US2894883A

US2894883A - Method of electropolishing uranium

Info

Publication number: US2894883A
Application number: US105456A
Authority: US
Inventors: David E Walker; Robert A Noland
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-07-18
Filing date: 1949-07-18
Publication date: 1959-07-14
Anticipated expiration: 1976-07-14

Description

United States Patent M METHOD OF EDECTROPOLISI-HNG URANIUM David E. Walker, Chicago Heights, and Robert A. Noland, Chicago, 11]., assignors to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application July 18, 1949 Serial No. 105,456

4 Claims. (Cl. 204-15) This invention deals with an electrolyte and a method of polishing the surfaces of uranium articles, and in particular with a method of electropolishing such surfaces.

For many uses of uranium articles and metal, the surfaces should be smooth. If metallographic studies are to be made on uranium surfaces, for instance, a smooth and homogeneous condition is desirable. Polishing of uranium metal by mechanical means was found to be unsatisfactory, because the uranium encountered plastic deformation so that the metallographic examination did not give a true picture of the original grain structure.

It is an object of this invention to provide a method of polishing uranium surfaces in which no plastic deformation of the uranium takes place.

It is another object of this invention to provide a method of polishing uranium surfaces by which an evenly smooth and bright surface is obtained.

It is another object of this invention to provide an electrolyte for electropolishing.

It is another object of this invention to provide a method of polishing uranium surfaces by which the corrosion resistance of the uranium is increased and by which the bright surface obtained is distinguished by a relatively long service life even when in contact with air.

It is another object of this invention to provide a method of polishing uranium surfaces so that the uranium metal may be stored after polishing and prior to coating or plating without thereby impairing the adherence of such coatings.

It is still another object of this invention to provide a process for preparing uranium for coatings by which the adherence or bond of said coatings is greatly improved.

According to this invention, an electrolyte has been found particularly successful which contains sulfuric acid, glycerine, and Water preferably in concentrations ranging from 35 to 65% by volume of sulfuric acid (96%), from 1 to 20% by volume of glycerine, and from 25 to 55 by volume of water. The best results were obtained with concentrations of 38 to 55% sulfuric acid, to 14% of glycerine, and 33 to 50% of water, which correspond to mixtures of three to five parts by volume of sulfuric acid, one part by volume of glycerine, and three to four parts by volume of-water. The electrolyte of this invention is especially useful for electropolishing uramum.

The process of this invention is carried out by immersing the uranium article into the electrolyte, making the article the anode in an electric circuit and passing electric current, preferably with a voltage of from 10 to 15 volts, through the circuit. It is advantageous, though optional, to discontinue the electrolysis by intermittently withdrawing the anode from the electrolyte whereby any polarized film formed is removed and an especially bright surface is obtained.

Uranium articles treated by the process described not only have an essentially improved surface condition but. also a decreased reactibility with the atmosphere, and,

2,894,883: Patented July 14, 1959 consequently, the polished surface condition lasts for an especially long time. It has been found that articles treated by the process of this invention stay bright for at least four to eight hours, but, in some cases, even for two weeks.

In the following example, the preferred embodiment of the process of this invention is illustrated without the intention to have the scope of the invention limited to the details given therein.

Example A uranium article to be polished was immersed in an electrolyte containing five parts by volume of sulfuric acid, one part by volume of glycerine, and three parts by volume of water. This uranium article was anodically connected in a circuit which included a cathode arranged three inches from said anode. By using a potential of from 10 to 15 volts, a current was passed through this electric circuit. The anode was alternately withdrawn from the bath and reimmersed at time intervals of from three to five seconds.

The article, thus polished, showed an extremely bright and smooth surface which remained in this condition after eight hours of contact with the atmosphere.

While a preferred embodiment of the present invention has been described above, modifications may be made without departing from the spirit of the invention. Thus, this invention is to be limited only by the scope of the appended claims.

What is claimed is:

1. The method of electropolishing a uranium article, comprising assembling an electrical circuit including said article as the anode, a cathode, and an electrolyte containing from 35 to by volume of sulfuric acid, from 1 to 20% by volume of glycerine, and from 25 to 55% by volume of water, and passing an electrical current through said circuit to polish the surface of said uranium article.

2. The method of electropolishing a uranium article, comprising assembling an electrical circuit including said article as the anode, a cathode, and an electrolyte containing from 38 to 5 5% by volume of sulfuric acid, from 10 to 14% by volume of glycerine, and from 33 to 50% by volume of water, and passing an electrical current through said circuit to polish the surface of said uranium article.

3. The method of electropolishing a uranium article, comprising assembling an electrical circuit including said article as the anode, a cathode, and an electrolyte at room temperature and containing from 35 to 65% by volume of sulfuric acid, from 1 to 20% by volume of glycerine, and from 25 to 55% of water, and passing an electrical current of from 10 to 15 volts through said circuit to polish the surface of said uranium article.

4. A method of electropolishing a uranium article, comprising assembling an electrical circuit including said article as the anode, a cathode about three inches away from said anode, and an electrolyte at room temperature containing about five parts by volume of sulfuric acid, one part by volume of glycerine, and three parts by volume of water, passing an electric current of 10 to 15 volts through said circuit, and alternately withdrawing and reirnmersing said anode from said electrolyte at time intervals of from three to five seconds.

References Cited in the file of this patent UNITED STATES PATENTS 1,462,421 Pearson et al. July 17, 1923 1,787,672 Davenport Jan. 6, 1931 2,315,695 Faust Apr, 6, 1943 FOREIGN PATENTS 500,009 Great Britain Feb. 1, 1939

Claims

1. THE METHOD OF ELECTROPOLISHING A URANIUM ARTICLE, COMPRISING ASSEMBLING AN ELECTRICAL CIRCUIT INCLUDING SAID ARTICLE AS THE ANODE, A CATHODE, AND AN ELECTROLYTE SAID TAINING FROM 35 TO 65% BY VOLUME OF SULFURIC ACID, FROM 1 TO 20% BY VOLUME OF GLYCERINE, AND FROM 25 TO 55% BY VOLUME OF WATER, AND PASSING AN ELECTRICAL CURRENT THROUGH SAID CIRCUIT TO POLISH THE SURFACE OF SAID URANIUM ARTICLE.