CERAMIC TO CERAMIC BRAZING THROUGH ACTIVE FILLER ALLOY

摘要

Ti based active filler alloy has been used for joining sintered alumina. Silver and copper base alloys with varying compositions of Ag:Cu = 72:28, 60:40, 50:50 and 30:70 (by wt percent) were prepared. 1-3 wt percent of Ti was incorporated in the Ag-Cu base alloys as an active filler element. The filler alloys thus obtained were characterised by XRD. SEM and EDX. Thin foil (0.2 - 0.1mm thick) of the filler alloy was obtained and placed in between the two ceramic (alumina) pieces. The ceramic-filler alloy-ceramic was held firm by placing a suitable weight and heated in a graphite resistance furnace under 30-50 millitorr pressure at temperatures such as 1073, 1173, 1273, 1373 and 1473 K. In all cases the soaking time was kept 15 min. The optimum temperature and time were determined after examining the brazed samples through electron probe micro analyser (EPMA). scanning electron microscopy-energy despersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The study of the interface between the ceramics by EPMA. SEM-EDX, TEM and XRD has shown interesting results. The average thickness of the interface was 4-9 m. Most of the Ti present in the filler alloy was found at the interface as TiO