JOINING OF SI-TI-C-O FIBER-ASSEMBLED CERAMIC COMPOSITES WITH 72AG-26CU-2TI FILLER METAL

Si-Ti-C-O fibre-assembled ceramic composites were joined with 72Ag-26C u-2Ti filler metal at 1123 K and 1223 K in vacuum. The composites cons isted of Si-Ti-C-O fibres, which were assembled unidirectionally, and oxide material filling the spaces between the fibres. During the joini ng process, frothing occurred at the joining interfaces. Joining inter faces were observed by SEM and analysed by electron probe microanalysi s and X-ray diffraction. The strength of the joints was evaluated by f our-point bending tests. Most of Si-Ti-C-O fibre/filler metal interfac es and the oxide material/filler metal interfaces were firm without cr acking and separation. At the fibre/metal interfaces, a high concentra tion of titanium was confirmed. Among the specimens joined at 1123 K, the average strength, measured by the bending test, was 96 MPa. It was inferred that the defects at the joining interfaces formed by frothin g had decreased the strength of the joints. Metallizing of the surface s to be joined with the same filler metal as a pretreatment before joi ning, was effective in preventing frothing during joining and improvin g the joining strength. The average strength of the joints with pretre atment was 211 MPa.