Joining of Metals Through Microwave Hybrid Heating

The source of heat is one of the crucial parameters that has varied significantly over the years for the fabrication of metal joints. A requirement for a new source of heat is justified by the fact that a single source of heat is not suitable for joining all the metals. Knowing the disadvantages of conventional welding processes, a novel heat source was developed for fabricating metal joints through microwave radiations. Microwaves are electromagnetic waves with a wavelength ranging between 1 to 1 mm and a frequency ranging between 0.3 to 300 GHz, respectively. Microwave heating of the materials depends upon the value of skin depth. Since metals have a low value of skin depth, metals are considered a reflector of microwaves at ambient temperature. However, at elevated temperatures, the metal starts absorbing microwaves. Thus, susceptor material is used to provide an initial rise in the temperature of metals. This heating of metals through susceptor material is termed microwave hybrid heating (MHH). Defining a new source of heat that provides various advantages like uniform heating, volumetric heating, eco-friendly, and energy efficiency has grabbed the attention of researchers. The MHH technique has been extensively used for joining different ceramics, composites, and metals. However, the metallurgical aspect of the microwave-processed joint is still not explored in detail. The present study describes the metallurgical aspects of the joints and base metals reported earlier and the scope of future study for particular metal joining.