On the spheroidization of rod-shaped particles of finite length

Nichols, F.A.

doi:10.1007/bf02396641

Cited by 158 publications

(61 citation statements)

References 11 publications

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“…(2) Expansion and contraction happened in radial direction, which finally caused the break-up of slender MnS. Numerical simulation of shape evolution for a rod has been done by Nichol et al 10,11) It's found that for the rod (L/D=7.19), the length recedes toward each other. Simultaneously, Bulges near the two ends and necking in the middle occur, which finally form two egg-shaped particles.…”

Section: In-situ Observationmentioning

confidence: 99%

Effect of Heat Treatment Conditions on Shape Control of Large-sized Elongated MnS Inclusions in Resulfurized Free-cutting Steels

et al. 2011

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Effect of heat treatment conditions on shape evolution of large-sized elongated MnS inclusions in resulfurized free-cutting rolled steel has been investigated using confocal scanning laser microscope and Si2Mo resistance furnace. The results show that the heating rate, soaking temperature and soaking time impose significant effects upon shape profiles of elongated MnS. The split of slender MnS was oberved in continuous heating with heating rate in the range of 0.5-2 K/s. In addition, split degree of MnS indicated a negative relation with the rise of heating rate. As a result, separation of elongated MnS was not observed at the heating rate of 6 K/s. During soaking experiments, there was no remarkable shape change for MnS at temperature lower than 1 073 K. While the elongated MnS splited up and spheroidized obviously at 1 473 K. Correspondingly, number density of inclusions increased while mean length reduced as the soaking time increased from 1 h to 4 h at 1 473 K. Significant shape change from slender to spindlelike or spherical was identified only when the soaking time exceeds 3 h or 4 h. Based on the Gibbs Thompson relation and the obtained experimental results, mechanism of shape evolution of MnS inclusions was discussed and morphology evolution of MnS was divided into three major steps: (1) first, the shrinkage occurred in the longitudinal direction at the beginning of heating process, (2) expansion and contraction in radial direction followed after the shrinkage which caused the split of slender MnS; (3) eventually, the spherical particles emerged from the split parts.KEY WORDS: large-sized elongated MnS inclusions; in-situ observation; resulfurized free-cutting steel.

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Section: In-situ Observationmentioning

confidence: 99%

Effect of Heat Treatment Conditions on Shape Control of Large-sized Elongated MnS Inclusions in Resulfurized Free-cutting Steels

et al. 2011

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“…It is caused by self necking phenomena from the large curvature ends. The average spacing among the broken-up voids, termed the critical wavelength l c , is given theoretically by l c ¼2 3/2 pR c $8.9R c , where R c is the initial pore radius [6,9,15]. The critical wavelength corresponds to a perturbation in the pore morphology, as determined by the mechanics of capillary motion.…”

Section: Resultsmentioning

confidence: 99%

Lift-off of epitaxial GaN by regrowth over nanoporous GaN

Kang

Lee

Ryu

2012

Journal of Crystal Growth

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“…From a micromechanical perspective, healing and sealing of cracks involves a sequence of modifications first of planar then of cylindrical void surfaces, and it has been suggested that the ovulation of cylindrical pores due to the RayleighTaylor instability (Nichols, 1976) is rate-controlling in this complex process (e.g., Smith and Evans, 1984). The ovulation in turn is controlled by the same kinetic parameters as hydrothermal grooving.…”

Section: Discussionmentioning

confidence: 99%

Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments

et al. 2014

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Abstract. We performed hydrothermal annealing experiments on quartzite samples at temperatures of 392 to 568 • C and fluid pressures of 63 to 399 MPa for up to 120 h, during which hydrothermal grooves developed on the free surfaces of the samples. An analysis of surface topology and groove characteristics with an atomic force microscope revealed a range of surface features associated with the simultaneous and successive operation of several processes partly depending on crystal orientation during the various stages of an experiment. Initially, dissolution at the quartzite-sample surface occurs to saturate the fluid in the capsule with SiO 2 . Subsequently, grooving controlled by diffusion processes takes place parallel to dissolution and precipitation due to local differences in solubility. Finally, quench products develop on grain surfaces during the termination of experiments. The average groove-root angle amounts to about 160 • , varying systematically with misorientation between neighboring grains and depending slightly on temperature and run duration. The grooving is thermally activated, i.e., groove depth ranging from 5 nm to several micrometers for the entire suite of experiments generally increases with temperature and/or run time. We use Mullins' classical theories to constrain kinetic parameters for the transport processes controlling the grooving. In the light of previous measurements of various diffusion coefficients in the system SiO 2 -H 2 O, interface diffusion of Si is identified as the most plausible rate-controlling process. Grooving could potentially proceed faster by diffusion through the liquid if the fluid were not convecting in the capsule. Characteristic times of healing of microfractures in hydrous environments constrained from these kinetic parameters are consistent with the order of magnitude of timescales over which postseismic healing occurs in situ according to geophysical surveys and recurrence intervals of earthquakes.

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On the spheroidization of rod-shaped particles of finite length

Cited by 158 publications

References 11 publications

Effect of Heat Treatment Conditions on Shape Control of Large-sized Elongated MnS Inclusions in Resulfurized Free-cutting Steels

Effect of Heat Treatment Conditions on Shape Control of Large-sized Elongated MnS Inclusions in Resulfurized Free-cutting Steels

Lift-off of epitaxial GaN by regrowth over nanoporous GaN

Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments

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