1、Designation: D 2803 09Standard Guide for TestingFiliform Corrosion Resistance of Organic Coatings onMetal1This standard is issued under the fixed designation D 2803; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This guide covers three procedures for de
3、termining thesusceptibility of organic-coated metal substrates to formationof filiform corrosion.1.2 This guide is limited to the determination of whetherfiliform corrosion will occur between the organic coating andsubstrate.1.3 The values stated in SI units are to be regarded as thestandard. The va
4、lues given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of r
5、egulatory limitations prior to use.NOTE 1Procedure B of this standard is equivalent to ISO 4623.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) ApparatusD 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings,
6、andRelated Coating ProductsD 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1654 Test Method for Evaluation of Painted or CoatedSpecimens Subj
7、ected to Corrosive EnvironmentsD 1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for PaintingD 7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-ings Applied to Non-Ferrous Meta
8、lsE 104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions2.2 International Standard:3ISO 46231 Paints and VarnishesDetermination of resis-tance to filiform corrosionPart 1: On steelISO 46232 Paints and VarnishesDetermination of resis-tance to filiform corrosionPart 2:
9、On aluminumISO 462810 Paints and VarnishesEvaluation of degrada-tion of coatingsDesignation of quantity and size ofdefects and of intensity of changesPart 10:Assessment offiliform corrosion3. Terminology3.1 Definitions:3.1.1 filiform corrosion, na special type of corrosion thatoccurs under coatings
10、on metal substrates that is characterizedby a definite threadlike structure and directional growth.3.1.1.1 DiscussionFiliform corrosion usually occurs be-tween 20 and 35C (70 and 95F), with a correspondingrelative humidity range of 60 to 95 %; above 95 % humidity,blistering rather than filiform corr
11、osion may occur.4. Summary of Method4.1 Coated metal specimens are scribed and placed in acorrosive atmosphere to initiate corrosion. The specimens arethen exposed to controlled temperature and humidity condi-tions known to be conducive to filiform corrosion.4.2 In Procedure A, panels are subjected
12、to a preliminaryexposure in the salt spray cabinet to initiate corrosion, rinsed,and placed in a humidity cabinet. In Procedure B, based on ISO4623, panels are either exposed to salt spray or dipped in a saltsolution but not rinsed before placing in the humidity cabinetoperated at a higher temperatu
13、re than in Procedure A. In1This guide is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.27 on Accelerated Testing.Current edition approved Aug. 1, 2009. Published September 2009. Originallyapp
14、roved in 1969. Last previous addition approved in 2003 as D 2803 - 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM
15、 website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
16、9, United States.Procedure C, specimens are exposed as in Procedure A exceptthe humidity cabinet is operated at a higher temperature.4.3 The procedures contained in this guide differ signifi-cantly in method of initiation, and or temperature, or both, andhumidity of exposure and therefore may not yi
17、eld comparableresults.5. Significance and Use5.1 Some organic coatings applied to metal substrates ex-hibit filiform corrosion when there is a break in the coating filmand the relative humidity is in the 70 to 95 % range.5.2 This guide can be used to determine the susceptibility oforganic coated met
18、al substrates to the formation of filiformcorrosion.6. Apparatus6.1 Salt-Spray Chamber as described in Practice B117, forsalt-spray (fog) testing.NOTE 2The preferred initiator of corrosion at the scribe is the salt-fogatmosphere described in Practice B117. Exposure of the specimens for 2to4hinaclose
19、d cabinet to the atmosphere above a 1 % acetic acidsolution is an acceptable alternative.6.2 Humidity CabinetAny cabinet with suitable tempera-ture and humidity controls with air circulation may be used.The size and detailed construction of the apparatus are op-tional, provided the conditions meet t
20、he requirements of thismethod.7. Test Specimen7.1 The composition, surface preparation, and number oftest specimens shall be agreed upon between the producer andthe user. Steel is the preferred substrate, but other metals suchas aluminum, copper magnesium, and stainless steel may beused. Zinc and zi
21、nc-coated steel are not recommended becausefiliform corrosion generally does not occur on zinc.NOTE 3Applicable test panel description and surface preparationmethods are given in Practice D 609 and Practices D 1730.7.2 Preparation of Test SpecimensThe method of appli-cation, film thickness, curing,
22、and conditioning shall be agreedupon between the producer and user.NOTE 4Practices D 823 gives application methods that can be used toproduce films of uniform film thickness.NOTE 5Test Method D 1005 and Practice D 7091 give proceduresthat can be used for measurement of dry film thickness.7.3 Scribe
23、the test specimen in accordance with Test MethodD 1654 or as agreed upon between the producer and user.7.4 The back and edges of the panel should be protectedwith an anti-corrosion coating or tape, unless edge failure isbeing evaluated.8. Use of Control or Reference Materials8.1 When several coating
24、s are being compared, select acoating as a control. Apply the control coating to the samesubstrate as the test coatings. For best results there should betwo controls, one known to perform well and one known toperform poorly.9. Procedure A9.1 Expose the test specimens to the salt-fog atmosphere inacc
25、ordance with Practice B117for at least 4 h and not morethan 24 h, or as agreed upon between the producer and user.9.2 Remove from the salt-fog cabinet and thoroughly rinsewith distilled or demineralized water. Do not permit specimensto dry before placing in the humidity cabinet.9.3 Place the specime
26、ns in the humidity cabinet so that theyare no closer together than 40 mm (1.5 in.) and not in contactwith any metal. Set the cabinet to operate at 25C (77F) and85 % relative humidity unless otherwise agreed upon betweenthe producer and user. The allowed operational limits are 62C(63.5F) and 610 % re
27、lative humidity.NOTE 6The recommended means of maintaining the specified rela-tive humidity is to utilize trays of saturated potassium chromate solution(650 g/L). Practice E 104 describes other methods for maintaining relativehumidity, but they may affect the degree and rate of filiform corrosion.9.
28、4 Inspect the specimens at intervals of approximately 168h for development of threadlike filaments from the scribe.Exercise care to maintain wetness of specimens during inspec-tion, since drying stops the original pattern of filiform corro-sion. New filiform may develop on continued exposure but atd
29、ifferent points.9.4.1 Filiform corrosion will be noted as threadlike fila-ments (see Note 7), initiating at the scribe. A standard methodof rating failure due to filiform is not available. The uniformityof filament growth in direction, width, height and frequencyprecludes a precise rating system. Ph
30、otographs of filiformfailure are preferred for recording test results. Otherwise, abrief description of the filament growth and their frequency canbe made. ISO 462810 provides a method for the measurementof filiform filaments. Filiform corrosion may continue todevelop after specimens are removed fro
31、m the humiditycabinet.NOTE 7The nature of grinding and grain direction on panels caninfluence the direction of filiform growth.9.5 The normal test period is 6 weeks (1008 h). Otherperiods may be used at the option of the producer and user.10. Procedure B (ISO 4623)10.1 Two alternative initiations of
32、 corrosion are available,based on initiation by dipping in sodium chloride solution (seeNote 8) or exposure to salt fog. The dipping technique isgenerally preferable for air drying and low-durability materi-als. For high-durability systems such as automotive finishesapplied to phosphated steel, the
33、dipping technique may notproduce filiform corrosion and for these systems, it is prefer-able to adopt the salt-fog technique. In such cases, thenecessary period of exposure to salt fog depends on thedurability of the material under test but should rarely need toexceed 24 h.NOTE 8Sodium chloride 0.1
34、% (w/v) solution (for dipping technique)is prepared by dissolving1gofreagent grade sodium chloride (NaCl) in1 L of distilled or demineralized water. Place this solution in a vesselsuitable for complete immersion of the test panel.10.2 Dipping Technique:D280309210.2.1 Immerse the scribed specimen for
35、 30 to 60 s in thesodium chloride solution (see Note 8).10.2.2 Take the specimen out of the solution and removeany drops of liquid adhering to it, taking care not to remove thesolution from the scribed marks.10.2.3 Place the specimen in a humidity cabinet set tooperate at 40C (104F) and 80 % relativ
36、e humidity. Theallowed operational limits are 62C (63.5F) and 610 %relative humidity.10.2.4 Repeat the immersion procedure every 3 or 4 daysuntil the end of the test cycle (21 days) or as agreed uponbetween the producer and the user.10.3 Salt-Fog Technique:10.3.1 Expose the scribed test specimen to
37、the salt-fogatmosphere in accordance with Practice B117for at least 4 hor not more than 24 h or as agreed upon between the producerand the user.10.3.2 Remove the test specimen from the salt-fog cabinetand remove any drops of liquid adhering to it, taking care notto remove the solution from the scrib
38、ed marks.10.3.3 Place the specimen in a humidity cabinet set tooperate at 40C (104F) and 80 % relative humidity for thespecified period agreed upon between the producer and theuser. The allowed operational limits are 62C (63.5F) and610 % relative humidity.10.4 Follow the procedures in 9.4 and 9.4.1.
39、11. Procedure C11.1 Expose the test specimens to the salt-fog atmospherein accordance with Practice B117for at least 4 h and not morethan 24 h, or as agreed upon between the producer and user.11.2 Remove from the salt-fog cabinet and thoroughly rinsewith distilled or demineralized water. Do not perm
40、it specimensto dry before placing in the humidity cabinet.11.3 Place the specimens in the humidity cabinet so theyare no closer together than 1.5 in. (40 mm) and not in contactwith any metal. Set the cabinet to operate at 40C (104F) and80 % relative humidity. The allowed operational limits are62C (6
41、3.5F) and 610 % relative humidity.11.4 Follow the procedures in 9.4 and 9.4.1.12. Report12.1 The report shall include the following:12.1.1 Initiation procedure,12.1.2 Humidity cabinet operating temperature,12.1.3 Exposure period, and12.1.4 Rating of coatings as described in 9.4.1.13. Keywords13.1 fi
42、liformSUMMARY OF CHANGESCommittee D01 has identified the location of selected changes to this standard since the last issue(D 2803 - 03) that may impact the use of this standard. (Approved August 1, 2009.)(1) Replaced withdrawn Test Methods D 1186 and D 1400 onDry Film Thickness measurement with the
43、 replacement Prac-tice D 7091.(2) Reworded the set point and operational limits to agree withguidelines from ASTM Committee G03.(3) Changed operational limits for relative humidity to610 %.(4) Added an ISO equivalency statement.(5) Added a Summary of Changes section.ASTM International takes no posit
44、ion respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibilit
45、y.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM
46、 International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address s
47、hown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D2803093
