Brazing of graphite to 6063 aluminum alloy with Al-Cu-Si-Ni-Mg filler metal and Ag-Cu-Ti paste

In the present work, an Al-Cu-Si-Ni-Mg brazing filler metal was developed for the joining of 6063 aluminum alloy and graphite metallized with Ag-Cu-Ti paste. The joint microstructures were studied by means of SEM and EDS. Results show that joints with a good quality can be produced at a brazing temperature of 550 °C for 10 min. TiC was formed at the graphite/active Ag-Cu-Ti paste interface due to the reaction between Ti and C, and thus, the wettability on the graphite was improved. Compared to the metallization stage, more diffusions of Al, Ag, Ti, and Cu from interlayer to graphite are observed. The bonding area mainly consists of α-Al, Ag rich phase, α + Al2Cu + Si, Al2Cu, and TiC. It is shown that joints with good quality can be produced and the average shear strength of the joints is 21 MPa.