Fatigue Threshold R-Curve Behavior of Grain Bridging Ceramics: Role of Grain Size and Grain-Boundary Adhesion

Abstract

Alternatively, Eq. (1) can be rewritten to separate the effects of DK and K max on the fatigue crack growth rate, as da/dN 5 A 0 (DK) p (K max ) n , where A 0 5 A(1ÀR) n and (n1p) 5 m.With brittle materials such as ceramics, n ) p. 8 J ournal

Intergranular Nanostructure Effects on Strength and Toughness of Si3N4

“…Achieving desirable combinations of high flexural strength, high fracture toughness, and good fatigue resistance in grain bridging toughened ceramics (Si 3 N 4 , SiC, Al 2 O 3 , etc.) is controlled not only by grain morphology, but also by the properties of the GBPs and IGFs . If grains are too well adhered, trans‐granular fracture will result, leading to low strength and toughness, as has been reported for minimally doped silicon nitrides .…”

Ceramics and ceramic coatings in orthopaedics

“…It uniquely incorporates and demonstrates the importance of R-curves in determining fatigue resistance. First elucidated by Kruzic et al [388] using Al 2 O 3 and Si 3 N 4 as model systems, and later expanded and verified by Gallops et al [389], Hartelt et al [390], and Greene et al [391,392], it deconvolutes K TH into two terms:…”

A direct comparison of non-destructive techniques for determining bridging stress distributions

“…The alumina ceramic is the same as in Fig. 2 and in Gallops et al (2011aGallops et al ( , 2011b. It has nominally equiaxed grains widely ranging in size with a majority having cross-sectional areas of o63 mm 2 (or diameter of o9 mm).…”

“…It has nominally equiaxed grains widely ranging in size with a majority having cross-sectional areas of o63 mm 2 (or diameter of o9 mm). Information on the grain size distribution may be found in Gallops et al (2011b).…”

“…In fatigue it is essentially impossible to control fatigue crack propagation at these size scales. Thus, the direct measurement of the fatigue threshold R-curve as described in Gallops et al (2011a), Gallops et al (2011b), Pippan et al (2001) is practically impossible. Nevertheless, understanding and predicting the fatigue failure behavior of these materials has technological importance (Danzer and Lengauer, 2010;Harrer et al, 2011) and knowledge the bridging stress distribution for a fatigue crack can enable the calculation of the fatigue threshold R-curve via Eqs.…”