Effect of graphene nanosheets on melting point and wettability of AgCuTi filler

Graphene nanosheets (GNSs) with different mass fractions were added to the AgCuTi filler by ball milling. The effects of trace amounts of graphene nanosheets on the morphology, melting point and wettability of AgCuTi fillers were investigated by differential scanning calorimetry (DSC), SEM and XRD. The results showed that the ball milling method had no effect on the phase of the GNSs-AgCuTi composite filler, and the graphene was uniformly dispersed around the AgCuTi particles. The melting point of the composite filler decreased as the graphene content increased. When the graphene content was 0.5%, the melting point was reduced by 3.2 °C. A trace amount of graphene improved the wettability of the filler on the sapphire surface. The wetting angle of the 0.3% GNSs-AgCuTi composite brazing filler was reduced by 4.4°, and the spreading area was increased by 10 mm², while the excessive graphene also deteriorated the wettability of the composite brazing filler. Graphene reacted with the element Ti to form TiC. The interfacial reaction product of the composite filler and sapphire was Ti₃Cu₃O phase.