Creep of hot-pressed silicon nitride

Uddin, Salah; Nicholson, Patrick S.

doi:10.1007/bf00540828

Cited by 45 publications

(9 citation statements)

References 7 publications

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“…In the present study, a stress exponent of 2.0 was determined for Si3N4-6Y203~2Al203 in agreement with data for SiAlON and silicon nitrides [17][18][19][29][30][31][33][34][35][36][37][38][39][40][41][42]. This apparent discrepancy has been reconciled by Evans and Rana [43], who developed statistical models The activation energy determined from the Arrhenius plot of strain rate 9 against reciprocal temperature in Fig.…”

Section: Stress Exponentsupporting

confidence: 82%

“…The creep properties of dense silicon nitride, which are mainly controlled by grain boundary sliding along the amorphous phase, can be improved by: (1) increasing the viscosity of the grain boundary phase; (2) crystallization of the grain boundary phase; and (3) production of high aspect ratio beta-Si3N4 grains, favored by high viscosity melts [1, [16][17][18][19]. Hence, additives such as Y203, which give a higher viscosity grain boundary phase, generally result in lower creep rates than for MgO-doped silicon nitride [20].…”

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confidence: 99%

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The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

Todd

1989

J Mater Sci

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The creep properties of silicon nitride containing 6 wt% yttria and 2 wt% alumina have been determined in the temperature range 1573 to 1673 K. The stress exponent, n, in the equation e « a , was determined to be 2.00 +_0.15 and the true activation energy was found to be 692 +_ 25 kJ mol~. Transmission electron microscopy studies showed that deformation occurred in the grain boundary glassy phase accompanied by microcrack formation and cavitation. The steady state creep results are consistent with a diffusion controlled creep mechanism involving nitrogen diffusion through the grain boundary glassy phase.

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Section: Stress Exponentsupporting

confidence: 82%

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confidence: 99%

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

Todd

1989

J Mater Sci

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“…The bending creep of monolithic silicon nitride with a Y 2 O 3 additive and of the corresponding nanocomposites has been studied by several authors. The values of stress exponent varied from 1 to 3.1 19,23,27–29 27 found stress exponents of a nanocomposite with 5 wt% Y 2 O 3 +20 wt% SiNC, in the range from 0.7 to 1.4 at temperatures in the range 1200°–1400°C prepared by a processing route similar to this study.…”

Section: Discussionsupporting

confidence: 62%

“…The values of stress exponent varied from 1 to 3.1. 19,23,[27][28][29] Sˇajgalı´k et al 27 found stress exponents of a nanocomposite with 5 wt% Y 2 O 3 120 wt% SiNC, in the range from 0.7 to 1.4 at temperatures in the range 12001-14001C prepared by a processing route similar to this study. These values agree with the results of the present measurements.…”

Section: Discussionsupporting

confidence: 58%

Microstructure and Creep Behavior of a Si₃N₄–SiC Micronanocomposite

Kašiarová

Shollock

Boccaccını

et al. 2009

Journal of the American Ceramic Society

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The microstructure and its influence on the creep behaviour of carbon derived Si3N4‐SiC micro/nanocomposite tested in bending at temperatures from 1200° to 1400°C in air has been studied. No phase and microstructure change after creep test implied that material is stable at tested temperature range. After creep test only partial crystallization of glassy intergranular phase has been observed. Creep parameters n close to 1, apparent activation energy around 350 kJ/mol together with TEM observation indicated that the main creep mechanisms is solution precipitation controlled by interface reaction in combination with grain boundary sliding caused by the amorphous intergranular phases present in microstructure. However, the grain boundary sliding is hindered by local SiC particles interlocking neighboring Si3N4 grains.

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“…Even when dislocations are observed, 22 there appears to be no difference in dislocation structure between the as-received and the deformed material. Only rarely do researchers note a change in dislocation density 61,62 after creep. Fig.…”

Section: (2) Experimental Observationsmentioning

confidence: 99%

A New Model for Tensile Creep of Silicon Nitride

Luecke

Wiederhorn

1999

Journal of the American Ceramic Society

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The tensile creep rate of most commercial grades of Si 3 N 4 increases strongly with stress. Although the usual powerlaw functions can represent the creep data, the data often show curvature and systematic variations of slope with temperature and stress. In this article, we present a new approach to understanding the creep of ceramics, such as Si 3 N 4 , where a deformable second phase bonds a deformation-resistant major phase. A review of experimental data suggests that the rate of formation and growth of cavities in the second phase controls creep in these materials. The critical step for deformation is the redistribution of the second phase away from the cavitation site to the surrounding volume. The effective viscosity of the second phase and the density of active cavities determine the creep rate. Assuming that the hydrostatic stresses in pockets of the second phase are normally distributed leads to a model that accurately describes the tensile creep rate of grades of Si 3 N 4 . In this model, the creep rate increases exponentially with the applied stress, is independent of Si 3 N 4 grain size, is inversely proportional to the effective viscosity of the deformable phase, and is proportional to the cube of the volume fraction of the deformable phase.

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Creep of hot-pressed silicon nitride

Cited by 45 publications

References 7 publications

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

Microstructure and Creep Behavior of a Si₃N₄–SiC Micronanocomposite

A New Model for Tensile Creep of Silicon Nitride

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Creep of hot-pressed silicon nitride

Cited by 45 publications

References 7 publications

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

The high temperature creep deformation of Si3N4-6Y2O3-2Al2O3

Microstructure and Creep Behavior of a Si3N4–SiC Micronanocomposite

A New Model for Tensile Creep of Silicon Nitride

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Microstructure and Creep Behavior of a Si₃N₄–SiC Micronanocomposite