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........ published in NEWSLETTER # 51

CORROSION OF ADVANCED CERAMICS _ MEASUREMENT AND MODELLING
by Professor K.G. Nickel, Eberhard_Karls_Universitaet, Tuebingen (Germany)

Advanced ceramics, in particular non_oxide ceramics, are almost exclusively in use outside their thermodynamic stability range. Therefore their resistance to alteration, both in the chemical and mechanical sense, i.e. their corrosion behaviour, is a basic prime factor in their applicability.

The present volume (NATO ASI SERIES E267) contains 34 papers presented at a NATO Advanced Research Workshop held in September 1993 in Tuebingen. It reviews the theory of corrosion of ceramics including the diffusion of gases and the prediction from thermodynamics and discusses critically the kinetic models and representation tools for layer growths and material destruction. Corrosion of nitrides, carbides and oxides by simple and complex gases (O2, H2O, SO2, Halides) and melts (ionic and metallic) highlight the current measurement and modelling methods. Advanced experimental techniques such as Laser Diagnostics, TV_holography, Raman_Spectroscopy and NDE surface methods are presented and frontiers (e.g. the modelling of porous materials corrosion and protection) are outlined. The major obstacle for widespread application of advanced ceramics _ poor long_term reliability _ is shown to be a corrosion_dependent property. Here creep, crack_growth, stress corrosion and design routes for improved corrosion resistance are major subjects.

Thus the book is both a synopsis of the state_of_the_art in corrosion of advanced ceramics and a source for addressing the most pressing questions. At a time when the goals of technological progress are set to higher temperatures (e.g. the gas turbine components with T >1400 degrees C as outlined by the new program of the ministry for research and technology in Germany) it will be impossible to develop the materials needed without knowledge about their corrosion behaviour.
Reference books: E23, E30, E65, E170, E173, E179, E185, E241, E267

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