KSEF R&D Excellence: Innovative Approach to Materials Joining in a Microwave Field

Traditional JOIning technologies involve metallurgical bonds formed by adding distinct filler/clad materials (as in the case of state-of-the-art brazing and soldering for mass production manufacturing). If multiple joints must be formed simultaneously, these technologies are characterized with a spatially uniformly distributed, i.e., not-necessarily localized thermal energy delivery. Regardless of whether such materials processing is to be accomplished in a tightly controlled atmosphere, vacuum or atmospheric conditions, the related thermal interactions involve gradual heating on the macro scale. These processes are notoriously energy-non efficient and often environmentally demanding. In addition, significant thermal non uniformities may often compromise the joint integrity. Dramatic improvement of the efficiency of such processes would be possible only if a localized but spatially distributed energy release at multiple joint locations can be secured simultaneously, not sequentially. Due to a complex architecture of mating surfaces and the nature of thermal energy release (by radiation and/or convection) this task is impossible to accomplish using traditional technologies. In this proposal, it is hypothesized that such an objective can be accomplished by using an electromagnetic tield if a selective thermal energy interaction between mating surfaces and an active fixture tliat participates in energy release can be facilitated and controlled. This energy release will be triggered and maintained through interaction of a microwave field and a susceptor (say SiC) in the matrix of the fixture (e.g., alumina). The fundamental problem is how to control the localized energy release simultaneously at different physical scales (from nano to macro length scales). This problem will be solved through spatially distributed dielectric susceptor imbedded in an insulator matrix. The distribution of the susceptor follows the topology of the joint or a pre-determined pattern of the required energy release. Such approach has not been attempted in existing applications of microwave heating. The project is devoted to an investigation of the plausibility of this novel technology for bonding highly conducting metals (such as metals, e.g., aluminum), and other materials. Experimental verification of the approach and numerical modeling aimed at the characterization of materials' processing (e.i. joint formation) will be offered.