Classifications

• • 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
  • C25D5/38—Pretreatment of metallic surfaces to be electroplated of refractory metals or nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C11/00—Alloys based on lead
  • C22C11/08—Alloys based on lead with antimony or bismuth as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C16/00—Alloys based on zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/186—High-melting or refractory metals or alloys based thereon of zirconium or alloys based thereon
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F15/00—Other methods of preventing corrosion or incrustation
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F17/00—Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/04—Electroplating: Baths therefor from solutions of chromium
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
• • 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
  • C25D5/48—After-treatment of electroplated surfaces
  • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C17/00—Monitoring; Testing ; Maintaining
  • G21C17/06—Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination
• • 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

• My invention relates to the protection of zirconium and zirconium-base alloys [hereinafter generically called zirconium] against corrosion by external agents at high temperatures.
• zirconium and zirconium-base alloys and particularly those alloys used in nuclear reac tors as cladding materials or in the fabrication of pressure or calandria tubes, have limited applications due to thecorroding action of the coolants, generally, presurized water, carbon dioxide, terphenyl or steam. Furthermore, the fabrication and transformation of the same alloys are diflicult and costly because of the rapid corrosion in air at temperatures above 800 to 900 C.
• zirconium oxide film of 10W ductility is formed on the surface of zirconium. This film has a tendency to thicken and to eventually scale off. Simultaneously with the thickening and scaling off of the zirconium oxide film, oxygen penetrates into the subjacent metal and causes these areas to become brittle. This phenomena is even more pronounced as the temperature increases.
• chromium has shown the greatest advantages. Chromium oxidizes very slowly, is hard, and is resistant to abrasion. It has practically no diffusion into zirconium up to a temperature of approximately 800 C., and only slowly above this temperature. Furthermore, it reacts with zirconium to form a fusible alloy only at approximately 1300 C. Also of importance, is the fact that chromium has a coefficient of expansion very close to that of zirconium.
• the electrolytic bath of my invention comprises an aqueous solution containing:
• the temperature at the bath is maintained near room temperature, for example, between 10 and 30 C.
• the current density is maintained between 5 and 40 A./dm. preferably near 20 A./dm and the bath is stirred.
• the anode is a lead-base alloy anode, preferably a PbSb alloy containing 6-8 percent by weight Sb, and the interpolar distance is preferably between 3 and 200 millimeters.
• my method it is possible to obtain a continuous deposit with a minimum thickness of about 2 microns. For best results, a thickness of from 5 to 15 microns is placed on the zirconium, and it is possible to realize even thicker coatings with my process. Furthermore, my coatings have excellent adhesion.
• the coatings protect zirconium against most of the usual agents brought into contact with it at high temperature and especially against organic coolants. In particular, the coating protects against terphenyls up to around 400-450 C., against air, oxygen, carbon dioxide, up to 700-800 C. for long periods of time.
• the chromium coating applied on the zirconium with my method also protects for short periods of time against air, oxygen, carbon oxides and molten salt baths which have temperatures as high as 1000 to 1200 C. In fact, the coating may protect at these high temperatures up to several hours, Moreover, it is possible to quench the coating in oil or water without any fission or cracking.
• the coatings of the invention protect zirconium and zirconium-base alloys when used at high temperatures, during hot deformations and during thermal treatments in air. In the latter case, the coating deposited according to my invention may be removed after thermal or quenching treatment.
• the electrolysis was carried out at C. with a 20 A./dm. current density.
• the anode was a cylindrical Pb-Sb tube with 6 percent Sb.
• the interpolar distance was between and mm.
• the coated samples were placed in an autoclave containing CO under atmospheric pressure at 700 C. After 3 days, their weight gain was ten times lower than that of identical noncoated cylinders placed under the same conditions.
• EXAMPLE 2 A Zr-Nb sheet with 2.5 percent Nb, and having a dimension of 500 x x 1.5 mm. was used as a cathode in a stirred electrolytic bath of the same composition as that of Example 1.
• the electrolysis was carried out at 15 C. with a 15 A./dm. current density.
• the anode was a Pb-Sn slab with 6 percent Sb.
• the interploar distance was 30 to 40 mm.
• the chromium film was deposited in 25 minutes and was approximately 12 thick.
• the coated sheets were placed in a furnace at 1000 C. in air for 15 minutes, then quenched in water at 25 C. Despite the thermal shock, the chromium coating neither blistered nor scaled, and the coating efficiently protected the alloy during the air treatment at 1000 C.
• EXAMPLE 3 A Zr-Cu tube portion with 2.5 percent copper and being 500 mm. in length, about 13 mm. in outer diameter and about 11 mm. in inner diameter, was utilized. Under conditions similar to those in the previous examples, a chromium film of 10 was deposited by electrolysis on both the inside and outside of the tube.
• the tube was maintained under vacuum for 30 hours at 800 C., then submitted to 40 successive thermal cycles of one hour each, comprising 20 minutes of heating.
• the heating temperature in air was 700 C.
• the cooling temperature was 40 C.
• the strips were placed into an atuoclave containing CO under atmospheric pressure at 700 C. In 6 days, their weight gain was ten times lower than that of noncoated samples of the same alloy placed under similar conditions.
• these tubes were heated in air at 1000 C., in a high frequency induction furnace. After 2 minutes at 1000 C., they were quenched in cold water. Under such conditions the chromium film was neither blistered nor scaled.
• EXAMPLE 6 Tube portions of Zr-Nb alloy with 2.5 percent Nb having a 600 mm. length, a 92 mm. inner diameter and a 98 mm. outer diameter were plated. After the chrome plating, the tubes were immediately introduced into a metal furnace at 900 C., and maintained for 30 minutes at 900 C. and quenched in water at the end of the furnace. It was found that after quenching, the chrome deposited according to the invention was always present, and after a chemical removing of the chrome, the metal was free of oxide pits or defects.
• EXAMPLE 7 A large piece of Zr-Nb (250 x 400 x 75 mm.) having a chromium film of 15 thickness deposited thereon according to the invention, was maintained for 1 hour, in air, at a temperature of 1200" C., prior to being rolled at a high temperature. It was found that the film had protected the piece against oxidation.
• a method for the protection of zirconium and zirconium-base alloys by electrolytic deposition of chromium comprising:
• said bath comprises 500 g./l. CrO 20 to 25 g./l. SrSO and 60 to 65 g./l. K SiF with a current density of 20 A./dm.
• the method of claim 1 including subjecting the coated metal to a vacuum-heat treatment from between 700 and 850 C. to form an intermetallic Cr-Zr compound of up to 5 thick between said coating and zirconium.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Electroplating Methods And Accessories (AREA)
• Electroplating And Plating Baths Therefor (AREA)

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ID=8628973

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Cited By (10)

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Citations (5)

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• 1967
  • 1967-04-17 FR FR102932A patent/FR1527055A/fr not_active Expired
• 1968
  • 1968-02-22 BE BE711125D patent/BE711125A/xx not_active IP Right Cessation
  • 1968-04-10 LU LU55872D patent/LU55872A1/xx unknown
  • 1968-04-13 DE DE19681771162 patent/DE1771162B1/de not_active Withdrawn
  • 1968-04-16 GB GB07951/68A patent/GB1203700A/en not_active Expired
  • 1968-04-16 CH CH554068A patent/CH492029A/fr not_active IP Right Cessation
  • 1968-04-17 NL NL6805383.A patent/NL159729B/xx not_active IP Right Cessation
  • 1968-04-17 US US721935A patent/US3502549A/en not_active Expired - Lifetime

Patent Citations (5)

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