Microstructure design of C/C composites through electrochemical corrosion for brazing to Nb

Abstract

• The interspace between carbon fiber and matrix was fabricated through electrochemical corrosion at the C/C surface without heating. • The zone of carbon fiber reinforced brazing alloy can be reached for joining to alloy or composites. • Residual stress caused by property mismatch can be modified. Joining quality has be increased efficiently. It is suitable for large size or tiny complicated structure. Surface structure of C/C composites has been regulated through electrochemical corrosion at room temperature to modify the residual stress and improve the joining strength when brazed to Nb. The unique crevice corrosion in C/C composites is investigated to reveal the change of corrosion depth and fiber size. The interlacing zone of carbon fiber reinforced brazing alloy replaces the reaction layer in the original joint. Joining area is increased dramatically and the continuous crack will be hindered. The interlacing zone eliminates the stress concentration and relieves the residual stress through reducing the property mismatch. All advantages contribute to the joining quality of C/C Nb. Shear strength of C/C Nb joint with 80 μm depth reached 37.7 MPa, which was 1.2 times higher than that of original joint. Surface structure design of C/C composites not only expands the application in structure component, but also exhibits the promising application in energy field.