramic polymers is shown for the first time. (C) 1998 Elsevier Science Limited. All rights reserved.