Finite element simulation of hybrid microwave sintering based on power approach
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ORIGINAL ARTICLE
Finite element simulation of hybrid microwave sintering based on power approach Akeem Damilola Akinwekomi 1,2
&
Ka-Wai Yeung 1 & Chak-Yin Tang 1 & Wing-Cheung Law 1 & Gary Chi-Pong Tsui 1
Received: 4 May 2020 / Accepted: 17 August 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract Microwave (MW) sintering offers higher heating rate, rapid processing, reduced energy consumption, and reduced sintering temperature. However, the technique is not fully understood, difficult to control, and often relies on experience and trial-and-error approach. Consequently, hot spots, uneven heating, thermal runaway, and shape distortion develop in sintered compacts. Therefore, developing a model that can simulate the sintering process, enhance predictability, and determine the critical sintering conditions is essential. Multiphysics finite element (FE) modelling of hybrid MW sintering of a magnesium alloy AZ61 compact was undertaken in this study. The FE model coupled the electromagnetic, heat conduction, and densification equations. The model utilised parameters related to the furnace, compact, and susceptor to predict the spatial distribution of electric field, thermal response, and densification in the compact. A power-based sintering criterion was developed to predict the sintering of the compact and estimate its critical sintering energy. Modelling results showed that heating time, compact size, and thickness of the susceptor are critical to the sintering process. It was also shown that the susceptor not only mediated the sintering of the compact but also homogenised its temperature and densification. Thus, MW sintering of the compact was predicted to occur at 500 °C for 8 to 10 min with a predicted relative density of about 0.98. Experimental MW sintering data showed good concurrence with the developed model. These results are useful for controlling the MW sintering process, eliminating trial-and-error, and determining the critical sintering conditions. Keywords Finite element model . Microwave sintering . Hybrid sintering . Densification . Sintering criterion . AZ61
1 Introduction Microwave (MW) processing has been successfully exploited for synthesizing nano-particles [1, 2], fabricating polymers and their composites [3, 4], and sintering of a variety of different ceramic matrices [5–7]. Before the seminal work of Roy et al. [8], MW processing of metallic materials is thought to be impossible. It is believed that metals reflect microwaves and the electron clouds that form on their edges due to their low MW penetration depths can result into sparking and formation of plasma [9, 10]. Subsequent studies have, however, shown
* Akeem Damilola Akinwekomi [email protected]; [email protected] 1
Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
2
Present Address: Department of Metallurgical and Materials Engineering, Federal University of Technology, PMB 704, Akure, Ondo State, Nigeria
that these ass
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