Novel Fabrication of Ultra-thin Copper/SS304L Composite Microchannels

Microchannels on metallic substrates are essential parts of microreactors, micro heat exchangers, micro heat sinks, and fuel cell bipolar plates. Because of superior properties, such as good corrosion resistance, excellent thermal conductivity, high strength, excellent ductility and structural stability, composite metal foils are gaining popularity as substrates for microchannels. With the increasing demands of low cost, high efficiency and accuracy, novel micro forming technologies must be capable of creating intricate and precise micro features of microchannels at a low cost. An ultra-thin metal foil rolling for the fabrication of micro composite channels is proposed in this study, which can improve product function and reduce operational costs. Copper/ stainless steel 304L (SS304L) composite foils with a thickness of 0.41 mm after annealing treatment at 800 ℃ and holding for 0.5 h, 1.0 h and 2.0 h are used to fabricate microchannels under the rolling reduction of 60.9%. The hardness of composite foils has been characterised before and after different annealing processes, in which the hardness decreases due to the synergistic effects of decreased dislocation density, grain coarsening and phase transformation. Further, the formability of composite foils after annealing is discussed. In addition, the processing characteristics, material deformation behaviours and mechanisms during micro rolling are also investigated.