Microwave sintering of complex shapes: From multiphysics simulation to improvements of process scalability

Manière, Charles; Chan, Shirley; Olevsky, Eugene A.

doi:10.1111/jace.15892

Cited by 20 publications

(11 citation statements)

References 25 publications

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“…Understanding the previously described microwave system requires numerically solving a very complex multiphysics problem, where the microwave physics, resonance phenomena, and thermal dependence of material properties are key parameters, as described by Maniere et al [11,12]. These parameters are coupled to each other, as the heating of the specimen and the tooling modifies the microwave properties, which in turn influence the cavity microwave distribution and the resonance performances.…”

Section: Methodsmentioning

confidence: 99%

Microwave Sintering of Alumina at 915 MHz: Modeling, Process Control, and Microstructure Distribution

Manière

Bilot

et al. 2019

Materials

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Microwave energy can be advantageously used for materials processing as it provides high heating rates and homogeneous temperature field distribution. These features are partly due to the large microwave penetration depth into dielectric materials which is, at room temperature, a few centimeters in most dielectric materials. However, up to now, this technology is not widely spread for high-temperature material processing applications (>1200 °C), because its reproducibly and ability to sinter large size samples (>30 cm3) still needs to be improved. In this context, this paper describes both an empirically designed 915 MHz single-mode cavity made from SiC susceptors and refractory thermal insulation, and the 3D modeling of the process in order to improve our understanding of it. Different susceptors geometries and coupling slit position were numerically tested in order to better understand how these parameters impact the field homogeneity and the process stability. It was found that positioning the largest surface of the susceptors parallel to the electrical field allows a very uniform and hybrid heating of the material, while avoiding plasma or thermal instabilities. This was correlated to the 3D modeling results. Finally, thanks to a fully-automatized system this apparatus was used to sinter large size (~30 cm3) low-loss dielectric alumina samples. The sintered materials were subsequently characterized in terms of density, grain size distribution, and homogeneity. The reproducibility was also discussed, demonstrating the process efficiency and reliability.

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Section: Methodsmentioning

confidence: 99%

Microwave Sintering of Alumina at 915 MHz: Modeling, Process Control, and Microstructure Distribution

Manière

Bilot

et al. 2019

Materials

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“…The study of microwave heating of ceramics has developed considerably over the last decade, both experimentally and theoretically 1–8 . Despite these advances, the process remains experimentally difficult to control, while the models, generally implemented in simulation codes, require the characterization of physical parameters that can be difficult to access: they depend on the microstructure of the material, which evolves throughout the sintering process.…”

Section: Introductionmentioning

confidence: 99%

Direct microwave heating of alumina for different densities: experimental and numerical thermal analysis

et al. 2023

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Microwave heating of pure alumina is studied experimentally and numerically, in a 2.45 GHz single‐mode cavity, for different density levels. Even considering a constant incident power, the results show a complex evolution of the alumina temperature: first a two‐step increase, then a maximum, and finally a cooling stage. In addition, a density dependence of the heating efficiency is observed: a more efficient heating occurs for lower densities. Using the effective medium approximation (EMA) to derive the physical data as functions of density, the numerical simulations are in contradiction with the experiments, proving that the EMA approach is not able to correctly predict the imaginary part of the permittivity. Furthermore, the simulations do not accurately describe the first moments of the heating, nor the long‐term evolution of the temperature (cooling). We then explain the origin of this discrepancy: the need to adjust the movable stub on the one hand, and to account for heat exchange between the cavity and its surroundings on the other.

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“…Further, these problems can become predominant for materials with very low viscosity at sintering temperatures, such as liquid-phase sintering [16]. Therefore, finite element simulation poses as a precisely efficient tool to predict the sintering distortion of weak structures [17,18].…”

Section: Introductionmentioning

confidence: 99%

3D printing of porcelain and finite element simulation of sintering affected by final stage pore gas pressure

Manière

Harnois

2021

Materials Today Communications

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Ceramic 3D printing involves various sintering phenomena such as shape distortions, crack formations, shrinkage anisotropy, and residual porosity that demands the development of a simulation tool. Moreover, liquid-phase sintering of materials such as porcelain exhibits an additional and challenging phenomenon at the end of the sintering process that reflects closed porosity growth and coalescence owing to the pressure created by the pore-trapped gases, which further implies swelling (or bloating) of the entire specimen accompanied by distortions. In this study, the swelling issue of 3D-printed porcelain samples was investigated through a sintering dilatometry parametric design to determine the optimal heating rate and holding temperature. A sintering modeling theory was employed to characterize the final stage pore gas pressure via an inverted sintering model formulation. Finally, a finite element sintering simulation was applied based on the analytical model data to predict the sintering shrinkage of a complex geometry.

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Microwave sintering of complex shapes: From multiphysics simulation to improvements of process scalability

Cited by 20 publications

References 25 publications

Microwave Sintering of Alumina at 915 MHz: Modeling, Process Control, and Microstructure Distribution

Microwave Sintering of Alumina at 915 MHz: Modeling, Process Control, and Microstructure Distribution

Direct microwave heating of alumina for different densities: experimental and numerical thermal analysis

3D printing of porcelain and finite element simulation of sintering affected by final stage pore gas pressure

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