SILVER IN BRAZING AND SOLDERING

Metal pieces such as pipes, faucets, ducts and electrical wires are usually joined together either by brazing or soldering, similar processes based on how much heat is applied to the junction. Without the addition of silver none of these connections would be as strong, leakproof, corrosion resistant or as electrically conductive as the original materials.

While people often confuse brazing and soldering the difference is that brazing requires temperatures above 450 degrees Celsius while soldering is performed at temperatures below 450 degrees Celsius. Either way, silver is an essential part of each process.

Silver-tin solders are used for bonding copper pipe in homes, where they not only eliminate harmful lead-based solders, but also provide the piping with silver’s natural antibacterial action. Major faucet manufacturers use silver-based solder to incorporate these advantages and refrigerator manufacturers use silver-based solder to provide the flexibility required for constant changes in the temperature of cooling tubes.

In 2006, the Restriction of Hazardous Substances (RoHS) Directive took effect in the European Union (EU) and banned all products containing more than a trace amount of lead and other hazardous substances. This is putting an end to lead-based solders (though there are exceptions) which had contained lead and tin and replaced it mainly with silver-tin-copper solders which contain about 45% silver.

Silver brazing alloys are used in everything from air-conditioning and refrigeration to electric power distribution. They are also crucial in the automobile and aerospace industries. It is especially useful in joining different metals with high melting points.

Brazing and alloys accounted for 50.2 million ounces of silver in 2023 representing a 2 percent decrease over 2022.