Conferences on technical and engineering ceramics are held with increasing frequency, having become fashionable because the potential of ceramics in profitable growth industries is an urgent matter of considerable debate and discussion. Japanese predictions are that the market value of ceramics will grow 10 at about 10% per annum to reach at least $10 by the end of the century. Seventy per cent of this market will be in electroceramics, applications for which include insulating substrates in integrated circuits, ferroelectric capacitors, piezoelectric oscillators and transdu cers, ferrite magnets, and ion-conducting solid electrolytes and sen sors. All these are oxides, and so are excluded by the title of the Limerick Conference. Why 'Non-oxide'? The other major ceramics potential is in struc tural engineering components and engine applications. Here, the greatest impetus to research and development has been the attempt to produce a ceramic gas turbine. Heat engines become more efficient as their working temperature increases, but nickel-base superalloy en gines have about reached their limit. Compared with metals, ceramics have higher strengths at high temperatures, better oxidation and corrosion resistance, and are also less dense. In general, ceramics have better properties above about 1000°C except in one respect-their inherent brittleness. The work of fracture is therefore much smaller than for metals and so the permitted flaw size is also smaller.

Conferences on technical and engineering ceramics are held with increasing frequency, having become fashionable because the potential of ceramics in profitable growth industries is an urgent matter of considerable debate and discussion. Japanese predictions are that the market value of ceramics will grow 10 at about 10% per annum to reach at least $10 by the end of the century. Seventy per cent of this market will be in electroceramics, applications for which include insulating substrates in integrated circuits, ferroelectric capacitors, piezoelectric oscillators and transdu cers, ferrite magnets, and ion-conducting solid electrolytes and sen sors. All these are oxides, and so are excluded by the title of the Limerick Conference. Why 'Non-oxide'? The other major ceramics potential is in struc tural engineering components and engine applications. Here, the greatest impetus to research and development has been the attempt to produce a ceramic gas turbine. Heat engines become more efficient as their working temperature increases, but nickel-base superalloy en gines have about reached their limit. Compared with metals, ceramics have higher strengths at high temperatures, better oxidation and corrosion resistance, and are also less dense. In general, ceramics have better properties above about 1000°C except in one respect-their inherent brittleness. The work of fracture is therefore much smaller than for metals and so the permitted flaw size is also smaller.

The nitrides and carbides of boron and silicon are proving to be an excellent choice when selecting materials for the design of devices that are to be employed under particularly demanding environmental and thermal con- tions. The high degree of cross-linking, due to the preferred coordination numbers of the predominantly covalently bonded constituents equalling or exceeding three, lends these non-oxidic ceramics a high kinetic stability, and is regarded as the microscopic origin of their impressive thermal and mechanical durability. Thus it does not come as a surprise that the chemistry, the physical properties and the engineering of the corresponding binary, ternary, and even quaternary compounds have been the subject of intensive and sustained efforts in research and development. In the five reviews presented in the volumes 101 and 102 of "Structure and Bonding" an attempt has been made to cover both the essential and the most recent advances achieved in this particular field of materials research. The scope of the individual contributions is such as to address both graduate students, specializing in ceramic materials, and all scientists in academia or industry dealing with materials research and development. Each review provides, in its introductory part, the chemical, physical and, to some extent, historical background of the respective material, and then focuses on the most relevant and the most recent achievements.

The nitrides and carbides of boron and silicon are proving to be an excellent choice when selecting materials for the design of devices that are to be employed under particularly demanding environmental and thermal con- tions. The high degree of cross-linking, due to the preferred coordination numbers of the predominantly covalently bonded constituents equalling or exceeding three, lends these non-oxidic ceramics a high kinetic stability, and is regarded as the microscopic origin of their impressive thermal and mechanical durability. Thus it does not come as a surprise that the chemistry, the physical properties and the engineering of the corresponding binary, ternary, and even quaternary compounds have been the subject of intensive and sustained efforts in research and development. In the five reviews presented in the volumes 101 and 102 of "Structure and Bonding" an attempt has been made to cover both the essential and the most recent advances achieved in this particular field of materials research. The scope of the individual contributions is such as to address both graduate students, specializing in ceramic materials, and all scientists in academia or industry dealing with materials research and development. Each review provides, in its introductory part, the chemical, physical and, to some extent, historical background of the respective material, and then focuses on the most relevant and the most recent achievements.

This volume contains the proceedings of the 2nd European Symposium on Engineering Ceramics held in London, 23-24 November 1987. The meeting was attended by almost 200 scientists and engineers, primarily drawn from industry, and the Sessions were chaired by Mr Eric Briscoe, past President of the Institute of Ceramics. Very effective symposium organisation was provided by IBC Technical Services Ltd. The engineering ceramics are a class of materials which has over some 50 years found well-established applications based on the materials' chemical stability and wear resistance. The last 20 years have seen intensified efforts to extend applications for these materials into areas traditionally occupied by metals, but in which the typical metallic weaknesses of wear, and of high temperature creep and oxidation, are now creating significant problems. These efforts have, however, in many cases been undermined on the one hand by the inherent ceramic weaknesses of brittleness and flaw sensitivity, and on the other by an inadequate understanding, and control, of the basic ceramic fabrication processes required for the low-cost mass production of relatively complex components. The positive results of the efforts of the last 20 years have been the development of a large new group of ceramic materials believed to possess intrinsic mechanical property advantages, of which the transformation toughened zirconias, and the ceramic matrix composites are good examples, together with improved powder production methods and powder shaping processes.

The nitrides and carbides of boron and silicon are proving to be an excellent choice when selecting materials for the design of devices that are to be employed under particularly demanding environmental and thermal con- tions. The high degree of cross-linking, due to the preferred coordination numbers of the predominantly covalently bonded constituents equalling or exceeding three, lends these non-oxidic ceramics a high kinetic stability, and is regarded as the microscopic origin of their impressive thermal and mechanical durability. Thus it does not come as a surprise that the chemistry, the physical properties and the engineering of the corresponding binary, ternary, and even quaternary compounds have been the subject of intensive and sustained efforts in research and development. In the five reviews presented in the volumes 101 and 102 of "Structure and Bonding" an attempt has been made to cover both the essential and the most recent advances achieved in this particular field of materials research. The scope of the individual contributions is such as to address both graduate students, specializing in ceramic materials, and all scientists in academia or industry dealing with materials research and development. Each review provides, in its introductory part, the chemical, physical and, to some extent, historical background of the respective material, and then focuses on the most relevant and the most recent achievements.

This volume is the proceedings of the 3rd European Symposium on Engineering Ceramics, held in London, 28-29 November 1989, under the auspices of IBC Technical Services Ltd. The Symposium sessions were chaired by Eric Briscoe, who also introduced the Symposium with the very appropriate review 'Ceramics in Europe'. The term 'engineering ceramics' is commonly taken to mean a group of special high-strength and heat-resistant ceramic materials developed almost exclusively for the advanced internal combustion engine of the next century. It is not always fully appreciated that high grade fine microstructure ceramics both of the oxide and of the non-oxide classes, whether they be termed engineering, fine, special, advanced, structural or technical, have been supporting a large number of diverse and profitable industries over many decades. Indeed, in some respects these materials can be regarded as natural developments from the long established refractories field, and the distinction between an engineering ceramic and a refractory can become blurred, as the contribution in this volume on 'Nitride Bonded Carbide Engineered Ceramics' shows. It is of significance that in Japan, for example, much development work in the engineering ceramics field was initiated by the refractories industries, seeking to diversify possibly but doing so on the basis oflong experience in the refractories area. The main objective of this Symposium was to help engineers and designers to assess the present state of the field of engineering ceramics.