US3288636A - Process for coating uranium alloy members - Google Patents
Process for coating uranium alloy members Download PDFInfo
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- US3288636A US3288636A US289749A US28974963A US3288636A US 3288636 A US3288636 A US 3288636A US 289749 A US289749 A US 289749A US 28974963 A US28974963 A US 28974963A US 3288636 A US3288636 A US 3288636A
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- uranium
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- Expired - Lifetime
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- 238000000034 method Methods 0.000 title claims description 22
- 229910000711 U alloy Inorganic materials 0.000 title claims description 13
- 238000000576 coating method Methods 0.000 title description 7
- 239000011248 coating agent Substances 0.000 title description 4
- 239000000446 fuel Substances 0.000 claims description 22
- 239000011651 chromium Substances 0.000 claims description 21
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 20
- 229910052804 chromium Inorganic materials 0.000 claims description 20
- 229910045601 alloy Inorganic materials 0.000 claims description 19
- 239000000956 alloy Substances 0.000 claims description 19
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 9
- 239000000243 solution Substances 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- 230000001464 adherent effect Effects 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 229910000838 Al alloy Inorganic materials 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 2
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 2
- 101100459267 Crotalus durissus terrificus CRO3 gene Proteins 0.000 claims 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims 1
- 235000011149 sulphuric acid Nutrition 0.000 claims 1
- 229910052770 Uranium Inorganic materials 0.000 description 29
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 29
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 229910052751 metal Inorganic materials 0.000 description 14
- 239000002184 metal Substances 0.000 description 14
- 229910052782 aluminium Inorganic materials 0.000 description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 9
- 150000002500 ions Chemical class 0.000 description 8
- 229910052759 nickel Inorganic materials 0.000 description 8
- 238000007598 dipping method Methods 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 150000001255 actinides Chemical group 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000009713 electroplating Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 2
- 229910052778 Plutonium Inorganic materials 0.000 description 2
- 229910052776 Thorium Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 2
- 238000007788 roughening Methods 0.000 description 2
- 239000002195 soluble material Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000978 Pb alloy Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910052768 actinide Inorganic materials 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 150000002366 halogen compounds Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- -1 nickel Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 239000004449 solid propellant Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
- G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/34—Pretreatment of metallic surfaces to be electroplated
- C25D5/46—Pretreatment of metallic surfaces to be electroplated of actinides
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C21/00—Apparatus or processes specially adapted to the manufacture of reactors or parts thereof
- G21C21/02—Manufacture of fuel elements or breeder elements contained in non-active casings
- G21C21/14—Manufacture of fuel elements or breeder elements contained in non-active casings by plating the fuel in a fluid
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/02—Fuel elements
- G21C3/04—Constructional details
- G21C3/16—Details of the construction within the casing
- G21C3/20—Details of the construction within the casing with coating on fuel or on inside of casing; with non-active interlayer between casing and active material with multiple casings or multiple active layers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Definitions
- the present invention relates to a process for producing metallic coatings on uranium members, more particularly to the process for producing high adhesion chromium coatings on uranium and alloys thereof by chemical displacement.
- a conventional fuel element for nuclear reactors comprises a solid fuel member of uranium or of alloys thereof, enclosed in an aluminum casing. It is desirable that a thin metallic intermediate layer, such as of nickel, be interposed between the uranium and the aluminum casing.
- a thin metallic intermediate layer such as of nickel
- the intermediate nickel layer is to prevent an undesired reaction of aluminum with uranium which would form an intermetallic compound UAl This reaction would result in the destruction of the aluminum casing during the operation of the reactor within a relatively short period of time.
- the intermediate nickel layer will provide through diffusion bonding, an intimate contact between the uranium and the aluminum. This intimate contact also results in providing excellent heat transfer properties between the aluminum casing and the fuel therein.
- This film of foreign matter which is not initially visible, is formed primarily in water and/ or oxygen bearing media.
- this film of foreign matter can be recognized by its black color which occurs after heating the film to higher temperatures for a short period of time. The same phenomenon of the film formation will also occur if the uranium is left at room temperature for a longer period of time.
- This black colored film will also be formed even under very thick galvanic deposits which may surround the uranium completely and which prevents the passage of any oxygen whatsoever from the atmosphere to the uranium.
- the previously proposed method of solving the above problem involved roughening the surface of the uranium fuel member in order to obtain at least a mechanical adhesion.
- This roughening of the surface was either produced by blasting with steel particles or by special chen ical pickling processes.
- nickel deposited upon a roughened uranium surface there is obtained only a limited adhesion and the diffusion resulting from the formation of intermetallic compounds under increased pressure and elevated temperatures either does not occur at all, or if it occurs, occurs only in spots and then to a limited extent.
- such fuel elements were characterized by having a low adhesion between the aluminum casing and the uranium and could only withstand very small thermal and mechanical loads without the aluminum casing becoming loosened from the fuel therein.
- the principal object of the present invention to provide a novel and improved process for applying aten a thin, highly adhesive metallic layer onto uranium and alloys thereof.
- the present invention essentially comprises immersing a member formed of a metal from the actinide group or alloys thereof into an aqueous solution containing chromium ions so that a metallic chromium coating is formed upon the metallic member by chemical displacement or by electrodeposition.
- a member formed of a metal from the actinide group or alloys thereof into an aqueous solution containing chromium ions so that a metallic chromium coating is formed upon the metallic member by chemical displacement or by electrodeposition.
- the quality of this film and the rate of deposition of the film are functions of the concentration of the aforementioned substances in the aqueous solution, the temperature of the bath, the nature of the uranium alloy, and the microstructure of the same.
- Such chromium coatings or films can be successfully formed on uranium and its alloys from solutions within the following range of concentrations.
- a variety of metals suitable for electroplating such as nickel can be electrodeposited on the member so as to :firmly adhere to the chromium film.
- various metals for encasing the fuel member, such as aluminum can be firmly bonded to the uranium by means of a diffusion process.
- a desired diffusion bond between the uranium and outer layer such as nickel is obtained which has great uniformity. This bond will withstand substantially higher thermal and mechanical loads than any other types of bonds previously produced to date.
- the resulting chromium film is extremely thin and difcult to detect under the microscope.
- a dense chromium film is formed on the surface of the uranium alloy. After completely covering the surface, the film does not become any thicker independent of the time of the dipping treatment.
- the maximum thickness observed under the microscope was less than 0.1 (0.004 mil).
- Example 1 A typical nuclear fuel member of the uranium alloymolybdenum type consisting of U3.5 Mo0.1 Al alloy was finished to the prescribed dimensions. This uranium alloy member was degressed in a conventional manner and pickled in semi-concentrated nitric acid for about minutes. The uranium alloy members were then cleaned anodically in a solution consisting of 2 parts H PO and 1 part methyl alcohol. After this preparatory treatment, the uranium alloy members were dipped for 1 to 3 minutes into an aqueous solution consisting of 70 grams per liter CrO 2.5 grams per liter NaF, 2.5 grams per liter NaCl, 5 cu. cc. per liter H SO having a pH value of less than 1.0 and a temperature of 30 C.
- the uranium alloy members were coated with a firmly adherent chromium film which was gray in color. The uranium members were then thoroughly rinsed in water and were then ready for nickel plating by galvanic means in a conventional and well known manner.
- the coating of uranium and alloys thereof by closely adhering metallic layers is important in many other applications, including affording protection against corrosion and wear in radiation shielding blocks and counterweights in aircraft, both of which are fabricated from depleted metallic uranium and alloys thereof.
- the present invention provides a novel and improved process for applying a chromium film to a fuel member comprising a metal from the actinide group or an alloy thereof.
- a process for applying a firmly adherent chromium intermediate layer to the fuel of a fuel element for a nuclear reactor wherein the fuel comprises a U-3.5 Mo0.1 Al alloy member comprising cleaning said uranium alloy member, and [immersing the cleaned uranium alloy member for approximately 1 to 3 minutes into an aqueous solution at a temperature of approximately 20 C.30 C. and a pH value 1, said solution comprising approximately grams per liter of chromium oxide CrO approximately 2.5 grams per liter NaF, approximately 2.5 grams per liter NaCl, approximately 5 cubic centimeters per liter H SO so that a metallic chromium layer is formed on the alloy member by a chemical displacement.
- a process for applying a firmly adherent chromium intermediate layer to the fuel of a fuel element for a nuclear reactor said fuel comprising an aetinide metal from the group consisting of uranium, thorium, plutonium and alloys thereof, the steps of said process comprising cleaning said aetinide metal and immersing the cleaned aetinide metal for approximately 1 to 10 minutes in an aqueous solution at a temperature of approximately 20 C. to 40 C.
- said solution comprising approximately 20 to 200 grams per liter CrO approximately 1 to 100 grams per liter soluble halogen compounds from the group consisting of HCl, HF, NaCl, NaF, HClO HC1O NaClO H'BF and mixtures thereof, and approximately 0.5 to 20 grams per liter soluble sulfate compounds from the group consisting of H and salts thereof whereby said chromium intermediate layer is formed on said aetinide metal by a chemical displacement.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- High Energy & Nuclear Physics (AREA)
- Organic Chemistry (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- General Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- Electroplating Methods And Accessories (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Chemical Treatment Of Metals (AREA)
Description
Unite tates The present invention relates to a process for producing metallic coatings on uranium members, more particularly to the process for producing high adhesion chromium coatings on uranium and alloys thereof by chemical displacement.
A conventional fuel element for nuclear reactors comprises a solid fuel member of uranium or of alloys thereof, enclosed in an aluminum casing. It is desirable that a thin metallic intermediate layer, such as of nickel, be interposed between the uranium and the aluminum casing. One reason for the intermediate nickel layer is to prevent an undesired reaction of aluminum with uranium which would form an intermetallic compound UAl This reaction would result in the destruction of the aluminum casing during the operation of the reactor within a relatively short period of time. In addition, the intermediate nickel layer will provide through diffusion bonding, an intimate contact between the uranium and the aluminum. This intimate contact also results in providing excellent heat transfer properties between the aluminum casing and the fuel therein.
However, it has been found that various metals, such as nickel, cannot be deposited upon uranium and its alloys by electroplating without producing a film of foreing matter, composed presumably of an oxide, between the uranium and the metal to be deposited. This film is disadvantageous since it prevents either wholly or par tially an adhesion by atomic forces and a subsequent diffusion bonding between the uranium and the metal deposited thereon.
This film of foreign matter which is not initially visible, is formed primarily in water and/ or oxygen bearing media. However, this film of foreign matter can be recognized by its black color which occurs after heating the film to higher temperatures for a short period of time. The same phenomenon of the film formation will also occur if the uranium is left at room temperature for a longer period of time. This black colored film will also be formed even under very thick galvanic deposits which may surround the uranium completely and which prevents the passage of any oxygen whatsoever from the atmosphere to the uranium.
The previously proposed method of solving the above problem involved roughening the surface of the uranium fuel member in order to obtain at least a mechanical adhesion. This roughening of the surface was either produced by blasting with steel particles or by special chen ical pickling processes. In the case of nickel deposited upon a roughened uranium surface there is obtained only a limited adhesion and the diffusion resulting from the formation of intermetallic compounds under increased pressure and elevated temperatures either does not occur at all, or if it occurs, occurs only in spots and then to a limited extent. As a result, such fuel elements were characterized by having a low adhesion between the aluminum casing and the uranium and could only withstand very small thermal and mechanical loads without the aluminum casing becoming loosened from the fuel therein.
It is, therefore, the principal object of the present invention to provide a novel and improved process for applying aten a thin, highly adhesive metallic layer onto uranium and alloys thereof.
It is another object of the present invention to provide a process for forming a fuel element comprising a metal from the actinide group or alloys thereof for a nuclear reactor wherein the outer metallic casing is closely bonded to the fuel member therein.
The present invention essentially comprises immersing a member formed of a metal from the actinide group or alloys thereof into an aqueous solution containing chromium ions so that a metallic chromium coating is formed upon the metallic member by chemical displacement or by electrodeposition. When uranium and alloys thereof are immersed into aqueous solutions of CrO to which has been added soluble materials containing chloride and/ or fiuoride ions as well as small quantities of soluble materials containing sulfate ions, the member will be coated with a firmly adherent chromium film which is light to dark gray in appearance. The quality of this film and the rate of deposition of the film are functions of the concentration of the aforementioned substances in the aqueous solution, the temperature of the bath, the nature of the uranium alloy, and the microstructure of the same. Such chromium coatings or films can be successfully formed on uranium and its alloys from solutions within the following range of concentrations.
pH value 1 Temperature C 2040 Time minutes 1-10 Bearing in mind the above figures, the optimum composition of a dipping bath for a particular uranium alloy can be readily determined.
After the chromium coated member has been thoroughly rinsed in water, a variety of metals suitable for electroplating such as nickel can be electrodeposited on the member so as to :firmly adhere to the chromium film. By means of this intermediate layer various metals for encasing the fuel member, such as aluminum, can be firmly bonded to the uranium by means of a diffusion process. As a result, a desired diffusion bond between the uranium and outer layer such as nickel is obtained which has great uniformity. This bond will withstand substantially higher thermal and mechanical loads than any other types of bonds previously produced to date.
The resulting chromium film is extremely thin and difcult to detect under the microscope. At optimum bath composition a dense chromium film is formed on the surface of the uranium alloy. After completely covering the surface, the film does not become any thicker independent of the time of the dipping treatment. The maximum thickness observed under the microscope was less than 0.1 (0.004 mil).
When the above designated CrO solution was used, it was found that during the coating of uranium with chromium a portion of the Cr+ ions was reduced to Cr+ ions at the same time. A significant proportion of Cr+ ions in the solution may render the dipping bath unservicable. The formation of such detrimental Cr+ ions can be eliminated to a large extent if metallic lead or lead alloys in sheet or rod form are inserted into the dipping bath. As a result, the reoxidation of Cr+ ions to Cr ions will occur at the lead surface similar to the action in chromium electroplating baths.
This same result can also be achieved by connecting the dipping bath to a low voltage (1-10 volts), low amperage (0.1-1 amp/dm?) DC. or A.C. electrical source by means of electrodes. In this process it is of minor importance whether or not the uranium member which is to be coated is connected to the electrical power circuit during the actual dipping operation.
In order to describe in detail a specific embodiment of the following invention, the following operating example is set forth solely as being illustrative of the process of the present invention, and is not to be considered as limiting this process in any way.
Example 1 A typical nuclear fuel member of the uranium alloymolybdenum type consisting of U3.5 Mo0.1 Al alloy was finished to the prescribed dimensions. This uranium alloy member was degressed in a conventional manner and pickled in semi-concentrated nitric acid for about minutes. The uranium alloy members were then cleaned anodically in a solution consisting of 2 parts H PO and 1 part methyl alcohol. After this preparatory treatment, the uranium alloy members were dipped for 1 to 3 minutes into an aqueous solution consisting of 70 grams per liter CrO 2.5 grams per liter NaF, 2.5 grams per liter NaCl, 5 cu. cc. per liter H SO having a pH value of less than 1.0 and a temperature of 30 C. After the previously designated period of time has elapsed, the uranium alloy members were coated with a firmly adherent chromium film which was gray in color. The uranium members were then thoroughly rinsed in water and were then ready for nickel plating by galvanic means in a conventional and well known manner.
Based on similar electrochemical potentials, other actinides in addition to uranium, including thorium, plutonium and their respective alloys, can be coated with a chromium film in a like manner. The specific compositions of the bath and conditions of the dipping will vary somewhat depending on the exact composition of the :member being coated.
Besides the manufacture of nucelar fuel elements as described herein, the coating of uranium and alloys thereof by closely adhering metallic layers is important in many other applications, including affording protection against corrosion and wear in radiation shielding blocks and counterweights in aircraft, both of which are fabricated from depleted metallic uranium and alloys thereof.
Thus it can be seen that the present invention provides a novel and improved process for applying a chromium film to a fuel member comprising a metal from the actinide group or an alloy thereof.
It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.
What is claimed as this invention is:
1. A process for applying a firmly adherent chromium intermediate layer to the fuel of a fuel element for a nuclear reactor wherein the fuel comprises a U-3.5 Mo0.1 Al alloy member, the step of said process comprising cleaning said uranium alloy member, and [immersing the cleaned uranium alloy member for approximately 1 to 3 minutes into an aqueous solution at a temperature of approximately 20 C.30 C. and a pH value 1, said solution comprising approximately grams per liter of chromium oxide CrO approximately 2.5 grams per liter NaF, approximately 2.5 grams per liter NaCl, approximately 5 cubic centimeters per liter H SO so that a metallic chromium layer is formed on the alloy member by a chemical displacement.
2. A process for applying a firmly adherent chromium intermediate layer to the fuel of a fuel element for a nuclear reactor, said fuel comprising an aetinide metal from the group consisting of uranium, thorium, plutonium and alloys thereof, the steps of said process comprising cleaning said aetinide metal and immersing the cleaned aetinide metal for approximately 1 to 10 minutes in an aqueous solution at a temperature of approximately 20 C. to 40 C. and apH value less than 1, said solution comprising approximately 20 to 200 grams per liter CrO approximately 1 to 100 grams per liter soluble halogen compounds from the group consisting of HCl, HF, NaCl, NaF, HClO HC1O NaClO H'BF and mixtures thereof, and approximately 0.5 to 20 grams per liter soluble sulfate compounds from the group consisting of H and salts thereof whereby said chromium intermediate layer is formed on said aetinide metal by a chemical displacement.
3. The process of claim 2, wherein said aetinide metal is uranium.
4. The process of claim 2, wherein said aetinide metal is the uranium alloy U3.5 Mo0.1 Al.
5. The process of claim 2, wherein the formation of Cr+ ions is prevented by the addition to said solution of a material from the group consisting of lead and alloys thereof.
6. A process for applying a firmly adherent chromium intermediate layer to the fuel of a fuel element for a nuclear reactor, said fuel comprising U3.5 Mo0.1 Al alloy member, the steps of said process comprising cleaning said alloy member, and immersing the cleaned alloy member for approximatley 1 to 3 minutes in an aqueous solution at a temperature of approximately 20 C. to 30 C. and a pH value less than 1, said solution consisting essentially of approximately 70 grams per liter CrO approximately 2.5 grams per liter NaCl and approximately 5 cubic centimeters per liter H 80 whereby said chromium intermediate layer is formed on said alloy member by a chemical displacement.
References Cited by the Examiner UNITED STATES PATENTS 2,114,151 4/1938 Romig 1486.2 2,127,202 8/1938 Boyle 148 6.2 2,507,956 5/1950 Bruno et a1. 1486.2 2,851,766 9/1958 Gray 204-15 X 2,894,884 7/1959 Gray 2041.5
ALFRED L. LEAVITT, Primary Examiner.
REUBEN EPSTEIN, RICHARD D. NEVIUS, R. S.
KENDALL, Assistant Examiners.
Claims (1)
1. A PROCESS FOR APPLYING A FIRMLY ADHERENT CHROMOUM INTERMEDIATE LAYER TO THE FUEL OF A FUEL ELEMENT FOR A NUCLEAR REACTOR WHEREIN THE FUEL COMPRISING A U-3.5 MO-0.1 AL ALLOY MEMBER, THE STEP OF SAID PROCESS COMPRISING CLEANING SAID URANIUM ALLOY MEMBER, AND IMMERSING THE CLEANED URANIUM ALLOY MEMBER FOR APPROXIMATELY 1 TO 3 MINUTES INTO AN AQUEOUS SOLUTION AT A TEMPERATURE OF APPROXIMATELY 20*C.-30*C. AND A PH VALUE <1, SAID SOLUTION COMPRISING APPROXIMATELY 70 GRAMS PER LITER OF CHROMIUM OXIDE CRO3, APPROXIMATELY 2.5 GRAMS PER LITER NAF, APPROXIAMATELY 2.5 GRAMS PER LITER NACL, APPROXIMATELY 5 CUBIC CENTIMETERS PER LITER H2SO4, SO THAT A METALLIC CHROMIUM LAYER IS FORMED ON THE ALLOY MEMBER BY A CHEMICAL DISPLACEMENT.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEJ22948A DE1211465B (en) | 1962-10-27 | 1962-10-27 | Process for the electroless deposition of firmly adhering coatings of chromium on metals or metal alloys of the actinide group, in particular uranium and transuranium elements |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3288636A true US3288636A (en) | 1966-11-29 |
Family
ID=7201198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US289749A Expired - Lifetime US3288636A (en) | 1962-10-27 | 1963-06-21 | Process for coating uranium alloy members |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3288636A (en) |
| DE (1) | DE1211465B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2231771A1 (en) * | 1973-05-29 | 1974-12-27 | Cerca | Corrosion protection of uranium radiation shields - by cleaning surface then electrode positing nickel, zinc, cadmium or nickel-tin alloy |
| US4092217A (en) * | 1973-03-30 | 1978-05-30 | Hochtemperatur-Kernkraftwerk Gmbh (Hkg) Gemeinsames Europaisches Unternehman | Fuel elements for nuclear reactors and method for testing the circulation of fuel elements in a core of a nuclear reactor |
| US4229260A (en) * | 1976-06-02 | 1980-10-21 | The United States Of America As Represented By The United States Department Of Energy | Nuclear reactor fuel element |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2114151A (en) * | 1935-07-09 | 1938-04-12 | American Chem Paint Co | Art of finishing ferrous metal |
| US2127202A (en) * | 1936-06-16 | 1938-08-16 | Clete L Boyle | Rust inhibiting composition |
| US2507956A (en) * | 1947-11-01 | 1950-05-16 | Lithographic Technical Foundat | Process of coating aluminum |
| US2851766A (en) * | 1945-01-09 | 1958-09-16 | Allen G Gray | Plural metallic coatings on uranium and method of applying same |
| US2894884A (en) * | 1945-01-09 | 1959-07-14 | Allen G Gray | Method of applying nickel coatings on uranium |
-
1962
- 1962-10-27 DE DEJ22948A patent/DE1211465B/en active Pending
-
1963
- 1963-06-21 US US289749A patent/US3288636A/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2114151A (en) * | 1935-07-09 | 1938-04-12 | American Chem Paint Co | Art of finishing ferrous metal |
| US2127202A (en) * | 1936-06-16 | 1938-08-16 | Clete L Boyle | Rust inhibiting composition |
| US2851766A (en) * | 1945-01-09 | 1958-09-16 | Allen G Gray | Plural metallic coatings on uranium and method of applying same |
| US2894884A (en) * | 1945-01-09 | 1959-07-14 | Allen G Gray | Method of applying nickel coatings on uranium |
| US2507956A (en) * | 1947-11-01 | 1950-05-16 | Lithographic Technical Foundat | Process of coating aluminum |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4092217A (en) * | 1973-03-30 | 1978-05-30 | Hochtemperatur-Kernkraftwerk Gmbh (Hkg) Gemeinsames Europaisches Unternehman | Fuel elements for nuclear reactors and method for testing the circulation of fuel elements in a core of a nuclear reactor |
| FR2231771A1 (en) * | 1973-05-29 | 1974-12-27 | Cerca | Corrosion protection of uranium radiation shields - by cleaning surface then electrode positing nickel, zinc, cadmium or nickel-tin alloy |
| US4229260A (en) * | 1976-06-02 | 1980-10-21 | The United States Of America As Represented By The United States Department Of Energy | Nuclear reactor fuel element |
Also Published As
| Publication number | Publication date |
|---|---|
| DE1211465B (en) | 1966-02-24 |
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