The Optimal Type of Glow Discharge as a Heating Source for Diffusion Welding

The study is devoted to selection of the optimal type of a glow discharge as a source of surface heating in a diffusion welding process. It was shown, that while heating, due to a cathode surface state and its geometry there are three types of a glow discharge: normal, abnormal and with the hollow cathode effect as well as their different combinations can occur. As was established, that the presence of different holes, gaps and cavities on the welded surfaces while operating in an abnormal glow discharge or in hollow cathode discharge at pressures above 3 – 5 kPa inevitably leads to a dramatic increase in discharge power and the current density accordingly. The latter resulted in loss of glow discharge’s stability with its transition to an electric arc and the workpieces melting consequently. Experimentally established, that for diffusion welding, where a long-term high temperature stable mode is required, the normal DC glow discharge is the most promising.