Effect of initial particle size distribution on the dynamics of transient Ostwald ripening: A phase field study

The effects of different particle size distributions on the real-time hydration of tricalcium silicate cement paste were studied in situ by quasi-elastic neutron scattering. The changing state of water in the cement system was followed as a function both of cement hydration time and of temperature for different initial particle size distributions. It was found that the length of the initial, dormant, induction period, together with the kinetics of hydration product nucleation and growth, depends on the hydration temperature but not on the particle size distribution. However, initial particle size does affect the total amount of cement hydrated, with finer particle size producing more hydrated cement. Furthermore, the diffusion-limited rate of hydration at later hydration time is largely determined by the initial tricalcium silicate particle size distribution.

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Effect of Initial Particle Size on Coarsening Kinetics of γ Prime Precipitate in Nickel-Based Superalloy - A Phase Field Study

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.117-119.1834 ◽

2011 ◽

Vol 117-119 ◽

pp. 1834-1838

Author(s):

Chang Bo Ke ◽

Bao Zhong Xie

Keyword(s):

Particle Size ◽

Size Distribution ◽

Phase Field ◽

Precipitate Size ◽

Initial Particle ◽

Initial Particle Size ◽

Initial Size ◽

Gamma Prime ◽

Coarsening Kinetics ◽

Kinetics Of

The effect of initia gamma prime particle size on coarsening kinetics of gamma prime precipitates in Nickel-based superalloys has been studied by means of phase field method which takes into account the lattice misfit. The simulation shows that the gamma prime precipitate morphology at the late stage of coarsening is independent of initial particle size, and the rectangle-like precipitates dominate the matrix which is in good agreement with experimental studies. The coarsening exponent increases with initial size, while the coarsening rate constant exhibits no apparent regularity. Although the coarsening trend is independent of initial particle size, the precipitate size increases with initial size at a given aging time. Through precipitate size distribution calculation, it is found that the size distribution is fairly stable, which is not sensitive to the initial particle size.

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Changes in particle size distribution of suspended sediment affected by gravity erosion: a field study on steep loess slopes

Journal of Soils and Sediments ◽

10.1007/s11368-019-02496-z ◽

2019 ◽

Vol 20 (3) ◽

pp. 1730-1741 ◽

Cited By ~ 3

Author(s):

Wenzhao Guo ◽

Xiangzhou Xu ◽

Tongxin Zhu ◽

Hongwu Zhang ◽

Wenlong Wang ◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Field Study ◽

Size Distribution ◽

Suspended Sediment

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Theoretical analysis of particle size re-distribution due to Ostwald ripening in the fuel cell catalyst layer

Open Physics ◽

10.1515/phys-2019-0081 ◽

2019 ◽

Vol 17 (1) ◽

pp. 779-789 ◽

Cited By ~ 2

Author(s):

Ambrož Kregar ◽

Tomaž Katrašnik

Keyword(s):

Particle Size ◽

Fuel Cells ◽

Fuel Cell ◽

Particle Size Distribution ◽

Size Distribution ◽

Electric Potential ◽

Ostwald Ripening ◽

Particle Growth ◽

Mean Particle Size ◽

Fuel Cell Catalyst

Abstract The limited durability of hydrogen fuel cells is one of the main obstacles in their wider adoption as a clean alternative technology for small scale electricity production. The Ostwald ripening of catalyst material is recognized as one of the main unavoidable degradation processes deteriorating the fuel cell performance and shortening its lifetime. The paper systematically studies how the modeling approach towards the electrochemically driven Ostwald ripening in the fuel cell catalyst differs from the classical diffusion driven models and highlights how these differences affect the resulting evolution of particle size distribution. At moderately low electric potential, root-law growth of mean particle size is observed with linear relation between mean particle size and standard deviation of particle size distribution, similar to Lifshitz-Slyozov-Wagner theory, but with broader and less skewed distribution. In case of high electric potential, rapid particle growth regime is observed and qualitatively described by redeposition of platinum from a highly oversaturated solution, revealing the deficiencies of the existing platinum degradation models at describing the Ostwald ripening in the fuel cells at high electric potentials. Several improvements to the established models of platinum degradation in fuel cell catalysts are proposed, aimed at better description of the diffusion processes involved in particle growth due to Ostwald ripening.

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