Strength anisotropy in cold compacted ductile and brittle powders

Galen, Steve; Zavaliangos, Antonios

doi:10.1016/j.actamat.2005.06.023

Cited by 43 publications

(46 citation statements)

References 25 publications

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“…This paper shows that direction of pore structure plays a significant role as can be deducted from Fig. 3 where it is shown that at a similar porosity the crushing force in the x-direction is significantly different from that in the z-direction (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Formulation approaches that minimize the anisotropy in pore structure, possibly by reducing wall effects by focussing on lubrication, will help to control this effect.…”

Section: Crushing Forcementioning

confidence: 92%

See 1 more Smart Citation

Pore Direction in Relation to Anisotropy of Mechanical Strength in a Cubic Starch Compact

Vliet

Frijlink

et al. 2008

AAPS PharmSciTech

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Abstract. The purpose of this research was to evaluate the relation between preferential direction of pores and mechanical strength of cubic starch compacts. The preferential pore direction was quantified in SEM images of cross sections of starch compacts using a previously described algorithm for determination of the quotient of transitions (Q). This parameter and the mechanical strength were evaluated in compacts of different porosities. Starch was chosen as a model compound for materials with ductile behaviour of which tablets with low porosities can be made and which shows some elastic recovery after compaction. At medium and high porosity Q was significantly higher in the images providing a side view of the compact than in the images providing a top view (0.973 vs. 0.927 and 0.958 vs. 0.874 at 0 mm from the side of the compact and 0.956 vs. 0.854 and 0.951 vs. 0.862 at 3.5 mm), indicating that the pores were mainly oriented in the direction perpendicular to the direction of compression. This was accompanied by a lower crushing force in this direction. This could be explained by considering the pores as cracks which propagate through the sample during crushing. For both directions the crushing force decreased with increasing porosity. The yield strength of the compacts also decreased with increasing porosity, but this parameter was not dependent on the direction of crushing when the porosity was below 10%. The results show that pore direction significantly influences the crushing force but does not influence the yield strength, at porosities below 10%.

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Section: Crushing Forcementioning

confidence: 92%

“…the mechanical strength depends on the direction of measurement (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). In earlier research Ando et al (9) and Galen and Zavaliangos (16) determined the mechanical strength and took SEM images of cross sections of the tablets.…”

Section: Introductionmentioning

confidence: 99%

Pore Direction in Relation to Anisotropy of Mechanical Strength in a Cubic Starch Compact

Vliet

Frijlink

et al. 2008

AAPS PharmSciTech

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“…Recently, Akseli et al (17) proposed the use of a contact ultrasonic method. Except this last work, it is often difficult to conclude on mechanical property anisotropy due to complicated sample preparations (13), complex experimental setups (11,13), conditions of testing which are not comparable (11) and difficulties of analysing the results (8). Moreover, most studies reported different test methods in the axial and radial directions (11)(12)(13).…”

Section: Introductionmentioning

confidence: 96%

“…At the same time, mechanical properties are known to be dependent on porosity (10). In some works, tablets are shown to have anisotropic mechanical properties (11)(12)(13)(14)(15)(16)(17), meaning that the mechanical properties vary with the orientation in which the properties are measured. This variability of mechanical properties is supposed to explain some manufacturing problems observed during compaction processes such as capping and lamination.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Porous Structure of Pharmaceutical Compacts Evaluated by PGSTE-NMR in Relation to Mechanical Property Anisotropy

Porion¹,

Busignies²,

Mazel³

et al. 2010

Pharm Res

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“…Particle's morphology and ductility of compacts has been reported by Galen and Zavaliangos (2005). Galen and Zavaliangos (2005) examined the anisotropic strength of compacts and attributed the anisotropy especially in the ductile powder compacts to the microscopic architectural structure of deformed particles after the compaction. For example, mechanism is different in each case.…”

Section: Quality: Strengthmentioning

confidence: 99%

Critical Review on Engineering Mechanical Quality of Green Compacts using Powder Properties

Pandeya²,

Karamchandani

et al. 2018

KONA

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For processes involving particulate materials, mechanical properties of green compacts are of great interest when they are final or intermediate products. Optimal quality of green compacts is achieved usually with empirical approaches, i.e., unexpected issues in processes or products' quality are usually mitigated by time and resource consuming trial-and-error methods. Issues of the powder compaction are commonly observed when there are problems in feed materials or operational conditions even without any substantial change in a formula. Such divergent behavior of particulate materials is especially problematic for product developments and reliable operations. It has been widely accepted hypothesis that properties of particles are determinants of mechanical behavior of powder during compaction and the quality of resulting compacts. With recent developments in nanotechnology, characterization and engineering of individual particles at a microscopic or sub-microscopic scale are now feasible. Leveraging recent technological advancements, there has been a good progress in regard to quantitative understanding of mechanical relationships between properties of particles, particle system and final product. This review highlights the recent developments and gaps in engineering mechanical quality of powder compacts in conjunction with the characterization of particle systems and compaction at multiple scales.

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Strength anisotropy in cold compacted ductile and brittle powders

Cited by 43 publications

References 25 publications

Pore Direction in Relation to Anisotropy of Mechanical Strength in a Cubic Starch Compact

Pore Direction in Relation to Anisotropy of Mechanical Strength in a Cubic Starch Compact

Anisotropic Porous Structure of Pharmaceutical Compacts Evaluated by PGSTE-NMR in Relation to Mechanical Property Anisotropy

Critical Review on Engineering Mechanical Quality of Green Compacts using Powder Properties

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