US3753870A - Process for pretreating steel plates for enamelling - Google Patents

Process for pretreating steel plates for enamelling Download PDF

Info

Publication number
US3753870A
US3753870A US00204324A US3753870DA US3753870A US 3753870 A US3753870 A US 3753870A US 00204324 A US00204324 A US 00204324A US 3753870D A US3753870D A US 3753870DA US 3753870 A US3753870 A US 3753870A
Authority
US
United States
Prior art keywords
nickel
enamelling
pickling
metallising
degreasing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00204324A
Other languages
English (en)
Inventor
H Hoffmann
G Trogel
W Immel
E Knaak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer AG
Original Assignee
Bayer AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bayer AG filed Critical Bayer AG
Application granted granted Critical
Publication of US3753870A publication Critical patent/US3753870A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • 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
    • 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

Definitions

  • degreasing is followed in the direct enamelling process by an intensive pickling treatment whose function is to cause etching (pickling loss) in a quantity of from 20 to 40 g. of metal per square metre of surface, depending upon the quality of the steel.
  • Pickling is in turn followed by a nickel plating in which from 1 to 1.5 g. of nickel per square metre are deposited.
  • Degreasing is a particularly important stage in any enamelling process and especially in direct enamelling, being carried out in several stages. Depending on the state in which it is delivered, the steel plate also has to be derusted and then degreased.
  • the entire pretreatment including the necessary rinsing baths, comprises at least eight and, in direct enamelling, at least eleven treatment stages. In most cases, however, the number of stages is even exceeded.
  • neutralising and drying are usually necessary to complete the process. After drying, the enamel frits are applied to the plate in the usual way and after further drying are fired.
  • the residence times in the individual stages amount to about eight minutes in cases where the immersion or dip process is used. Degre'asing can even take two to four times longer. Accordingly, time consumption is considerice able for the completion of an average of seven to twelve pretreatment stages.
  • a process of pretreating steel plate for enamelling by degreasing, pickling, metallising, neutralising and drying has now been found, in which metallisation is carried out galvanically, in an acid magnesium ions containing bath with a nickeland/or cobalt-salt-content of between about 8 and 30 g./l., calculated as metal, nickel and/or cobalt being deposited onto the surfaces to be enamelled in quantities of from about 0.3 to 0.7 g. per square metre, expressed as metal.
  • the galvanically deposited layer of nickel is suitable for both the conventional enamelling processes and the direct enamelling processes. It is also surprising that, instead of or in addition to the nickel, cobalt can also be deposited in a form which ensures firm adhesion of enamel. Hitherto, cobalt has only been used in the form of its oxide in the ground coat as a binder, and satisfactory metallic deposition in pretreatment baths has not been possible. It is known that cobalt is a much more effective component than nickel in ground coat enamels. Accordingly, the process according to the invention enables the enameller optionally to deposit nickel and/or cobalt layers in order to obtain optimum adhesion between the enamel and the substrate according to the prevailing conditions.
  • the galvanically deposited nickel and/or cobalt layers provide the layer of enamel with an excellent surface finish.
  • No special steps have to be taken to carry out the process according to the invention.
  • the containers used in conventional nickel-plating processes for example, of plastics such as polyvinyl chloride or polypropylene, or even rubber coated steel containers, may be used as the tanks.
  • the plate to be pretreated is connected as the cathode in the usual way, whilst pure nickel or cobalt or their alloys are used as anodes.
  • the bath is operated at average current densities of from about 0.3 to 0.8 amps/dm. although it may also be operated at higher current densities in special cases where particularly quick deposition is required. In cases such as these, appropriate measures must be taken to ensure that the workpieces are not burnt or scorched in any way. It is best to use either moving electrolytes of moving electrodes.
  • the baths are best prepared with water-soluble nickel and/or cobalt salts, sulphates and/or chlorides in particular.
  • concentration expressed as metal should amount to between about 8 and 30 g. per litre of bath liquid. It is best not to add any complex formers to the baths, although it can be of advantage to add boric acid or other butler substances in such quantities that the pH value of the baths does not exceed a value of 7.
  • the baths can be operated at pH values of from 7 to 1, pH values of from 3.5 to 6 being preferred. Most of the metal should be present in substrate form.
  • chlorides are with advantage added to the baths, preferably in quantities of from 3 to 20 g. of Cl/litre.
  • the chloride ions can be introduced in the form of metal chlorides or as alkali metal chlorides, including ammonium chlorides. Deposition of the nickel and/or cobalt is further promoted by the presence in the baths of magnesium ions. Very small quantities of from 0.1 to 10 g. Mg. per litre are sufficient. Larger quantities are not harmful because the magnesium is not deposited and only indirectly affects the form in which the nickel and/or cobalt is deposited along the required lines.
  • the magnesium is introduced in the form of the water-soluble salts, preferably in sulphate and/or chloride form.
  • the baths can be used for an almost unlimited period providing impurities are not entrained into them by the workpieces introduced. There is no need for regeneration as the nickel or cobalt concentration is automatically adjusted to the required level because as much nickel or cobalt from the electrodes is dissolved in the bath as is deposited on to the metal surfaces to be treated.
  • insoluble anodes for example of platinum, titanium, graphite and so on, but only at the expense of one advantage of the process according to the invention over conventional processes, because the metal salt concentration not only has to be replenished during operation but also has to be checked.
  • the process according to the invention is not only suitable for pretreatments completely carried out by the dip process.
  • the electrolytic dip-metallising process affords special advantages when combined with processes in which the remaining pretreatment stages are carried out in spraying machines. In this case, the basically short pretreatment times in the spraying machines can be maintained or made even shorter in the metallisation stage also. Accordingly, the process can readily be incorporated into already existing spraying plants so that these too can readily be used for direct enamelling.
  • the process according to the invention is suitable for any type of enamelling.
  • conventional enamelling i.e. in cases where ground coat enamels are used, the quantity of oxide binders in the frits can be considerably reduced.
  • lt is a major advantage of the process according to the invention that the absolute quantity of binders in the form of nickel and/or cobalt can be reduced because, through their deposition in metal form on to the objects to be enamelled, these adhesion promoters are able to act much more effectively.
  • the process according to the invention is of particular advantage in cases where loW- melting enamels with firing temperatures below 760 C.
  • the process according to the invention can replace all hitherto described nickel-plating processes in pretreatment for direct enamelling. Both low-carbon and normal enamelling steels can be pretreated.
  • the present nickel-plating process does not require any special enamel frits. All the hitherto known ground coating and covering or surfacing enamels, including in particular borontitanium white enamel, are suitable, governed of course by the usual limitations in terms of materials and processing techniques. It has also been found that it can be advisable in some cases to carry out a thin-phosphate treatments after the usual pickling treatment and before galvanic nickel plating.
  • the pickled and rinsed plates are immersed in a solution which contains non-layer forming phosphates, preferably magnesium phosphate. It has proved to be of particular advantage to use I to 5% solutions of magnesium dihydrogenphosphate.
  • the phosphating treatment is able to correct differences in the behaviour of dilferent types of steel.
  • the pickling is optionally performed with current densities of between 2 and 20 a./dm. in acid sulphate and/or phosphate containing solution at temperatures of between 40 and C. Normally a pickling time of 3 minutes is sufficient with a pickling loss of about 20 g./l. of iron per 111. with decarburised steel.
  • the SO -ion concentration, expressed as sulphate should amount to between 2 and 25% by weight, and the PO -ion concentration, expressed as phosphate, to between 2 and 20% by weight.
  • the sulphate ions can be introduced in the form of sulphuric acid, alkali metal sulphates and/or alkali metal bi-sulphates.
  • alkalins preferably sodium and/or potassium
  • magnesium sulphate or the bi-sulphate of magnesium can be present in the form of phosphoric acid, alkali metal phosphates, magnesium phosphates, alkali metal phosphates, alkali metal dihydrogen phosphates, magnesium hydrogen phosphate and/or magnesium dihydrogen phosphate. It has been proved to be particularly suitable to use a bath containing about 1 to 5% by weight of magnesium dihydrogen phosphate.
  • Phosphate-containing baths are generally of advantage because they have a favourable effect upon the subsequent metallising stage, especially the nickel-plating of the plates to be enamelled.
  • Phosphate-containing baths have the further advantage that the iron which is dissolved during pickling is cathodically deposited. The service life of the baths is considerably lengthened in this way.
  • the process is suitable for both low-carbon and normal steels. In either case, firmly adhering direct enamel finishes are obtained by the pickling process according to the invention in conjunction with the other necessary pretreatment stages.
  • the longer service life of the baths affords another advantage, i.e. it enables some of the pressure to be taken off the effluent purification plants.
  • a further improvement in the process is obtained by combining the electrolytic pickling according to the invention, and, optionally, the electrolytic degreasing stage with a galvanic metallisation stage following the pickling stage.
  • the oxide binder contents had to be increased for the described pretreatment in the frit of the above composition from 0.3% of C00 of 0.6% of C00 and from 0.7% of NiO to 1.5% of NiO. If, however, pickling was followed by treatment with a galvanic metallising bath according to the invention of the following composition: CoSO -7H O 30 g./litre, (NH SO 60 g./litre, NiSO -7H O 30 g./litre, NH Cl g./litre, H BO anhydrous 12 g./litre, MgSO -7H O 12 g./litre, the remainder being water made up to 1 litre and binder metal was applied to the metal surface with this bath in a quantity of 0.2 to 0.3 g. of metal per square metre of surface at a current density of 0.45 a./dm. it was possible to obtain 100% adhesion even with the frit of low oxide binder content.
  • EXAMPLE 2 A steel plate of the above analysis was subjected to alkaline degreasing, rinsed first hot and then cold, pickled in 9% sulphuric acid and then electrolytically degreased in accordance with the invention.
  • a bath of the composition 80 g. of NiSO -7H O, 10 g. of NH Cl, 20 g. of MgSO -7H O, 5 g. of anhydrous H BO the remainder being water made up to 1 litre, nickel was deposited in a quantity of approximately 0.3 g. of Ni/sq. metre of surface at a pH value of from 5.3 to 5.7 and at a current density of 0.5 a./dm.
  • the plates were coated in the usual way with an NiO- free primer enamel of the composition: 38.7% of SiO 7% of A1 0 22% of B 0 25% of alkali metal oxides,
  • EXAMPLE 3 A decarburisecl steel plate of the composition: C 0002-0003, Mn 0.32, P 0.015, S 0.025, Si 0.01, Cu 0.03, was pretreated in the manner usual for direct enamelling, subjected to alkaline degreasing, intensively pickled (erosion 25 g./m. of surface area) and then nickel-plated. Nickel plating was carried out in accordance with the invention, i.e. electrolytically in a bath of the composition 70 g. of NiSO -7H O, 15 g. of NH Cl, 12 g. of MgSO -7H O', 7 g.
  • H BO anhydrous H BO the remainder being water made up to 1 litre at pH 5.5 and at a current density of 0.7 a./dm.
  • the nickel was applied in a quantity of 0.5 g. of nickel per square metre of surface area.
  • the plate was then directly coated with a boron-titanium white enamel of the composition 38% of Si0 0.5% of A1 0 21% of B 0 15% of alkali metal oxide, 2% of fluoride, 19% of TiO 0.5% of MgO, 3% of P 0 and the enamel was fired at 820 C. Both the adhesion and the finish of the direct enamel coating were outstanding.
  • Normal enamelling steels can also be similarly pretreated for direct enamelling providing special acid mixtures for example, 15 to 20% of H 1 to 3% of HNO and 2 to 4% of urea, are used instead of the 9% sulphuric acid.
  • magnesium ions in an amount in the range of 0.1

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
US00204324A 1968-10-10 1971-12-02 Process for pretreating steel plates for enamelling Expired - Lifetime US3753870A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1802182A DE1802182C3 (de) 1968-10-10 1968-10-10 Verfahren zur Vorbehandlung von Stahlblechen für Emaillierungen
US20432471A 1971-12-02 1971-12-02

Publications (1)

Publication Number Publication Date
US3753870A true US3753870A (en) 1973-08-21

Family

ID=25756236

Family Applications (1)

Application Number Title Priority Date Filing Date
US00204324A Expired - Lifetime US3753870A (en) 1968-10-10 1971-12-02 Process for pretreating steel plates for enamelling

Country Status (8)

Country Link
US (1) US3753870A (enrdf_load_html_response)
AT (1) AT299650B (enrdf_load_html_response)
BE (1) BE740104A (enrdf_load_html_response)
CH (1) CH535838A (enrdf_load_html_response)
DE (1) DE1802182C3 (enrdf_load_html_response)
FR (1) FR2020356A1 (enrdf_load_html_response)
GB (1) GB1289335A (enrdf_load_html_response)
NL (1) NL166986C (enrdf_load_html_response)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3927460A (en) * 1972-08-07 1975-12-23 Kawasaki Steel Co Pretreating process for vitreous enamelling
GB2281310A (en) * 1993-08-31 1995-03-01 Bosch Gmbh Robert Method of electrolytic cleaning of metal parts, using a cyanide-free bath containing phosphate in aqueous solution
US5766374A (en) * 1995-09-28 1998-06-16 Sollac Process for preparing the metal surface of an article, especially one made of steel sheet, for direct-on enameling
US6199263B1 (en) 1997-03-21 2001-03-13 Sollac Process for preparation of an article made of enameled sheet steel by a direct method
US7514153B1 (en) 2005-03-03 2009-04-07 The United States Of America As Represented By The Secretary Of The Navy Method for deposition of steel protective coating
WO2020193307A1 (de) * 2019-03-27 2020-10-01 Robert Bosch Gmbh Vorbehandlungsverfahren zum vorbehandeln von bauteilen vor einem galvanischen beschichten

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE390299B (sv) * 1973-10-01 1976-12-13 Bofors Ab Sett och anordning att torka vatt krut i en ram med perforerade sidor
US4268429A (en) * 1975-07-18 1981-05-19 General Electric Company Novel flame retardant polycarbonate compositions
DE19743461A1 (de) * 1997-10-01 1999-04-08 Buehler Ag Trockner-Wärmetauscher

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1975818A (en) * 1932-08-24 1934-10-09 Aluminum Co Of America Coating for pistons
GB459887A (en) * 1935-07-18 1937-01-18 Max Schloetter Improvements in nickel plating
US2581310A (en) * 1951-11-06 1952-01-01 Ferro Corp Porcelain enamel article and method of producing same
BE529496A (enrdf_load_html_response) * 1953-06-11 1954-06-30
FR1286330A (fr) * 1960-04-13 1962-03-02 Perfectionnements apportés au traitement de l'acier doux

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3927460A (en) * 1972-08-07 1975-12-23 Kawasaki Steel Co Pretreating process for vitreous enamelling
GB2281310A (en) * 1993-08-31 1995-03-01 Bosch Gmbh Robert Method of electrolytic cleaning of metal parts, using a cyanide-free bath containing phosphate in aqueous solution
US5766374A (en) * 1995-09-28 1998-06-16 Sollac Process for preparing the metal surface of an article, especially one made of steel sheet, for direct-on enameling
US6199263B1 (en) 1997-03-21 2001-03-13 Sollac Process for preparation of an article made of enameled sheet steel by a direct method
US7514153B1 (en) 2005-03-03 2009-04-07 The United States Of America As Represented By The Secretary Of The Navy Method for deposition of steel protective coating
US7803428B1 (en) 2005-03-03 2010-09-28 The United States Of America As Represented By The Secretary Of The Navy Method for deposition of steel protective coating
WO2020193307A1 (de) * 2019-03-27 2020-10-01 Robert Bosch Gmbh Vorbehandlungsverfahren zum vorbehandeln von bauteilen vor einem galvanischen beschichten
JP2022525782A (ja) * 2019-03-27 2022-05-19 ロベルト・ボッシュ・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング 電気めっき被覆前に部品を前処理する前処理方法
US12249810B2 (en) 2019-03-27 2025-03-11 Robert Bosch Gmbh Pretreatment method for pretreating components prior to electroplating

Also Published As

Publication number Publication date
DE1802182C3 (de) 1979-05-31
NL166986C (nl) 1981-10-15
DE1802182B2 (de) 1974-06-12
AT299650B (de) 1972-06-26
GB1289335A (enrdf_load_html_response) 1972-09-13
BE740104A (enrdf_load_html_response) 1970-04-10
CH535838A (de) 1973-04-15
NL166986B (nl) 1981-05-15
FR2020356A1 (enrdf_load_html_response) 1970-07-10
DE1802182A1 (de) 1970-04-23
NL6915235A (enrdf_load_html_response) 1970-04-14

Similar Documents

Publication Publication Date Title
EP1571237B1 (en) Treating fluid for surface treatment of metal and method for surface treatment
JPS6136588B2 (enrdf_load_html_response)
US3753870A (en) Process for pretreating steel plates for enamelling
EP0060716A1 (en) Phosphating metal surfaces
CH661529A5 (it) Procedimento per la protezione di laminati piani di acciaio zincato mediante rivestimento elettrolitico multistrato.
NO873904L (no) Sjiktdannende passivering ved multimetallfremgangsmaate.
JPH0813154A (ja) 塗装性に優れた亜鉛含有金属めっき鋼板複合体、およびその製造方法
US3840441A (en) Pickling of steel plates prior to nickel plating and coating
US4220486A (en) Conversion coating solution for treating metallic surfaces
US3454483A (en) Electrodeposition process with pretreatment in zinc phosphate solution containing fluoride
EP0030305B1 (en) Chemical pretreatment for method for the electrolytical metal coating of magnesium articles
US5707505A (en) Method for the electrophoretic dip coating of chromatizable metal surfaces
CN104313562A (zh) 一种常温磷化液及其制备方法
US4867853A (en) Process of producing phosphate coatings
US5688340A (en) Preparation of metal surfaces for vitreous enameling
JPS6141987B2 (enrdf_load_html_response)
US2768904A (en) Vitreous enameling process
US5108554A (en) Continuous method for preparing steel parts for resin coating
KR100402730B1 (ko) 마그네슘합금에 동-니켈 도금층을 전해 도금으로 형성하는방법
GB1583194A (en) Phosphating of metallic substrate
US3523067A (en) Selective galvanizing of steel strip
US3725218A (en) Process for pretreating decarbonized steel to be directly enamelled
US4547269A (en) Method of electrodepositing zinc on steel prior to phosphating
JPS63274797A (ja) 化成処理性の優れたＺｎ系電気めっき鋼板の製造方法
PL124218B1 (en) Process for wasteless metallizing,especially zinc coating of steel surface