Achieving interfacial thermal expansion matching between C/C composites and metal through ultrafast high-temperature shock (UHS)

A novel surface modification and joining method utilizing ultrafast high-temperature shock (UHS) has been investigated to achieve interfacial bonding between C/C composites and TC4 alloy by using Joule heating effect. The process involves surface selective oxidation of the C/C composites and subsequent ultrafast joining, both achieved within short time periods of 30 s and 20 s, respectively. Surface selective oxidation created annular gaps on the C/C composite surface which increased the contact area between the filler alloy and the base material, while suppressing the propagation of cracks. Joule heating of the C/C composites induced a non-equilibrium temperature field, which melted the filler alloy and facilitated interfacial joining through heat conduction. Notably, the temperature of TC4 metal (CTE ∼9.5 × 10−6 K−1) was significantly lower than that of the C/C composites (CTE ∼1.5 × 10−6 K−1), thus suppressing the expansion of TC4 near the heterointerface due to the self-limiting effect exerted by the cold end. As a result, the thermal expansion matching was improved and the residual stress in C/C-TC4 heterostructure was relieved. The shear strength of optimal joints reached 31.7 MPa, representing a 2.4 times increase compared to the conventional joining method.