アモルアァスCu-Ti合金ろうによる窒化ケイ素の接合

抄録

Si₃N₄/Si₃N₄ joint was made using Cu₆₆Ti₃₄, Cu₅₀Ti₅₀ and Cu₄₃Ti₅₇ amorphous filler metals, where pressureless sintered Si₃N₄ was used. The joining strength of Si₃N₄ joint was measured by fracture shear testing, and the joining mechanism was investigated by microstructure observation with SEM, and elements analyses at the joint interface with EDX and EPMA. The results obtained are summarized as follows.
(1) The molten Cu-Ti alloys containing 20 at% Ti or more exhibit the equilibrium contact angle of about 8°, and are applicable to the filler metal for joining of Si3N4.
(2) The joining strength of Si₃N₄ using Cu₆₆Ti₃₄ filler is higher than that of Si₃N₄ using other Cu-Ti fillers at any brazing temperature except for brazing temperature of 1273 K. Thus, the joining strength of Si₃N₄ with Cu₆₆Ti₃₄ filler shows the maximum value of 313.8 MPa at brazing temperature of 1323 K. At the brazing temperature of 1373 K, Si₃N₄ joint with Cu₅₀Ti₅₀ filler shows the maximum value of 176.5 MPa at brazing time of 1.8 ks, and gradually decreases with longer brazing lime, and to 19.6 MPa at brazing time of 7.2 ks. The elevated temperature fracture shear strength of Si₃N₄ joint brazed at 1373 K for 1.8 ks using Cu₅₀Ti₅₀ filler increases to 199.1 MPa at 373 K, and gradually decreases to 105.9 MPa at 973 K.
(3) During brazing Ti in molten Cu₅₀Ti₅₀ filler reacts with Si₃N₄ by the following reactions. Si₃N₄(s) +4Ti(1)=4TiN(s)+3Si(s), and Si₃N₄(s)+9Ti(1)=4TiN(s)Ti₅Si₃(s). TiN at the interface between Si₃N₄ and the filler, Ti₅Si₃, and Cu-Si phase at the central part of the filler are formed. The activation energy for growth of TiN at the joining interface is 206.3 kJ/mol, and the growth of TiN is dominated by the diffusion of N in TiN. The silicon content of the Cu-Ti phase increases about 7 at%Si to about 20 at%Si with increasing the brazing temperature.