Journal ArticleDOI
Creep Deformation of Reaction‐Sintered Silicon Nitrides
TLDR
In this paper, the steady-state creep behavior of reaction-bonded silicon nitride, prepared by slip casting and injection molding, was examined in 4-point bending with stresses ranging from 10,000 to 20,000 psi at temperatures from 1200° to 1450°C.Abstract:
The steady-state creep behavior of reaction-bonded silicon nitride, prepared by slip casting and injection molding, was examined in 4point bending with stresses ranging from 10,000 to 20,000 psi at temperatures from 1200° to 1450°C. Creep rates were proportional to the 1.4 power of the stress. The creep process exhibited an activation energy of 130±5 kcal/mol. The microstructure of deformed specimens, which was revealed by transmission and scanning electron microscopy, contained triple-point voids suggesting that the rate-controlling mechanism of creep is grain-boundary sliding.read more
Citations
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Journal ArticleDOI
Creep of ceramics: Part 1 Mechanical characteristics
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
Creep of ceramics
TL;DR: In this article, a wide range of experimental data on the creep of ceramics was analyzed and it was shown that there is an enhanced role of diffusion creep, and in the power-law regime, Ceramics divide into two categories with stress exponents of ∼ 5 and ∼ 3, respectively.
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.
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Estimation of power-law creep parameters from bend test data
TL;DR: In this paper, the authors derived governing equations for the location of the neutral axis of a beam under bending which does not in general pass through the centroid of the cross-section, and for the creep response in terms of both curvature rate and load-point displacement rate as functions of the applied moment and power-law creep parameters.
References
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Journal ArticleDOI
A mechanism for the formation of intergranular cracks when boundary sliding occurs
Journal ArticleDOI
The microstructure of hot-pressed silicon-nitride
TL;DR: In this paper, the distribution of impurities and inclusions, phases and dislocation structures in two grades of hot-pressed Si3N4 were investigated by means of replica and thin foil transmission microscopy, and by X-ray diffraction, microprobe and Auger analyses.
Journal ArticleDOI
Creep of hot-pressed silicon nitride
Salah UdDin,Patrick S. Nicholson +1 more
TL;DR: In this article, the authors investigated the effect of grain-boundary sliding accommodated by void deformation at triple points and local plastic deformation on hot-pressed silicon nitride in the temperature range 1200 to 1400° C and determined the activation energy for creep was 140 kcal mol−1 and the stress exponent of creep rate was 1.7.
Journal ArticleDOI
The effect of creep rate on the mechanism of cavity growth
A. Gittins,H. D. Williams +1 more
TL;DR: In this article, the effect of creep rate on the angular distribution of cavitated grain boundaries has been investigated and it was found that at high creep rates cavities formed mainly on boundaries at 45° to the stress axis while at lower creep rates, cavitation occurs preferentially on boundaries making greater angles with the stressaxis.