Fractures, fractals and breakage energy of mineral particles

Thomas, Ajith; Filippov, L.O.

doi:10.1016/s0301-7516(99)00029-0

Cited by 45 publications

(10 citation statements)

References 4 publications

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“…The most general form proposed in the literature for the energy consumed per mass unit to reduce the average particle size, x, to the final material is [ Hukki , 1961; Thomas and Filippov , 1999]: where K is a constant of proportion. This expression generalizes that proposed by Lynch [1977]: dE = −Kx −n dx and it remains valid for specific grain size intervals.…”

Section: Discussionmentioning

confidence: 99%

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Fragmentation in the Val Pola rock avalanche, Italian Alps

2007

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[1] Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) are compared with data concerning rock avalanching, rock fragmentation, and comminution. The Weibull distribution fits a small part of the entire particle-size distribution of debris samples, with a mean value of the curve shape factor of 0.54 ± 0.28. This is typical of multiple comminution, or fragmentation with much shearing. A fractal distribution fits over a greater size range. Computed fractal dimensions range between 1.3 and 3.2 within the deposit, with average values of about 2.6-2.7. These values cover the range between the theoretical values of the plane-of-weakness model (1.97) and the pillar-of-strength model (2.84) and are close to the theoretical value for the constrained comminution model (2.58). These suggest that both texturally mature and immature deposits are present and that more than a single comminution process acted during the rock avalanche motion. Variation of the grain size distribution within the deposit and grain size segregation show as trends in the fractal dimension and arise from variation in the fragmentation process. A variety of different physical and empirical laws suggest that 1-30% of the energy expended in the rock avalanche was consumed in fragmentation.

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Section: Discussionmentioning

confidence: 99%

“…[58] The most general form proposed in the literature for the energy consumed per mass unit to reduce the average particle size, x, to the final material is [Hukki, 1961;Thomas and Filippov, 1999]:…”

Section: Estimating Fragmentation Energymentioning

confidence: 99%

Fragmentation in the Val Pola rock avalanche, Italian Alps

2007

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“…A caveat to note is that Hukki's combined law is empirically derived for brittle materials, and while work has been done to consider elastic deformation and fracture in terms of a combined law 26 , it does not appear that a satisfactory model currently exists to describe grain refinement in ductile materials during milling. That should not detract from the general applicability of the model in this instance, as the central point is that particle size reduction or grain refinement during milling is not inversely proportional to milling dose for relatively large starting particle size.…”

Section: Time To Msr Ignitionmentioning

confidence: 99%

Mechanochemical synthesis and spark plasma sintering of the cerium silicides

Alanko

Jaques

Bateman

et al. 2014

Journal of Alloys and Compounds

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The cerium silicides, Ce 5 Si 3 , Ce 3 Si 2 , CeSi, CeSi 2-y , and CeSi 2-x , have been prepared from the elements by mechanochemical processing in a planetary ball mill. Preparation of the cerium silicide Ce 5 Si 4 was unsuccessfully attempted and potential reasons for this are discussed. Temperature and pressure of the milling vial were monitored in situ to gain insight into the mechanochemical reaction kinetics, which include a mechanically-induced self-propagating reaction (MSR). Some prepared powders were consolidated by spark plasma sintering to high density. Starting materials, as-milled powders, and consolidated samples were characterized by x-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results obtained help elucidate key questions in mechanochemical processing of intermetallics, showing first phase formation similar to thin films, MSR ignition times that are composition-and milling speed-dependent, and sensitivity of stable compound formation on the impact pressure. The results demonstrate mechanochemical synthesis as a viable technique for rare earth silicides.

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“…The calculation of the total energy released by the milling bodies took into account the mill geometrical and functional characteristics, the milling bodies and the powder mixture masses subjected to processing, and so on [6][7][8][9][10][11][12].…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Reinforced Al-Matrix Composites with Ni-Aluminides, Processed by Powders

Cojocaru

Brânzei

Tudose

et al. 2020

MMS

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The paper addresses issues of interest related to the uniform distribution of the reinforcement phase and the continuity of the metal matrix, for two ways of obtaining the powder composites, the hot extrusion and the spark plasma sintering (SPS) respectively. The reinforcement phase is the nickel aluminides obtained by mechanical alloying in ball mills, and the metal matrix is made of aluminum powders. Prior to extrusion, the mixture of aluminum powders and nickel aluminides was pressed and subsequently sintered in environments with high carbon potential, so that in the final product, nickel aluminides, carbide and aluminum oxides were found as reinforcement phases. The obtained results confirmed the hypothesis that, from a blank product with a random distribution of the reinforcement phase, a product with an ordered distribution of the reinforcement phase is obtained after extrusion and that for the same initial proportion of nickel aluminides as reinforcement phase, the composite hardness obtained by hot extrusion is higher compared to that obtained by SPS, the difference being determined by the increase of the proportion of the reinforcement phase by the appearance of aluminum carbide and aluminum oxides during the sintering operation in the high carbon environment.

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Fractures, fractals and breakage energy of mineral particles

Cited by 45 publications

References 4 publications

Fragmentation in the Val Pola rock avalanche, Italian Alps

Fragmentation in the Val Pola rock avalanche, Italian Alps

Mechanochemical synthesis and spark plasma sintering of the cerium silicides

Reinforced Al-Matrix Composites with Ni-Aluminides, Processed by Powders

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