| Copper-flo™ No.3 is a copper-phosphorus brazing filler metal containing a nominal 6.2% phosphorus and conforming to EN 1044 1999 CP203. It is primarily used for the brazing of copper tubes and pipes in refrigeration and air-conditioning applications and is a popular choice for this type of work. When it is used to braze copper the phosphorus within the alloy imparts a metallurgical based self-fluxing capability. If 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, inter-metallic, phosphide compounds at the joint interface. Copper-flo™No.3 is not suitable for use in joints exposed to sulfurous atmospheres at elevated service temperatures. When selecting a copper-phosphorus brazing filler metal it is necessary to understand about their flow properties and ductility. The level of phosphorus within the filler metal controls these two characteristics - the higher this is the more free flowing the filler metal and the lower its ductility. Copper-flo™No.3 due to its lower phosphorus content is less free flowing and slightly more ductile than Copper-flo™. It has a long melting range and a tendency to liquate. This property can be used to aid bridging of comparatively wide joint gaps. Copper-flo™No.3 is suited for joint clearances of 0.75-0.2 mm. Copper-flo™No.3 is widely used for brazing copper pipes, tubes and fittings in the refrigeration, heating and ventilating and air conditioning systems. Information provided by Johnson Matthey Metal Joining |
