Interfacial behaviours of Sn-Ti/graphite system bonded via ultrasonic-vibration–assisted metallization

Graphite components serve as irreplaceable structural and functional parts in multiple engineering applications. However, the necessary processing requirements, including high temperatures (∼850 °C), prolonged durations (several hours), and high-vacuum conditions, pose significant challenges for the efficient manufacturing of graphite components. Aiming to achieve the rapid bonding of graphite (pyrolytic graphite (PG) and porous graphite (G)), a novel two-step method that combines ultrasonic-vibration–assisted metallization with dip soldering is proposed in this study. The surfaces of PG and G are metallized by an Sn Ti (ST) alloy under ultrasonic vibrations at 300 °C within 10 s in air. Under an oxygen-containing conditions, the active Ti from the ST melt preferentially reacts with O to form an amorphous nanocrystalline TiO₂ transition layer, which plays a decisive role in establishing metallurgical bonding and transmitting loads and heat flux between the graphite and ST alloy. The soldered joints exhibit exceptional property retention, with PG/PG and G/G joints maintaining equal and 98 % (21.8 MPa) of the shear strength, and 93 % (389 W/m·K) and 92 % (105 W/m·K) of the thermal conductivity, respectively, of the base materials. The proposed two-step method offers an efficient approach for the rapid manufacture of graphite components, addressing key challenges in graphite-bonding technology.