Molybdenum-fiber strengthened brazing of carbon/carbon composite and nickel-based superalloy

Abstract

The robust and reliable joining of carbon/carbon (C/C) composites and metals has important application value in the aerospace field. However, the low interface bonding strength when joining the two dissimilar materials remains a persistent problem and leads to low joint strength. In this work, a novel interface strengthened brazing process has been developed for joining a C/C composite and a nickel-based superalloy (GH3044). Before joining, high-strength molybdenum (Mo) fibers are planted on the surface of the C/C composite, then the fiber-treated C/C composite is brazed to the GH3044 superalloy using a BNi-2 filler. The results show that a sound joint with robust Mo fibers crossing the interface between the C/C substrate and the brazing layer is obtained. Owing to the pinning effect of the Mo fibers, the joining interface area is increased and cracking is effectively prevented. As a result, the bonded joint exhibits excellent mechanical properties. The maximum shear strength of the joint was measured to be 60 MPa, which is 2.14-times that of the joint without fiber-planting. The maximum three-point bending strength of the joint was measured at 31 MPa, which is 2.58-times that of the joint without fiber-planting.