Electropolishing of alloys containing platinum and other precious metals
AssigneeAbbott Cardiovascular Systems Inc.
InventorWilliam E. Webler, JR.
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Abstract
Radiopaque cobalt-based alloys having a smooth electropolished surface with rounded edges and methods for electropolishing such alloys. A cobalt-based alloy includes cobalt, chromium, and one or more radiopaque elements. In one embodiment, examples of radiopaque elements include so-called platinum group metals (i.e., platinum, palladium, ruthenium, rhodium, osmium, or iridium). Group 10 elements (i.e., platinum or palladium) are particularly preferred. Because of the presence of the platinum group metal(s), such alloys are generally difficult to electropolish. Electrolyte formulations and methods for electropolishing such alloys are also disclosed.
Claims29
A radiopaque body having an electropolished surface, comprising:
- the radiopaque body formed from a cobalt-based alloy comprising from about 18 weight percent (wt %) to about 39 wt % cobalt, from about 10 wt % to about 25 wt % chromium, from about 20 wt % to about 65 wt % platinum, and wherein the cobalt-based alloy is substantially free of molybdenum.
A method for electropolishing a metallic body, comprising:
- positioning the metallic body in an electropolishing electrolyte solution in an electropolishing cell, wherein the electropolishing electrolyte includes one or more of HCl, H2SO4, or H3PO4, and one or more thickening agents;
- and
- electropolishing the metallic body in the electropolishing electrolyte solution in the electropolishing cell, wherein the electropolishing includes an alternating current with a forward:reverse voltage ratio of about 2 and the forward and reverse pulses each having a duration in a range of about 0.003 to about 0.010 seconds.
A method for electropolishing a radiopaque alloy containing cobalt, chromium, and platinum, the method comprising:
- positioning the radiopaque body in an electropolishing electrolyte solution in an electropolishing cell, wherein the electropolishing electrolyte includes sulfuric acid (H2SO4), hydrochloric acid (HCl), phosphoric acid (H3PO4), a thickening agent selected from the group consisting of ethylene glycol, 2-butoxyethanol, glycerol, polyethylene glycol, and one of water or a C1-C4 alcohol;
- and
- electropolishing the radiopaque body in the electropolishing electrolyte solution in the electropolishing cell, wherein the electropolishing includes an alternating current with a forward:reverse voltage ratio of about 2 and the forward and reverse pulses each having a duration in a range of about 0.003 to about 0.010 seconds.
Dependencies are inferred from the claim text.