Copper and copper alloys are usually divided into copper ( copper ) , brass , bronze and copper-nickel alloy four categories, they brazing surface oxide film mainly depends on the stability and brazing process on the material properties. The surface may be formed of copper oxide, copper oxide, cuprous oxide is easily reduced both gas reduction, it is easy to remove the flux , the brazing of copper is very good. To prevent the occurrence of hydrogen embrittlement , can not be a hydrogen containing reducing atmosphere brazing. Containing only zinc brass , surface can be zinc oxide or cuprous oxide of oxides , zinc oxide, although relatively stable, but difficult to remove . Manganese oxide, manganese brass surface is relatively stable , difficult to remove , should be the active agent in order to ensure a Brazing Alloys  solder wettability . Bronze, cadmium bronze surface oxide film are easily removed , silicon bronze , beryllium oxide film , while relatively stable, but difficult to remove . And w (A1) more than 10% of aluminum bronze, mainly aluminum oxide surface , it is difficult to remove , to adopt a special flux . Copper-nickel alloy on the surface of nickel oxide and copper oxide easily removed , but should be used containing no phosphorus brazing solder , since the joint in order to avoid cracking .