Measurement of viscosity of the grain-boundary phase in hot-pressed silicon nitride

Mosher, Don R; Raj, Rishi; Kossowsky, Ram

doi:10.1007/bf00541073

Cited by 106 publications

(46 citation statements)

References 9 publications

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“…The peaks arose from a sliding process along glassy grain boundaries within the polycrystal. 5,6) According to a lowered intergranular viscosity, additions of Ca-cation produced (i) shift of the peak-top temperature toward lower values, and (ii) a remarkable change in the peak morphology. The change of the intergranular SiO 2 -glass network structure due to Ca dopant obviously led to both these trends.…”

Section: Internal Friction Measurementsmentioning

confidence: 99%

“…Recently, we have shown that the inherent rheological behavior of the grain-boundary glass phase in polycrystalline ceramics can be quantitatively evaluated by means of internal friction measurements. [1][2][3][4] The use of internal friction to quantitatively evaluate the intrinsic viscosity of residual glasses segregated to ceramic grain boundaries has been first proposed by Mosher et al, 5,6) based on the anelastic relaxation mechanism discussed by Zener and Ke. [7][8][9] In the internal friction behavior (as a function of temperature) of glassy bonded ceramic polycrystals, a relaxation peak systematically appears at relatively high temperature, which arises from the anelastic phenomenon of viscous slip along grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

“…5,10) When a glassy film continuously encompasses the grains as, for example, in Si 3 N 4 or SiC ceramics, the peak is sufficiently intense to allow a quantitative analysis and, thus, the evaluation of the activation energy for viscous flow of the intergranular glass and the related viscosity magnitude. Reliable activation energy analyses can be performed by applying the peak-shift method 1,6,10) that makes use of the peak shift occurring upon varying the damping frequency.…”

Section: Introductionmentioning

confidence: 99%

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Internal Friction Analysis of CaO-Doped Silicon Carbides

et al. 2002

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Internal friction originated from sliding and diffusional flow along grain boundaries was monitored (as a function of both temperature and damping frequency) in model SiC polycrystals with an intergranular SiO 2 glassy film. Emphasis was placed on the change of the internal friction characteristics upon additional Ca cation. It is expected that Ca cation segregates to the intergranular glass phase and modifies its network structure. The presence of a relaxation peak of internal friction due to grain-boundary sliding enabled quantitative evaluation of the activation energy for viscous flow of the intergranular glass and the related viscosity magnitude. A peak-analysis procedure, according to the peak-shift method (i.e., monitoring peak shift upon damping frequency change), is proposed, which quantitatively revealed the activation energy for viscous flow in various impurity-doped intergranular glasses. The presence of chemical gradients at grain boundaries, namely the presence of families of boundaries within the SiC polycrystal with different chemical characteristics, has also been analyzed by taking into account the dependence of peak morphology on damping frequency.

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Section: Internal Friction Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Friction Analysis of CaO-Doped Silicon Carbides

et al. 2002

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“…Internal friction measurements [6] and Auger spectroscopy experiments [7] suggested the presence of an amorphous phase in hot pressed silicon nitride. Transmission electron microscopy (TEM) studies also indicated the presence of an amorphous phase, located at triple grain junctions [8,9].…”

Section: Introductionmentioning

confidence: 99%

Structure of special grain boundaries in SiAlON ceramics

Schmid¹,

Rühle²

1984

J Mater Sci

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The microstructure of hot-pressed samples of the 15 R polytype phase in the Si-AI-O-N system was studied by means of TEM. Emphasis was put on studies of high angle grain boundaries. In this material high angle boundaries of arbitrary orientation usually possess a vitreous grain boundary phase. However, special grain boundaries were found, which were free of any vitreous grain boundary phase. From the orientation relation of the adjacent grains 2; = 1 (coherent reflection twin boundary), 2; = 7 and 2; = 13 boundaries were found. For their explanation a coincidence site lattice (CSL) model was developed for (0001) twist boundaries. By assuming an exponential form for the potential of atomic interaction, the calculation of minimum grain boundary energies for special twist angles was in accordance with the experimental observations.

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“…5,[14][15][16][17] The sintering aids added to the powder compacts for improving the powder compressibility and densification during the processing, together with powder impurity, result in the formation of amorphous phases at triple junctions and grain boundaries. Indeed, a few percent of sintering aids in Si 3 N 4 ceramics, in particular, instigates large amorphous-phase agglomerates (amorphous pockets) at multiple junctions and thin or even thick amorphous film at grain boundaries.…”

mentioning

confidence: 99%

How do the grains slide in fine-grained zirconia polycrystals at high temperature?

Daraktchiev

Schaller

Grémillard

et al. 2007

Applied Physics Letters

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Degradation of mechanical properties of zirconia polycrystals is hardly discussed in terms of solution-precipitation grain-boundary sliding due to experimental controversies over imaging of intergranular amorphous phases at high and room temperatures. Here, the authors applied the techniques of mechanical spectroscopy and transmission electron microscopy (TEM) to shed light on the amorphization of grain interfaces at high temperature where the interface-reaction determines the behaviour of fine-grained zirconia polycrystals. They present mechanical spectroscopy results, which yield evidences of an intergranular amorphous phase in silica doped and high-purity zirconia at high temperature. Quenching of zirconia polycrystals reveals an intergranular amorphous phase on TEM images at room temperature.

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Measurement of viscosity of the grain-boundary phase in hot-pressed silicon nitride

Cited by 106 publications

References 9 publications

Internal Friction Analysis of CaO-Doped Silicon Carbides

Internal Friction Analysis of CaO-Doped Silicon Carbides

Structure of special grain boundaries in SiAlON ceramics

How do the grains slide in fine-grained zirconia polycrystals at high temperature?

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