DEVELOPMENT OF A NEW CUNITIB BRAZING ALLOY FOR JOINING SI3N4 TO SI3N4

Joining Si3N4 to S3N4 was carried out initially with a Cu34Ni27Ti39 br azing alloy prepared by double melting under a vacuum condition. Howev er, the strength of the joints was not as high as expected. The causes were studied. Based on the results of the analysis, a CuNiTiB brazing filler metal was designed. The Si3N4/Si3N4 joints were then brazed wi th this new brazing alloy in the paste form, and joints with a three-p oint bend strength of 338.8 MPa at room temperature were obtained. The interfacial reactions of the joint are also discussed. With the rapid ly solidified foils of the brazing alloy, the bend strength of the Si3 N4/Si3N4 joints under the same brazing conditions is raised to 402 MPa at room temperature. The Si3N4/Si3N4 joints brazed with this newly de veloped brazing alloy exhibit a rather high and steady bend strength ( about 406 MPa) at 723 K.