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→Fluxes
== Fluxes ==
Brazing fluxes consist of non-metallic materials, mostly salt mixtures of boron and halogen compounds ''<xr id="tab:tab4.2"/> (Table 4.2)''. Their purpose is to remove oxides fromthe brazing surfaces and prevent their new build-up in order to allow a thorough wetting of these surfaces by the liquefied brazing alloy. Fluxes have to be activated already at a temperature below the working range of the brazing alloy. They are selected mainly according to the working temperature of the brazing alloy and the base material to be joined.
'''Tab 4.1 Commonly Used Brazing Alloys for Electrical Contacts''' als Bild gemacht
[[File:Commonly Used Brazing Alloys for Electrical Contacts.jpg|right|thumb|Commonly Used Brazing Alloys for Electrical Contacts]]
Since the residues of fluxes are hygroscopic and can cause corrosion they have to be removed completely after the brazing process in very hot or boiling water. Depending on the type and process used, fluxes are being applied in liquid form or as powders or pastes.
<figtable id="tab:tab4.2">'''Table 4.2: Fluxes for the Brazing of Heavy Metals'''
<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Designation</p><p class="s8">DIN EN 1045</p></td><td><p class="s8">Designation US (similar)</p></td><td><p class="s8">Active tempe- rature range [°C]</p></td><td><p class="s8">Chemical ingredients</p></td><td><p class="s8">Base materials used for</p></td></tr><tr><td><p class="s8">TYP FH 10</p></td><td><p class="s8">FB 3-A</p></td><td><p class="s8">550 - 800</p></td><td><p class="s8">Boron compounds, Fluorides</p></td><td><p class="s8">All metals and alloys except light metals, alloyed steels, carbide steels</p></td></tr><tr><td><p class="s8">TYP FH 11</p></td><td><p class="s8">FB 4-A</p></td><td><p class="s8">550 - 800</p></td><td><p class="s8">Boron compounds,</p><p class="s8">Fluorides, Chlorides</p></td><td><p class="s8">Copper,</p><p class="s8">Aluminum bronze</p></td></tr><tr><td><p class="s8">TYP FH 12</p></td><td><p class="s8">FB 3-C</p></td><td><p class="s8">550 - 850</p></td><td><p class="s8">Boron,</p><p class="s8">Boron compounds, Fluorides</p></td><td><p class="s8">Special brass,</p><p class="s8">any steel alloys, carbide steel</p></td></tr><tr><td><p class="s8">TYP FH 21</p></td><td><p class="s8">FB 3-I</p></td><td><p class="s8">750 - 1100</p></td><td><p class="s8">Boron compounds, Chlorides</p></td><td><p class="s8">All metals and alloys</p><p class="s8">except light metals</p></td></tr></table>
</figtable>
==References==
