Pre-oxidation of carbon/carbon composites to improve the bonding strength of Ti-Ni-Si joints

To improve the bonding properties of the interface between carbon/carbon (C/C) composites and a Ti-Ni-Si interlayer, an interlocking interface structure was obtained by a two-step technique involving pre-oxidation and hot-pressing. The results show that a porous layer could be obtained on the surface of C/C composites by pre-oxidation treatment at 1173 K in air and that an interlocking C/C-Ti-Ni-Si interface was formed after hot-pressing. With increasing pre-oxidation time, the average shear strength of the Ti-Ni-Si joint initially increased and then decreased. After a pre-oxidation time for 3 min, the shear strength of the joint reached a maximum of 29.81±1.76 MPa, which is 20.1% higher than the joint strength obtained without pre-oxidation. The improvement in the shear strength is primarily attributed to the 'pinning effect' generated by the interlocking interface, which could play a positive role in extending the crack propagation path by inducing crack deflection.