US3719884A - Process and apparatus for determining the porosity of a dielectric layer coating a metallic surface - Google Patents

Process and apparatus for determining the porosity of a dielectric layer coating a metallic surface Download PDF

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Publication number
US3719884A
US3719884A US00115429A US3719884DA US3719884A US 3719884 A US3719884 A US 3719884A US 00115429 A US00115429 A US 00115429A US 3719884D A US3719884D A US 3719884DA US 3719884 A US3719884 A US 3719884A
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United States
Prior art keywords
current
varnish
electrolyte
porosity
metallic
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Expired - Lifetime
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US00115429A
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English (en)
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R Laroche
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Alcan Holdings Switzerland AG
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Alusuisse Holdings AG
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/20—Investigating the presence of flaws
    • G01N27/205—Investigating the presence of flaws in insulating materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/42—Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte
    • G01N27/423—Coulometry

Definitions

  • ABSTRACT [30] Foreign Application Priority Data A process for determining the porosity of a layer of Feb. 17,1970 Switzerland ..2220/70 dielectric material coating a metallic Surface prises electrophoretically depositing an insulating 52 U.S. CI. ..324/54, 204/1 T component of an electrophoretic varnish on parts of 1 0 31 12 the metallic surface in the to pores.
  • the quantity of 58 Field of Search ..324/54, 65; 204/1 T, 181 the current Consumed is measured and displayed in units of surface area.
  • the permeability of a protective layer determines its effectiveness against corrosion. of metallic objects. It has already been proposed (US. Pat. No. 2,572,597, German Patent No. 664 598) to measure the permeability or porosity of dielectric layers by the passage of a continuous or alternating current between the metallic substratum and an electrolyte on the surface of the protective layer. The results of these measurements, expressed in milliamperes or in ohms, indicate only very approximately the overall quality of the protective layer. These measurements are, moreover, liable to errors of interpretation depending on insufficiently defined factors, such as: the applied voltage the polarity of the dc.
  • the localization of defects enables the analysis of the causes of the defect by marking by means of a chemical or electro-chemical reaction.
  • U.K. Patent No. 1,081,858 proposes electrodeposition of copper or other metal, using the metallic surface as one electrode, so that a detectable deposit is formed at the pores in the surface.
  • German Patent No. 664 598 discloses changing a colored indicator by the electro-chemical reaction of one of the compounds of an electrolyte during the passage current.
  • a further aim is to enable, if required, determination of the distribution of the pores.
  • a process for determining the porosity of a layer of dielectric material coating a metallic surface comprises the steps of i. covering the layer with an electrolyte containing an electrophoretic varnish ii. applying an e.m.f. between a first electrode in the electrolyte with the metallic surface as second electrode to cause electrodeposition of a non-conducting component of the varnish on parts of the metallic sur- 7 face in the pores and iii. measuring the quantity of current consumed.
  • the principle upon which the process according to the invention is based is that the electrodeposition of the electrophoretic varnish can only take place on the non-protected metallic parts of a dielectric layer.
  • the amount of current required to deposit the varnish is proportional to the accessible area of the metallic surface. The validity of this relationship depends upon the following conditions:
  • the quantity of material deposited at the electrodes is directly proportional to the quantity of current used, if the conditions of deposit are defined and constant.
  • the quantity of an electrophoretic deposit on the non-protected surface i.e. the pores
  • the non-protected surface area i.e. the surface area of the pores
  • the quantity of electrophoretic deposit will be slightly different according to the arrangement and properties of the surface to cover. If an extreme case is taken as an example, the renewal of the electrophoretic solution into depositable particles will be more difficult near a uniform surface than near a multitude of points over the electrode. This distortion decreases very rapidly as the electrodepositing time increases.
  • the invention proposes a process which is carried out such that the measurement of the quantity of electrophoretic current continues until the current is very small; with semi-colloidal solutions of the acid polar resin type, this time varies between 5 and 30 seconds.
  • the readings taken of the current consumed can be calibrated by electrodepositing varnish onto a metallic surface of known surface area in conditions identical to testing a coated metallic surface.
  • an electrophoretic varnish of a different color to that of the dielectric layer can be used, which enables localization of the defects in the protective layer, after rinsing with water, by color contrast.
  • Specimens can also be cooked in an oven, which fixes indication of the defects, in order to conserve them, for proof or study.
  • FIGURE of the accompanying drawings shows schematically and by way of an example, an embodiment of a device for carrying out the process ac cording to the invention.
  • a mains-fed stabilized rectifier l delivers a stabilized voltage at a value selected between 20 and 100V, for example V stabilized atil percent.
  • the negative pole of the rectifier is connected to an electrode 2.
  • the positive pole of the rectifier is connected to a time switch 3, for example an electronically delayed triggering device closing the circuit for a selected interval, for example, 10 seconds following actuation by a pushbutton, not shown.
  • a shunt 4 and an integrator 5 are connected in parallel between the time switch 3 and a conducting support 7.
  • I is the value of the current.
  • This integrator comprises a display device 6, where the results'of measurements are indicated by a hand moving in front of a scale graduated directly in surface area units (mm or by a digital computor.
  • the integrator 5 has several selectable sensitivities so that the units shown on the graduated scale of display device 6 can be multiplied by a factor of 10, 100, or 1,000.
  • the operating button of time switch 3 also operates the time zero setting of the device 6. Calibration of the display device 6 will be explained later on.
  • the illustrated measurement device is used to check the surface state of a metallic container such as a box, or a flexible or rigid can or tube, the inner surface of which has a coating of dielectric material to protect against corrosion.
  • the dielectric layer can, for example, be a varnish, paint, a layer of synthetic material applied by atomization, an enamel, or a layer of anodic oxide.
  • the container 8 is filled up to a fixed level, for example 1 cm below the top edge, with an electrolyte in which the electrode 2 is immersed.
  • the electrolyte is an electrophoretic varnish based on acrylic esters with a concentration comprised between 5 and 15 percent in water. It'is strongly colored or pigmented in order to contrast with the layer to be checked.
  • the deposit time is selected by means of the time switch, and the sensitivity of the integrator is also selected as a function of the type of container being tested.
  • the time switch is then actuated by a pressure on the operating button, the display device 6 is consequently automatically set to zero, and the electric circuit is closed for the selected time, for example 10 seconds.
  • varnish is deposited by electrophoretic action on the parts of the metallic surface adjacent to pores.
  • the circuit is automatically cut off by the time switch and the result of the measurement can be read on the display device 6 until the next measurement takes place.
  • a similar procedure is used to calibrate the display device 6.
  • the metallic container 8 is replaced by a test container with no porosity.
  • An enamelled wire with a 1 mm cross-sectional area is connected to the external conducting surface of the container so that it acts as electrode instead of the metallic surface.
  • the end surface of the free end of the wire is polished so that the varnish can be deposited thereon by electrophoresis when the free end is immersed in the electrolyte.
  • a test is carried out by actuating the time switch 3, and at the end of the test, the display device 6 should indicate a free surface of 1 mm. If the reading is not exact, the composition of the varnish is corrected by modification of its pH and its amine content.
  • the device for carrying out the process can be adapted to measurements on a planar metallic surface covered by a dielectric.
  • the modified device comprises a suction valve applying hermetically against the surface over a certain surface area thereof.
  • the shunt 4 is connected to the metallic part of the surface, the electrode 2 is immersed in an electrophoretic solution in the suction valve, and measurements are carried out in the same way as has been described.
  • the tested surface is washed with water and the distribution of the pores are visible in the form of colored traces or points. If it is desired to conserve the sheet, it is then baked for approximately 5 minutes at 220 C.
  • a process for determining the porosity of a layer of dielectric material coating a metallic surface comprising the steps of:
  • Apparatus for determining the porosity of a layer of dielectric material coating a surface of a metallic body comprising a circuit including a stabilized source of direct current e.m.f. having opposite terminals, means for contacting said coated surface with an electrolyte containing an electrophoretic varnish, an electrode in contact with said electrolyte, and means for connecting said metallic body with one terminal of said source and said electrode with the other terminal of said source to cause current to flow through said electrolyte to electrodeposit said electrophoretic varnish in pores of said dielectric coating, said connecting means including a time switch permitting said current to flow during a preset selected period, and current integrator means for measuring the integrated quantity of current consumed by such electrodeposition during said selected period.
  • An apparatus comprising I means for displaying a measurement of the current integrator means in units of surface area.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
US00115429A 1970-02-17 1971-02-16 Process and apparatus for determining the porosity of a dielectric layer coating a metallic surface Expired - Lifetime US3719884A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH222070A CH520331A (fr) 1970-02-17 1970-02-17 Procédé électro-chimique de caractérisation des pores traversants d'un diélectrique recouvrant une surface métallique et dispositif de mise en oeuvre du procédé

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US00115429A Expired - Lifetime US3719884A (en) 1970-02-17 1971-02-16 Process and apparatus for determining the porosity of a dielectric layer coating a metallic surface

Country Status (9)

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US (1) US3719884A (fr)
CH (1) CH520331A (fr)
DE (1) DE2106593C3 (fr)
DK (1) DK138134B (fr)
ES (1) ES388371A1 (fr)
FR (1) FR2078581A5 (fr)
GB (1) GB1317683A (fr)
NL (1) NL155653B (fr)
SE (1) SE364364B (fr)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3831085A (en) * 1973-04-12 1974-08-20 Hoffmann La Roche Reactor vessel lining testing method and apparatus
US3858114A (en) * 1972-11-15 1974-12-31 Hoffmann La Roche Method and apparatus for the testing of protective linings
US3965415A (en) * 1974-03-29 1976-06-22 Pfaudler-Werke Ag Alternating voltage method of electrically detecting damage to an enamel layer having one or more tantalum plugs
US4010416A (en) * 1975-08-08 1977-03-01 Westinghouse Electric Corporation Method and apparatus for testing dielectric adequacy and for indicating physical defects in a nonconducting material
US4019129A (en) * 1975-06-02 1977-04-19 Bell Telephone Laboratories, Incorporated Metallic plating testing apparatus
US4206407A (en) * 1978-08-30 1980-06-03 American Can Company Continuity tester for container linings
US4227145A (en) * 1977-10-19 1980-10-07 Bicc Limited Apparatus for detecting faults in electric cables
US4416736A (en) * 1980-01-08 1983-11-22 Bodenseewerk Perkin-Elmer & Co., Gmbh Procedure for the enrichment of the element of interest from a solution for nonflame atomic absorption spectroscopy
US4523141A (en) * 1982-04-16 1985-06-11 The Kendall Company Pipe coating
EP0529409A2 (fr) * 1991-08-22 1993-03-03 Klaus Jörgens Procédé et dispositif pour tester la porosité d'objets couverts d'une couche
US6248601B1 (en) 1999-04-19 2001-06-19 Taiwan Semiconductor Manufacturing Company Fix the glassivation layer's micro crack point precisely by using electroplating method
US6261852B1 (en) 1999-04-19 2001-07-17 Taiwan Semiconductor Manufacturing Company Check abnormal contact and via holes by electroplating method
US6392420B1 (en) * 1998-02-24 2002-05-21 Crown Cork & Seal Technologies Corporation Can coating tester
US20030224544A1 (en) * 2001-12-06 2003-12-04 Shipley Company, L.L.C. Test method
US7006546B2 (en) * 2000-03-15 2006-02-28 Komatsu Ltd. Gas laser electrode, laser chamber employing the electrode, and gas laser device
US11181462B2 (en) 2018-11-30 2021-11-23 International Business Machines Corporation Non-destructive method to determine porosity in metallic coatings
RU2796204C1 (ru) * 2022-12-21 2023-05-17 Федеральное государственное бюджетное учреждение науки Институт физической химии и электрохимии им. А.Н. Фрумкина Российской академии наук (ИФХЭ РАН) Экспресс-способ определения сквозной пористости микродуговых покрытий

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5629153A (en) * 1979-08-20 1981-03-23 Toyo Seikan Kaisha Ltd Measuring method of exposed iron part for coated steel plate or its processed product
CN103163058A (zh) * 2013-03-25 2013-06-19 北京邮电大学 一种利用亚硫酸蒸汽测定镍基底银镀层孔隙率的方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2572597A (en) * 1951-01-02 1951-10-23 Gen Electric Porosity tester for coating materials
US3252155A (en) * 1962-05-18 1966-05-17 American Potash & Chem Corp Liquid receptacle and method for preparing same
GB1081858A (en) * 1964-11-23 1967-09-06 Sperry Rand Corp A method of testing the continuity of a layer of electrically resistive material
US3366554A (en) * 1964-01-06 1968-01-30 Boeing Co Method for evaluating coating discontinuities
US3385777A (en) * 1964-12-30 1968-05-28 Shell Oil Co Electrochemical deposition of organic films
US3555414A (en) * 1968-01-24 1971-01-12 Pfaudler Werke Ag Method and apparatus for detecting faults in the enamel coating of a vessel having electrically conductive tantalum plugs wherein a passivating insulating layer is formed on the plugs
US3556972A (en) * 1968-09-05 1971-01-19 Dow Chemical Co Depositing a polymer from an emulsion by electrophoresis

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2572597A (en) * 1951-01-02 1951-10-23 Gen Electric Porosity tester for coating materials
US3252155A (en) * 1962-05-18 1966-05-17 American Potash & Chem Corp Liquid receptacle and method for preparing same
US3366554A (en) * 1964-01-06 1968-01-30 Boeing Co Method for evaluating coating discontinuities
GB1081858A (en) * 1964-11-23 1967-09-06 Sperry Rand Corp A method of testing the continuity of a layer of electrically resistive material
US3384556A (en) * 1964-11-23 1968-05-21 Sperry Rand Corp Method of electrolytically detecting imperfections in oxide passivation layers
US3385777A (en) * 1964-12-30 1968-05-28 Shell Oil Co Electrochemical deposition of organic films
US3555414A (en) * 1968-01-24 1971-01-12 Pfaudler Werke Ag Method and apparatus for detecting faults in the enamel coating of a vessel having electrically conductive tantalum plugs wherein a passivating insulating layer is formed on the plugs
US3556972A (en) * 1968-09-05 1971-01-19 Dow Chemical Co Depositing a polymer from an emulsion by electrophoresis

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3858114A (en) * 1972-11-15 1974-12-31 Hoffmann La Roche Method and apparatus for the testing of protective linings
US3831085A (en) * 1973-04-12 1974-08-20 Hoffmann La Roche Reactor vessel lining testing method and apparatus
US3965415A (en) * 1974-03-29 1976-06-22 Pfaudler-Werke Ag Alternating voltage method of electrically detecting damage to an enamel layer having one or more tantalum plugs
US4019129A (en) * 1975-06-02 1977-04-19 Bell Telephone Laboratories, Incorporated Metallic plating testing apparatus
US4010416A (en) * 1975-08-08 1977-03-01 Westinghouse Electric Corporation Method and apparatus for testing dielectric adequacy and for indicating physical defects in a nonconducting material
US4112353A (en) * 1975-08-08 1978-09-05 Westinghouse Electric Corp. Method for testing dielectric adequacy and for indicating physical defects in a nonconducting material by depositing traces of carbon on the material
US4227145A (en) * 1977-10-19 1980-10-07 Bicc Limited Apparatus for detecting faults in electric cables
US4206407A (en) * 1978-08-30 1980-06-03 American Can Company Continuity tester for container linings
US4416736A (en) * 1980-01-08 1983-11-22 Bodenseewerk Perkin-Elmer & Co., Gmbh Procedure for the enrichment of the element of interest from a solution for nonflame atomic absorption spectroscopy
US4523141A (en) * 1982-04-16 1985-06-11 The Kendall Company Pipe coating
EP0529409A2 (fr) * 1991-08-22 1993-03-03 Klaus Jörgens Procédé et dispositif pour tester la porosité d'objets couverts d'une couche
EP0529409A3 (en) * 1991-08-22 1994-09-28 Klaus Joergens Method and device for testing the porosity of coated objects
US6392420B1 (en) * 1998-02-24 2002-05-21 Crown Cork & Seal Technologies Corporation Can coating tester
US6248601B1 (en) 1999-04-19 2001-06-19 Taiwan Semiconductor Manufacturing Company Fix the glassivation layer's micro crack point precisely by using electroplating method
US6261852B1 (en) 1999-04-19 2001-07-17 Taiwan Semiconductor Manufacturing Company Check abnormal contact and via holes by electroplating method
US6433575B2 (en) 1999-04-19 2002-08-13 Taiwan Semiconductor Manufacturing Company Check abnormal contact and via holes by electroplating method
US7006546B2 (en) * 2000-03-15 2006-02-28 Komatsu Ltd. Gas laser electrode, laser chamber employing the electrode, and gas laser device
US20030224544A1 (en) * 2001-12-06 2003-12-04 Shipley Company, L.L.C. Test method
US11181462B2 (en) 2018-11-30 2021-11-23 International Business Machines Corporation Non-destructive method to determine porosity in metallic coatings
RU2796204C1 (ru) * 2022-12-21 2023-05-17 Федеральное государственное бюджетное учреждение науки Институт физической химии и электрохимии им. А.Н. Фрумкина Российской академии наук (ИФХЭ РАН) Экспресс-способ определения сквозной пористости микродуговых покрытий

Also Published As

Publication number Publication date
DK138134C (fr) 1978-12-11
NL7102128A (fr) 1971-08-19
SE364364B (fr) 1974-02-18
DE2106593B2 (de) 1978-05-18
NL155653B (nl) 1978-01-16
DE2106593C3 (de) 1979-01-18
ES388371A1 (es) 1973-05-01
FR2078581A5 (fr) 1971-11-05
CH520331A (fr) 1972-03-15
DE2106593A1 (de) 1971-08-26
GB1317683A (en) 1973-05-23
DK138134B (da) 1978-07-17

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