Joining of SiO2 glass and 316L stainless steel using Bi\u2013Ag-based active solders

Felix Weber,Markus Rettenmayr

doi:10.1007/s10853-020-05426-4

Felix Weber, Markus Rettenmayr

Open Access

https://doi.org/10.1007/s10853-020-05426-4

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Abstract

Active brazing is a commonly used method for joining dissimilar materials with at least one non-metallic component. In the present study, joining of SiO2 glass to 316L stainless steel was performed utilizing Bi–Ag-based solders. Ti up to a concentration of 4 and Mg up to 1 wt.% were added as active elements. Microstructures of the solder alloys in the as-cast state and of cross sections of the joined compounds were analysed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. In the as-cast state of the solder, Ti is found in Bi–Ti intermetallic phases; Mg is partially dissolved in the fcc-(Ag) phase and additionally contained in a ternary Ag-Bi-Mg phase. After soldering, a tight joint was generated using several alloy compositions. Ti leads to the formation of reaction products at the steel/solder and glass/solder interfaces, and Mg is exclusively accumulated at the glass/solder interface.

Highlights

Besides the optical transparency of SiO2 glass, its thermal stability is one of the reasons for its increasing use, e.g. as packaging material for electronic and optical devices [1, 2] or for viewing and measuring windows in vacuum applications [3, 4]
We focus on active solder alloys on the basis of eutectic Ag-Bi, an alloy system with an equilibrium eutectic temperature of 262.5 °C [40]
The presence of the Bi3Ti2 phase is only observed in alloys with a nominal Ti content of [ 1 wt.%

Summary

Introduction

Besides the optical transparency of SiO2 glass, its thermal stability is one of the reasons for its increasing use, e.g. as packaging material for electronic and optical devices [1, 2] or for viewing and measuring windows in vacuum applications [3, 4]. Many of such applications require joining of the SiO2 glass and a metallic substrate. Wetting with the aid of active elements is associated with their enrichment at the substrate/solder interface, reaction with the substrate and the formation of a reaction phase layer [28,29,30,31]

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