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3/10wt.% SiC Ceramic Composites Synthesized by Microwave Sintering
Published in Samson Jerold Samuel Chelladurai, Suresh Mayilswamy, Arun Seeralan Balakrishnan, S. Gnanasekaran, Green Materials and Advanced Manufacturing Technology, 2020
Materials with very low effective dielectric values, such as ceramics, were developed by using microwave-assisted heating methods. These methods depend on a susceptor that produces heat by absorbing microwaves and supplies it to the sample. The main purpose of the susceptors is to raise the temperature of a sample high enough that the material starts to absorb microwaves and heat by itself, independent of the susceptor material. In the early stages of this method, the sample would experience a conventional heating, and at the later stage, samples are subjected to microwave heating. Some of the most normally used susceptors are SiC-based Al2O3 composite, ZrO2 fibre boards, Pure-SiC rods and SiC grit layer. One of the downsides to using these susceptors is that there is a limited control over the amount of conventional heat supplied to the sample. To overcome this, a new design for microwave-assisted heating was developed by modifying the microwave cavity to include heating elements with an independent power supply. This arrangement substantially controls the amount of conventional heat needed for raising the temperature of the sample (Wroe & Rowley, 1996).
Analysis of Mechanical Properties and Microstructural Characterization of Microwave Cladding on Stainless Steel
Published in Amit Bansal, Hitesh Vasudev, Advances in Microwave Processing for Engineering Materials, 2023
C. Durga Prasad, Mahantayya Mathapati, Hitesh Vasudev, Lalit Thakur
The MHH is the new and effective method of absorption whereby powders with a low absorption coefficient are melted using microwave energy. To absorb microwave energy by composite powder particles, susceptor materials are usually used. The susceptor materials like silicon carbide, charcoal, and so on can absorb all the microwave radiations impinged on it. Silicon carbide was used as a susceptor material for cladding. The susceptor absorbs microwave radiation and increases the rate of heat transfer. However, still there is a demand to enhance the cladding performance by using a susceptor that increases the rate of heat transfer as shown in Figure 6.1b.
Epitaxial Methods
Published in Ferdinand Scholz, Compound Semiconductors, 2017
The epitaxial growth (see Fig. 4.10) takes place on the substrate, i.e., an adequate wafer (c.f. Chapter 3) acting as a nucleation crystal. It is placed on a susceptor which can be heated from outside. Typically, the susceptor is made of graphite, coated with SiC to have a chemically inert surface. Heating is typically done either by RF induction or by lamp heating, i.e., only the susceptor is directly heated. Therefore, MOVPE is a cold wall reactor method (whereas LPE and in particular HVPE is a hot-wall system). Hence, the thermally induced chemical reactions of the precursor gases take place only near the substrate or on the substrate surface.
Optimization of pressure-less microwave sintering of Ti6Al4V by response surface methodology
Published in Materials and Manufacturing Processes, 2018
Dilpreet Singh, Pulak Mohan Pandey, Dinesh Kalyanasundaram
However, microwave sintering of titanium is challenging due to its paramagnetic properties. Sato et al. investigated microwave sintering of magnetic materials such as Fe2O3 and Fe2O4 as well as non-magnetic materials such as Ti, TiO2, and TiO. The group reported that the magnetic materials are easier to sinter under the influence of pure microwave than non-magnetic materials [17]. To achieve sintering of non-magnetic materials, silicon carbide (SiC) susceptors were used by Roy et al. [18]. The susceptors absorb microwave radiations and emit thermal radiation to sinter the target material.
Evaluation of graphite and TiO2 as susceptors for microwave dewaxing in ceramic shell casting processes of artworks
Published in Journal of Microwave Power and Electromagnetic Energy, 2022
I. Pérez-Conesa, J. Fayos-Fernández, J. A. Aguilar Galea, J. Monzó-Cabrera, R. Pérez-Campos
On the other hand, the susceptors are chemical substances that act as catalysts of the transduction of microwave energy into thermal energy, having a high value of dielectric and/or magnetic losses. In microwave-heating processes for the recovery of synthetic polymers, small additions of metallic powder or graphite have increased microwave absorption and thus increased temperature growing rates (Suriapparao and Vinu 2015). Other studies show how the addition of carbonaceous materials can dramatically increase microwave heating in pyrolysis processes of urban waste (Beneroso et al. 2016).
The use of microwaves in the process of obtaining nanopowders
Published in Journal of Microwave Power and Electromagnetic Energy, 2021
Livia Bandici, Geanina Banu, Anton Ficai, Denisa Ficai
The need to use susceptors also comes from the fact that some materials do not absorb microwaves. The advantage of using susceptors is that these materials interact with the microwave, so that volumetric heating can be achieved even for transparent microwave materials. Microwave heating using susceptors results in a uniform temperature compared to the direct action of microwaves or conventional heating. Research has shown a dramatic reduction in processing time (from hours to minutes) and energy consumption (by up to 99%) when using the susceptor (Bhattacharya and Basak 2016).