Debonding of interfaces between beta-silicon nitride whiskers and SiAlY oxynitride glasses

Becher, Paul; Sun, Ellen Y.; Hsueh, Chun‐Hway; Alexander, K.B.; Hwang, Shyh‐Lung; Waters, Shirley B.; Westmoreland, C.

doi:10.1016/s1359-6454(96)00069-9

Cited by 103 publications

(76 citation statements)

References 22 publications

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“…The interfacial debonding process depends on the chemistry of the grain boundary phase, which is directly determined by the additive composition. It was reported that, in Si-Al-Y-O-N glasses, the increase in the Y/Al and O/N ratios promotes interfacial debonding, thereby improving fracture resistance [23,26,29]. Kleebe et al [27] reported that Sc 2 O 3 -doped Si 3 N 4 exhibits a high fracture toughness of ≈10 MPa m 1/2 , because the nearly complete devitrification of the glassy phase allows the formation of a residual tensile stress field at triple pockets to trigger interfacial debonding and thus an elastic bridging effect.…”

Section: Introductionmentioning

confidence: 99%

Textured silicon nitride: processing and anisotropic properties

Zhu

Sakka

2008

Science and Technology of Advanced Materials

157

104

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Textured silicon nitride (Si 3 N 4 ) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si 3 N 4 , with emphasis on the anisotropic and abnormal grain growth of β-Si 3 N 4 , texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si 3 N 4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si 3 N 4 single crystals are presented. Various anisotropic properties of textured Si 3 N 4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si 3 N 4 with a unique microstructure composed of oriented elongated β-Si 3 N 4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured α-Sialon using the same methods as those used for textured β-Si 3 N 4 and β-Sialon.

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Section: Introductionmentioning

confidence: 99%

Textured silicon nitride: processing and anisotropic properties

Zhu

Sakka

2008

Science and Technology of Advanced Materials

157

104

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“…samples containing two rare earth oxides, present a brittle interface compared with those with higher alumina content. A brittle interface induces intergranular fracture due to enhanced detachment between grains and the intergranular phase, promoting higher fracture toughness values 22 . The aspect ratio is an important parameter to discuss the mechanical properties of silicon nitride based ceramics 39 .…”

Section: +mentioning

confidence: 99%

“…This can be circumvented by using different sintering additives, especially rare earth elements 20 . According to Becher et al 21 , the aspect ratio of silicon nitride grains is influenced by the size of the rare earth element used as an ad- 22 , others have concluded the opposite, i.e. additions of rare earth elements with larger ionic radii tend to reduce the liquid viscosity, which in turn decreases the aspect ratio of the silicon nitride grains 23 .…”

Section: Introductionmentioning

confidence: 99%

Influence of additive system (Al2O3-RE2O3 , RE = Y, La, Nd, Dy, Yb) on microstructure and mechanical properties of silicon nitride-based ceramics

Marchi

Silva²,

Silva

et al. 2009

Mat. Res.

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Silicon nitride based ceramics have been widely used as structural ceramics, due mainly to their thermomechanical properties such as high density, high thermal shock resistance, corrosion resistance and chemical stability. The aim of this study was to determine the influence of rare earth and aluminum oxide additions as sintering aids on densification, microstructure and mechanical properties of silicon nitride. Silicon nitride mixtures with 91 wt. (%) Si 3 N 4 and 9% wt. (%) additives were prepared and sintered. The density, microstructure and mechanical properties of the sintered specimens of these mixtures were determined. In most specimens, scanning electron microscopic examination and X ray diffraction analysis revealed elongated grains of β-Si 3 N 4 with aspect ratio of about 2.0 and dispersed in a glassy phase. The density of the sintered specimens was higher than 94% of the theoretical density (td) and specimens with La 2 O 3 and Al 2 O 3 additions exhibited the highest value. The results of this investigation indicate that the rare earth ion size influences densification of silicon nitride, but this correlation was not observed in specimens containing two different rare earth oxides. The hardness values varied in direct proportion to the density of the specimens and the fracture toughness values were influenced by the composition of the intergranular glassy phase.

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“…It is also probable that oxygen replaces nitrogen along the thin grain boundary, consistent with calculated binding energies of Si-clusters with various O/N compositions, which show that Si-O is the more favorable bond to Si-N [3]; this implies that a low N:O ratio strengthens the atomic bonding along the boundary. However, Becher et al [4] has observed that a decrease in N:O ratio apparently reduces the interfacial debonding energy for β-Si 3 N 4 whiskers embedded in a Si-Al-Y oxynitride glass. Furthermore, other sintering additives used to densify Si 3 N 4 have been found to affect the complex intergranular bonding state too.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Amorphous Oxide Intergranular Layer Structure and Bonding on the Fracture Toughness of a High Purity Silicon Nitride

Ziegler

Kisielowski

Hoffmann³

et al. 2002

MRS Proc.

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The microstructural evolution and structural characteristics and transitions in the thin grainboundary oxide films in a silicon nitride ceramic, specifically between two adjacent grains and not the triple junctions, are investigated to find their effect on the macroscopic fracture properties. It is found that by heat treating a model Si 3 N 4 -2wt% Y 2 O 3 ceramic for ~200 hr at 1400°C in air, the fracture toughness can be increased by ~100%, coincident with a change in fracture mechanism from transgranular to intergranular. Structural phase transformations occur in the thin grain boundaries during oxidation that are revealed by XRD, EDX, Raman and EELS analyses. They affect the local bonding of atoms. It is concluded that only specific crystal "building blocks", i.e., tetrahedra, are transformed along the grain boundary and the resulting difference in the atomic structure of the oxide interface is seen directly to alter the macroscopic fracture behavior.

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Debonding of interfaces between beta-silicon nitride whiskers and SiAlY oxynitride glasses

Cited by 103 publications

References 22 publications

Textured silicon nitride: processing and anisotropic properties

Textured silicon nitride: processing and anisotropic properties

Influence of additive system (Al2O3-RE2O3 , RE = Y, La, Nd, Dy, Yb) on microstructure and mechanical properties of silicon nitride-based ceramics

Effects of the Amorphous Oxide Intergranular Layer Structure and Bonding on the Fracture Toughness of a High Purity Silicon Nitride

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