Electrochemical machining of array flow channels using cathode tool with comb-shaped insulator

The machining quality of array flow channels directly affects the performance of solid oxide fuel cells as they are the key structures on the metallic interconnects of these cells. Electrochemical machining (ECM) is an efficient and low-cost technology for fabricating array flow channels. In the conventional ECM method, the cathode tool is usually designed to have cavity structures above the ribs to avoid collisions between the tool and workpiece. These cavities provide a passage for stray current to corrode machining fillets, causing electrolytes to flow away, and resulting in an uneven distribution of electrolyte flow velocity. To address these challenges, the authors propose a novel type of ECM cathode tool with a comb-shaped insulator. As the cathode tool is fed, the comb-shaped insulator is pressed tightly to the ribs by the spring compression device. This allows the insulator to shield the stray current and block the electrolyte shunt gap, thus enhancing the profile accuracy of the ribs and stability of the electrolyte flow field significantly. Furthermore, to verify the beneficial effect of comb-shaped insulator tools, the authors carry out simulations of the forming processes and flow field in the ECM of array flow channels. Finally, the experiments were carried out to compare 13 flow channels with lengths of 60 mm using the conventional and proposed methods. The experimental results show that the machined specimen exhibited better flatness at the top surface of the ribs and an enhanced surface quality of the channels’ bottom when the cathode tool with a comb-shaped insulator was used.