Papers by Keyword: Selective Heating

Abstract: Microwave heating was discovered more than 60 years ago. And nowadays, it became popular for the use as domestic ovens. Microwave has also been utilized for the industrial processes, such as drying and roasting. On the other hand, there have been many applications of microwave, being investigated for materials' processing and environmental technologies. They are attempted to take advantage of some specific characteristics in microwave heating, which differs from that of the conventional one. Rapid heating, internal heating, selective heating are the features to be taken into consideration. Moreover, so-called "non-thermal effect" is the additional feature in which researchers are particularly interested. In this article, it is intended to describe fundamental aspects in microwave heating and introduce some selected topics of research projects performed in our research group. They include researches on fabrication of some functional materials and on handling industrial wastes etc. In this article, it is also intended to interpret the phenomena observed in these applications from the fundamental view points of electromagnetic wave interaction with materials.

Abstract: A new strategy termed selective heating and press hardening, for hot stamping of boron steel parts with tailored properties is proposed in this paper. Feasibility studies were carried out through a specially designed experimental programme. The main aim was to validate the strategy and demonstrate its potential for structural optimisation. In the work, a lab-scale demonstrator part was designed, and relevant manufacturing and property-assessment processes were defined. A heating technique and selective-heating rigs were designed to enable certain microstructural distributions in blanks to be obtained. A hot stamping tool set was designed for forming and quenching the parts. Demonstrator parts of full martensite phase, full initial phase, and differentially graded microstructures have been formed with high dimensional quality. Hardness testing and three point bending tests were conducted to assess the microstructure distribution and load bearing performance of the as-formed parts, respectively. The feasibility of the concept has been validated by the testing results.

Abstract: Microwaves represent an alternative way of power input into distillation process. Through dielectric heating, reaction mixtures are homogenously heated without contact to a wall. Reaction times are significantly reduced compared to conventionally (thermally) heated systems while maintaining selectivity. In this paper, microwave field select heating on two-phase system has been investigated numerically and experimentally. Temperature increasing, heat transfer and evaporation during heating process were analyzed. The possibility of microwave used for distillation was examined and proposed.

Abstract: Eco (Ecology & Economy)-fabrication is important in the future manufacturing. There are some elements to achieve this synthesis. When synthesizing, neither waste nor the air pollutant are not generated, and it is safe material is preferable with cheap fabrication device. We developed a new metal nanoparticle related materials synthesis method that achieved in these viewpoints. This new synthesis method is with microwave as non-equilibrium reactor and the metal oxide and alcohol based solvent are used for the raw material. Moreover, the oxide and alcohol generally are cheap without toxicity. We synthesized metal nanoparticle related materials by microwave in liquid-solid (alcohol - metal oxide) slurry and controlled morphology of products. Microwave irradiation in liquid-solid process can be expected as chemical non-equilibrium and nonlinear reactors for metal nanoparticle related materials synthesis. The alcohol based solvent and the metal oxide powder are put in the beaker and only irradiated by ultrasound or microwave. The metal oxide simply was reduced into metal and morphology of metal nanoparticles was changed by various conditions. Various metal nanoparticle related materials were fabricated by microwave irradiation as non-equilibrium reaction field.

Abstract: Characteristics of heating processing based on millimeter-wave or pulsed high current are discussed from the standpoint of the interaction between electromagnetic energy and solid materials. Capabilities of the electromagnetic processing are indicated by exemplifying several successful results such as millimeter-wave sintering of AlN, millimeter-wave post-annealing of aerosol-deposited PZT films and synthesis of single-phase nano-structured anatase by SPS (or pulsed high current heating). It is shown in these examples that well-characterized properties such as high thermal conductivity and preferential orientation are created by the inherent effect due to the electromagnetic field, which is called microwave or SPS effect in millimeter-wave or SPS processing.