A PROCESS FOR MAKING A HEAT EXCHANGER

• Main Authors: NIELSEN, HENRIK, AURAN, LARS, LEWIN, CARL, NORDLIEN, JAN HALVOR
• Format: Patent
• Language: English; French; German
• Published: 14.03.2012
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; PERFORMING OPERATIONS; SOLDERING OR UNSOLDERING; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; WELDING; WORKING BY LASER BEAM

A process for making a heat exchanger comprising extruding a number of heat exchanging tubes, connecting the end portions of the heat exchanger tubes with connection elements, and optionally applying fins to the outer surface of the heat exchanging tubes, in which prior to the assembling of the heat exchanger the tubes are provided with a Si-containing coating, and after assembling the different element are brazed together, whereby that heat exchanging tubes are made of an aluminium alloy containing : 0,45 - 1 ,40 % by weight Mn 0,00 - 0,20 % by weight Si 0,00 - 0,30 % by weight Fe 0,00 - 0,45 % by weight Cu 0100 - 0,05 % by weight Mg 0,00 - 0,30 % by weight Cr and the remainder aluminium. Unavoidable impurities is set to a maximum of 0,05 % by weight. The amount of Mn in solid solution is preferably at least 0.4%. During brazing, a dense band of Al-Mn-Si precipitates is formed, which cowers the corrosion potential in the diffusion zone compared to the core, thereby reducing pitting corrosion.