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Theses
Etude de la broyabilité de différents matériaux pulvérulents à l'aide d'un test d'impact à jet d'air
Etude de la broyabilité de différents matériaux pulvérulents à l'aide d'un test d'impact à jet d'air
Abstract : The behaviour of a powder impacted on a target depends on its size, its particle size distribution, the material mechanical properties and the industrial rig. Aside from all the possible approaches to study the impact of pulverulent materials, our experimental equipments and methodology are different in providing complete and rigorous information on an elementary impact : the normal impact of single particles on a target.
An experimental test rig for the study of impact in an air jet mill allows one to evaluate the relationship between the impact energy and the fineness of the impacted solids. From one side qualitative comparison is possible with the fragmentation profiles. On the other side quantitative comparison can be carried out with the definition of grindability parameters : attrition threshold and grindability expressed in created surface per energy.
The test provides for a behaviour classification. In single impact tests, so far, three types of behaviour are highlighted : fragile, "complex" and ductile. Multi-impact study reveals the non-equivalence between multiple impact and single impact : a solid is not broken similarly if a given energy is provided in one or several times.
The test also allows one to study the influence of the powder size, its structure, its processing, and more generally its "history" on its behaviour at impact on a target. Furthermore, more fundamental information can be obtained : relation structure-grindability parameters, fragmentation mechanisms, brittle-ductile transition, breakage efficiency, estimation of the reached impact temperature...
An experimental test rig for the study of impact in an air jet mill allows one to evaluate the relationship between the impact energy and the fineness of the impacted solids. From one side qualitative comparison is possible with the fragmentation profiles. On the other side quantitative comparison can be carried out with the definition of grindability parameters : attrition threshold and grindability expressed in created surface per energy.
The test provides for a behaviour classification. In single impact tests, so far, three types of behaviour are highlighted : fragile, "complex" and ductile. Multi-impact study reveals the non-equivalence between multiple impact and single impact : a solid is not broken similarly if a given energy is provided in one or several times.
The test also allows one to study the influence of the powder size, its structure, its processing, and more generally its "history" on its behaviour at impact on a target. Furthermore, more fundamental information can be obtained : relation structure-grindability parameters, fragmentation mechanisms, brittle-ductile transition, breakage efficiency, estimation of the reached impact temperature...
https://tel.archives-ouvertes.fr/tel-00261869
Contributor : Olivier Lecoq <>
Submitted on : Monday, March 10, 2008 - 11:47:42 AM
Last modification on : Wednesday, June 24, 2020 - 4:19:21 PM
Long-term archiving on: : Friday, May 21, 2010 - 12:06:47 AM
Contributor : Olivier Lecoq <>
Submitted on : Monday, March 10, 2008 - 11:47:42 AM
Last modification on : Wednesday, June 24, 2020 - 4:19:21 PM
Long-term archiving on: : Friday, May 21, 2010 - 12:06:47 AM