Welding of Silicon to Invar for Application in Synchrotron Light Instrumentation

Abstract

The Double Crystal Monochromator (DCM) will be developed at the Brazilian Synchrotron Light Laboratory (LNLS) to select the desired X-Ray wavelength of Sirius, the new Brazilian fourth generation synchrotron. Components of this optical instrumentation can be obtained through welding processes, such as brazing, soldering, and diffusion bonding. The use of vacuum welding technique ensures union of silicon with FeNi alloy, Invar36 (64Fe-36Ni) from Grupo Metal and Invar39 (61Fe-39Fe) from Scientific Alloys. Union of these materials was performed with filler alloys from Nihon Superior, such as ALCONANO (nanosilver paste), SnSb (95Sn-5Sb), Sn100C (Sn-0.7Cu-0.05Ni-0.01Ge), and Sn100CV (Sn-5Bi-0.8Cu-0.05Ni). Following welding tests, microstructural and metallographic analysis of the interface region between the materials involved are performed to investigate the junction among silicon, filler alloy, and base metal. Microstructural characterization carried out by a QUANTA SEM (Scanning Electron Microscope) with EDS (Energy Dispersive Spectroscopy) technique to identify the composition, distribution, and morphology of the phases. Based on these analyses, the best parameters were Invar39/Sn100CV/Si samples using base materials coated with different depositions: one gold and the other copper. In the mechanical test, the specimen with copper film presented higher shear strength.