Quantification of Particle Morphology in Powder Process Technology (original) (raw)
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Characterization of Powder Particle Morphology
Proceedings of the Estonian Academy of Sciences. Engineering, 2001
Technological properties of powders depend on their granulometry and particle morphology. Most of the image analysis methods provide only average size parameters (diameter, area, perimeter, etc.) which are often inadequate for characterizing the morphology of the particles. For particle abrasivity characterization, angularity factors are more sensitive. This paper studies different parameters for describing the hardmetal powder granulometry and morphology. The main aim is to find numerical descriptors for the shape factors that adequately characterize the hardmetal powders produced by the mechanical method-milling in a disintegrator. For the characterization of the powder particle morphology, irregularity parameter IP (relation of the diameters of the maximum inscribed and minimum circumscribed circles) suits best, taking into account the ellipticity and irregularity of the particle form. For describing the angularity of ground powders, the so-called "spike parameter-quadratic fit" can be used.
Korean Journal of Chemical Engineering, 2009
We report the particle size distribution of poly component particulate systems studied in three kinds of experimental methods. Six analyzers, such as Mastersizer Microplus (Malvern Instruments Ltd., UK), LS230 (Coulter Electronics Ltd., USA) LMS30 (Seishin, Japan), Analysette22 (Fritsch, Germany), HELOS (Sympatec, Germany) based on a laser diffraction and scattering method, and the SKC-2000S (Seishin Co., Ltd., Japan) based on the centrifugal sedimentation method, were used to study the particle size distribution. The results do not show reasonably good agreement between the different analyzers and different sample systems. There is a discrepancy regarding the absolute values, which can be explained by the fact the techniques used are based on different measuring principles. The results of the present study reflect that the investigator must carefully select the particle size analyzer for a particular application. Therefore, we suggest that it is necessary to measure the particle size distribution by using at least two types of analyzers or more of different makers.
Effect of Process Parameters on Powder Quality
Both free fall (ffa) and close coupled atomization (cca) were used in a new powder plant. Different powder quality features were defined to estimate the influence of the process parameters. The particle size distribution, the appearance of satellite particles, the circularity, and the flowability of the powders were also used as quantitative criteria. Main process parameters such as atomization pressure and melt mass flow were evaluated with respect to powder quality features. CuSn10 was used as feed stock material. The crucible volume was 1000 ml and melt mass flow was varied between 50 and 300 kg/h. For atomizer gas pressures between 1 MPa and 2.5 MPa, mass median diameter between 162 µm and to 94 µm with a d 84,3 /d 50,3 ≈ 1.61 were achieved using ffa. For the cca, a mass median diameter of 41 µm was achieved with an atomizer gas pressure of 2 MPa. The geometric standard deviation d 84,3 /d 50,3 was achieved with the ffa was between 1.8 and 2.2.
Analysis of the Mean Diameters and Particle-Size Distribution in Powders
Particle & Particle Systems Characterization, 2010
The granulometric characterization of a pulverulent material requires quantification of the particle size and its distribution frequency. From these primary data, the mean size (mean diameters) of the pulverulent material is calculated and the data are adjusted to the distribution functions. In this study, the most frequent mean diameters are defined and calculated, and the application of the distribution functions to the experimental results is discussed. It is concluded that the Rosin-Rammler distribution function and a modified Nukiyama-Tanasawa function are the most suitable equations to fit the differential and the cumulative undersize distribution frequencies. This review is accompanied by calculations that illustrate the application of the equations related to this work.
Influence of particle properties on powder bulk behaviour and processability
International Journal of Pharmaceutics, 2017
Understanding interparticle interactions in powder systems is crucial to pharmaceutical powder processing. Nevertheless, there remains a great challenge in identifying the key factors affecting interparticle interactions. Factors affecting interparticle interactions can be classified in three different broad categories: powder properties, environmental conditions, and powder processing methods and parameters. Although, each of these three categories listed is known to affect interparticle interactions, the challenge remains in developing a mechanistic understanding on how combination of these three categories affect interparticle interactions. This review focuses on the recent advances on understanding the effect of powder properties, particularly particle properties, its effect on interparticle interactions and ultimately on powder bulk behaviour. Furthermore, this review also highlights how particle properties are affected by the particle process route and parameters. Recent advances in developing a particle processing route to prepare particles with desired properties allowing desired interparticle interaction to deliver favoured powder bulk behaviour are also discussed. Perspectives for the development of potential particle processing approaches to control interparticle interaction are presented.
Morphology of powder particles produced by spray atomization and other processes
Vojnotehnicki glasnik, 2015
The physical and mechanical properties of coatings are heavily influenced by the technologies of powder production and by the parameters of the plasma spray process. One of the most important parameters that affects the physical and mechanical properties of coatings is the morphology of powder particles-homogeneity, granulation and granulation range, directly related to the technologies of powder production. This paper describes the technological processses of powder production most commonly used and shows the SEM micrographs of powder morphologies. Depending on the manufacturing process, powder particles have different characteristics regarding their shape, size, specific gravity, purity, etc. Since these characteristics have a significant impact on the quality and properties of deposited coatings, it is necessary to possess knowledge about the characteristics of powders in order to better control the behavior of particles in the plasma jet, in order to produce the expected characteristics of the coating.Powders have a variety of characteristics to be set for the operating parameters of the deposition in order to obtain the desired coating characteristics.
Control of Particle Characteristics in the Production of Fine Powder by Grinding
Particulate Science and Technology, 1997
ABSTRACT The development of improved methods of grinding and separation of fine particles is becoming increasingly important in a wide variety of industries. The requirements on the powder production differ widely, and depend on both the material and the specific application. This paper describes the effects of a variety of parameters on the production of fine powder by dry grinding; these parameters include particle agglomeration, the classification method employed, and air moisture in the mill. It is also demonstrated that particle shape is affected by the type of machine, by the specific breakage mechanism in a grinding device, and by the time spent in the grinding environment.
The purpose of this study is to establish a modeling approach that can be used to predict bulk powder flowability of pharmaceutical materials from their particle size and shape distributions. To build and validate the model, 23 commonly used pharmaceutical excipients and 38 binary blends were fully characterized for their particle size and shape distributions. The particle size and shape of each sample was characterized by multiple descriptors to fully reflect their morphological characteristics. The flow properties of these materials were analyzed using the Schulze Ring Shear Tester at a fixed humidity condition. A partial least squares (PLS) approach was used to build the mathematical model. Several different modeling approaches were attempted and the best method was identified as using a combination of formulation composition and particle size and shape distributions of single-component powder systems. The PLS model was shown to provide excellent predictions of powder flow function coefficient (FFC) of up to approximately 20. The results also revealed that both particle size and shape play an important role in determining the powder flow behavior. ß
2014
The formation of lumps during large scale wetting of spray dried powders is a common problem in the industry. The result is a large energy demand if an efficient mixing is to be achieved at the industrial scale. If more knowledge regarding the phenomena governing lump formation is obtained, the unit operation could be optimized and made more efficient. As a part of increasing the understanding of lump formation, the wetting of the porous media that is a powder bed needs to be understood. This wetting relates to the structure and void space (porosity) of the powder bed, which is why a relation between powder bed porosity and readily obtainable powder particle morphology parameters is sought. In this study a thorough investigation of the morphology of five different spray dried milk powders, with arbitrary particle shapes, was performed using manual image analysis of scanning electron microscope (SEM) images as well as automated methods based on light scattering and projected image analysis. The results of the automated methods, when utilized on the complexly shaped samples, were validated by a comparison to the SEM image analysis. This enabled the development of a relation between powder morphology and powder bed porosity based on data from automated methods. The results indicate that automated methods based on light scattering underestimate the particle sizes of arbitrary shaped particles. Methods based on projected image analysis, however, show a better agreement with SEM image analysis. The developed relation between powder bed porosity and powder particle morphology is based on defining the bed as having either an "Agglomerates in fines", "Bicontinuous" or "Fines in agglomerates" structure. The structure of each powder is determined based on calculation of a "BedRatio" which is a function of the ϕ agglomerate and ϕ fines both shown to be readily obtainable by automated methods. The calculated porosities of the powders investigated in this study show a good agreement with experimental measurements and are considered to correspond well to earlier literature. It is, however, clear from the experiments that care needs to be taken during bulk density measurement of spray dried powders so that no intra particle void space is taken into consideration in the calculations.