Electropolishing process for titanium

Abstract

The present invention relates to a method of electrochemical polishing of surfaces of titanium or titanium-containing alloys, such as Nitinol. An electrolyte is used that comprises methanesulfonic acid and one or more alkanediphosphonic acids. These alkanediphosphonic acids can optionally be substituted with hydroxy and/or amino groups. A further aspect of the present invention relates to the use of said electrolyte for the electropolishing of titanium or titanium-containing alloys.

1 . A method of electropolishing and/or electrochemical deburring of surfaces of titanium or titanium-containing alloys, wherein the electrolyte used comprises methanesulfonic acid and one or more alkanediphosphonic acids, and the one or more alkanediphosphonic acids can optionally be substituted with hydroxy and/or amino groups. 
     
     
         2 . The method as claimed in  claim 1 , wherein the concentration of methanesulfonic acid in the electrolyte is at least 95 wt. %, based on the total weight of the electrolyte. 
     
     
         3 . The method as claimed in  claim 1 , wherein the one or more alkanediphosphonic acids comprise 1-hydroxyethane-1,1-diphosphonic acid. 
     
     
         4 . The method as claimed in  claim 1 , wherein the concentration of the one or more alkanediphosphonic acids is between 1 and 50 g/kg electrolyte. 
     
     
         5 . The method as claimed in  claim 1 , wherein the concentration of the one or more alkanediphosphonic acids is between 5 and 20 g/kg electrolyte. 
     
     
         6 . The method as claimed in  claim 1 , wherein the electrolyte consists substantially of methanesulfonic acid and of one or more alkanediphosphonic acids. 
     
     
         7 . The method as claimed in  claim 1 , wherein it is carried out at a temperature between 20° C. and 70° C. 
     
     
         8 . The method as claimed in  claim 1 , wherein the method is carried out at an anodic current density of 2-50 A/dm 2 . 
     
     
         9 . The method as claimed in  claim 1 , wherein the method is carried out at an anodic current intensity of 5-30 A/dm 2 . 
     
     
         10 . The method as claimed in  claim 1 , wherein the titanium-containing alloys include titanium at a proportion of at least about 50 mol. %. 
     
     
         11 . The method as claimed in  claim 10 , wherein the titanium-containing alloy is Nitinol. 
     
     
         12 . Use of an electrolyte as claimed in  claim 1  for the electropolishing of surfaces of titanium and/or titanium-containing alloys. 
     
     
         13 . The use as claimed in  claim 12 , wherein the titanium-containing alloy is Nitinol.