PROCESS FOR RESTRICTED LEAD CONTENT SOLDERING OF COPPER FINS TO COPPER ALLOY TUBING WITH CONTROLLED COPPER CONTAMINATION OF THE MOLTEN SOLDER RESERVOIR

摘要

14 52,842ABSTRACT OF THE DISCLOSUREThis is an article and process which provide thefirst essentially continuous high tin flow soldering methodfor attaching copper based fins to copper based tubing.This invention avoids sludge buildup in the reservoir andgenerally avoids lead carbonate formation when the heatexchanger is in service. In addition, a novel structure isproduced having a braze like joint with eta phase layersadjacent to the copper based surfaces. The inventionutilizes an essentially lead free, high tin solder cascadeonto a preferably cool tube, generally with a limited timeof contact between the liquid solder and the tube, and witha combination air quench and wipe to remove excess solderand solidify the remaining solder. Thus a braze like jointis achieved having better heat conduction and closerthermal expansion match. This finned heat exchanger tubingis generally useful for liquid to gas type heat exchangersand especially useful for hydrogen coolers for electricalgenerators.