Effect of particle size in aggregated and agglomerated ceramic powders

Balakrishnan, Avinash; Pizette, Patrick; Martín, Christophe; Joshi, Shrikant V.; Saha, B.P.

doi:10.1016/j.actamat.2009.09.058

Cited by 112 publications

(65 citation statements)

References 44 publications

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“…The stress tensor ij  , averaged over the model cell, is calculated by the known expression [8][9][10]:…”

Section: Resultsmentioning

confidence: 99%

“…The theoretical model of [12,13] includes the contact interaction laws, such as the modified Hertz law, which describes the elastic repulsion of particles, the linearized Cattaneo -Mindlin law [14,15], which describes the "friction" forces at particle shift, the Lurie law [16], which describes the contact elasticity to the particle rolling, as well as modified Hamaker's formula [17], which describes the dispersion attractive forces, and (in the case of II type systems) the possibility of interparticle solid bridges formation [10]. Note that the dispersion attractions and the agglomeration tendency for the nanosized powders, as distinct from powders of micron (or larger) sizes, take on special significance and, in particular, owing to introduction this factors the size effect in compaction processes, well-known from the experimental studies [1][2][3]6], is reproduced by the granular dynamics method.…”

Section: Objects Of Study and Investigation Methodsmentioning

confidence: 99%

“…However it is hampered by absence of a valid phenomenological theory describing the powder body properties. Thereupon the direct simulations of nanopowders by the granular dynamics method, also known as the discrete element method [4,5,[7][8][9][10][11], have attractive prospects. Different regularities of nanopowder systems, for example, the size effect in nanopowder compaction processes, have been already investigated in the framework of the granular dynamics method [4,5,12,13].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of particle size distribution on nanopowder cold compaction processes

Boltachev

Volkov

Lukyashin

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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“…The stress tensor ij  , averaged over the model cell, is calculated by the known expression [8][9][10]:…”

Section: Resultsmentioning

confidence: 99%

Section: Objects Of Study and Investigation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of particle size distribution on nanopowder cold compaction processes

Boltachev

Volkov

Lukyashin

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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“…The granular dynamics method (or discrete element method) suggested for the first time by Cundall and Strack [21] and being developed strongly at present time [12,13,14,15,22,23,24,25,26,27,28,29,30] is a convenient alternative to real and laborious experiments and is a very promising approach, which allows finding the detailed information on powder systems. Due to a great extent of the sphericity and the nondeformability (strength) of individual particles of oxide nanopowders being studied, the granular dynamics method is particularly attractive and promising tool of the theoretical analysis.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the size effect in the compaction processes is known. It is harder to compact the nanopowders as compared to the powders consisting of larger size particles in view of the presence of relatively large adhesion forces [8,9,10,11], which resilt from dispersion forces of attraction [12,13,14,15]. To overcome the strong adhesion of nanopowders it is necessary to use very high pressures, which can turned out beyond the ultimate strength of experimental setup [16].…”

mentioning

confidence: 99%

Simulation of the macromechanical behavior of oxide nanopowders during compaction processes

et al. 2015

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Abstract. Two granular systems (I and II) corresponding oxide nanopowders having different agglomeration tendency are simulated by the granular dynamics method. The particle size is 10 nanometer. The interaction of particles involves the elastic forces of repulsion, the tangential forces of "friction", the dispersion forces of attraction, and in the case of II system the opportunity of creation/destruction of hard bonds of chemical nature. The processes of the uniaxial compaction, the biaxial (radial) one, the isotropic one, the compaction combined with shear deformation as well as the simple shear deformation are studied. The effect of the positive dilatancy is found out in the processes of shear deformation. The loading surfaces of nanopowders are constructed in the space of stress tensor invariants, i.e., the hydrostatic pressure and the deviator intensity. It is revealed that the form of the loading surfaces is similar to an ellipse, which is shifted along the hydrostatic axis to compressive pressures. The associated flow rule is analyzed. The nonorthogonality of the deformation vectors to the loading surface is established in the both systems modeled.Keywords: nanopowder, granular dynamics method, loading surface, associated flow rule. I. IntroductionAt present time high hopes concerning the development of promising structural and functional materials are pinned on the production and the investigation of nanostructured ceramics based on different oxides, for example, Al 2 O 3 , ZrO 2 , Y 2 O 3 , YSZ, and so on [1,2,3,4,5]. The powder metallurgy methods, which include such stages as the nanopowder production, compaction, and sintering, are the most debugged and fruitful methods for manufacture of the nanosized ceramic materials [2,3,4,5,6,7]. The nanostructure preservation during the sintering stage needs the use of reduced temperatures that makes great demands of compacts prepared in previous stage [2,3,4,5]. Generally, the compacts must be uniform and have large density. On the other hand, the size effect in the compaction processes is known. It is harder to compact the nanopowders as compared to the powders consisting of larger size particles in view of the presence of relatively large adhesion forces [8,9,10,11], which resilt from dispersion forces of attraction [12,13,14,15]. To overcome the strong adhesion of nanopowders it is necessary to use very high pressures, which can turned out beyond the ultimate strength of experimental setup [16]. Such high pressures are achieved, for example, in the processes of magnetic pulsed compaction owing to the application of inertial effects [7]. In spite of the considerable experimental progress in this line [2,3,4,5], it can be claimed that the further progress is impeded by the lack of theoretical description of nanosized powders.As a rule, present-day theoretical approaches to nanopowder description are the application of principles, which have developed for larger particle powders and do not take into account the peculiarities of new subjects of inquiry. So, for...

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Powder Compaction by Dry Pressing

Oberacker

2013

Ceramics Science and Technology

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Effect of particle size in aggregated and agglomerated ceramic powders

Cited by 112 publications

References 44 publications

Influence of particle size distribution on nanopowder cold compaction processes

Influence of particle size distribution on nanopowder cold compaction processes

Simulation of the macromechanical behavior of oxide nanopowders during compaction processes

Powder Compaction by Dry Pressing

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