Microscopic analysis on the consolidation process of granule beds

Naito, Makio; Nakahira, Kenji; Hotta, Tadashi; Ito, Akinobu; Yokoyama, Toyokazu; Kamiya, Hidehiro

doi:10.1016/s0032-5910(97)03340-8

Cited by 24 publications

(4 citation statements)

References 16 publications

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“…For m҃ 1 the Hertzian regime is recovered for which exists ample experimental validation. For m→ȍ, a linear dependency is predicted by (4) which is in a good agreement with the recent experiments of [10] for nearly ideal plastic materials.…”

Section: Local Constitutive Equationssupporting

confidence: 88%

Consolidation Behavior of Inhomogeneous Granular Beds of Ductile Particles using a Mixed Discrete-Continuum Approach

Zheng

Cuitiño

2002

KONA

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Section: Local Constitutive Equationssupporting

confidence: 88%

Consolidation Behavior of Inhomogeneous Granular Beds of Ductile Particles using a Mixed Discrete-Continuum Approach

Zheng

Cuitiño

2002

KONA

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“…Fig.6 shows a comparison of the compressive strength of the granules prepared from the three different slurries 9) . The strength of granules was measured with a micro compression test machine (MCTM-500, Shimadzu Co., Japan) and the compressive strength was calculated by applying the model proposed for the elastic deformation of spherical particle 10,11) . Fig.7 shows the transmission optical micrograph of the thinned ceramics specimens 9) .…”

Section: Powder Slurr Y Preparation Conditionsmentioning

confidence: 99%

“…Effectively using these tools, we can investigate what those processing conditions in the ceramic manufacturing create large pores in sintered ceramics causing product reliability problems. So far, on the microstructure and sintered strength of ceramics, the following issues were clarified using these characterization tools: seasonal variation of microstructure and sintered strength of dry-pressed alumina [21][22][23] , effects of spray drying conditions [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] , dewaxing procedures [25][26][27] and granule compaction procedures [28][29][30] on the fracture origin of sintered ceramics. Of course, these tools are also suitable for other manufacturing processes, such as injection molding process 31) , to improve the properties of their ceramic parts.…”

Section: Importance Of Powder Characterization Toolsmentioning

confidence: 99%

Powder Processing Issues for High Quality Advanced Ceramics

Naito

Okumiya

Abe

et al. 2010

KONA

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In this paper, the effect of powder processing conditions on the fracture strength of advanced ceramics is discussed. Manufacturing processes of silicon nitride ceramics and alumina ceramics are utilized to explain the relationship between powder processing conditions and major fracture origin in the ceramics. The preparation conditions of powder slurry are found affecting the structure and strength of powder granules, which can influence the properties of green compact and thus the quality of sintered ceramics. These phenomena can be investigated by using new characterization tools such as the liquid immersion method and the observation technique using thinned ceramics specimen under the transmission mode. Also, very small amount of coarse particles contained in the powder slurry is found starting the fracture in ceramics by using wet sieve analysis and the observation technique with thinned ceramic specimen. As a result, it is found that the major ceramics fracture is originated from the large pores and coarse particles in powder granules, green compact and sintered ceramics. They can be unintentionally introduced in the manufacturing steps of ceramics, such as powder slurry preparation, spray drying, and forming process of green compact. By making use of these characterization tools, effective processing conditions to eliminate the large pores and coarse particles can be identified for producing high quality advanced ceramics.

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“…The pressure transmissibility was based on the compaction curve 14) and the consolidation curve, 15) and the logarithm in Eq. 3 was applied to distinguish clearly the three steps of the compression process according to the change in the rheological behavior.…”

Section: Rheological Analysis Of S S Indexmentioning

confidence: 99%

Rheological Analysis and Quantitative Evaluation of Wet Kneaded Wax Matrix

Abe¹,

Suzuki²,

Ootsuki³

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Clarification of various factors affecting the quality characteristics of product and establishment of an acceptable range of characteristics play an essential role in stable manufacturing of the sophisticated and desired products. Wet mass properties during agitating granulation process provide strong influence on the quality of final products, and this process is widely used in the pharmaceutical, the plastic and the foods industries. However, agitating granulation process is associated with many operating parameters, which can be classified as apparatus variables (vessel shape and impeller shape), process variables (method of binder addition, wet kneading time and impeller speed) and product variables (powder properties, formulation and binder liquid volume). Both the evaluation of wet granulation and the analysis of observed behavior are very difficult.Many researchers [1][2][3][4][5][6] have studied the determination method for the critical parameters involved in wet granulation and wet kneaded mass; furthermore, they investigated the effects of such parameters on the granule size, its distribution and density. Although properties of wet granules are not directly and universally quantified by using the torque rheometry and power consumption measurements specific to respective machines, some attempts 7-9) have been carried out on the evaluation of granulation and its end point determination. Nevertheless, few reports have focused on the related properties of the wet kneaded mass to the dissolution of sustained-release drug despite of the fact that many different types of sustained-release dosage forms are urgently needed by medical circles to improve clinical efficacies and relevant patient compliance. 10)Watano et al. [11][12][13] have recently demonstrated that properties of the wet kneaded mass are directly characterized by internal pressure transmissions which are determined by using a newly developed compression tester instead of the torque rheometry. Furthermore, it was also documented that the pressure transmissions were strongly associated with water dispersion among the wet kneaded mass. Despite of these available findings, however, the pressure transmissions of the wet kneaded mass are not well identified. What's worse, to make full use of the features of the wet kneaded mass for manufacturing the sustained-release dosage forms, e.g. wax matrix products, all we have to do is to address the relationship between the pressure transmissions and the drug dissolution. In the present study, the author managed to expand the pressure transmission to the form of the rheological behavior to identify the character of the transmission. Scrutinized investigations about the expanded pressure transmission disclosed the plastic property of the wet kneaded mass that turned out to be the most decisive and direct criterion in the kneading process control. It is because the kneading process subjects the powder sample to be plastic for the preparation of the extrusion granulation. From a theoretical point of view, the e...

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Microscopic analysis on the consolidation process of granule beds

Cited by 24 publications

References 16 publications

Consolidation Behavior of Inhomogeneous Granular Beds of Ductile Particles using a Mixed Discrete-Continuum Approach

Consolidation Behavior of Inhomogeneous Granular Beds of Ductile Particles using a Mixed Discrete-Continuum Approach

Powder Processing Issues for High Quality Advanced Ceramics

Rheological Analysis and Quantitative Evaluation of Wet Kneaded Wax Matrix

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