16th International Conference
on Microwave and High Frequency Heating

18-21 September 2017, Delft, The Netherlands
13:30   Microwave assisted chemistry and processing (2)
Chair: Dariusz Bogdal
13:30
15 mins
MICROWAVE REACTOR USING SOLID STATE OSCILLATOR AND RESONANT CAVITY, AND ITS APPLICATIONS TO CHEMICAL SYNTHESIS
Hiromichi Odajima, Tadashi Okamoto, Aki Tomita
Abstract: We succeeded in developing microwave (MW) advanced reactor system based on solid state high power oscillator and resonant cavity. Fig. 1 shows high pressure & high temperature MW flow system, composed of 1) control unit, 2) oscillating and reaction unit, 3) pumping system with Fig.4 reactor tube. Fig.3 cavity & reactor design are done by electric field analysis using 3D computer simulation. That system proved to complete time consuming reactions reducing reaction time drastically, which also realizes the potential to produce product at production level by small desk top system. Current applications are organic/inorganic reactions, nanomaterial creations and reactions with fixed bed catalyst. Conditions of reaction is set from PC and all the reaction data is logged up to PC showing up graphs at monitor. The system has automated 1) Gradient mode and 2) Step mode. By integrating such a mode with DoE and MVA, it becomes easy to find optimized reaction condition without doing many tests. By having high Q cavity, it is proven that the system can heat up non polar solvent, such as Toluene, higher than 200C under substantial flow rate. This is leading new reaction scheme in MW chemistry. Recently started, development of PWM and impedance matching system. Fig. 1 MW Flow System Fig. 2 Oscillator Fig. 3 Cavity Fig.4 Reactor References 1) Saori Yokozawa, et al : Development of a Highly Efficient Single-Mode Microwave Applicator with a Resonant Cavity and its Application to Continuous Flow Syntheses, RSC Advances 2) Biagia Musio, Steven V. Ley, et al : Microwave-assisted stereo selective Wolff-Staudinger reactions in flow with a web-based augmented molecular visualization of the computed data, doi.org/10.17863/CAM.654
13:45
15 mins
A NEW MULTI PRINCIPLE ELEMENT ALLOY SYNTHESIZED BY MICROWAVE ASSISTED POWDER METALLURGY TECHNIQUE
Elena Colombini, Roberto Rosa, Marco Gabriele Poletti, Livio Battezzati, Angelo Casagrande, Paolo Veronesi, Cristina Leonelli
Abstract: Multi principal element alloys (MPEAs), consisting of five or more alloying elements at near equiatomic concentrations and forming bcc and/or fcc solid solution phase, were recently developed. According to the literature research, the synthetic route to produce MPEAs should guarantee short alloying time, efficient cooling and capability to operate in controlled atmosphere. Such conditions can be achieved using high frequency electromagnetic fields, like microwave heating. Microwave assisted combustion synthesis of pure metal powders mixtures as reactants has already been used during the last decade by the authors to prepare intermetallics [1], functionally-graded materials [2] , and recently to produce multi-principle alloys [3-5]. Moreover the addition of SiC in these alloys increases the mechanical properties and oxidation resistance at high temperature, as demonstrated in a recent paper by the authors. In this work a new MPEA (Al15Mn20Fe25Co15Ni25) was prepared with and without the addition of SiC, using powder metallurgy route and exploiting microwave as way of generating heat inside the precursors and hence start the reactive sintering. Results show that direct microwave heating at 2450 MHz of the powder precursors leads to the ignition conditions and then self-sustaining of the synthesis occurs. The temperature and duration of the microwave-assisted process results in being much lower than other conventional powder metallurgy routes, but at the cost of a higher residual porosity. Sample characterization confirmed that the powder metallurgy approach is suitable to retain the shape of the load imparted during forming by uniaxial pressing .
14:00
15 mins
CAN A SEMICONDUCTOR GENERATOR BE USED AT MICROWAVE HEATING APPLICATIONS (ORGANIC AND NANOMATERIAL SYNTHESIS, IN-LIQUID PLASMA, COOKING OVEN AND BIOLOGY)?
Satoshi Horikoshi
Abstract: Recently years, the microwave chemistry using a semiconductor generator is researched extensively. The feature of the microwave chemical equipment with a semiconductor generator also substituted in our laboratory from 2003 [1]. Generally, problems of a semiconductor generator are the excessive cost and maximum output power. But these are improved rapidly every year, and it'd become the extinct in the near future. On the other hand, an advantage of a semiconductor generator isn't argued enough. In this presentation, the advantages or the problems for microwave chemistry, the nano-material microwave synthesis, in-liquid microwave plasma, cooking oven and microwave biology fields using a semiconductor generator are reported, and the heating process which can be made only a semiconductor generator will be mentioned. Note that this presentation is a study of microwave science as the user of a semiconductor generator. The contents for the equipment of a semiconductor generator aren't included as the microwave engineering.