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Aluminum Brazing |
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Weeks distributors Durafix 3-in-1 aluminum brazing rod: The picture (Movie 1 / Movie 2) at left is of the "no-scrub" tests using only stainless steel sheet heated prior to rod application over the area to be repaired which is a hole is punched into bottom of soda can with a screwdriver. The hypothesis is that it's the chromium in the stainless steel brush that is acting as a fluxing agent for the aluminum thus allowing good intermetallic bonding (Alloying of the base metal and filler metal), as opposed to mechanical preparation. For a particular project, a circular heater is being built to pre-heat the aluminum for brazing. | ||||||||||||||||
 Whetting test |
The whetting test is two segments of
the same aluminum material having brazing rod applied after preheating. The one on the left had a SS overlay
during heating and the one on the right had a ceramic (Alumina) overlay
during heating. The overlays were pushed off just before the rod was
applied to the surface. Heating was to 400C in both cases with the
same torch and approximate heating time.
See
resistance heater page. |
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   Flux test |
This test is using AL-BRAZE flux from Harris with two sections of aluminum firmly clamped together with no mechanical preparation done to the pieces to be brazed. Flux mixed with water was brushed onto the joint prior to heating and the brazing rod was dipped in water and then flux prior to application on the joint. Notice the seepage on the second image: There was no pre-tinning yet the filler metal flowed all the way from the front of the joint where the heat was applied to the back, through the contact area between the two sections. The part was bent towards the front after cooling, applying the maximum force to the weakest part of the joint without any apparent change in the width of the rear gap. | ||||||||||||||||
 Comparisons |
Pictured at left is a 6061-T6, 1/4" x 3/4" bar butt joint bend-over-test for Airco-720 aluminum soldering rod. For comparison of the relative strengths of the various brazing rods, a 1/2" x 1" x 3" long 6061-T6 aluminum bar will be brazed perpindicular to a 1/2" thick plate using the same procedure as shown at the beginning of the HTS-2000 video. For the brazing rods tested, the best of three tests for each will provide the comparison value. | ||||||||||||||||
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