Journal ArticleDOI
Controlled Surface Flaws in Hot‐Pressed SiC
J. J. Petrovic,L.A. Jacobson +1 more
TLDR
In this article, semi-elliptical surface flaws were produced in hot-pressed SiC by Knoop microhardness indentation and placed in 4-point bending in order to determine their critical stress intensity factor, KIC, at both room and high temperatures.Abstract:
Controlled semi-elliptical surface flaws were produced in hot-pressed SiC by Knoop microhardness indentation. Flawed specimens were placed in 4-point bending in order to determine their critical stress intensity factor, KIC, at both room and high temperatures. Room-temperature fracture and KIC values after annealing were sensitive to the annealing environment; this behavior correlated with the active/passive nature of the oxidation process. Flaw healing was observed for annealing exposures in air. Room-temperature KIC values increased with increasing annealing temperature. High-temperature KICvalues decreased with increasing temperature as a result of a decrease in the fracture surface energy.read more
Citations
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Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: I, Direct Crack Measurements
TL;DR: In this paper, the application of indentation techniques to the evaluation of fracture toughness is examined critically, in two parts: the first part is focused on an approach which involves direct measurement of Vickers-produced radial cracks as a function of the indentation load.
A Critical evaluation of indentation techniques for measuring fracture toughness
TL;DR: In this paper, the application of indentation techniques to the evaluation of fracture toughness is examined critically, in two parts: the first part is focused on an approach which involves direct measurement of Vickers-produced radial cracks as a function of the indentation load.
Journal ArticleDOI
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: II, Strength Method
TL;DR: In this paper, the sharp-indentation technique of strength-test precracking for toughness evaluation is examined and the residual-stress term discussed in Part I of this study is now introduced explicitly into the strength formulation.
A Critical Evaluation of Indentation Techniques for Measuring Fracture Toughness: I, Direct Crack Measurements
R. C. Garvie,R. H. J. Hannink,R. R. Hughan,N. A. McKinnon,R. T. Pascoe,R. K. Shinger,D. L. Porter,A. H. Heuer +7 more
TL;DR: In this paper, the application of indentation techniques to the evaluation of fracture toughness is examined critically, in two parts: the first part is focused on an approach which involves direct measurement of Vickers-produced radial cracks as a function of the indentation load.
Journal ArticleDOI
Grain size and porosity dependence of ceramic fracture energy and toughness at 22 °C
TL;DR: In this article, a review of fracture energy and toughness data for dense ceramics at 22 °C shows that fracture toughness and fracture energy commonly show less porosity dependence than strength and Young's modulus.
References
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Journal ArticleDOI
Relation Between Strength, Fracture Energy, and Microstructure of Hot-Pressed Si3N4
TL;DR: In this paper, a fracture mechanics approach was used to investigate the high strength of hot-pressed Si3N4 powders, and room-temperature flexural strengths, fracture energies, and elastic moduli were determined for material fabricated from α- and β-phase Si3 N4 powder.
Journal ArticleDOI
The high-temperature oxidation, reduction, and volatilization reactions of silicon and silicon carbide
TL;DR: In this article, a thermochemical analysis was made of the oxidation, reduction, and volatilization reactions which occur in the Si-O-C system, showing that one characteristic feature is the high SiO (g) and SiO(g + CO(g) pressures at the Si(s) or SiC(s)-SiO2 interfaces.
Journal ArticleDOI
Crack propagation and failure prediction in silicon nitride at elevated temperatures
TL;DR: In this article, a technique for studying high temperature crack propagation in ceramic materials is developed, which is used to obtain relationships between the crack propagation rate and the stress intensity factor for hot-pressed silicon nitride up to 1400° C.
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