| Sil-fos™ Plus is used to braze copper and copper alloys. When brazing copper the phosphorus within the alloy imparts a metallurgical based self-fluxing capability. When Sil-fos™ Plus 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. Sil-fos™ Plus is not suitable for use in sulfurous atmospheres at elevated service temperatures. Phosphorus is the key element, the higher this is the more free flowing the filler metal, the lower its ductility. Silver is used to improve the filler metal’s ductility, but reduces its flow properties. Sil-fos™ Plus is the most free flowing filler metal from the Sil-fos™ range. However, due to its high phosphorus content it is one of the least ductile. The low ductility of the alloy imparts it with glass like properties, making it both ‘notch’ sensitive and sensitive to impact type loadings. This filler metal should therefore not be used in applications involving exposure to strong vibration, impact loads or where some deformation of the joint might be expected in service. Sil-fos™ Plus is best suited for making copper joints that are of the true capillary type and where tight joint clearances of 0.025-0.075 mm are used. When used in such joints, the poor mechanical properties of the filler metal are exposed and satisfactory joints, suitable for use in all but the most extreme conditions can generally be produced. Sil-fos™ Plus is ideal for the flux free brazing of copper pipes and tubes and other copper to copper joints, including those used in electrical applications. Information provided by Johnson Matthey Metal Joining |
