Molybdenum or tungsten electrodes (Tungsten) and Tantalum,

Refractory materials
Molybdenum, tungsten

The non-ferrous materials they are more difficult they imply a greater challenge when it comes to welding. Because its limited range of plasticity, low electrical resistance and excellent thermal conductivity, translate into greater control of your process.

Welding these materials requires a shorter “Weld time” and a higher electric current for its equivalent in gauge of ferrous material.. This results in faster expansion and contraction., this translates into a requirement for more dynamic behavior for the electrodes.

Note: Parameters like UpSlope and Downslope decrease the range of expansion and shrinkage and regularly improves the quality of the weld.

REFRACTORY METALS

Electrodes for soldering silver inserts

Metals such as TUNGSTEN AND MOLYBDENE are usually classified as refractory, due to its high melting point. The melting point of tungsten is 3380º, that of molybdenum is at 2620ºC and tantalum is 2850º.

In resistance welding, metals bond together providing heat generated by a high electrical current and, with the application of force, a weld is formed between the two materials. In certain metals, actual fusion at the interfaces is necessary to produce a substantial weld, while in other metals the welding may be due to a recrystallization process that takes place below the melting point of the metal. There are reasons to believe that, in the case of high melting point materials, tungsten, molybdenum and tantalum, welding occurs by recrystallization between metals.

So for processes where copper soldering is required, silver or some material with high conductivity, it is recommended to use materials it is recommended to use a refractory material.