Then they were bonded under different VDB conditions in a ZTY-50e23 vacuum hot pressing furnace
(104-103 Pa). The load used in this investigation was 30 MPa for
all joints. The isothermal bonding temperatures were designed to
be 850 C, 900 C and 950 C, respectively. Fig. 1 showed the
temperature schedule, the bonding durationwas fixed to 60 min at
each welding temperature