Patent ID: 7566385

Claim:
An apparatus for use in membrane-mediated electropolishing of a work-piece having a surface comprising metal, said apparatus comprising: (a) a source of low-conductivity fluid adapted to supply low-conductivity fluid to at least a portion of the surface of the work-piece, wherein the conductivity of the low-conductivity fluid is less than about 2000 μS/cm; (b) a cathode half-cell comprising: (i) a fully or partially enclosed volume, cavity or vessel; (ii) a conductive electrolyte solution or gel which partially or essentially fills the fully or partially enclosed volume, cavity or vessel, wherein the conductive electrolyte solution or gel comprises positively and negatively charged ions, and has a conductivity greater than about 10 mS/cm; (iii) a cathode in contact with the electrolyte solution or gel; and (iv) an ion-conducting membrane which forms a surface of the fully or partially enclosed volume, cavity or vessel, wherein at least a portion of the internal surface of said membrane contacts the electrolyte solution or gel and the external surface of that portion of the membrane is accessible to contact a metal work piece, and wherein at least a portion of the conductive electrolyte solution or gel is interposed between the cathode and the internal surface of the ion-conducting membrane; (v) an inlet and an exit adapted to allow conductive electrolyte solution or gel to be circulated through the volume, wherein the inlet and exit are fluidly connected to a pump adapted to circulate the conductive electrolyte solution or gel between the partially or fully enclosed volume and the pump; (c) a DC electrical power source having a positive voltage terminal adapted to be electrically connected to the surface of the work-piece and having a negative voltage terminal electrically connected to the cathode; (d) a structure for movably contacting a portion of the external surface of the membrane to the work-piece; and (e) at least one of a filter, a de-gasser, a heat exchanger, and an apparatus to adjust the composition of the conductive electrolyte solution or gel, fluidly connected to the pump.