In this study, the low-temperature ultrasound-activated joining of ZrO2 ceramics using Sn-4Al-0.7Cu solder was achieved at 350 degrees C. It was found that a nanoscale amorphous Al2O3 layer formed at the solder-ceramic interface during the ultrasonic soldering process. The occurrence of the interfacial oxidation of aluminum could be attributed to the sonochemical effects of acoustic cavitation and turbulent streaming induced by the propagation of ultrasonic waves in the liquid solder. The formed butt joints exhibited an average tensile strength of 47.3 MPa.