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The heat treatment and brazing of aluminum is best carried out in a protective nitrogen atmosphere. Under controlled atmospheric conditions, it is possible to avoid discoloration due to reactions between adhering lubricants and the metal and oxidation. When brazing at high temperatures, an inert atmosphere of nitrogen also minimizes the need for flux.
During the annealing of aluminum coils, reaction between the metal and lubricants and oxidization at temperatures above 400°C can lead to discoloration. To avoid these problems, Linde has developed a system whereby cold-rolled aluminum strip coils are annealed using an atmosphere optimizing program to control flow and purity. The result is effective protection from oxidation even for sensitive alloys. Linde's system optimizes the consumption of nitrogen and also accurately reproduces the same protective atmosphere every time. |
