Carbon nanomaterials exhibit outstanding electrical and mechanical properties, but these superior properties are often compromised as nanomaterials are assembled into bulk structures. This issue of scaling limits the use of carbon nanostructures and can be attributed to poor physical contacts between nanostructures. To address this challenge, we propose a novel technique to build a 3D interconnected carbon matrix by forming covalent bonds between carbon nanostructures. High temperature Joule heating was applied to bring the carbon nanofiber (CNF) film to temperatures greater than 2500 K at a heating rate of 200 K/min to fuse together adjacent carbon nanofibers with graphitic carbon bonds, forming a 3D continuous carbon network. The bulk electrical conductivity of the carbon matrix increased four orders of magnitude to 380 S/cm with a sheet resistance of 1.75 Ω/sq. The high temperature Joule heating not only enables fast graphitization of carbon materials at high temperature, but also provides a new strategy to build covalently bonded graphitic carbon networks from amorphous carbon source. Because of the high electrical conductivity, good mechanical structures, and anticorrosion properties, the 3D interconnected carbon membrane shows promising applications in energy storage and electrocatalysis fields.

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.

In this paper, the ultrafast joining of Ti3SiC2 is successfully achieved using FeCoCrNiCu alloy in air within 15 s via thermal shock. Carbon felts create an ultra-high temperature by the Joule heating generated via applying a current of 30 A and realize the rapid heating of the sample through radiation and conduction. During the joining process, tight bonding between Ti3SiC2 and alloy is created through reaction in a short time. The brazing seam consists of the matrix of the FeSi2Ti, micron-sized TiC, and precipitated Cu9Al4 compounds. The joint features an excellent shear strength of 120.5 MPa. This approach greatly improves the efficiency of the ceramic joining and has shown promising applications in different aspects.