Composite Coatings from Layered Precursors: Material Structure Modeling and Thermal Control

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This research project introduces and analyzes new technologies for deposition of metal-matrix composite (MMC) coatings. The coating methods use novel custom precursor materials, made of the matrix metal in sheets and the reinforcing phase in powder or fiber form, rolled or twisted in a layered sandwich sheet or particulate-cored wire. Aluminum or nickel aluminide matrix is used in combination with alumina and/or silicon carbide reinforcement materials. The precursors are fused on the substrate by a robotically scanned laser-beam or plasma-arc welding source, under infrared thermal monitoring and feedback regulating the heat and mass deposition variables. Thus, the desired coating structure is obtained by real-time, adaptive control of the temperature distribution to reference thermal conditions, obtained experimentally and coded in a material database. The advantages of this technology include implementation simplicity, elimination of chamber enclosures, coating geometry and structure control, better adhesion, high material yield and low cost. Diversified applications in the aerospace, automotive, appliance and metalworking industry are explored in cooperation with Honda R&D and Starmet Corp. The collaborative research between Tufts and Northeastern University, combining complementary resources and expertise, also extends to educational activities, including a new Thermal Manufacturing course and a joint Tufts/Northeastern Thermal Material Processing Seminar.