A partial surface treatment apparatus, comprising:
- a first electrode member electrically connected to a treatment object made of metal, the treatment object including an outer circumferential surface and a circumferential groove formed at the outer circumferential surface;
- a second electrode member including an inner circumferential surface facing the outer circumferential surface and the circumferential groove, the inner circumferential surface being spaced apart from the outer circumferential surface and the circumferential groove along an entire circumference of the inner circumferential surface;
- a pair of annular-shaped elastic sealing members each of which is nonconductive, the annular-shaped elastic sealing members being configured to seal, at both sides relative to the circumferential groove, a clearance formed between the outer circumferential surface and the inner circumferential surface;
- an accommodation portion accommodating each of the annular-shaped elastic sealing members in such a manner that the annular-shaped elastic sealing member is spaced apart from the outer circumferential surface and that the annular-shaped elastic sealing member is movable in a diameter reduction direction, the accommodation portion including groove side surfaces arranged to face each other;
- a pressure applying mechanism configured to supply a pressurized fluid to an outer circumferential side of the annular-shaped elastic sealing members fitted into the accommodation portions in order to move the annular-shaped elastic sealing members in the diameter reduction direction, an inner circumferential side of each of the annular-shaped elastic sealing members being in pressure contact with the outer circumferential surface in a case where the annular-shaped elastic sealing members are moved in the diameter reduction direction, the pressure applying mechanism configured to release the pressure contact between the annular-shaped elastic sealing members and the outer circumferential surface;
- a supply flow passage through which electrolyte solution is supplied to a space formed between the outer circumferential surface and the inner circumferential surface, the space being sealed with the pair of annular-shaped elastic sealing members;
- each of the annular-shaped elastic sealing members being formed in a shape including a pair of annular-shaped side wall portions and an annular-shaped end portion, the pair of annular-shaped side wall portions being configured to be in slidably contact with the corresponding groove side surfaces of the accommodation portion while the pair of annular-shaped side wall portions being apart from each other in a groove width direction, the annular-shaped end portion connecting inner circumferential portions of the respective annular-shaped side wall portions to each other serially;
- and
- a cutout being formed at each of the annular-shaped elastic sealing members to be extended from an outer circumferential side edge portion of the annular-shaped elastic sealing member towards the inner circumferential side of the annular-shaped elastic sealing member, the cutout being provided at at least one position which is along a circumferential direction of the annular-shaped elastic sealing member.