材料期刊网

Ultrasonic-assisted brazing of SiC ceramics was performed by filling with an Al--12Si alloy at a low temperature of 620 ℃ in air.The interfacial characteristics and formation mechanism were investigated.The joint shear strength reached 84-94 MPa using the ultrasonic time of 2-16 s.The fracture morphology showed that the fracture path initiated and propagated in the joint alloy.The thin film of amorphous SiO2 that formed on the SiC surface was non-uniformly decomposed and diffused into the liquid Al-12Si alloy under the cavitation erosion effect of ultrasound.Abnormal isolated blocks of Al2SiO5 compounds formed at the interface between Al--12Si and a thicker SiO2 layer formed during the thermal oxidation treatment of the SiC ceramic.The SiO2 layer on the SiC ceramic did not hinder or impair the wetting and bonding process,and a stronger bond could form between Al-12Si and SiO2 or SiC in ultrasonicassisted brazing.