Plasma rotating electrode process is a process in which the molten metal is atomized with plasma by a rotating electrode. The resulting powder is a spherical powder with minimal internal pores. It is used for producing high-temperature alloy powders.
Similar technologies are used in Japan and China. Various process modifications have been investigated to produce finer powder. One of the most important modifications is using a large diameter disk electrode instead of a conventional cylindrical electrode. These types of electrodes have been reported to reduce the cost of input materials. Increasing the rotation speed of the rotating electrode can also be effective in producing smaller particles.
Another modification is gas atomization. Plasma rotating electrode process is combined with a method of molten metal atomization, known as gas atomization. This method involves the introduction of gas blast around the rotating electrode to enhance the granulation process. Gas atomization can also contribute to the powder refinement.
In this study, numerical modeling based on computational thermo-fluid dynamics was developed to analyze granulation behavior. It was shown that the shape and depth of the electrode end surface affect the granulation process. Moreover, the simulations indicated that the size of the PREP-powder can be controlled by manipulating the plasma arc current.
Typical powder sizes of Ti-6A1-4V are between 100 and 300 /’m. When comparing the CtFD-simulated PREP process to the conventional REP process, it was observed that the yield of titanium powder increased from less than 1% to over 20%.