US3850137A - Apparatus for use in processes for producing coatings on surfaces - Google Patents

Apparatus for use in processes for producing coatings on surfaces Download PDF

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Publication number
US3850137A
US3850137A US00285313A US28531372A US3850137A US 3850137 A US3850137 A US 3850137A US 00285313 A US00285313 A US 00285313A US 28531372 A US28531372 A US 28531372A US 3850137 A US3850137 A US 3850137A
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Prior art keywords
liquid composition
liquid
source
strip
station
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Expired - Lifetime
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US00285313A
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English (en)
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M Prust
W Glassman
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Individual
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Individual
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Priority to US00285313A priority Critical patent/US3850137A/en
Priority to CA179,884A priority patent/CA990501A/en
Priority to AU59819/73A priority patent/AU475398B2/en
Priority to FR7331339A priority patent/FR2198392A5/fr
Priority to BE135170A priority patent/BE804287A/fr
Priority to IT52260/73A priority patent/IT990434B/it
Priority to JP48098153A priority patent/JPS49100158A/ja
Priority to DE19732343997 priority patent/DE2343997A1/de
Priority to GB4116773A priority patent/GB1425379A/en
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Publication of US3850137A publication Critical patent/US3850137A/en
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    • 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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals

Definitions

  • the conversion coating usually is formed by applying a suitable aqueous solution containing chromium to the zinc or cadmium surface, the solution reacting with the surface to form a thin gel-like film of complex chromates.
  • Thefilm is substantially non-porous to moisture, and also is non-crystalline, so that it provides an adequate paint bond. Examples of processes for producing such a coating are given in US. Pat. No. 3,457,124, issued July 22, 1969 to Cowles Chemical Company, the solution including specified amounts selected from sodium dichromate, chromic acid,sulfamic acid, ammonium sulphate, boric acid, sodium silicofluoride and nitric acid.
  • apparatus for the application of a liquid composition to a surface of a moving strip at an application station comprising means for moving the strip through the liquid application station, applying means at the station for applying the liquid composition and a rinse liquid to the surface, a source of the liquid composition to be applied, feeding means. operative to feed rinse liquid from the source thereof to the applying means.
  • An aqueous solution comprising a composition in accordance with the invention is stored in a tank 14 and fed from there via pump 15, valve 16, pipe 17, automatically controlled valve 18 and header 19 to two sets of spray nozzles 20, which are disposed above and below the strip and direct sprays of the liquid on to the surfaces thereof. Excess liquid that runs from the strip is collected by a catch basin 21 and returned to the tank 14 via automatically controlled valve 22, valve 23 and pipe 24.
  • a second tank 25 at a higherlevel than tank 14 contains rinse water which can be fed when required to the spray nozzles 20 via pump 26, pipe 27 and automatically controlled valve 28.
  • the rinse liquid draining from the strip is' received by the catch basin 21 and returned to the tank 25 via an automatically controlled valve 29, valve 30 and pipe 31.
  • the tank I4 is heated and maintained at the required elevated temperature by any convenient means, which are not illustrated, and the tanks 14 and 25 are connected by a pipe 32 and valve 33 to permit the contents of tank 25 to be used as make-up water for the liquid in tank 14 when needed.
  • the contents of tank 25 (the temperature of which may also be controlled if required) are replenished when required from any suitable source of demineralized water via a pipe 34 including valve 35.
  • the strip 10 unwinding from its supply reel passes at substantially constant. speed through the station where it is sprayed with liquid from the tank 14. Excess liquid is removed from the strip, and some control of the thickness of the resultant protective coating is provided by the pressure rollers 13, which are pressed intp contact with one another at a predetermined pressure by air-operated motors 36;
  • the speed of movement of the strip, and the distance between the nozzles 20 and the rollers 13, is made such as to give the desired effective immersion time of the strip in the liquid, which typically will be a period of from 1 to seconds.
  • any suitable detector which, in this embodiment, is illustrated as a detector 37 coupled to the rolls 11.
  • the detector controls relay 38 which in turn controls the operation of the valves 18, 22, 28 and 29 and of the pumps and 26.
  • the relay 38 Under normal conditions of operation the relay 38 is operative to maintain the valves 18 and 22 open, the valves 28 and 29 closed, the pump 15 fully operative, and the pump 16 inoperative, or perhaps idling with the pressure relieved by a relief valve 39.
  • the detector 37 sensing that the speed of the strip has dropped below a predetermined value
  • the relay 38 is operative to close the valves 18 and 22 and stop the pump 15, cutting off the supply of the liquid from the tank 14.
  • the valves 28 and 29 are opened and the pump 26 operated to supply rinse water to the nozzles and rinse the liquid from the strip, thereby preventing excessive exposure of that part of the strip to the effect of the liquid, which usually will render it unfit for commercial usage because of discolouration. Normal operation will be resumed when the strip again is moving at above the minimum speed.
  • the length of the abovementioned period is such as to permit normal short stoppage of the line without operation of the rinse apparatus.
  • the control of the pressure applied to the strip by the rollers 13 is found to be important in obtaining the desired results, and will be discussed in detailbelow. lt is found necessary in practice to change the rolls relatively frequently as they becomeworn and to re-work them to the required profile, while will change the weight of the rolls thus altering the pressure control characteristic. This effect is avoided in apparatus in accordancewith the invention by providing that the pres sure motors 36 are double-acting cylinders, the upper and lower parts ofthe cylinder being fed independently with compressed air from pipes 40 and 4] including valves 42 and 43 respectively.
  • Spectrophotometric analysis shows that the chromium is present in both a water soluble hexavalent form and an insoluble trivaconstituents of the aqueous coating composition of the present invention are a source of chromium ion, a source of perchlorate ion, and a source of fluoride ion. the chromium ion being the only metallic ion present therein.
  • ammonium and like complex ions e.g., H is not a complex ion
  • the pH value of the solution is made less than l.l5 and preferably is in the range 0.9 to 1.0, with a preferred minimum of 0.8.
  • sludge does not contain a buffering agent or agents, the most common of which are usually solid materials with a tendency to form insoluble compounds that will settle as sludge.
  • a buffering agent or agents usually solid materials with a tendency to form insoluble compounds that will settle as sludge.
  • the avoidance of sludge deposits is of course important in a commercial system to avoid the need for elaborate filter arrangements and to prevent blocking of the pipes by sludge particles, etc.
  • the chromium ion is supplied to the solution most conveniently in the form of anhydrous chromium trio'xide, in which the chromium is in hexavalent form.
  • This compound can constitute ,a convenient medium for specifying the required concentration of the chromium in the solution, which should be present as ion in the amount of 5 to 15 grams per litre, preferably 9 to 13 grams per litre.
  • the corresponding quantities of the trioxide to be added are 10 to 30 grams per litre, preferably 18 to 25 grams per litre. The calculation of any other suitable material added to the solution will be apparent to those skilled in the art.
  • the perchlorate is added in the form of 60 percent perchloric acid to provide the required amount of ion of 0.5 to 0.85 grams per litre, and forthis concentration the solution should contain from 0.3 to 0.5 ml per litre of the said 60 percent perchloric acid.
  • the fluoride ion conveniently is added as 48 percent hydrofluoric acid to provide from 0.l to 0.27 grams per litre of the fluoride ion, preferably 0.15 to 0.27 grams per litre, and this amount of ion requires the addition of about 0.1 to 0.25 ml per litre ofthe acid, preferably 0.15 to 0.25 ml per litre.
  • the usable operating temperature range for the solution is l50F to 200F, while the preferred temperature range is F to F.
  • the time of application is of the order of l to 10 seconds only, and the provision for rinsing described above is made operative if the exposure time increases to above 15 seconds.
  • An excessive exposure time is indicated by brown discolouration and even etching of the zinc sur face.
  • the exact mechanism for the formation of the chromate film is not known to the applicants at this time, and accordingly the invention disclosed and claimed herein is not to be limited by any mechanism which is postulated at this time.
  • the composition solution in contact with the zinc or cadmium surface generates hydrogen which is believed to reduce some of the hexavalent chromium to trivalent chromium, some of which may then be oxidised by the perchlorate ion back to the hexavalent state to balance the relative concentrations in the solution.
  • the balance of the trivalent chromium goes into film formation on the zinc or cadmium surface.
  • the trivalent chromium is believed more effective than the hexavalent form in combining with the fluoride ion, with which it complexes readily during film formation.
  • An examination of typical films produced shows trivalent chromium in the amount of from about 5 to about 12 micrograms per sq. inch (m.s.i.) while the hexavalent form is present in the amount of from about 2 to about 7 m.s.i., giving a total chromium content of from about 7 to about 19 m.s.i., most usually in the neighbourhood of about 16 m.s.i. This thickness may be compared to the usual thickness of about 9 m.s.i. obtained with known systems. Excellent results have also been achieved with film weight outside these values.
  • the films produced by the application of the invention are found to be unexpectedly much more protective than those of known prior methods.
  • One test known as the humidity cabinet test involves the use of a Cleveland condensation tester cabinet having its interior maintained at 100F, wherein strips of galvanized steel are suspended above a water trough, the side ex posed to the trough being at the said temperature of 100F, while the other side is at the ambient temperature, usually about 70F.
  • the humidity of the cabinet interior is 100 percent and the water that condenses on the inner surface trickles back into the trough, giving the effect of a constant exposure to a rainy atmosphere.
  • the strips are maintained under this condition until visual inspection shows that about l percent of the zinc coating has corroded to white rust.
  • an average exposure of 30 hours was sufficient to produce the specified corrosion, while this degree of attack is only obtained with the processes etc. of this invention after an exposure of about 400 1,000 hours.
  • the hexavalent chromium is considerably more mobile in the film forming complexes than the trivalent form, in addition to being more soluble, and does operate to provide a sealing mechanism whereby the mobile hexavalent ion migrates to potential holes in the film and reacts readily with the zinc to close such holes.
  • the trivalent form complexed with the zinc and the fluorine that provides the essential protective film. The excess solution removed by the pressure rolls has the chromium predominantly in the hexavalent form because of its higher solubility and concentration.
  • Apparatus for the application of a liquid composition to a surface ofa moving strip at an application station comprising means for moving the strip through the liquid application station, applying means at the station for applying the liquid composition and a rinse liquid to the surface, a source of the liquid composition to be applied.
  • feeding means coperative to feed liquid composition from the source thereof to the applying means, a source of rinse liquid, feeding means operative to feed rinse liquid from the source thereof to the applying means, means responsive to slowing or stopping of the strip resulting in exposure of the strip at the station to liquid composition for longer than a predetermined period of time for stopping operating of the liquid composition feeding means and starting operation of the rinse liquid feeding means to rinse liquid composition from the strip at the station, liquid composition return means at the station for receiving excess liquid composition and returning it to the source thereof, rinse liquid return means at the station receiving excess rinse liquid and returning it to the source thereof; and pipe means including valve means connecting the source of liquid composition with the source of rinse liquid to permit the supply of rinse liquid to the liquid composition source for replenishment of the liquid composition.
  • liquid composition applying means and the rinse liquid applying means are constituted by a single applying means
  • the liquid composition feeding means include valve means that are closed in response to said stopping or slowing of the strip to stop feed of liquid composition to the applying means
  • the rinse liquid feeding means include valve means that are opened in response to said stopping or slowing of the strip to feed rinse liquid to the applying means.
  • Apparatus as claimed in claim 1 and including means for removing excess liquid composition from the strip surface before the strip leaves the station.
  • Apparatus for the application of a highly reactive liquid composition to a surface of a moving metal strip at an application station comprising means for moving the metal strip through the liquid application station, spray means at the station for applying the liquid composition and a rinse liquid to the surface, a source of the liquid composition to be applied, a pump and pipe means including a valve connecting the spray means and the liquid composition source and operative to feed liquid composition to the spray means, a source of rinse liquid, a pump and pipe means including a valve connecting the spray means to the rinse liquid source and operative to feed rinse liquid to the spray means, means responsive to slowing or stopping of the strip resulting in application of liquid composition to the strip for longer than a predetermined period of time to close the respective valve for stopping feeding of liquid composition to the spray means, and opening of the respective valve to start feeding of rinse liquid to the spray means, liquid composition return means at the station for receiving excess liquid composition and returning it to the source thereof, rinse liquid return means at the station receiving excess rinse liquid and returning it to the source thereof; and pipe means including valve means connecting the
  • liquid composition return means and the rinse liquid return means comprise catch means at the station for receiving excess liquid composition and excess rinse liquid, pipe means including a valve for returning the excess liquid composition to the source thereof, and pipe means including a valve for returning the excess rinse liquid to the source thereof, the said responsive means being operative upon said slowing or stopping of the strip to close the respective valve to stop return of caught liquid to the liquid composition source and to open the respective valve to start return of caught liquid to the rinse liquid source.
  • Apparatus as claimed in claim 4 and including means for removing excess liquid composition from the strip surface before the strip leaves the station.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Coating Apparatus (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US00285313A 1972-08-31 1972-08-31 Apparatus for use in processes for producing coatings on surfaces Expired - Lifetime US3850137A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00285313A US3850137A (en) 1972-08-31 1972-08-31 Apparatus for use in processes for producing coatings on surfaces
CA179,884A CA990501A (en) 1972-08-31 1973-08-29 Apparatus for use in processes for producing coatings on surfaces
FR7331339A FR2198392A5 (fr) 1972-08-31 1973-08-30
AU59819/73A AU475398B2 (en) 1972-08-31 1973-08-30 Apparatus for use in processes for producing coatings on surfaces
BE135170A BE804287A (fr) 1972-08-31 1973-08-31 Appareil pour la production de couches protectrices sur des surfaces
IT52260/73A IT990434B (it) 1972-08-31 1973-08-31 Apparecchio per l applicazione di rivestimenti protettivi su superfi ci
JP48098153A JPS49100158A (fr) 1972-08-31 1973-08-31
DE19732343997 DE2343997A1 (de) 1972-08-31 1973-08-31 Vorrichtung zum herstellen von deckschichten aus chrom
GB4116773A GB1425379A (en) 1972-08-31 1973-08-31 Apparatus for use in processes for producing coatings on surfaces

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00285313A US3850137A (en) 1972-08-31 1972-08-31 Apparatus for use in processes for producing coatings on surfaces

Publications (1)

Publication Number Publication Date
US3850137A true US3850137A (en) 1974-11-26

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Application Number Title Priority Date Filing Date
US00285313A Expired - Lifetime US3850137A (en) 1972-08-31 1972-08-31 Apparatus for use in processes for producing coatings on surfaces

Country Status (9)

Country Link
US (1) US3850137A (fr)
JP (1) JPS49100158A (fr)
AU (1) AU475398B2 (fr)
BE (1) BE804287A (fr)
CA (1) CA990501A (fr)
DE (1) DE2343997A1 (fr)
FR (1) FR2198392A5 (fr)
GB (1) GB1425379A (fr)
IT (1) IT990434B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113102191A (zh) * 2021-04-15 2021-07-13 李彦双 一种3d打印用阳磨表面镀层设备

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0633518B2 (ja) * 1986-03-31 1994-05-02 株式会社神戸製鋼所 薄板洗浄設備における黄変色防止方法及び装置
DE102019121347A1 (de) * 2019-08-07 2021-02-11 Atlas Copco Ias Gmbh Überwachungsverfahren sowie Auftragsvorrichtung für mehrkomponentiges viskoses Material

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2775952A (en) * 1955-06-08 1957-01-01 Ecusta Paper Corp Spray device
US3121024A (en) * 1960-03-22 1964-02-11 Gen Motors Corp Electrostatic painting apparatus
US3166441A (en) * 1962-05-08 1965-01-19 Triangle Conduit & Cable Co In Machine for color coating strands
US3220377A (en) * 1962-03-29 1965-11-30 West Virginia Pulp & Paper Co Control of machine components

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2775952A (en) * 1955-06-08 1957-01-01 Ecusta Paper Corp Spray device
US3121024A (en) * 1960-03-22 1964-02-11 Gen Motors Corp Electrostatic painting apparatus
US3220377A (en) * 1962-03-29 1965-11-30 West Virginia Pulp & Paper Co Control of machine components
US3166441A (en) * 1962-05-08 1965-01-19 Triangle Conduit & Cable Co In Machine for color coating strands

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113102191A (zh) * 2021-04-15 2021-07-13 李彦双 一种3d打印用阳磨表面镀层设备
CN113102191B (zh) * 2021-04-15 2023-04-14 东莞塔夫纳米科技有限公司 一种3d打印用阳磨表面镀层设备

Also Published As

Publication number Publication date
DE2343997A1 (de) 1974-03-07
CA990501A (en) 1976-06-08
IT990434B (it) 1975-06-20
AU475398B2 (en) 1976-08-19
AU5981973A (en) 1975-03-06
BE804287A (fr) 1973-12-17
JPS49100158A (fr) 1974-09-21
FR2198392A5 (fr) 1974-03-29
GB1425379A (en) 1976-02-18

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