The welding on cogged surfaces between aluminium and copper to be useful so as to replace the mechanical aluminium-metal contact with the copper-metal contact. The possible applications in this respect have been analyzed for the following concrete directions: The welding of electric aluminium conductor bars; The sheathing of electric aluminium conductor bars; The sheathing of the aluminium clips. The contact electric resistance measurements made with a CA 10 Microhmeter indicates negligible values of 1-5 µ?. These values are constant in time during the exploitation of the electrical contact (tests during months of exploitations were also performed). The temperature in the contact area was measured with a Therma Cam PM 675 PAL thermographic camera. The efficiency of the sheathing is obvious if we were to consider the overheating inside the substation with only 3°C as compared to the 30-40°C normally existing there in the case of classical joints.