Nearly 15 years ago, according to an editorial in IH, microwave technology for industrial heating processes was in its infancy, but that the inherent advantages of this alternative heating method-rapid processing cycles, novel internal heating patterns, precise and automated heating control, capability of developing new, unique microstructures and provision of high product quality and reliability-likely would increase its application in industry. Recently at a conference related to the heat-treating industry, a presenter mentioned that several alternative heating methods for industrial processes were getting greater attention due to ever increasing energy costs including microwave, infrared, fluidized bed and some others.
While microwave heating has not seen widespread commercialization at this point, a wide range of applications discussed in the article in this issue entitled "Advancements in Microwave Heating Technology," have demonstrated the feasibility of the technology, and it may be on the threshold of commercial use as microwave-equipment manufacturers and potential users come together and the economics of the process become more favorable.
Microwave processing of materials possibly has emerged as having the greatest near-term potential for meeting goals such as improved overall part performance including product durability, improved process-cycle time, energy savings and cost effectiveness and being environmentally friendly. Materials processing includes metal melting, heat treating metal parts, brazing, producing metal parts for automobiles, sintering tungsten-carbide cutting tools, drying wood, waste remediation and precious metal recovery, and more. Other innovations on the horizon include synthesis of simple and multicomponent ceramic phases, quickly sintering virtually any ceramic phase, sintering metals from gold to tungsten to superalloys to hardmetals with improved properties. According to Prof. Dinesh Agrawal of Penn State University, major scientific developments include the ability to conduct materials reaction between two or more phases where the phases are held at different temperatures, and the ability to transform a vast array of ceramic, semiconductor and metallic materials into a noncrystalline state without melting in a matter of minutes in extremely simple and inexpensive apparatus.
Before the potential of microwave processing can be tapped fully, industry must have a good understanding of how microwaves heat materials and what the limitations are. With the help of universities, national laboratories and specialists in the field, several companies highlighted in the article are leading the way.
While we're not quite at the level where Dr. Percy Spencer at Raytheon Corp. in the 1940s developed a way to contain microwaves generated from magnetrons, which led to the use of microwaves in cooking and a microwave oven in practically every household, we may be closer than you think to commercialization of microwave heating for quite a few industrial processes. IH