The influence of brazing temperature and surface roughness on the wettability of reactive brazing alloys

Using two active brazes based on silver–copper, the wetting behaviour was investigated on hard metals and diamond. Here, it was possible both to characterise the in-situ wetting angle as a function of temperature, the surface roughness and the time by using the flow rate and the wetting angle as well as to analyse the underlying mechanisms. A directly proportional relationship between temperature and the formed wetting angle was demonstrated during the tests up to a material dependent limiting value. Moreover, the wetting behaviour was shown to deteriorate with increasing surface roughness values. By means of investigating the diffusion zone between the carbide metal and the braze using scanning electron microscopy, it was possible to establish that the penetration depth of the active element titanium into the carbide metal increased with increasing brazing temperature.