Processing Strategy for Producing Highly Anisotropic Silicon Nitride

Hirao, Kiyoshi; Ohashi, Masayoshi; Brito, Manuel E.; Kanzaki, Shuzo

doi:10.1111/j.1151-2916.1995.tb08871.x

Cited by 241 publications

(123 citation statements)

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“…Compared with untextured Si 3 N 4 , textured Si 3 N 4 has the capability of reaching a bending strength of up to 1.4 GPa and a fracture toughness of up to 14 MPa m 1/2 in the direction perpendicular to the grain alignment. The grain orientation provides more opportunities for crack deflection and bridging in the crack propagation plane perpendicular to the grain alignment, thereby higher fracture toughness [15,[41][42][43]186]. On the one hand, the high bending strength is due to the more uniform 2-D distribution of larger elongated grains, thereby preventing the formation of large defects such as clusters.…”

Section: Rt Strength and Toughnessmentioning

confidence: 99%

“…The higher toughness allows textured Si 3 N 4 to have higher tolerance to flaws generated during machining, thereby improving the mechanical reliability. Hirao et al [43] developed c-axis aligned Si 3 N 4 that exhibited a Weibull modulus of 46. Moreover, Ohji et al [188] observed a steep R-curve behavior for textured Si 3 N 4 , as shown in figure 27, which is believed to be advantageous for avoiding catastrophic fractures and for increasing the Weibull modulus by narrowing the strength distribution.…”

Section: Rt Strength and Toughnessmentioning

confidence: 99%

“…Tape casting can produce a green body with unidirectionally oriented rodlike β-Si 3 N 4 seed particles. Figure 14 shows a typical tape-casting procedure for producing textured Si 3 N 4 ceramics, in which a nonaqueous slurry is prepared by a three-step milling process [43]. The initial planetary milling is used to homogenize the Si 3 N 4 powder and sintering additives, which is followed by a two-step ball milling process.…”

Section: Tca Techniquementioning

confidence: 99%

“…Using seeding and tape casting, Hirao et al [43] developed textured β-Si 3 N 4 with a bending strength of 1.1 GPa and a fracture toughness of 11.1 MPa m 1/2 in the direction perpendicular to the grain alignment as well as a high Weibull modulus of 46. Using seeding and extrusion, Teshima et al [50] obtained highly textured Si 3 N 4 with a bending strength of ≈1.…”

Section: Introductionmentioning

confidence: 99%

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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: Rt Strength and Toughnessmentioning

confidence: 99%

Section: Rt Strength and Toughnessmentioning

confidence: 99%

Section: Tca Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Textured silicon nitride: processing and anisotropic properties

Zhu

Sakka

2008

Science and Technology of Advanced Materials

157

104

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“…Ceramics having textured structures can be produced by such processes as templated or seed grain growth, 1,2) hot forging or pressing 3,4) and tape casting. 5) On the other hand, since technologies of superconducting magnets were developed, high magnetic field has become one of the effective ways to get the textured structures by controlling crystal alignment. 6) Recently, a lot of new phenomena and functions of materials have been found in the fields of science and engineering relating to the high magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Analysis on Crystal Alignment of Feeble Magnetic Materials under High Magnetic Field

Li²,

Sassa

et al. 2005

Mater. Trans.

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Since superconducting magnet was developed, high magnetic field has been used as one of the effective ways to get textured structures by aligning crystals in materials. It is well known that the high magnetic field can align crystals having magnetic anisotropy. However, effects of Brownian motion of crystals in liquid medium and gravity force on the crystal alignment are not well known. In this study, it has been found that there is a size range of crystal particles in which the crystals can be aligned by high magnetic field under actions of Brownian motion of crystals and gravity force. Moreover, by taking account of these factors, theoretical analysis of crystal alignment under high magnetic field has been carried out to elucidate the phenomena of the crystal alignment in both feeble magnetic materials having well or poor electric conductivity.

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In situ study of fracture mechanisms in advanced ceramics using fluorescence and Raman microprobe spectroscopy

Pezzotti

1999

J. Raman Spectrosc.

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A procedure is described for the evaluation of the fracture behaviour of polycyrstalline ceramics using an in-situ stress analysis involving either fluorescence or Raman microprobe spectroscopy. The full details of the experimental set-up, calibration procedures and stress calculations are shown, and their reliability discussed in some detail. Stress maps were obtained along the wake of cracks stably propagated in six selected polycrystalline ceramics with representative microstructures. A conventional fracture mechanics assessment was concurrently performed to relate microscopic stress data to the macroscopic fracture resistance of the materials. It is demonstrated that the most effective toughening mechanism in polycrystalline ceramics takes place in the crack wake and arises from both elastic and frictional shielding tractions operated by crystallites which are left unfractured behind the crack tip.

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Processing Strategy for Producing Highly Anisotropic Silicon Nitride

Cited by 241 publications

References 13 publications

Textured silicon nitride: processing and anisotropic properties

Textured silicon nitride: processing and anisotropic properties

Theoretical Analysis on Crystal Alignment of Feeble Magnetic Materials under High Magnetic Field

In situ study of fracture mechanisms in advanced ceramics using fluorescence and Raman microprobe spectroscopy

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