Classifications

• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/044—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material coatings specially adapted for cutting tools or wear applications
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/048—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material with layers graded in composition or physical properties
• • 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
  • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
  • C23D5/00—Coating with enamels or vitreous layers

Definitions

• the present invention relates to the manufacture of a metal part coated with mineral materials.
• the invention relates to the manufacture of a metal part coated with a mineral coating based on silica and sodium oxide.
• the mineral coating constitutes an effective protection of the metal part and has good chemical inertness with respect to a fluid in contact with it.
• the object of the invention is to obtain a metal part whose coating which provides a protective role and chemical inertness, is adhered to the substrate, and has few open porosities so as to form a passive barrier between the fluid and the substrate.
• the first coating layer must be sufficiently covering to form an antioxidant film and said layer must be thin enough to allow degassing and decantation of the gas bubbles resulting from the reaction between the first layer and the metal.
• a first coating layer with a thickness of less than 200 ⁇ m is produced.
• the production of the first coating layer is carried out by application of the mineral material in powder form, in particular a dry powder. .
• the fluidity of the mineral material must be adapted to ensure a fusion of the powder, necessary for coating the substrate and for adhesion to the substrate, and for limiting the chemical reactions between the substrate and the first coating layer.
• a reducing substrate such as cast iron
• a first layer of oxidizing coating present a risk of redox reaction with degassing and appearance of blisters.
• a composition that is too fluid can cause a flow of the coating, with the defects that would follow, loss of the covering appearance and oxidation of the substrate.
• An insufficiently fluid composition will not allow good melting of the powder, and therefore a lack of adhesion and poor coverage, hence a risk of oxidation of the substrate.
• Oxidation of the substrate is particularly marked during heat treatments at high temperature.
• the fluidity of the composition largely depends on the silica content and the content of fluxes.
• the mineral material applied to form the first coating layer is an enamel having the following composition by weight:
• the first coating layer with a thickness of 100 ⁇ m is produced.
• the second coating layer is produced by applying the mineral material in the form of dry powder.
• the second coating layer is produced by applying a slip of the mineral material.
• the slip is a very fluid mixture of finely ground mineral material and water with various adjuvants such as antioxidants and suspending agents.
• the second coating layer of mineral material In order to absorb the first coating layer, to dissolve the skin of iron oxides formed on the surface of the metal substrate, when the latter consists of a ferrous metal, and to cause a surface attack on the substrate, the second coating layer of mineral material by application of said mineral material which is an enamel of the following composition by weight:
• the second coating layer is produced at a thickness greater than 100 ⁇ m. To prevent the second coating layer from being too porous, it is produced at a thickness of 200 ⁇ m.
• a coating is produced on the surface of the part of revolution by application.
• the third layer is produced by applying an enamel having the following composition by weight:
• the third layer is produced at a thickness greater than 100 ⁇ m. In order to obtain a good fusion on deposit, the third layer is produced at a thickness of 200 ⁇ m.
• the manufacture of tubular cast iron parts coated with glass is known (see for example document FR-2 297 817 in the name of the Applicant).
• This process makes it possible to deposit the coating during the manufacture of the metallic piece of revolution and to take advantage of the thermal energy of the metal to achieve the melting of the first layer.
• the subject of the invention is also a hollow metal part of revolution, coated on the internal part of its surface with mineral materials, this part being manufactured in accordance with the method described above.
• the invention makes it possible to transport aggressive fluids without the characteristics of these fluids being altered or the hollow part of revolution being deteriorated.
• the invention also relates to the use of the part obtained according to the process defined above for the transport of aggressive fluids.
• the present invention is represented by an exemplary implementation applied to an element of water supply or sanitation piping in ductile iron, illustrated by appended figures, in which: - Fig. 1 shows in perspective a pipe element obtained -i according to the method of one invention;
• - Fig. 2 is a micrograph at 100 magnification of the enamel coating with the joint area of the cast iron substrate of the piping element shown in FIG. 1.
• the liquid iron undergoes a magnesium treatment then an inoculation.
• the inoculation of the cast iron is carried out using an inoculant such as ferro-silicon introduced into the liquid cast iron in the form of powder or wire, in known manner, for example the document FR-A-2 546 783 in the name of the Applicant.
• the method includes an operation of centrifuging the cast iron. During the centrifugation operation, the first layer 4 of coating 2 is produced at a thickness of 100 ⁇ m, by application of a reduced enamel of the following composition:
• the pipe element 1 After the centrifugation operation, the pipe element 1 is graphitized. Then, the second coating layer 5 2 is produced at a thickness of 200 ⁇ m, by applying an enamel in powder form, said enamel being of the following composition by weight: Si0 2 balance CaO + MgO 0.5% Li 2 0 4%
• the second coating layer 5 is applied to the piping element 1 at a temperature between 800 ° and 700 ° C.
• the piping element 1 is ferritized in a temperature range of less than 800 ° C., which ensures the baking of the second coating layer 2.
• the third coating layer 6 is produced with a thickness of 200 ⁇ m by application of enamel in the form of powder of composition identical to the composition of the enamel of the second layer 5 of coating 2 presented above. This powder is deposited on the pipe element 1 at a temperature below 800 ° C.
• the third layer is glazed, that is to say a firing of a duration of less than five minutes at a temperature between 750 ° C and 700 ° C.
• the cast iron obtained after centrifugation is a gray perlitic cast iron with spheroidal graphite.
• the process then differs from that described above in that there is no graphitization of the piping element 1.
• the second coating layer 5 during or after the centrifugation operation, by depositing the enamel in the form of a dry powder.
• the pipe element is subsequently subjected to a ferritization treatment in a temperature range of less than 800 ° C., and the baking of the second layer 5 coating 2 takes place simultaneously with the ferritization of the piping element 1.
• the cast iron obtained after centrifugation is a gray ferritic cast iron with spheroidal graphite.
• the method then differs from the method of the first variant in that there is no ferritization of the piping element 1 and that the second coating layer 5 of coating 2 is baked at a temperature included between 800 ° and 700 ° C of said element 1 after the application of the second coating layer 5 2.
• the method differs from that initially described in that the enamel is deposited in the form of a slip to produce the second layer 5 of coating 2, after graphitization and while the pipe element 1 is at room temperature.
• the method differs from the first variant in that the enamel is deposited in the form of a slip after centrifugation and while the piping element is at ambient temperature.
• the third enamel layer is deposited in the form of a slip while the pipe element 1 is at ambient temperature.
• the pipe element 1 obtainable by the process according to the invention, including the five variants described above, is a ductile iron pipe 3 having on the internal part of its surface a coating 2 of enamel consisting of three layers 4, 5, 6.
• This pipe has at one end a plain end 8 and at its other end a socket 7 adapted to receive the plain end of another identical pipe.
• the micrograph of the enamel coating 2 on a joint area of the cast iron substrate represents the substrate, the interface between the substrate 3 and the coating 2, the second layer 5 of coating 2 and the third layer 6 coating 2.
• the substrate 3 is a ferritic cast iron with spheroidal graphite. At the level of the interface between the substrate and the coating, the oxide skin was dissolved.
• the first coating layer 4 2 has been absorbed by the second coating layer 5 2.
• the interface between the coating and the cast iron substrate 3 is consistent, and has few porosities. The localized surface attack of the substrate leads to the formation of anchoring sites for the coating 2.
• the second layer 5 has a limited porosity.
• the third coating layer 6 2 does not show any decohesion with the second coating layer 5 2. It has a very low porosity, forms a smooth surface and achieves very good closure of the coating.
• the method according to the invention makes it possible to coat even oxidized metal parts which have an adherent oxide skin with a thickness of less than 20 ⁇ m.
• the invention allows a gain in productivity and in thermal energy.
• the invention makes it possible to eliminate one or more specific stages of firing the enamel.
• Variants of the process in which the application of the enamel is in the form of a slip make it possible to obtain great flexibility in production.
• the pipes obtained make it possible to carry out transport lines for aggressive fluids, such as acid solutions, solutions with a high content of dissolved C0 2 , abrasive fluids, industrial discharges, waste water or sewage sludge.
• aggressive fluids such as acid solutions, solutions with a high content of dissolved C0 2 , abrasive fluids, industrial discharges, waste water or sewage sludge.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Glass Compositions (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Laminated Bodies (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Chemically Coating (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Priority Applications (10)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9444591

Family Applications (1)

Country Status (22)

Citations (7)

• 1993
  • 1993-02-26 FR FR9302419A patent/FR2701963B1/fr not_active Expired - Fee Related
• 1994
  • 1994-02-22 SI SI9400090A patent/SI9400090A/sl unknown
  • 1994-02-23 CZ CZ952134A patent/CZ284752B6/cs not_active IP Right Cessation
  • 1994-02-23 WO PCT/FR1994/000197 patent/WO1994019511A1/fr active IP Right Grant
  • 1994-02-23 RU RU95119995A patent/RU2131483C1/ru active
  • 1994-02-23 AT AT94907607T patent/ATE193906T1/de not_active IP Right Cessation
  • 1994-02-23 DE DE69424933T patent/DE69424933T2/de not_active Expired - Lifetime
  • 1994-02-23 BR BR9406163A patent/BR9406163A/pt not_active IP Right Cessation
  • 1994-02-23 TR TR00169/94A patent/TR28278A/xx unknown
  • 1994-02-23 PL PL94310406A patent/PL310406A1/xx unknown
  • 1994-02-23 CA CA002157008A patent/CA2157008A1/fr not_active Abandoned
  • 1994-02-23 ES ES94907607T patent/ES2147572T3/es not_active Expired - Lifetime
  • 1994-02-23 AU AU61113/94A patent/AU678818B2/en not_active Ceased
  • 1994-02-23 SK SK1042-95A patent/SK104295A3/sk unknown
  • 1994-02-23 HU HU9502510A patent/HUT72451A/hu unknown
  • 1994-02-23 EP EP94907607A patent/EP0686212B1/de not_active Expired - Lifetime
  • 1994-02-24 TN TNTNSN94019A patent/TNSN94019A1/fr unknown
  • 1994-02-25 HR HR9302419A patent/HRP940138A2/xx not_active Application Discontinuation
  • 1994-02-25 ZA ZA941307A patent/ZA941307B/xx unknown
  • 1994-02-28 EG EG11394A patent/EG20502A/xx active
• 1995
  • 1995-08-24 BG BG99883A patent/BG99883A/xx unknown
  • 1995-08-25 NO NO953355A patent/NO953355D0/no not_active Application Discontinuation

Patent Citations (7)

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