Nitrogen Ceramics

The suggestion that a NATO Advanced Study Institute would be an excellent forum for reviews and informed discussion on the broad subject of Nitrogen Ceramics, arose out of discussions with colleagues in the Department of Ceramics at the University of Leeds early in 1975. There was no doubt that such a meeting would be both very valuable and timely. Scientific and technological interest in the nitride ceramics and in silicon nitride in part­ icular had been growing steadily during the 20-year period following 1955. The intensive five-year programme initiated by the Advanced Research Projects Agency of the U. S. Department of Defence, on the development of a design capability in brittle materials for high temperature applications, had been based principally on silicon nitride and silicon carbide ceramics, and was due to reach the end of its first stage in the autumn of 1976. It was clear that by then a considerable volume of information covering many aspects of silicon nitride would be available for presentation or review. Coincidentally, the same five-year period had seen the discovery, and increasingly detailed investigation, of ceramic materials based on the AI-Si-N-O and similar systems. Besides being of great interest for their crystal chemistry and structural relationships, some of these materials could be assumed potentially to be of equal importance to the silicon nitride ceramics. More recently progress had also been made in the sintering of covalent materials, as demonstrated for the case of silicon carbide.

(R) Introductory Lecture.- Section A Bonding and Phase Relationships.- (R) Bonding in Nitrogen Ceramics.- (R) Representation of Multicomponent Silicon Nitride Based Systems.- A Simple Thermochemical Model for the Si-AI-O-N System.- Solid-State Reactions in the SiAlON System.- Section B Crystal Chemistry.- (R) Some Aspects of the Structure and Crystal Chemistry of Nitrides.- (R) The Crystal Chemistry of the Sialons and Related Nitrogen Ceramics.- The Crystal Structures of 8H and 15R Sialon Polytypes.- Crystal Chemistry of Nitrided Compounds Containing Lanthanides.- The ?/? Silicon Nitride Phase Transformation.- Section C Thermodynamics and General Kinetics.- (R) Some Considerations of the Thermodynamics of Gas-Solid Reactions.- Reactions in the SiO2-C-N2 System.- Thermodynamics of Silicon Nitride and Oxynitride.- (R) Defect Equilibria in the Solid State.- (R) Kinetics of Gas-Solid Reactions.- (R) Solid State Diffusion in Binary Ceramic Compounds.- The Feasibility of Studying Nitrogen Transport in Ceramic Materials by Proton Activation Analysis.- Section D The Vitreous State.- (R) The Structure of Glass and its Relation to the Solubility and Mobility of Gases.- Sialon Glasses.- Section E Formation of Nitrides.- (R) Nitridation and Reaction Bonding.- The Role of Impurities in the Formation of Reaction-Bonded Silicon Nitride.- The Effects of Iron on the Nitridation of Silicon.- Nitridation of Si and Si + Al Compacts under Directed Gas Flow Conditions.- The Effects of Aluminium and Alumina Additions on the Formation of ?-Silicon Nitride.- Preparation and Characterization of Silicon Nitride Powders for Hot-Pressing.- Nitridation of Calcium Hexaboride.- Direct Preparation of Sialon-Type Materials from Naturally Occurring Minerals.- Section F Densification Processes.- (R) Basic and Practical Aspects in Sintering Nitrogen Ceramics.- The Sintering Behaviour of Covalently-Bonded Materials.- Pressureless Sintered Silicon Nitride.- (R) Densification of Nitrides by Hot Pressing.- Mass Transport in the Hot Pressing of ?-Silicon Nitride.- High Strength Silicon Nitride Prepared with Eutectic Flux Additions.- The Formation of Single Phase Sialon Ceramics.- Status Report on Densification of ?-Si3N4 Solid Solutions Containing AIN:Al2O3 During Chemical Reaction.- Section G Microstructure.- (R) Grain Boundary Engineering and Control in Nitrogen Ceramics.- Direct Observation of Lattice Planes at Grain Boundaries in Silicon Nitride.- Microstructural Aspects of Deformation and Oxidation of Magnesia-Doped Silicon Nitride.- Section H Mechanical Properties.- (R) The Fracture of Brittle Materials.- Monte Carlo Technique for Estimating Uncertainties in Lifetime Predictions.- Properties of Polyphase Ceramics.- Assuring Mechanical Reliability of Ceramic Materials.- Application of Proof Tests to Silicon Nitride Components.- (R) Dense Si3N4: Interrelation Between Phase Equilibria, Microstructure and Mechanical Properties.- Deformation and Mass Transport in Silicon Nitride.- Elastic and Anelastic Properties of Nitrogen Ceramics.- Improving the Impact Properties of Silicon Nitride.- Some Properties of ?-Si6-xAlxOxN8-x.- Synthesis, Characteristics and Sintering of ?’ (Si,Al,O,N) Compound Powders.- (R) Mechanical Properties of Reaction Bonded Silicon Nitride.- A Structural Model Explaining the Development of Strength in Reaction Sintered Silicon Nitride.- Strength-Density-Nitriding Cycle Relationships for Reaction-Sintered Si3N4.- Critical Defects in Reaction Bonded Silicon Nitride General discussion, and short contribution of.- The Development of Microstructure and Young’s Modulus in Reaction-Bonded Silicon Nitride.- High Temperature, Time Dependent Physical Property Characterization of Reaction Sintered Si3N4.- Section I Electrical Properties.- Electrical Properties of Some Sialons.- Electrical Conductivity in Nitrogen Ceramics.- Section J Oxidation and Corrosion.- (R) Oxidation of Silicon Nitride and Related Materials.- Oxidation and Hot Corrosion Behaviour of Si3N4 and SiAlON.- Problems Raised in the Oxidation of Sintered Ceramics: The Case of Silicon Oxynitride.- Section K Applications.- Applications of Nitrogen Ceramics — Gas Turbines: U.S. National Programs.- The Use of Ceramics in Diesel Engines.- Economic and Energetic Considerations for Nitrogen Ceramics.- A Consideration of Some Silicon Nitride Applications.- Survey and Conclusions.- Concluding Remarks.- Author Index.- Index of Crystal Structures.- Index of Systems and Sub-Systems.