Applications: Sil-Fos was developed primarily for use on copper, but their use has extended to other nonferrous copper base alloys. It is used extensively on refrigeration units, air conditioning apparatus, electrical conductors, copper and brass pipe fittings, and other copper and brass equipment.

Characteristics: Sil-Fos is copper rich, filler metals that are self-fluxing on copper by virtue of their phosphorus content. Sil-Fos, because of its higher phosphorus content, is more fluid than Sil-Fos 5 when heated rapidly to its flow point. Sil-Fos has less tendency to form large fillets or to fill poorly fitted joints with large clearances cannot be maintained or where fillets are specified.

The self-fluxing of these filler metals is effective on copper only. With copper-base alloys, such as bass or bronze, the joints should be fluxed with Handy-Flux. Sil-Fos should not be used on nickel-base alloys, as the phosphorus reacts with the nickel or iron to form brittle compounds at the interface of the joints.

Both Sil-Fos is mutually soluble with copper and copper alloy base metals.

This metal has a strong tendency to liquate (i.e. to separate into low and high melting constituents) if heated slowly through its melting range, as normally occurs in furnace brazing. The results in leaving a skull of unmelted alloy behind which may objectionable from the standpoint of appearance. In furnace brazing it is preferable to preplace the alloys inside the joint where the skull is not visible.

Specifications:This filler metal conform to the following specifications: AWS A5.8 BCuP-5, ASME Boiler & Pressure Vessel Code, Sec II-C, SFA5.8 BCuP-5

Information provided by Lucas-Milhaupt, Inc.