| Silver-flo™ 20 is a high melting point cadmium free silver brazing filler metal. It has a high melting temperature (776 to 815°C) but a narrow melting range of only 39°C providing good flow properties when molten. The high brazing temperature of the filler metal makes it less easy to use than the high silver content alloys. Consequently it is not widely used. This product is a relatively inexpensive filler metal to purchase. However the cost per brazed joint of actually using the alloy may not be favorable in comparison to lower melting point, higher silver content filler metals. Optimum joint gaps at brazing temperature are 0.075-0.2mm. Silver-flo™ 20 is not widely used. It may be considered for joining mild steel and copper in for example tube applications. It can be used as the first stage, high melting point alloy in a step or sequential brazing operation. It may also be used for brazing brass joints where filler metal with color matching characteristics is required. However in this instance care should be taken, as the difference between the melting point of the filler metal and that of the brass could be as little as 80°C for 60/40 brass. Information provided by Johnson Matthey Metal Joining |
