Electropolishing process

Abstract

The present invention relates to a method for the electropolishing of surfaces of metals and metal alloys. Said method is characterized in particular in that it can be applied to a wide range of metals. Thus, it is suitable for the electropolishing of metal surfaces comprising iron, tungsten, magnesium, aluminum or an alloy of these metals. The electrolyte used in the method comprises methanesulfonic acid and at least one alcoholic compound selected from aliphatic diols of general formula C n H 2n (OH) 2 with n=2-6 and alicyclic alcohols of general formula C m H 2m-1 OH with m=5-8.

What is claimed is: 
     
         1 . A method for the electropolishing of surfaces of metals, comprising exposing a metal surface to an electrolyte in the presence of an electric current,
 wherein the metal surface is selected from iron, tungsten, a light metal, and an alloy thereof, and   wherein the electrolyte comprises:
 methanesulfonic acid, and 
 at least one alcoholic compound selected from the group comprising aliphatic diols of general formula C n H 2n (OH) 2  with n=2-6 and alicyclic alcohols of general formula C m H 2m-1 OH with m=5-8. 
   
     
     
         2 . The method as claimed in  claim 1 , wherein the surface comprises iron or an iron alloy, hardened or unhardened. 
     
     
         3 . The method according to  claim 2 , wherein the iron alloy is ferro-nickel, special steel, or carbon steel. 
     
     
         4 . The method as claimed in  claim 1 , wherein the surface comprises tungsten or a tungsten alloy. 
     
     
         5 . The method as claimed in  claim 1 , wherein the surface comprises magnesium, a magnesium alloy, aluminium, or an aluminum alloy. 
     
     
         6 . The method as claimed in  claim 1 , wherein the surface comprises an aluminum-silicon alloy. 
     
     
         7 . The method as claimed in  claim 1 , wherein the alcoholic compound comprises at least one aliphatic diol of general formula C n H 2n (OH) 2  with n=3-6. 
     
     
         8 . The method as claimed in  claim 7 , wherein the aliphatic diol comprises 1,2-propanediol and/or 1,2-butanediol. 
     
     
         9 . The method as claimed in  claim 1 , wherein the electrolyte comprises 5 to 93 wt. % methanesulfonic acid and 95 to 7 wt. % of the alcoholic compound or compounds. 
     
     
         10 . The method as claimed in  claim 1 , wherein the electrolyte comprises 10 to 80 wt. % methanesulfonic acid and 90 to 20 wt. % of the alcoholic compound or compounds. 
     
     
         11 . The method as claimed in  claim 1 , wherein the alcoholic compound comprises at least one aliphatic diol and at least one alicyclic alcohol. 
     
     
         12 . The method as claimed in  claim 1 , wherein the alicyclic alcohol comprises cyclohexanol. 
     
     
         13 . The method as claimed in  claim 1 , wherein the electrolyte does not contain any chromic acid or chromates. 
     
     
         14 . The method as claimed in  claim 1 , wherein the method is carried out at a temperature between 40 and 100° C. 
     
     
         15 . The method as claimed in  claim 1 , wherein the method is carried out at a temperature between 60 and 100° C. 
     
     
         16 . The method as claimed in  claim 1 , wherein the method is carried out at an anodic current density of 3 to 40 A/d m 2 . 
     
     
         17 . An electrolyte for the electropolishing of surfaces of metals, which are selected from iron, tungsten and light metals, and from alloys of these metals, wherein the electrolyte comprises
 methanesulfonic acid and   at least one alcoholic compound consisting of an aliphatic diol of general formula C n H 2n (OH) 2  with n=2-6 or an alicyclic alcohol of general formula C m H 2m-1 OH with m=5-8.   
     
     
         18 . The electrolyte as claimed in  claim 17 , wherein the alcoholic compound comprises at least one aliphatic diol of general formula C n H 2n (OH) 2  with n=3-6. 
     
     
         19 . The electrolyte as claimed in  claim 17 , wherein the aliphatic diol comprises 1,2-propanediol and/or 1,2-butanediol. 
     
     
         20 . The electrolyte as claimed in  claim 17 , wherein the electrolyte comprises 5 to 93 wt. % methanesulfonic acid and 95 to 7 wt. % of the alcoholic compound or compounds. 
     
     
         21 . The electrolyte as claimed in  claim 17 , wherein the electrolyte comprises 10 to 80 wt. % methanesulfonic acid and 90 to 20 wt. % of the alcoholic compound or compounds. 
     
     
         22 . The electrolyte as claimed in  claim 17 , wherein the alcoholic compound comprises at least one aliphatic diol and at least one alicyclic alcohol. 
     
     
         23 . The electrolyte as claimed in  claim 17 , wherein the alicyclic alcohol comprises cyclohexanol.