SOLDERS AND BRAZING FILLER METALS

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

In any brazing/soldering process, a molten alloy comes in contact with a surface of solid, which may be an alloy, a ceramic, or a composite material (see Ceramics Composite materials). For a molten alloy to advance over the soHd surface a special relationship has to exist between surface energies of the hquid—gas, soHd—gas, and Hquid—soHd interfaces. The same relationships should, in principle, hold in joining processes where a molten alloy has to fill the gaps existing between surfaces of the parts to be joined. In general, the molten alloy should have a lower surface tension than that of the base material. 

Because the surface tension of oxides such as Fe O, AI2O2, etc, is much lower than that of the majority of metals and alloys, the presence of 

Solders. In spite of the wide use and development of solders for millennia, as of the mid-1990s most principal solders are lead- or tin-based alloys to which a small amount of silver, zinc, antimony, bismuth, and indium or a combination thereof are added. The principal criterion for choosing a certain solder is its melting characteristics, ie, soHdus and Hquidus temperatures and the temperature spread or pasty range between them. Other criteria are mechanical properties such as strength and creep resistance, physical properties such as electrical and thermal conductivity, and corrosion resistance. 

Base metal 1 metal preform (paste) Base metal 1 

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Orthodontics - [DENTAL MATERIALS] (Vol 7) -brazing filler metals for [SOLDERS AND BRAZING FILLER METALS] (Vol 22) -shape-memory alloys for [SITAPE-MEMORY ALLOYS] (Vol 21)... 

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