Cadmium brazing alloys

Silver Brazed Joints These are similar to soldered joints except that a temperature of about 600°C (1100°F) is required. A 15 percent silver, 80 percent copper, 5 percent phosphorus solder is used for copper and copper alloys, while 45 percent silver, 15 percent copper, 16 percent zinc, 24 percent cadmium solders are used for copper, copper alloys, carbon steel, and alloy steel. Silver-brazed joints are used for temperatures up to 200°C (400°F). Cast-bronze fittings and valves with preinserted rings of 15 percent silver, 80 percent copper, 5 percent phosphorus brazing alloy are available. 

Silver-brazed joints are used when temperature or the combination of temperature and pressure is beyond the range of soldered joints. They are also more reliable in the event of plant fires and are more resistant to vibration. If they are used for fluids that are flammable, toxic, or damaging to human tissue, appropriate safeguarding is required by the code. There are OSHA regulations governing the use of silver brazing alloys containing cadmium and other toxic materials. 

Brazing alloys that contain cadmium have been used extensively since mid-19th century. A small amount of cadmium in a gold matrix can lower the melting point below that obtained by adding equivalent concentrations... 

Use and exposure Silver is a very ductile and malleable precious metal. A major use of silver is as jewelry and silverware made from sterling silver and standard silver for traditional purposes. Silver also is used in photography and to make solder and brazing alloys, electrical contacts, and high-capacity silver-zinc and silver-cadmium batteries. Silver has the highest electrical conductivity of all metals—even higher than copper. ... 

Soldering and brazing alloys containing lead, zinc, or cadmium should be used with proper ventilation. The noble metals themselves present no direct problems because the reactive osmium is not used in these alloys. 

Note that many braze alloys for brazing in air contain zinc or cadmium which should not be used in vacuums. 

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