Bridging stresses in sintered reaction-bonded Si3N4 from COD measurements

Fett, T.; Münz, D.; Njiwa, A.B. Kounga; Rödel, Jürgen; Quinn, George D.

doi:10.1016/j.jeurceramsoc.2004.03.005

Cited by 22 publications

(11 citation statements)

References 24 publications

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“…However, the condition (X ( a) limits [15,16] the range of COD data that can be used for the estimation of the K I0 , as the influence of the crack and specimen geometry, possible shielding and residual stresses in modifying the COD profile become more pronounced at large X. An improved procedure for the evaluation of the overall COD profile for K I0 estimation that takes into account the above factors has been recently reported by Kounga et al [16,17] and Fett et al [18], which is based on the COD relation of Rice [19] in integral form:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Fracture toughness evaluation of precursor-derived Si–C–N ceramics using the crack opening displacement approach

Janakiraman

Burghard

Aldinger

2009

Journal of Non-Crystalline Solids

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Section: Theoretical Backgroundmentioning

confidence: 99%

Fracture toughness evaluation of precursor-derived Si–C–N ceramics using the crack opening displacement approach

Janakiraman

Burghard

Aldinger

2009

Journal of Non-Crystalline Solids

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“…In the case of sintered reaction‐bonded silicon nitride (SRBSN) containing yttria and alumina (fig. 6 in Fett et al 3 ) a rather flat curve is visible. This can, in principle, indicate either a material without significant R ‐curve behavior but also a material with an extremely steep R ‐curve at the beginning of the test which could not be resolved.…”

Section: Introductionmentioning

confidence: 83%

“… (a) Schematic of an R ‐curve (b) R ‐curves for MgO‐doped zirconia, 1 sintered reaction‐bonded silicon nitride (SRBSN), 3 and coarse‐grained alumina 2 …”

Section: Introductionmentioning

confidence: 99%

R‐Curve Determination for the Initial Stage of Crack Extension in Si₃N₄

Fett

Fünfschilling

Hoffmann

et al. 2008

Journal of the American Ceramic Society

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In experimental R‐curve investigations crack development usually starts from notches. The validity of R‐curves depends on the size of the notch root radius. This influence is ignored in many cases. In this study it will be shown how the notch radius affects the formally computed crack resistance curve and how the initial true R‐curve can be obtained from the same data. The tests were performed on a silicon nitride with 5 wt% Y2O3 and 2 wt% MgO. The evaluation of load versus displacement measurements during fracture showed a very steep R‐curve with the saturation reached even after about 10 μm crack extension.

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“…The lower the threshold fracture resistance, the lower the grinding forces. As noted above, some experiments [43,44] to measure an R curve and the threshold fracture resistance of the SRBSN showed the threshold toughness of our particular SRBSN may be quite low (< 2.0 MPaVm [44] or = 3.0 MPaVm [43]). …”

Section: Figure 26mentioning

confidence: 92%

“…The surface crack in flexure (SCF) and singleedged precracked beams (SEPB) methods gave values of 5.4 MPaVm ± 0.4 MPaVm and 5.6 MPaVm ± 0.2 MPaVm, respectively [41].^Chevron notch (CN) testing [42] Although these three methods produce converging results for a very broad range of crack sizes (50 fim -2 mm), there is evidence that the material does have a rising R-curve. [43,44,45] Figure 6 The four-point fixtures used for the rod flexural strength tests. Cradles on the top (arrows) and bottom apply the load evenly to the specimens on the top and bottom.…”

Section: Introductionmentioning

confidence: 99%