US3731653A - Coating rate cell - Google Patents
Coating rate cell Download PDFInfo
- Publication number
- US3731653A US3731653A US00132240A US3731653DA US3731653A US 3731653 A US3731653 A US 3731653A US 00132240 A US00132240 A US 00132240A US 3731653D A US3731653D A US 3731653DA US 3731653 A US3731653 A US 3731653A
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- United States
- Prior art keywords
- coating
- solution
- cell
- processing solution
- weight
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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
- ABSTRACT An open top coating cell defining a slot.
- a plurality of [52] US. Cl. .,...l18/429, 95/89 R apposed ribs are disposed on the inner Side walls of [51] Int. Cl. ..B05c 3/04 the l to fol-m expansion chambers whereby mrbw [58] Field of Search ..1 18/429, 500, 602, lence is imparted to ti liq id passing through 118/603; 95/89 R, 89 L, 89 D, 96, 97, 98, 99, 100; 96/63; 259/4; 134/182 said cell.
- This invention relates to an improved apparatus for controlling the ratio and concentration of the chemical components of processing solutions for coating metal surfaces.
- the chemically reactive processing solutions for coating metal surfaces contain both coating components and accelerating components.
- concentration of the coating and accelerating components of these solutions which, if maintained, will produce the optimum coating results on the metal surfaces treated.
- the solution components are depleted both by chemical reaction with the metal surface as well as by mechanical losses, e.g., drag our or entrapment of the solution in and on the metal surface, leaks and the like.
- compensation for all of these depleting factors must be made.
- an object of the present invention to provide an improved apparatus for operating chemically reactive processing solutions for treating metal surfaces, whereby the optimum coating results may be maintained without the need for destructive testing of the metal surfaces treated.
- a further object of the present invention is to provide an improved testing cell by means of which a determination may be made of the coating weight which is produced on the metal surface being treated without the need for destructive testing of the surface.
- FIG. 11 is a schematic representation of a control system for carrying out the process of the present invention
- FIG. 2 is a top plan view of a coating weight cell for use in the present process
- FIG. 3 is a sectional view of the coating weight cell taken along the lines AA of FIG. 2
- FIG. 4 is a sectional view of the coating weight cell taken along the line BB of FIG. 2
- FIG. 5 is a top plan view of an alternative configuration of a coating weight cell for use in the present process
- FIG. 6 is a sectional view of the coating weight cell taken along the line AA of FIG. 5
- FIG. 7 is a sectional view of the coating weight cell taken along the line BB of FIG. 5.
- the present invention includes apparatus for forming a chemically reacted coating on a metal surface which comprises contacting the metal surface to be treated with a chemically reactive processing solution containing coating components and activating components, maintaining the processing solution in contact with the metal surface for a period sufficient to form the desired coating thereon, periodically replenishing said processing solution by adding a first replenishing composition containing coating and accelerating components in substantially the same ratio as in the processing solution as originally formulated and a second replenishing composition containing coating and accelerating components in a ratio suitable to compensate for the depletion of these components in the processing solution by reaction with the metal surface being treated, the ratio of the two replenishing solution being such as to reestablish the concentration and ratio of coating and accelerating components in the processing solutions substantially as originally formulated, periodically passing a portion of the processing solution through a test zone, contacting a test specimen having a metal surface with the thuspassed processing solution, within said test zone, determining the weight of coating produced on the metal surface of the test specimen in a given period of
- the weight of coating formed by a chemically reactive processing solution on a test specimen may be correlated to the coating weight which is actually produced on metal surfaces treated during production with this processing solution. Accordingly, by coating a test specimen, determining the coating weight produced under the particular coating conditions used and then correlating this to the weight of coating produced with the same processing solution in the actual production line, the coating weight produced on the production line can be determined without the necessity of destructive testing of the actual product being produced.
- the formation of the coating on the test specimen may be effected in the actual production line, it has been found that variations, such as in the flow rate on the production line, build up of impurities such as cleaner residues and the like, may adversely affect the reproducability which is obtained, thus making it difficult to maintain a good correlation between the coating weight on the test specimen and that on the production material. Additionally, it is desirable that a sufficiently high coating weight be formed on the test specimen as to minimize any errors which may occur in weighing, due to the limits of accuracy with which this may be carried out. Often the coating weights produced on the production line are sufficiently low as to make this difficult. Accordingly, in the present method, it is desirable to contact the test specimen with the chemically reactive processing solution in a separate test zone. in this manner, a closer control over the processing solution flow rate, and contact time with the metal surface of the test specimen can be maintained and a heavier, more easily reproducable coating weight is obtained.
- a metallic surface such as metallic sheet or strip or formed articles such as cans
- the chemically reactive processing solution by operating in accordance with the procedure which is described in copending application Ser. No. 572,907, filed Aug. 17, 1966.
- a portion of the processing solution used is passed through a test zone in which there is contained a test specimen having a metallic surface.
- the metallic surface of the test specimen is the same as the metallic surface being treated on the actual production line with the processing solution.
- the metal surface on the test specimen is the same as the metal surface actually being treated with the processing solution on the production line.
- the test specimen may be of any suitable configuration, although for ease of handling a test specimen in the form of a metal sheet or panel is preferred.
- the test zone in which the coating on the test panel is produced may be of any suitable configuration, having means for flowing the processing solution in contact with the metal surface of the panel.
- a particularly suitable test zone is the coating weight cell, as shown in FIGS. 2 through 7 of the drawings, as will be discussed in more detail hereinafter.
- the test panel is positioned in the test zone and the processing solution, taken from the main body of the processing solution on the production line is passed in contact with the metal surfaces of the panel for a period of time sufficient to form a chemical coating on the metal surface, at the processing solution flow rate which is used.
- the test panel is maintained in the test zone in contact with the processing solution for a period of from about 30 seconds to 10 minutes, depending upon the makeup of the processing solution which is used.
- a contact time of about 3 minutes has been found to be suitable while contact times of about one minute have been found to be suitable where the processing solution is one used in a strip line.
- the desired coating When the desired coating has been formed on the test panel, it is removed from the testing zone and the weight of coating which has been produced is determined. This may be done in any convenient manner, as for example, by weighing the test panel prior to the time it is inserted in the test zone and then reweighing the panel after it is removed from the test zone, the difference in weight being the amount of coating which has been applied to the panel. Alternatively, after removing the panel from the test zone it may be weighed and then the coating formed on the panel surfaces stripped off, following which the panel is reweighed, the difference in weight again being the amount of coating which was produced on the test specimen surface. When using the latter technique, the method of removing the coating from the panel will, of course, depend upon the nature of the coating which has been formed.
- the coatings are the type which contain hexavalent chromium
- the coating may be stripped from the panel with a concentrated nitric acid solution, for example, a solution having a ratio of nitric acid to water of at least about 1:1.
- a concentrated nitric acid solution for example, a solution having a ratio of nitric acid to water of at least about 1:1.
- Other methods of stripping the coating from the test panel surface may also be used. It has been found that the surface of the test panels should be rinsed with water, after being removed from the test zone, regardless of which coating weight determination technique is used.
- the correlation of the coating weight produced on the test specimen with the coating weight actually produced on the production line may be made by, initially, actually determining the coating weight produced on the production line under the particular processing solution and operating conditions which are used. Similar determinations for test panels coated in the test zone are also made, using the same processing solution, and a curve can be drawn plotting the coating weights on the processing line against the coating weights obtained on the test panels. Thereafter, in controlling the operation of the coating process, when the periodic treatment of the test panel in the test zone is effected and the weight of the coating produced on the panel is determined, it may then be correlated to the actual coating weight produced on the production line with this same processing solution by means of the curve which has been plotted. Where this correlation indicates that the actual coating weight produced on the production line has varied from that which is desired, adjustments can then be made in the operating conditions so as to bring the coating weight produced back to the desired level.
- the coating weight produced is directly proportional to the time the metal surface is in contact with the coating solution, for a given application method.
- a hexavalent chromium containing coating solution it is possible to determine the coating weight being produced on the production line without measuring the coating actually produced on the workpieces. This can be determined by knowing the contact time on the line and the coating weight produced on the test specimen in the test zone, for the conditions used, with the same coating solution.
- the chemical coating solutions which may be used in the present process are desirably those wherein the components of the replenishing composition may be added as solutions.
- coating solutions wherein the replenishing compositions are added as a dispersion, paste, slurry, powder, or the like may also be used, for ease and simplicity in handling, the addition of the replenishing compositions in the form of solution is preferred.
- Exemplary of such coating solutions are the chromate coating solutions, including those based on chromic acid, combinations of chromic acid and phosphoric acid and the like.
- these solutions also contain one or more activating materials, as are known in the art, such as fluoride ions.
- coating solutions which may also be used include oxalate coating solutions, e.g., those based on oxalic acid, alkali metal oxide, or the like; phosphate coating solutions, such as those containing alkali metal phosphates, e.g., the so called iron phosphate coating process solutions, zinc acid phosphates, and the like. These coating solutions may be used in the treatment of ferrous metal surfaces, aluminum surfaces and zinc surfaces, to provide a protective and/or paint base coating thereon.
- oxalate coating solutions e.g., those based on oxalic acid, alkali metal oxide, or the like
- phosphate coating solutions such as those containing alkali metal phosphates, e.g., the so called iron phosphate coating process solutions, zinc acid phosphates, and the like.
- These coating solutions may be used in the treatment of ferrous metal surfaces, aluminum surfaces and zinc surfaces, to provide a protective and/or paint base coating thereon.
- the application of the coating solution is preferably carried out either by immersing the metal surfaces to be coated in the solution or by spraying the solutions on the surface.
- the control of these processing solutions is effected by the use of two replenishing compositions, one of which is formulated so as to compensate for mechanical losses from the processing solution, e.g., by dragout, or entrapment in an on the metal surface, and the second is formulated to compensate for the chemical consumption of the solution components in reacting with the metal surface being treated.
- the addition of these two replenishing materials to the processing solution is carried out so that the ratio and concentration of the components in the processing solution will be maintained at substantially the level-.as they are originally formulated.
- the change in the coating weight produced has been caused by some other factor in the operation of the coating process, as for example a change in flow rate, temperature, or the like. Where this is the situation, the production of the desired coating weight may be reestablished by an adjustment of these operating conditions, where this is practical. Where this can not be done, however, the change in these operating conditions may be compensated for by varying the amount of the chemical replenishing material, thus establishing a new ratio of the mechanical replenishing material to the chemical replenishing material which will produce the desired coating weight on the production line under the same processing conditions.
- FIG. 1 is a schematic representation of the processing system of the present invention.
- solution tank 1 contains a chemically reactive coating solution 3.
- Pump 5 is provided which delivers solution from the tank through lines 7 and 9 to the spray headers 15 which spray the solution on a workpiece 41 to form a chemically reacted coating thereon.
- a catch basin 17 is provided beneath the spray headers 15 to collect the overspray material and return it to the solution tank 1 through line 19.
- a side line 11, having a valve 13, is provided from the main solution line 9, whereby a portion of solution being pumped from the tank I to the headers 15 may be directed through a coating weight cell or test zone 2. Within this test zone, the solution is flowed in contact with a test specimen, to form a coating thereon. The solution overflows at the top of the cell 2, through the serations 12, and is returned to the solution tank 1. Additionally, auxiliary tanks 21 and 23 are provided which contain, respectively, the chemical and mechanical replenishing compositions. Pumps 25 and 27 deliver these replenishing materials, through lines 31 and 35 and 29 and 33, respectively, to the solution tank l.
- a control means, shown generally as 37 with electric lines 39, is provided whereby the operation of the pumps 25 and 27 are controlled so as to deliver the desired amounts of each of the replenishing materials to the solution tank.
- FIGS. 2, 3 and 4 are a top plan view and two sectional views of a coating weight cell for use in the present process.
- the cell 2 is a box-like structure having a bottom member 4, two endwall members 6 and two sidewall members 8.
- the sidewalls and endwalls are positioned so as to receive a test specimen which is to be contacted with the processing solution, such a test panel.
- the bottom member is provided with an interior passageway 10 having an opening 14 through one of the end walls, whereby the processing solution is introduced into the test cell.
- This interior passageway in the bottom member is provided with a series of openings 16 into the main body of the test cell, whereby the processing solution introduced into the passageway 10 is passed into contact with a test specimen positioned within the cell.
- substantially uniform flow of the processing solution in contact with both sides of the test specimen is effected.
- Means are provided within the cell whereby turbulence is imparted to the processing solution as it is passed in contact with the test specimen, thereby insuring a more rapid reaction of the coating solution with the surfaces of the test panel, by bringing more fresh coating solution in contact with the panel surfaces.
- this turbulence is imparted to the processing solution by providing an enlarged chamber 18 adjacent the base of the test cell into which the openings in the bottom member, which are at an angle, direct the processing solution, initially, away from the surfaces of the test panel.
- the top edges of the side members of the coating cell are provided with serrations 12, through which the processing solution flows after it has passed through the coating weight cell in contact with the panel surfaces.
- the number and size of these serrations are selected so as to provide the desired, constant volume and level of coating solution in the cell.
- FIGS. 5, 6 and 7 of the drawing show a top plan view and two sectional elevations, of a modified form of the coating weight cell 2.
- an interior passageway 10 is formed in the bottom of the cell by means of a perforated member 22 which is positioned above the bottom member 4 of the cell thus forming the passageway 10 into which the processing solution is introduced through the opening 14 in one end wall member 6.
- the side wall members 8 are provided with a series of projecting rib members 24 which are substantially parallel to the bottom member of the cell and are oppositely disposed on each of the side wall members 8. These rib members 24, with the side wall members 8, form a series of chambers throughout the heigth of the cell.
- the desired turbulence is imparted to the processing solution as it flows from the interior passageway, through the openings 16 in the perforated member 22, upwardly between the two sidewall mem bers of the cell, in contact with the test panel.
- the upper edges of the side wall members are provided with serrations 112 through which the coating solution overflows out of the cell.
- the upper portion of the side wall members in this variation are also provided with an offset section26 to form an enlarged zone or chamber which, with the chamber 20 on the uppermost rib members on both side wall members make insertion of the test panel into the cell easier.
- a by-pass from the pump supplying treating solution to the fourth stage sent a flow of the solution through a coating rate cell, having a structure as shown in FIGS. 5, 6, and 7.
- the flow through the cell was adjusted to about 2,000 milliliters per minute.
- a 4 inch by 6 inch panel of the same 5052 aluminum alloy being treated in the line was placed in the cell in contact with the solution for 1 minute. The panel was then removed, water rinse, air dried and weighed. After stripping the panel in concentrated nitric acid (1:1 HNO it was reweighed and the coating weight was found to be 30 milligrams. This was equivalent to a coating weight of 90 milligrams per square foot.
- SOLUTION 1 Physical Components by Weight H O balance SOLUTION 2 (Chemical) Components by Weight CrO; 4.96
- Acid cleaner 20 second spray at 65C 2.
- Cold water spray rinse 3.
- Water spray rinse 5.
- Deionized water spray rinse The cans, on a conveyor, were passed through the line at the rate of about 250 cans per minute. The conductivity of the treating solution was measured as in the previous example and based on this and the number of cans treated, the solution was maintained at the desired concentration by adding the two replenishing compositions in the ratio of 9 parts of the first to 1 part of the second.
- the coating rate was determined, using the coating rate cell, in the same manner as in Example 1, with the exception that the panel was maintained in contact with the treating solution in the cell for 3 minutes.
- the coating weight produced on the 4 inch by 6 inch panel was 30 milligrams, which was determined to be equal to a coating weight on the cansof 6.7 milligrams per square foot. Thus, each 1 milligram per square foot of coating on the cans was equivalent to 4.5 milligrams of coating on the test panel.
- the testing procedure was repeated periodically and the ratio of the two replenishing materials varied as indicated by the test results to maintain desired concentration and ratio of components in the treating solution, as in Example 1.
- a coating weight cell useful in the operation of chemically reactive processing solutions for treating metal surfaces comprising:
- said side walls including a plurality of pairs of opposed rib means, each rib disposed within the cell and extending transversely thereto, whereby to form a series of expansion chambers so as to impart turbulence to the treating fluid passing therethrough.
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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)
- Application Of Or Painting With Fluid Materials (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
Description
Claims (1)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US65084467A | 1967-07-03 | 1967-07-03 | |
US13224071A | 1971-04-07 | 1971-04-07 |
Publications (1)
Publication Number | Publication Date |
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US3731653A true US3731653A (en) | 1973-05-08 |
Family
ID=26830205
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US00132240A Expired - Lifetime US3731653A (en) | 1967-07-03 | 1971-04-07 | Coating rate cell |
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US (1) | US3731653A (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2402313A (en) * | 1943-04-06 | 1946-06-18 | American Viscose Corp | Apparatus for the liquid treatment of strand material |
US2456650A (en) * | 1944-10-20 | 1948-12-21 | Redding Mfg Company Inc | Method of coating filaments |
US3077155A (en) * | 1960-08-08 | 1963-02-12 | Pako Corp | Device for treating photographic sheet material |
US3362315A (en) * | 1964-02-03 | 1968-01-09 | Werner W. Buechner | Photographic treating vessel |
US3373674A (en) * | 1964-02-03 | 1968-03-19 | Werner W. Buechner | Photographic wash vessel |
US3427949A (en) * | 1966-04-07 | 1969-02-18 | Ibm | Laminar flow film developing apparatus |
-
1971
- 1971-04-07 US US00132240A patent/US3731653A/en not_active Expired - Lifetime
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2402313A (en) * | 1943-04-06 | 1946-06-18 | American Viscose Corp | Apparatus for the liquid treatment of strand material |
US2456650A (en) * | 1944-10-20 | 1948-12-21 | Redding Mfg Company Inc | Method of coating filaments |
US3077155A (en) * | 1960-08-08 | 1963-02-12 | Pako Corp | Device for treating photographic sheet material |
US3362315A (en) * | 1964-02-03 | 1968-01-09 | Werner W. Buechner | Photographic treating vessel |
US3373674A (en) * | 1964-02-03 | 1968-03-19 | Werner W. Buechner | Photographic wash vessel |
US3427949A (en) * | 1966-04-07 | 1969-02-18 | Ibm | Laminar flow film developing apparatus |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: HOOKER CHEMICALS & PLASTICS CORP 32100 STEPHENSON Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OXY METAL INDUSTRIES CORPORATION;REEL/FRAME:003942/0016 Effective date: 19810317 |
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AS | Assignment |
Owner name: OXY METAL INDUSTRIES CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:OXY METAL FINISHING CORPORATION;REEL/FRAME:003967/0084 Effective date: 19741220 |
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Owner name: OCCIDENTAL CHEMICAL CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:HOOKER CHEMICAS & PLASTICS CORP.;REEL/FRAME:004126/0054 Effective date: 19820330 |
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Owner name: PARKER CHEMICAL COMPANY, 32100 STEPHENSON HWY., MA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:OCCIDENTAL CHEMICAL CORPORATION;REEL/FRAME:004194/0047 Effective date: 19830928 |