Shrinkage-free ZrSiO4-ceramics: Characterisation and applications

Dense, shrinkage-free ZrSiO4-ceramics can be produced by a reaction-bonding process using ZrSi2, ZrO2, and a polysiloxane as starting materials. Sinte r shrinkage is compensated by the volume increase during oxidation of ZvSi( 2). In addition, the use of a Si-containing so called low-loss-binder [poly methylsilsesquioxane (PMSS)] reduces shrinkage further. Near net-shape cera mic compacts can be produced by an embossing process. As the green bodies a re extremely dense but not brittle, they can be mechanically machined. The reaction-bonding process has to be controlled in a way that first the pyrol ysis of PMSS, followed by the oxidation of ZrSi2, and finally the formation of ZrSiO4 and the sintering to dense compacts take place. Due to the absen ce of shrinkage and the good mechanical properties obtained, these ceramics open up new applications in fields requiring high dimensional accuracy suc h as microsystem engineering or dentistry. (C) 1999 Elsevier Science Ltd. A ll rights reserved.