| Silbralloy™ is used to braze copper and copper alloys. When brazing copper the phosphorus within the alloy imparts a metallurgical based self-fluxing capability. When Silbralloy™ is used to join copper alloys (such as brass, bronze or gun metal) a separate flux will be required because the self-fluxing action only occurs on copper. This filler metal should not be used to braze iron containing materials like carbon or stainless steels or nickel containing materials as the phosphorus within the filler metal will form brittle, intermetallic, phosphide compounds, at the joint interface. Silbralloy™ is not suitable for use in sulfurous atmospheres at elevated service temperatures. When selecting a brazing filler metal from the Sil-fos™ range it is necessary to understand about the flow and ductility of the different products. Phosphorus is the key element, the higher this is the more free flowing the filler metal, but the lower its ductility. Silver is used to improve the filler metal’s ductility, but reduces its flow properties. Due to its low ductility, it should only be used with capillary type joints. ‘Bell mouthed’ joints should be avoided. The optimum joint gap for brazing is normally 0.05-0.2mm. Silbralloy™ is widely used in the refrigeration, heating and ventilating and air conditioning industries for the brazing of copper pipework systems. Silbralloy™ has been used for fittings of copper cylinders where greater ductility is required than the standard copper-phosphorus products used on the seams. It is also used in electrical engineering applications such as the brazing of electric motor rotor bars to end rings. Information provided by Johnson Matthey Metal Joining |
