JOINING OF SI3N4 TO SI3N4 USING RAPIDLY-SOLIDIFIED CUNITIB BRAZING FILLER FOILS

Joining of Si3N4 to Si3N4 was performed using newly developed rapidly- solidified CuNiTiB brazing foils of different thickness, three-point b ending tests then being employed at room temperature to measure the st rength of the joints. The microstructures of the joints were observed and the element area distribution of Cu, Ni and Ti was examined by sca nning electron microscope with an X-ray wave-dispersion spectrometer. The results of the strength test show that when using rapidly-solidifi ed brazing filler foils of suitable thickness (for example; 40 mu m an d 80 mu m) the joint strength was increased greatly (up to 402 MPa and 380 MPa respectively) compared with the use of paste brazing filler o f the same alloy. Moreover, the fracture form of the Si3N4/Si3N4 joint s also varied with the change of strength. The thickness of the brazin g foils used has an important effect on the corresponding joint streng th, reasons for which are discussed. (C) 1998 Elsevier Science S.A.