Hello, we are doing some corrosion testing of titanium based alloys which have been welded and heat treated.
I would like to prepare a sample for corrosion rate measurements via Tafel Scans in the lab.
I want to connect a wire the alloy sheet which will then be cold mounted. The normal lead-tin solder is not quite adhesive to the alloy, I would like to know what can I do to attach that wire to the alloy?
I also do not want to braze the wire as this may overheat the sample and may lead to changes in the stresses inside.
I would be grateful for your help.
one option would be welding in argon atmosphere.. like laser welding, or TIG.
For soldering titanium in air you need a special flux that contains fluoride salts that may dissolve the titanium oxides that cover titanium. However, Im not sure if these fluxes can melt at thje 180°C where tin solders work. Probably use some slighty higher temperature solder.
I know of CuAgTi paste that should connect to titanium, but it needs some 900°C if I remember right.
Not sure If I was of help...
it should ... see here http://www.hilderbrand.ch/?Brazing_Alloys___Active_Brazing_Alloys only I suppose you should work in argon still? and probably 900 °C might be too much for your samples to heat them...
one more idea..
do you have anybody around who is into batteries, accumulators.. these people often use small spark welders (resistance spot welding) and that works nice and might do the trick for you. In the most simple form its a capacitor that you discharge in your joint - might be denagerous a bit but pretty ok if you know basics about electricity,
One more idea.. why not plate the titanium, and then soft solder it on the plating...
there is the electro-less nickel coating method or maybe just very simple copper coating from copper sulphide bath may even help?.. in both cases you would neet to cover the coating and the soldered spot and most importantly the edgr of the coating by some asphalt or wax or something, otherwise the Ni-Ti or Cu-Ti connection would totally distort your corrosion measurements.
One of the successful ways of welding Cu to titanium and titanium alloys is capacities electrical retardation. This method is also known in the production of a thermal pair with heterogeneous properties Another method is front-end elector-welding welding with a certain force of compression.
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