3. Materials and MethodsThe followi

3. Materials and MethodsThe following section describes the prototype system for electrolytic plasma polishing of internal surfaces of pipes, the necessary electrolyte, the developed polishing head, analytical methods for determining the surface roughness and the used sample materials.3.1. Electrolytic Plasma Polishing of Inner SurfacesRegarding the schematic design of the electrolytic polishing, described in Figure 1, exterior surfaces can be processed both with electro polishing and with electrolytic plasma polishing. If this design is to be used to process, for example, inner surfaces of fluid-carrying tubes, there will be no removal of material inside the tube, since the electric field only encloses the outer surface. In order to use the process of electrolytic plasma polishing and its associated benefits for internal pipe surfaces, a prototype apparatus for inner surface polishing by means of plasma was designed, developed and tested.As seen in Figure 5, the tube to be polished (4) is not inserted into the electrolyte basin (7). Rather, a polishing head (2) has been developed, which makes it possible that the inner surface of the tube is submerged by the electrolyte.