Modelling of transport mechanisms and drying shrinkage for multilayer ceramic membrane structure

Harun, Zawati; Ong, Tze Ching; Matsuura, Takeshi; Hubadillah, Siti Khadijah; Othman, Mohd Hafiz Dzarfan; Ismail, Ahmad Fauzi

doi:10.1016/j.cherd.2018.02.039

Cited by 10 publications

(6 citation statements)

References 33 publications

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“…There exist at least two strategies to model drying behavior. On the one hand, several approaches are suggested to describe and to model the complex behavior taking place at the vapor–liquid interface [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], and they apply RVEs, as shown in Figure 2 . The advantage of the RVE approach is that information on particle orientation and particle morphology can be directly imposed.…”

Section: Introductionmentioning

confidence: 99%

“…A common solution to overcome the numerical limitations, on the other hand, is thereby to not resolve the individual particles and to rather use a continuum framework in terms of average field quantities to consider the moisture and heat transport of each phase, as well as the temperature gradients. This approach, predominantly pioneered by Luikov [ 35 ], Whitaker [ 36 ], and coworkers, allows modeling the system’s full scale [ 25 , 26 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

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Reorientation of Suspended Ceramic Particles in Robocasted Green Filaments during Drying

et al. 2022

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This work considers the fabrication of ceramic parts with the help of an additive manufacturing process, robocasting, in which a paste with suspended particles is robotically extruded. Within the final part, the material properties depend on the orientation of the particles. A prediction of the particle orientation is challenging as the part usually undergoes multiple processing steps with varying contributions to the orientation. As the main contribution to the final particle orientation arises from the extrusion process, many corresponding prediction models have been suggested. Robocasting involves, however, further processing steps that are less studied as they have a smaller influence on the orientation. One of the processing steps is drying by natural convection, which follows directly after the extrusion process. A quantification of the reorientation that occurs during drying is mostly unknown and usually neglected in the models. Therefore, we studied the amount of reorientation of suspended particles in robocasted green filaments during drying in detail. For our study, we applied the discrete element method, as it meets various requirements: The exact particle geometry can be resolved precisely; particle–particle interactions can be described; the paste composition is reproduced exactly; the initial particle orientation can be set in accordance with the prediction from the analytical models for the extrusion part; macroscopic force laws exist to represent capillary forces due to the remaining fluid phase that remains during drying. From our study, we concluded that the magnitude of particle reorientation during drying is small compared to the orientation occurring during the extrusion process itself. Consequently, reorientation during drying might further be neglected within analytical orientation prediction models.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reorientation of Suspended Ceramic Particles in Robocasted Green Filaments during Drying

et al. 2022

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“…This made it difficult to fabricate “ultimate‐dimension” laser ceramics with high optical quality by gelcasting. In addition, as known, the ineffective control of drying process led to the cracks and deformation of green body, and it also hindered the preparation of laser ceramics with required properties …”

Section: Introductionmentioning

confidence: 99%

“…In addition, as known, the ineffective control of drying process led to the cracks and deformation of green body, and it also hindered the preparation of laser ceramics with required properties. 32 Therefore, in this work, considering the high requirements for laser ceramics, only artificial, fine, and controllable gelling systems could be used. The classical acrylamide (AM) and novel Isobam (PIBM) gel systems were chosen to systematically compare and investigate the rheological behaviors of slurries and the mechanical strengths of green bodies.…”

Section: Introductionmentioning

confidence: 99%

Viscoelastic behaviors and drying kinetics of different aqueous gelcasting systems for large Nd: YAG laser ceramics rods

Yao

Gao

et al. 2020

J Am Ceram Soc

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Large and nondeforming Nd: YAG ceramic prepared by wet forming is of great importance as gain medium to obtain high‐power solid‐state lasers. However, it is difficult to achieve high‐quality laser ceramics due to insufficiency of the in‐depth understanding of transformation mechanism of gels viscoelasticity and effective control means during drying process. In this work, the rheological behaviors, viscoelastic characteristics, and mechanical strengths in classical acrylamide (AM) and novel Isobam (PIBM) gelcastings were systematically compared to explore the suitable route for the large‐sized 2% Nd: YAG transparent ceramics with high aspect ratio (>10). AM system exhibited a higher complex viscosity (1.82 × 105 Pa s), a shorter gel time (92.9 seconds), and a higher flexural strength (about 24.46 MPa) than PIBM system, and especially its ability to quickly gel was beneficial to the homogeneity of green body. In addition, the order of drying rates of wet gels in four drying media was observed as follows: 55℃ hot air> ethanol> solid desiccant> PEG‐11000 and the moisture diffusion coefficients were calculated and simulated to offer the deep consideration of drying kinetics. The “ethanol + 55℃ hot air” was regarded as an effective composite drying method to eliminate defect and to achieve φ8 mm × 160 mm Nd: YAG ceramic with the in‐line transmittance of 83% @1064 nm. Therefore, not only the cognition of gel process, but also the defects control strategy is proposed. More importantly, this work greatly promotes the application of wet forming and laser ceramics in high‐power lasers.

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“…Drying process has different zones of drying rates [1] that make difficult the control of the time of drying. Due to the change of porosity of the solids [2], and the many variables involved in transport mechanisms [3], drying becomes one of the most complex operations in a manufacturing process [3]. This phenomenon involves heat, mass and momentum transfer [4] and the percentage contribution of each of then depends on the type of drying being applied, conduction, convection or radiation drying [5].…”

Section: Introductionmentioning

confidence: 99%

An overview of the literature on drying processes: contributions and trends

Forero¹,

Ochoa²,

Quiñones³

2018

ces

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Drying is an important industrial process that is highly used in the handling of solids, and its study has increased during the last years due to the upsurge of new technologies. It is necessary to determine the direction of science in the area of drying process to give a valuable research contribution. It was performed a research evolution of drying processes for the period of 2007-2017, using HistCiteTM software. This study evaluated a total of 992 publications related to drying processes which were used to analyze the patterns of publications outputs, main journal, institutions, author, and keywords.

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Modelling of transport mechanisms and drying shrinkage for multilayer ceramic membrane structure

Cited by 10 publications

References 33 publications

Reorientation of Suspended Ceramic Particles in Robocasted Green Filaments during Drying

Reorientation of Suspended Ceramic Particles in Robocasted Green Filaments during Drying

Viscoelastic behaviors and drying kinetics of different aqueous gelcasting systems for large Nd: YAG laser ceramics rods

An overview of the literature on drying processes: contributions and trends

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