Tensile creep of whisker-reinforced silicon nitride

Hockey, B. J.; Wiederhorn, Sheldon M.; Liu, W.; Baldoni, J.G.; Buljan, S. T.

doi:10.1007/bf01184994

Cited by 84 publications

(32 citation statements)

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“…Such a macroscopic asymmetric creep behavior between tension and compression, with slower creep rates and higher creep failure strains in compression, appears to be a general feature of Si 3 N 4 containing a residual grain-boundary glassy phase. [22][23][24][25] At higher levels of applied stress, Ͼ 300 MPa, steady-state creep was almost absent. Accelerated creep started immediately, resulting in a short lifetime and lower creep strain.…”

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confidence: 99%

Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride

Crampon

Duclos

Peni

et al. 1997

Journal of the American Ceramic Society

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The compressive creep properties of hot-pressed Si 3 N 4 -purpose, compressive creep tests were performed at temperatures of 1543-1603 K in air. Flexural dynamic and static fatigue 8Y 2 O 3 -3Al 2 O 3 (wt%) have been investigated in the temperature range of 1543-1603 K in air. The stress exponent, n, of tests also were conducted in the temperature range of 1373-1573 K and will be analyzed in detail in a later paper. 20 A the power creep law was determined to be 1.5, and the activation energy was determined to be 650 kJ/mol. Transmajor part of our attention was directed to the high-temperature mechanisms that control the creep and failure of this material. mission electron microscopy observations showed that grain-boundary sliding occurred with cavitation formation Furthermore, microstructural observations allowed us to distinguish the dominant cavitation process that occurs during comin the grain-boundary glassy phase. The quasi-steady-state creep results were consistent with that of the diffusionpressive creep-rupture tests. controlled solution-diffusion-precipitation creep mechanism, and the distinguished failure mechanism was II. Materials and Testing cavitation creep damage controlled by the viscosity of the boundary glassy phase. The compressive creep failure time,The selected material, designated as RAY 38 SM, was prepared by mechanically mixing an ␣-Si 3 N 4 powder (S-Stark LC obtained at 1573 K, in the stress range of 175-300 MPa, followed the Monkman-Grant relation, indicating that cav-12 SX, H. C. Starck, New York, NY) with 8 wt% Y 2 O 3 and 3 wt% Al 2 O 3 as sintering aids. The powder mixture was uniaxiity growth was mainly controlled by the creep response of the material.ally hot-pressed in an induction-heated graphite die under a pressure of 30 MPa at 1983 K for 1 h. X-ray diffractometry (XRD) of the as-sintered material revealed that the main phases I. Introductionwere ␤-Si 3 N 4 with ϳ10% residual ␣-Si 3 N 4 . The density was evaluated by the Archimedes method and S ILICON NITRIDE (Si 3 N 4 ) has an exceptionally high strength at room temperature, but its strength degradation can be was 3.27 g/cm 3 . The material was considered to be fully dense. Specimens with dimensions of ϳ3 mm ϫ 3 mm ϫ 9 mm significant at high temperatures. Thus, despite its high and quasiinvariant fast-fracture strength to temperatures up to 1173-were deformed during compressive creep tests performed in air in a constant-load machine. 21 The variation of specimen length 1273 K, silicon nitride is susceptible to slow crack growth, which limits long-term reliability for structural components. [1][2][3][4][5][6] was determined by an extensometer system constituted by an Al 2 O 3 probe connected to a linear-variable differential transConsequently, the use of silicon nitride in high-temperature strength applications has motivated numerous studies on fatigue former (LVDT). Temperature monitoring was performed by using a Pt/Pt-10% Rh thermocouple. Most of the compressive behavior. 7-15 These studies have shown that creep rupture also...

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confidence: 99%

Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride

Crampon

Duclos

Peni

et al. 1997

Journal of the American Ceramic Society

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“…1 In the majority of cases, though, the improvement was mediocre, and even degraded creep strength was reported. 2,3 The characteristic rate parameters such as activation energy and stress exponent fall into the range of silicon-nitride monoliths and share the same inconsistency as those for silicon nitride. The creep mechanism in the micro-composites is believed to be not much different from that of silicon nitride, which suggests that the liquidphase based solution-precipitation process is controlling the deformation.…”

Section: Introductionmentioning

confidence: 89%

“…Niihara et al 3 found that for up to 25% SiC, the aspect ratio of Si 3 N 4 in the nanocomposites increases with increasing SiC content, while the trend reverses when SiC content is greater than 25%. Yamada et al, 9 however, observed a reduced number of elongated grains when SiC is more than 10%.…”

Section: Microstructural Featuresmentioning

confidence: 99%

“…The possibility of introducing more oxygen and the tendency of suppressing the growth of elongated Si 3 N 4 grains (which is capable of increasing creep resistance) might be the cause of the observed inferior creep property in this type of composites as compared with silicon-nitride monoliths. 3 Nanocomposites can be defined as composites with at least one phase having at least one dimension in the nano-meter range. In the silicon-nitride/siliconcarbide system, nanocomposites that have been processed and examined are particulate composites, with the siliconcarbide phase as the "nano" phase.…”

Section: Introductionmentioning

confidence: 99%

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The creep behavior of Si3N4/SiC nanocomposites

Wan

Mukherjee

2003

JOM

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a In an investigation of the creep properties of silicon nitride/silicon carbide nanocomposites, the micro-nano type composites with nano-SiC at intragranular and inter-granular regions show behavior not much different from that of silicon-nitride monolith. The improvement of creep resistance is modest, up to about one order of magnitude decrease in steady-state creep rate. The creep rate parameters such as activation energy and stress exponent measured for this type of nanocomposite are within the range of those of silicon nitride. This evidence suggests that a special strengthening mechanism may not be necessary for this type of material. Nano-nanocomposites show remarkably lower creep rates, possibly pointing to a new creep mechanism such as solid-state diffusion.

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“…Creep of silicon nitride based ceramics has been extensively tested in tension and bending [13][14][15][16][17] [18] shows that only few researchers performed tests in those materials under compressive stress. Test atmospheres in these cases were basically air [8,[19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Silicon nitride compressive creep behavior in argon atmosphere

Silva

Neto

Araújo

et al. 2008

Materials Science and Engineering: A

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Tensile creep of whisker-reinforced silicon nitride

Cited by 84 publications

References 16 publications

Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride

Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride

The creep behavior of Si3N4/SiC nanocomposites

Silicon nitride compressive creep behavior in argon atmosphere

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Tensile creep of whisker-reinforced silicon nitride

Cited by 84 publications

References 16 publications

Compressive Creep and Creep Failure of 8Y2O3/3Al2O3‐Doped Hot‐Pressed Silicon Nitride

Compressive Creep and Creep Failure of 8Y2O3/3Al2O3‐Doped Hot‐Pressed Silicon Nitride

The creep behavior of Si3N4/SiC nanocomposites

Silicon nitride compressive creep behavior in argon atmosphere

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Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride

Compressive Creep and Creep Failure of 8Y₂O₃/3Al₂O₃‐Doped Hot‐Pressed Silicon Nitride