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 CnH2n(OH)2 with n=2-6 and alicyclic alcohols of general formula CmH2m-1OH with m=5-8.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for the electrochemical polishing of surfaces of metals and metal alloys.BACKGROUND OF THE INVENTION[0002]The purpose of the process of electrochemical polishing or electropolishing is to produce metal surfaces of high purity, and to smooth and deburr the metal surfaces. Smoothing in the micro-range can also produce gloss of the surfaces so treated. Furthermore, electropolishing can also remove any stresses from the outer layers of the material.[0003]There are a great many different electropolishing processes that can be used for the processing of various metals or metal alloys. As a rule these processes are based on the use of electrolytes that comprise a concentrated inorganic acid such as phosphoric acid or sulfuric acid or a mixture of concentrated inorganic acids, often with additives for further enhancing the action of the electrolytes so as to obtain smoother and shinier metal surfaces. Some examples of suc...

AI Technical Summary

Benefits of technology

[0018]In a special embodiment of the present invention the method is carried out at a temperature between 40° C. and 100° C. It is especially preferred for the method to be carried out at a temperature between 60° C. and 100° C. Since the electrolyte of the present method does not contain any highly volatile constituents, higher temperatures can be used, for example temperatures up to 80° C., up to 90° C., up to 100° C. or even higher, without the need for special precautions, for example for reliable capture and removal of vapors that form. The possibility that the method can also be carried out at higher temperatures makes it possible, on the one hand, for the electropolishing process to be carried out if necessary in a relatively short time, and on the other hand it means that expensive removal of the heat released in the electropolishing process becomes unnecessary. Accordingly, expensive cooling becomes largely or completely unnecessary. If cooling is used, it therefore does not have to satisfy high performance requirements.

Problems solved by technology

However, a feature that is common to all of these existing electrolytes, which are widely used industrially, is that they can only be used successfully for certain metals and / or alloys and thus have a very restricted application profile.

Often the individual electrolytes must be kept strictly separate and in particular must not be mixed, as any mixing may damage them and make them unusable.

Sometimes this can even result in certain constituents of the electrolytes reacting together and, for example, releasing substances that are hazardous or injurious to health.

This in turn causes considerable expenditure and the associated costs.

Often, however, this mixture cannot be used industrially owing to the associated explosion risk, or can only be used with considerable expenditure on safety measures.

This electrolyte has, however, the serious drawback that because of its high proportion of more than 80% of highly volatile methanol it is a health hazard, and presents a risk of fire and explosion.

10° C., or with an expensive system for trapping the resultant vapors and carrying them away.

Furthermore, suitability of this process for carbon steels, magnesium, magnesium alloys or aluminum-silicon alloys has not been disclosed.