Copper  base metal heat exchangers are typically brazed in vacuum furnaces using silver alloys. Partial pressure is used to assist preventing volatilization of the silver braze alloys in vacuum brazing.  It is important to closely control the brazing temperature and time at brazing temperature relative to the liquidus of the silver brazing alloy.  Prolonged periods of heating can cause an alloying effect of the silver with the copper which can lead to erosion of the base metal.  The erosion of heavy sections of copper may be slight, but erosion of thin copper sections could prove to be disastrous.
An effort was made to increase base metal hardness, maintain or lower the grain size and minimize intergranular  braze alloy penetration of final assemblies.
This paper will evaluate traditional vacuum brazing and continuous furnace brazing to examine both methods.