THESSCO LIMITED - Sheffield England

Standard Specification designations enclosed in brackets are near equivalents which do not correspond over the whole compositional range.

1. The upper melting point figure is the true liquids of the alloy but in practice brazing may be carried out at temperature significantly lower than those listed, as indicated [ ] thus.

2. * Brittish Patent 1.237.791 made under license to manufacture agreement.

1. Health & Safety Data sheets covering phosphorus alloys are available on request.

2. Phosphorus containing alloys must not be used on ferrous or nickel based parent metals. Since they will result in brittle joints.

3. They must not be exposed to hot sulphur bearing atmospheres in service due to the danger of selective phase corrosion.

Brazing with silver copper - phosphorus is widely used for joining copper to copper, where the absence of a flux is a major benefit. The self - fluxing action of phosphorus ensures that flux entrapment problems are largely avoided and that high standards of joint soundness can be maintained.

High phosphorus levels give excellent capillary penetration, since the fluidity of the molten brazing alloy is controlled by the phosphorus content. An example of this may be seen in phos 6 which has the highest fluidity of this group of alloys, with only Phos 0 approaching its performance in this respect.

Alloys with high phosphorus levels are less ductile than the lower phosphorus grades, particulary those with significant silver contents. For applications where optimum mechanical strength or resistance to vibration is required the lower phosphorus alloys such as Phos 5, Phos 2 and Phos CP6 are preferred. The 15% silver alloy, Phos 15, is the only grade available in foil form and is generally restricted in use to electrical and high integrity applications.

The tin containing alloy, Phos OT, offers controlled fluidity, a low melting point and joints of good appearance.