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)
• Chemical Treatment Of Metals (AREA)
• Electroplating Methods And Accessories (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=7201198

Family Applications (1)

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Cited By (3)

Citations (5)

• 1962
  • 1962-10-27 DE DEJ22948A patent/DE1211465B/de active Pending
• 1963
  • 1963-06-21 US US289749A patent/US3288636A/en not_active Expired - Lifetime

Patent Citations (5)

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