The study on joining carbon/carbon composites using Ti-Ni-Si compound

2D carbon/carbon (C/C) composites have been successfully joined by partial transient liquid phase (PTLP) bonding using Ti-Ni-Si compound as interlayer. The shear strengths of C/C joints were found to be affected observably by joining temperature, joining pressure and holding time. The optimum process parameters were determined at 1150°C, 30MPa, 45min, and the maximum joint shear strength was obtained under this optimum process condition with an average value of 23.58MPa. Microstructures and compositions of joints were analyzed by scanning electronic microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD). Results showed that element interdiffusions and chemical reactions took place in the joining zone and various compounds including Ni₄Si₇Ti₄, TiSi₂, SiC and TiC were produced, by which compact interlayer and strong interface were formed in C/C joints. The shear morphology indicated there were three fracture modes in C/C joints and the fracture was apt to occur through interlayer, interface and C/C matrix in strong joints. Thermal shock resistance experimental results revealed that joint shear strength has a rapid drop after 5 thermal cycles and then reduces gradually with the increase of thermal cycles between room temperature and 1000°C.