The effect of contiguity on growth kinetics in liquid-phase sintering

Yang, S.-N.; Mani, S. S.; German, Randall M.

doi:10.1007/bf03220917

Cited by 20 publications

(15 citation statements)

References 5 publications

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“…From the contribution of liquid phase, size of grains of modified BNZ ceramic at maximum Bi 2 O 3 concentration sintered at temperature of 850 and 900°C were decreased up to 27% when compared with pure material fired at the same temperature. This behaviour was in agreement with several reports attempting to explain the dependence of grain growth on the volume fraction of liquid [21][22][23] . In addition, the presence of Bi 2 O 3 -based liquid phase and inhibition of grain growth were expected to assist filling and elimination of pore during the fabrication process.…”

Section: Discussionsupporting

confidence: 93%

Untitled

Jaiban¹,

Jiansirisomboon²,

Watcharapasorn³

2011

ScienceAsia

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Lead-free bismuth sodium zirconate (BNZ) ceramics with formula Na 0.5 Bi 0.5 ZrO 3 /xBi 2 O 3 with x = 0, 2, 3, 4, and 6 wt% were prepared by liquid-phase sintering method. The specimens were sintered at 850 and 900°C. Phase identification was investigated using X-ray diffraction technique. BNZ/4 wt% Bi 2 O 3 and BNZ/6 wt% Bi 2 O 3 ceramics sintered at 900°C showed impurity phase of Bi 7.38 Zr 0.62 O 12.31 compound due to excess additive reacted with zirconium in system. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were employed to study microstructure and measure chemical composition of ceramics, respectively. The results revealed creation of bismuth oxide liquid phase at BNZ grain boundaries inhibited grain growth and decreased pore size. This caused the relative densities of the modified samples to increase.

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Section: Discussionsupporting

confidence: 93%

Untitled

Jaiban¹,

Jiansirisomboon²,

Watcharapasorn³

2011

ScienceAsia

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“…A wide range of grain-growthrate constants have been reported for higher W contents. [8,[42][43][44][45][46] The results of this study from sintering in microgravity are within the ranges previously reported. As shown in Figure 7, the microgravity data strongly support the previously identified [8] dependence of the grain-growth-rate constant on the liquid-volume fraction raised to the -2/3 power and show that it holds for very low W contents.…”

Section: A Grain-growth-rate Constantsupporting

confidence: 90%

“…The growth-rate exponent is related to the grain-growth mechanism, but is generally equal to 3, from previous reports for tungsten heavy alloys in standard gravity. [8,[39][40][41][42][43][44][45][46] The experimental data presented in the previous section permit the analysis of grain growth for compositions that cannot be sintered in standard gravity due to grain settling. The cube of the grain size as a function of sintering time for microgravity-sintered 78 W samples is plotted in Figure 5.…”

Section: A Grain-growth-rate Constantmentioning

confidence: 99%

Grain Growth in Dilute Tungsten Heavy Alloys during Liquid-Phase Sintering under Microgravity Conditions

Johnson¹,

Campbell

Park

et al. 2009

Metall Mater Trans A

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Tungsten heavy alloys with compositions ranging from 35 to 93 wt pct tungsten were liquidphase sintered at 1500°C under microgravity conditions for isothermal hold times ranging from 1 to 600 minutes. The solid-volume fraction, grain size, grain size distribution, connectivity, and contiguity of the sintered microstructures were quantitatively measured. From these data, graingrowth-rate constants are determined for solid-volume fractions ranging from 0.048 to 0.858 and are compared to the predictions of several grain-coarsening models. The measured grain size distributions are shown to be self-similar and are fit to a Weibull distribution. Threedimensional (3-D) grain size distributions from several coarsening models are transformed into grain size distributions for two-dimensional (2-D) cross sections, for comparison with the experimental data. Chi-squared tests and G-tests show that a coalescence model for grain growth fits the experimental observations better than solution-reprecipitation models, even for dilute tungsten heavy alloys.

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“…In these cases, the reduced solid-liquid interface area gives slower growth. [30][31][32][33][34][35][36][37] This has been traced to a change in contiguity [25,38,39] or increase in dihedral angle. [31,40] Several studies [41][42][43][44][45][46][47] further show grain growth in LPS includes coalescence.…”

Section: Introductionmentioning

confidence: 99%

Modeling grain growth dependence on the liquid content in liquid-phase-sintered materials

German

Olevsky

1998

Metall Mater Trans A

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A model for grain growth during liquid-phase sintering (LPS) is presented. A Rayleigh grain size distribution is assumed based on both experimental and theoretical results. This asymmetric distribution provides a continuous driving force for coarsening. The model uses the solid grain contiguity to calculate the relative solid-state and liquid-phase contributions to coarsening. The level of grain agglomeration affects both the mean diffusion distance and interface area over which diffusion occurs. A cumulative grain growth rate is calculated assuming independent solid and liquid contributions to coarsening. Consequently, only the liquid volume fraction and solid-liquid dihedral angle are required to predict the change in grain coarsening rate with solid-liquid ratio. A prior empirical correlation between the grain growth rate constant and the liquid volume fraction is compared to the resulting analytic form, showing excellent agreement. The new model is projected to be generically applicable to microstructure coarsening in multiple phase materials, including porous structures.

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The effect of contiguity on growth kinetics in liquid-phase sintering

Cited by 20 publications

References 5 publications

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Grain Growth in Dilute Tungsten Heavy Alloys during Liquid-Phase Sintering under Microgravity Conditions

Modeling grain growth dependence on the liquid content in liquid-phase-sintered materials

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