電解研摩における浴電圧と陽極表面状態

金属材料の電解研摩に関する研究 (第9報)

抄録

In electrolytic polishing, it is very difficult to observe the behavior of anode, as higher current density and bath voltage than other electrolysis, such as electro-plating or electrolytic refining, are required for electropolishing, moreover the electrolyte has higher concentration and viscosity. In investigating conditions for electropolishing, therefore, the current-anode potential currve is not used, but is used in general the current-bath voltage curve.
Using the latter curve, the investigation to find out the optimum condition of electropolishing of various metals and alloys was carried out. The appearance of anode surface differs considerably depending on bath voltage.
In this paper the result of microscopic examination and roughness of quenched high carbon steel electropolished at various bath voltage in phosphoric acid-chromic acid bath and of macrographic analysis of electropolishing mechanisum is reported as follows:
1) Polishing is not effective at 1 volt of bath voltage, and the roughness is the same before and after treatment.
2) At 2 volts, anode surface is covered with dark gray film of insoluble phosphate, and comparatively smooth that means thick film.
3) At 3 volts, the surface is aventurine with small, deep pits, which may be attributed to oxygen bubbles evolved on the anode surface, and sticking to it.
4) Current increases proportionally to voltage from 3 to 5 volts and large but shallow pits appear on the surface that means polishing becomes effective.
5) Between 5 and 6 volts, current does not increase with an increase of voltage, and to the smooth and glossy surface thus obtained, copper deposits little even in cupric sulfate solution which may be attributed to the fact that anode is covered uniformly with oxide film.
6) Over 6 volts, streaks appear on the anode surface.