Abstract: If incorporated in a cleaning system using persulfuric acid, the invention serves for continuous cleaning while increasing the persulfuric acid concentration adequately to ensure enhanced cleaning performance. The invention provides a feeding apparatus that feeds persulfuric acid to a cleaning apparatus. The cleaning system uses an electrolysis reactor 10 that regenerates the persulfuric acid solution by performing electrolytic reaction to produce persulfate ions from sulfate ions contained in the solution, and a circulation line 4, 5, 6 that circulates the persulfuric acid solution between the cleaning vessel 1 and the electrolysis reactor 10. Configured as above, the invention can provides a feeding apparatus. The cleaning system comprises said configuration and a cleaning vessel 1 that cleans objects 30 using a persulfuric acid solution 2 as cleaning fluid.

Abstract: A diamond electrode having an oxidation resistant diamond film which will not separate from the electrode during electrolysis with highly oxidizing materials. The thickness of the diamond film is 20 pm or more and the diamond film should preferably cover opposite side surfaces of a substrate in such a manner as to also cover end surfaces 2a of the substrate. The surfaces of the substrate are covered with a plurality of diamond layers to form the film using repeated steps of forming separate diamond layers with each diamond layer having a thickness of 10 to 30 pm on one of the surfaces of the substrate and then forming a diamond layer having a thickness of 10 to 30 pm on the other surface of the substrate. Thus, it is possible to form a nonporous surface of diamond layer and prevent deterioration of an electrode caused by the separation of a diamond film.

Abstract: If incorporated in a cleaning system using persulfuric acid, the invention serves for continuous cleaning while increasing the persulfuric acid concentration adequately to ensure enhanced cleaning performance. The invention provides a feeding apparatus that feeds persulfuric acid to a cleaning apparatus. The cleaning system uses an electrolysis reactor 10 that regenerates the persulfuric acid solution by performing electrolytic reaction to produce persulfate ions from sulfate ions contained in the solution, and a circulation line 4, 5, 6 that circulates the persulfuric acid solution between the cleaning vessel 1 and the electrolysis reactor 10. Configured as above, the invention can provides a feeding apparatus. The cleaning system comprises said configuration and a cleaning vessel 1 that cleans objects 30 using a persulfuric acid solution 2 as cleaning fluid.

Abstract: This invention provides a method for the surface treatment of a metal, which comprises the steps of: placing at least a surface to be treated of a metal to be treated between two electrodes facing each other under an atmosphere of a mixed gas consisting of an inert gas and a reactant gas; and plasma exciting said mixed gas under atmospheric pressure to effect glow discharge between said electrodes. The method of the present invention uses an apparatus simpler than that used in a conventional method and can inject into the surface layer of a metal, even those elements which have been difficult to with the conventional method, and can readily modify surface properties of a metal such as surface hardness, surface wettability, etc.