Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
  • C21D3/02—Extraction of non-metals
  • C21D3/04—Decarburising
• • 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
  • C23D3/00—Chemical treatment of the metal surfaces prior to coating
• • 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
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/03—Use of materials for the substrate
  • H05K1/05—Insulated conductive substrates, e.g. insulated metal substrate
  • H05K1/053—Insulated conductive substrates, e.g. insulated metal substrate the metal substrate being covered by an inorganic insulating layer

Definitions

• ABSTRACT OF THE DISCLOSURE Process for pretreating decarbonized steel to be directly enamelled and in particular fiat pieces of steel to be used as linings for hearths and refrigerators in which following the purification and etching of the steel work piece, an adhesive coating layer is applied comprising the steps of subjecting such steel work piece to a boiling degreasing, then to an electrolytic alkaline degreasing, a rinsing, an electrolytic etching using a sulfuric acid electrolyte, a rinsing an electrolytic application of an adhesive metal coating, a rinsing, neutralization and a drying.
• This invention relates to a process for pretreating decarbonized steel prior to the direct enamelling of the same and more particularly relates to a process for pretreating decarbonized fiat pieces of steel as for instance the lining sheets for forges, hearths, refrigerators and the like in which after the purification or refining and etching of the steel work piece an adhesive met-a1 coating is applied thereto.
• a process is already known for pretreating iron articles having a carbon content of at most 0.15% for improving the adhesiveness of a subsequently applied enamel coating in accordance with which the iron article or work piece is subjected to a treatment in an electrolytic purifying or refining bath using a current density of 1M a./cm. for a period of 30 seconds.
• the electrolytically purified article is electrolytically etched with sulfuric acid of 50 B. for a period of 30 seconds using a current density of 5M a./cm.
• a further disadvantage of applying the adhesive metal coating layer by chemical means lies in that the bath temperature required for the nickel exchange amounts to at least 80 C. necessitating a high energy consumption. Further, the chemical application of adhesive metal coatings does not make it possible to keep the back or reverse side of the iron work piece which is not to be provided with enamel, free of the adhesive metal coating. This situation is not only economically disadvantageous but also has technical disadvantages. Because of the finely distributed adhesive metal precipitate formed on the unprotected reverse side of the work piece, there arises through local element formation, an increased susceptibility to corrosion. The chemical adhesive metal layering process is further associated with high costs for chemicals, short periods of stability of the baths and the need to provide regeneration equipment, etc.
• the electrolytic nickel coating step as carried out in this process takes place in a nickel cyanide or in a nickel ammonium cyanide bath or in a dilute solution of a somewhat altered Watts bath.
• the electrolyte consists in this case of at least nickel sulfate and nickel chloride in aqueous solution.
• the current density as used in the electrolytic nickel coating step amounts to- 2.1 to 3.2 a./dm.
• Still another object of the invention is to provide such a method particularly adapted for use with decarbonized steel work pieces.
• the steel work pieces to be treated prior to the enamelling thereof are first subjected to a boiling degreasing or scouring, followed by an electrolytic degreasing or scouring, and after a rinsing to an electrolytic etching in sulfuric acid. After a further rinsing of the etched work piece, the electrolytic adhesive layer formation is carried out and is followed by the conventional rinsing, neutralization and drying steps.
• the work piece and specifically the decarbonized steel work piece is subjected to a boiling degreasing, then to an electrolytic alkaline degreasing, rinsing, electrolytic etching in sulfuric acid, rinsing, electrolytic application of an adhesive metal coating layer, rinsing, neutralization and drying.
• the electrolytic boiling alkaline degreasing is carried out using a current density of about a./ dm.
• the electrolytic etching is carried out using a dilute sulfuric acid solution as electrolyte and a current density of about 12 a./dm.
• Still a further embodiment of the invention lies in carrying out the electrolytic adhesive metal coating step in an ammonium Ni(II) sulfate bath at a temperature of about 20 C. and a current density of 1.0 to 3.0 a./dm.
• the advantage of the process of the invention lie in the decreased costs for chemicals and also for alkalies required to be used in the adhesive metal layer deposition and in the etching steps. Also the stability of the baths involved is increased. It is also important that only nontoxic electrolyte solutions are used. Still another advantage is that the formation of the adhesive metal layers take place at room temperature whereby energy costs are reduced.
• the electrolyte used in the nickel coating step is composed of only one substance which considerably simplifies matters.
• the process of the invention further makes possible the application of the adhesive metal layer to one side only of the work piece whereby in addition to the attendant economic advantages, a lowered susceptibility to corrosion of the enamel free reverse side of the work piece is achieved. Still further through the use of chlorine free nickel electrolytes the waste or defective pieces obtained in the enamelling are significantly lowered.
• EXAMPLE A steel plate having a content of 0.005% carbon was treated by the process of the invention.
• the steel plate was treated so that only one side thereof was prepared for, i.e., pretreated for subsequent enamelling.
• the treatment of one side was realized by arranging the opposite electrodes with respect to one another so that the side of the steel sheet to be subsequently enamelled faced in wardly and toward the other electrode.
• both sides of the steel plate it is also possible in accordance with the invention for both sides of the steel plate to be simultaneously pretreated so as to prepare both sides for subsequent enamelling.
• an electrolytic alkaline degreasing treatment was carried out in a 4% boiling Siliron KE solution within one minute and at a current density of 5 a./dm.
• the steel plate to be treated served as the anode.
• a rinsing with water was thereafter carried out at a temperature of 50 C. within a five minute period. This was followed by a one minute cold water rinsing step.
• the etching step was conducted using a sulfuric acid which had a temperature of 75 C. and was carried out over a period of 0.5 minute, the necessary metaletching being achieved in that time.
• the current density amounted to 12 a./dm. for the etching step and again the work piece constituted the anode.
• a five minute cold water rinsing step was then carried out afterwhich the electrolytic nickelizing took place.
• the work piece was now the cathode.
• electrolyte there was used a solution containing 50 g. ammonium Ni(II) sulfate per liter.
• the electrolytic adhesive metal coating step was carried out at room temperature using a current density of 1.5 a./dm. in a constantly stirred bath within about one minute. After the electrolytic adhesive metal coating had been completed, a one minute cold water rinsing was carried out and was followed by the passivating and drying steps.
• Process for the pretreatment of decarbonized steel prior to the enamelling thereof which comprises subjecting a decarbonized steel metal work piece to the following steps in the sequence indicated: (1) boiling degreasing, (2) electrolytic alkaline degreasing, (3) rinsing of the degreasing steel work piece, (4) electrolytic etching in sulfuric acid, (5) rinsing of the etched work piece, (6) electrolytic adhesive metal coating in an ammonium Ni(II) sulfate bath of concentration about 50 g./l. and temperature of 20 C. and at a current density of 1.0-3.0 a./dm. and for a period of about 1 minute thereby to deposit finely divided nickel on the work piece, (7) rinsing, (8) neutralizing and (9) drying.
• step 2 Process according to claim 1 wherein the electrolytic alkaline degreasing step (step 2) is carried out at a current density of about 5 a./dm.
• step 4 Process according to claim 1 wherein the electrolytic etching (step 4) is carried out with a dilute sulfuric acid solution and using a current density of about 12 a./dm.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Electrochemistry (AREA)
• Electroplating Methods And Accessories (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=27179760

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (1)

• 1970
  • 1970-12-31 GB GB6195170A patent/GB1333259A/en not_active Expired
• 1971
  • 1971-01-15 FR FR7101342A patent/FR2092331A5/fr not_active Expired
  • 1971-02-08 DE DE19712103766 patent/DE2103766A1/de active Pending
  • 1971-02-08 CH CH180071A patent/CH563463A5/xx not_active IP Right Cessation
  • 1971-02-11 US US00114705A patent/US3725218A/en not_active Expired - Lifetime
  • 1971-03-31 SE SE04212/71A patent/SE367660B/xx unknown

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