Journal ArticleDOI
The strength and oxidation of reaction-sintered silicon nitride
A. G. Evans,R. W. Davidge +1 more
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In this paper, the structure of reaction-sintered silicon nitride is studied using scanning electron and optical microscopy at various stages during nitriding, for a range of nit riding and compacting conditions.Abstract:
The structure of reaction-sintered silicon nitride is studied using scanning electron and optical microscopy at various stages during nitriding, for a range of nitriding and compacting conditions. The strength is then evaluated and interpreted in terms of the microstructure. It is found that fracture always occurs in a brittle manner by the extension of the largest pores. The effects of prolonged annealing in air above 1000† C on both the structure and strength are investigated. At 1400† C, cristobalite is formed. If the temperature is then maintained above 250† C, the strength is enhanced, but below this temperature the oxide layer cracks and reduces the strength.read more
Citations
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Corrosion of Silicon-Based Ceramics in Combustion Environments
TL;DR: In this paper, the processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling.
Journal ArticleDOI
Relationships between processing, microstructure and properties of dense and reaction-bonded silicon nitride
TL;DR: In this paper, the relationship between powder properties, process conditions, densification and microstructure, as well as the interdependence between microstructures and properties is discussed.
Journal ArticleDOI
Reaction-bonded silicon nitride: its formation and properties
TL;DR: In this paper, a model of reaction-bonded silicon nitride is presented, with emphasis on kinetics and on phase composition and microstructure of the reaction product.
Journal ArticleDOI
Influence of Microstructure on Fracture Propagation in Rock
TL;DR: In this paper, the authors measured the fracture resistance of Salem limestone measured in terms ofR, the energy dissipated per unit area of projected surface, was found to increase in the initial stage of crack extension but finally reached a constant value which was strongly dependent on crack orientation with respect to the bedding plane.
Journal ArticleDOI
Overview no. 5: Fracture-mechanism maps for materials which cleave: F.C.C., B.C.C. and H.C.P. metals and ceramics
C. Gandhi,Michael F. Ashby +1 more
TL;DR: In this paper, a large body of published data is combined with their own observations to construct maps for a number of polycrystalline metals and ceramics: the refractory b.c.p. metals: tungsten, molybdenum, tantalum, niobium and chromium.
References
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Book
Introduction to Ceramics
TL;DR: In this paper, the authors present a model for the development of the MICROSTRUCTURE in CERAMICS based on phase transformation, glass formation and glass-Ceramics.
Journal ArticleDOI
Plastic flow in glass
TL;DR: The authors discusses the evidence for flow, evaluates the flow stresses by re-interpretation of the indentation hardness figures, and shows that flow stresses are much lower than the theoretical cohesive strengths.
Journal ArticleDOI
Extension of Griffith's theory of rupture to three dimensions
TL;DR: In this article, it was shown that the tensile strength of brittle materials in one direction is not affected by stresses at right angles to it, and the result differs from Griffith's by a factor depending on Poisson's ratio of the material and lying between 1.57 and 1 81.