Soldering each type of solder and alloy has different melting temperatures. The term "silver solder" denotes the type of solder that is used. Some soft solders are "silver-bearing" alloys used to solder silver-plated items. Lead-based solders should not be used on precious metals because the lead dissolves the metal and disfigures it. The distinction between soldering and brazing is based on the melting temperature of the filler alloy. A temperature of 450 °C is usually used as a practical demarcation between soldering and brazing. Soft soldering can be done with a heated iron whereas the other methods typically require a higher
Alkali-metal thermal to electric converter Alkali-metal thermal to electric converter The alkali-metal thermal-to-electric converter (AMTEC), originally called the sodium heat engine (SHE) was invented by Joseph T. Kummer and Neill Weber at Ford in 1966, and is described in US Patents , , and . It is a thermally regenerative electrochemical device for the direct conversion of heat to electrical energy. It is characterized by high potential efficiencies and no moving parts except the working fluid, which make it a candidate for space power applications. This device accepts a heat input in a range 900–1300 K and produces direct current with predicted device efficiencies of