Papers by Keyword: Microwave Hybrid Heating

Abstract: This paper presents the current major research developments and growths in the area of microwave hybrid heating-based joining of similar and dissimilar materials. The study discusses on the different types of specimen materials, susceptor materials, fillers and microwave power level used by researchers for joining process. Comparative studies of joints using different parametric conditions are also mentioned. Physical characterization of joint has been investigated with optical microscope, scanning electron microscope, energy dispersive spectroscopy, electron probe micro analysis, X-ray diffraction and mechanically with hardness test, tensile test, 3-point bend test, impact test. Various methods for design of experiment and optimization are also used to obtain better results. Current study will facilitate the proper choice of input parameters for easy and good joints formation through the microwave hybrid heating method.

Abstract: This article discusses the fundamentals and benefits of microwave hybrid heating. High dielectric loss materials can be processed using direct microwave heating, whereas low dielectric loss materials can only be process using microwave through microwave hybrid heating. It was shown that it is possible to virtually process any type of materials via microwave hybrid heating. Microwave hybrid heating offers faster heating rate than direct microwave heating. It reduces the problem of thermal runaway experience in direct microwave heating of high dielectric loss materials. The two basic types of microwave hybrid heating techniques were discussed with emphasis on the use of susceptor. Microwave hybrid heating using susceptor offers the advantage of using single energy source.

Abstract: The low thermal conductivity of Lanthanum hexaaluminate, abbreviated as LHA, combined with high structural reliability of alumina matrix ceramics attracted our attention to develop a new functionally graded layered LHA-Al2O3-composite, with a LHA and a porosity gradient along the thickness of a bulk oxide ceramic. LHA is formed by in–situ reaction during sintering of the alumina/LHA composite. The high sintering temperature required for completion of LHA formation in LHA-rich layers causes grain growth and a degradation of mechanical strength in alumina-rich layers. Therefore, microwave hybrid heating was investigated as a method to enhance the reaction rate without excessive grain growth. Comparison of conventionally and microwave assisted sintered homogenous composite ceramics with 20–80 volume percent LHA showed that utilization of microwave heating could enhance the solid–state reaction and densification in samples containing more than 20 volume percent LHA. Enhanced microwave absorption in LHA rich layers assisted the sintering of a functionally graded composite at lower temperatures, enabling LHA formation without any abnormal grain growth in alumina rich layers.