Papers by Keyword: Active Brazing

Abstract: Joining of dissimilar metals leading to better material utilization with improved functionality encouraged the research thrust on various dissimilar material joining processes including laser brazing. This papers reports the development of laser brazing joints and their characterization for 3 mm thick Cu sheet with 3 mm thick AISI 316L stainless steel (SS) sheet in butt joint configuration using 63Ag-35.25Cu-1.75Ti active brazing foil as filler metal. Comprehensive experiments were carried out to identify the optimum processing parameters for controlled simultaneous heating of the filler metal and sh-7eets by laser beam resulting in melting of the filler metal without melting Cu and SS sheets. Using this methodology, a number of brazed joints were successfully prepared at different set of processing parameters. The brazed joints were subjected to various non-destructive (visual and dye-penetrant test) and destructive (microscopic examination, energy dispersive spectroscopy, four point bend testing etc.) characterization techniques. The results demonstrated that laser energy per unit length of 100 J/m is threshold limit for feasibility of brazing process for selected metal and thickness combination. Microscopic studies of transverse section of laser brazed joint showed full penetration across the thickness without the melting of parent metals. EDS studies showed the diffusion of filler material (Ag) more towards the Cu sheet as compared to that of SS sheet. Four point bend test showed that the alignment of laser beam-metal joint was critical for the brazing joint strength and improved joint strength was achieved when the beam was at the centre of the brazing joint. A maximum joint strength of 343.7 MPa was achieved for laser power of 550 W at scan speed of 3 mm/min.

Abstract: Active metal brazing of a new high thermal conductivity SiC-polycrystalline fiber-bonded ceramic (SA-Tyrannohex™) has been conducted using a Ti-containing Ag-Cu active braze alloy (Ticusil®). The brazed joints were characterized using SEM-EDS and Knoop hardness scans across the interfaces. The effects of fiber orientation in the composite on the microstructure, elemental composition, and microhardness are presented. Results show that this material can be successfully joined using judiciously selected off-the shelf active braze alloys to yield metallurgically sound joints possessing high integrity.

Abstract: Diamond tools are increasingly gaining importance as cutting materials for various construction materials. The quality of synthetic diamonds, monocrystalline as well as polycrystalline or CVD-diamonds has been significantly improved over the last years. Integrating these cutting materials requires adequate joining technologies that produce sound joints without exposing the temperature sensitive diamond to too elevated temperatures. The paper highlights current developments in the joining of synthetic diamonds to steel. Owing to their covalent atomic bonding diamonds cannot easily be wetted and joined by employing conventional brazing alloys. Hence, active agents are needed to foster an interfacial reaction. Different active filler concepts are presented and discussed regarding their joint formation. The brazing temperatures influence not only possible diamond degradation but also the interfacial decomposition of the diamond due to the formation of corresponding reaction layers.