1、Designation: D5894 16Standard Practice forCyclic Salt Fog/UV Exposure of Painted Metal, (AlternatingExposures in a Fog/Dry Cabinet and a UV/CondensationCabinet)1This standard is issued under the fixed designation D5894; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers basic principles and operatingpractice for cycl
3、ic corrosion/UV exposure of paints on metal,using alternating periods of exposure in two different cabinets:a cycling salt fog/dry cabinet, and a fluorescent UV/condensation cabinet.1.2 This practice is limited to the methods of obtaining,measuring, and controlling exposure conditions, and proce-dur
4、es. It does not specify specimen preparation nor evaluationof results.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
5、It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D610 Practice for Evaluating Degree of Rusting on PaintedSteel SurfacesD714 Te
6、st Method for Evaluating Degree of Blistering ofPaintsD1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD4587 Practice for Fluorescent UV-Condensation Expo-sures of Paint and Related CoatingsG85 Practice for Modified Salt Spray (Fog) TestingG113 Termin
7、ology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materials for Natural and Artificial Weathering TestsG151 Practice for Exposing Nonmetallic Materials in Accel-erated Test Devices that Use Laboratory Light
8、SourcesG154 Practice for Operating Fluorescent Ultraviolet (UV)Lamp Apparatus for Exposure of Nonmetallic Materials3. Terminology3.1 DefinitionsThe definitions given in Terminology G113are applicable to this practice.4. Summary of Practice4.1 The test specimens are exposed to alternating periods ofo
9、ne week in a fluorescent UV/condensation chamber followedby one week in a cyclic salt fog/dry chamber. The fluorescentUV/condensation cycle is 4-h UV at 0.89 W/(m2 nm) at 340nm at 60C followed by 4-h condensation at 50C, usingUVA-340 lamps. The fog/dry chamber runs a cycle of 1-h fogat ambient tempe
10、rature and 1-h dry-off at 35C. The fogelectrolyte is a relatively dilute solution, with 0.05 % sodiumchloride and 0.35 % ammonium sulfate.5. Significance and Use5.1 The outdoor corrosion of painted metals is influenced bymany factors, including: corrosive atmospheres, rain, con-densed dew, UV light,
11、 wet/dry cycling, and temperaturecycling. These factors frequently have a synergistic effect onone another. This practice is intended to provide a morerealistic simulation of the interaction of these factors than isfound in traditional tests with continuous exposure to a staticset of corrosive condi
12、tions.5.2 Results obtained from this practice can be used tocompare the relative durability of materials subjected to thespecific test cycle used.5.3 No single exposure test can be specified as a completesimulation of actual use conditions in outdoor environments.Results obtained from exposures cond
13、ucted according to thispractice can be considered as representative of actual outdoor1This practice 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
14、approved April 1, 2016. Published May 2016. Originallyapproved in 1996. Last previous edition approved in 2010 as D5894 10. DOI:10.1520/D5894-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
15、volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1exposures only when the degree of ran
16、k correlation has beenestablished for the specific materials being tested. The relativedurability of materials in actual outdoor service can be verydifferent in different locations because of differences in UVradiation, time of wetness, temperature, pollutants, and otherfactors. Therefore, even if r
17、esults from a specific artificial testcondition are found to be useful for comparing the relativedurability of materials exposed in a particular exteriorenvironment, it cannot be assumed that they will be useful fordetermining relative durability for a different environment.5.4 Even though it is ver
18、y tempting, it is not recommendedto calculate an “acceleration factor” relating x hours oflaboratory exposure to y months of exterior exposure. Differentmaterials and different formulations of the same material canhave significantly different acceleration factors. The accelera-tion factor also varie
19、s depending on the variability in rate ofdegradation in the laboratory test and in actual outdoorexposure.5.5 This practice is best used to compare the relativeperformance of materials tested at the same time in the sameexposure device. Because of possible variability between thesame type of exposur
20、e devices, it is not recommended tocompare the amount of degradation in materials exposed forthe same duration at separate times, or in separate devicesrunning the same test condition. This practice should not beused to establish a “pass/fail” approval of materials after aspecific period of exposure
21、 unless performance comparisonsare made relative to a control material exposed simultaneously,or the variability in the test is rigorously quantified so thatstatistically significant pass/fail judgments can be made.5.6 This practice has been found useful for air-dry industrialmaintenance paints on s
22、teel3,4,5,6,7and zinc-rich primers but itsapplicability has not yet been assessed for highly UV-stabilizedcoating systems, such as for automotive applications.6. Apparatus6.1 Fluorescent UV-Condensation Exposure Chamber, com-plying with Practices G151 and G154.6.2 UVA-340 Fluorescent Lamps.6.3 Salt
23、Fog/Dry Cabinet, complying with Practice G85Annex 5, Dilute Electrolyte Cyclic Fog/Dry Test.7. Test Specimens7.1 The composition and preparation of the substrate, speci-men preparation, and the number of specimens shall be agreedupon prior to testing.7.2 Follow the guidelines of Practice G85 and Pra
24、cticeD4587 on the preparation of specimens for the needs of thoseparticular exposures.7.2.1 Follow the guidelines of Practice G147 on condition-ing and handling of specimens.7.3 Unless otherwise agreed, flat specimens shall be 75 by150 mm.7.4 Expose at least one control specimen with every test.The
25、control specimen should have known durability and be ofsimilar composition to the test specimens. It is preferable tohave two control materials: one of higher durability and one oflower durability.7.5 It is recommended that at least three replicates of eachspecimen be tested, to compensate for varia
26、tion within thechambers and variation between specimens.8. Procedure8.1 Fluorescent UV-Condensation Exposure:8.1.1 Start the exposure in the fluorescent UV-condensationchamber.NOTE 1It has been found that in certain cases the exposure must startin the fluorescent UV/condensation device in order to g
27、et realistic rustingand staining as well as faster corrosion. It is thought that the initial UVdamage to the coating allows the subsequent salt fog to produce a morerealistic corrosion attack on the substrate.8.1.2 Perform the fluorescent UV-condensation exposure incompliance with Practice G151 and
28、G154, and Cycle 2 ofPractice D4587.8.1.3 For irradiance-controlled devices and unless otherwisespecified, set the irradiance level to 0.89 W/(m2 nm) at 340nm; the maximum allowable deviation from the set point at thecontrol point indicated by the readout of the calibrated controlsensor during equili
29、brium operation is 60.02 W/(m2 nm) forirradiance. If mutually agreed upon by all parties, use ofnon-irradiance controlled devices is permitted, but use of thesedevices must be included in the test report.8.1.4 Program a UV/condensation cycle of 4-h UV at 60Cfollowed by 4-h condensation at 50C. The t
30、emperaturesspecified refer to the uninsulated black panel control sensor inthe chamber, as described in Practice G154. The maximumallowable deviation from the set point at the control pointindicated by the readout of the calibrated control sensor duringequilibrium operation is 62.5C for temperature.
31、8.1.5 Use UVA-340 fluorescent lamps.8.1.6 Expose the specimens for 21 cycles, in the fluorescentUV-condensation chamber before transferring them to thefog/dry chamber. These 21 cycles equal a total of 168 h (1week).8.1.7 Other cycles and lamps are acceptable if agreed uponprior to the test, and repo
32、rted in compliance with Section 10.8.2 Cyclic Salt Fog/Dry Exposure:3Skerry, B. S. and Simpson, C. H., “Combined Corrosion/Weathering Acceler-ated Testing of Coatings for Corrosion Control,” Presented at Corrosion 91, TheNationalAssociation of Corrosion Engineers (NACE)Annual Conference 1991, andava
33、ilable from NACE, P.O. Box 218340, Houston, TX 77218.4Simpson, C. H., Ray, C. J., and Skerry, B. S., “Accelerated Corrosion Testingof Industrial Maintenance Paints Using a Cyclic Corrosion Weathering Method,”Journal of Protective Coatings and Linings, Vol 8, No. 5, May 1991, pp. 2836.5Cleveland Soci
34、ety for Coatings Technology, “Correlation of AcceleratedExposure Testing and Exterior Exposure Sites,” Journal of Coatings Technology,Vol 66, No. 837, October 1994, pp. 4961.6Boocock, S. K., “A Report on SSPC Programs to Research PerformanceEvaluation Methods,” Journal of Protective Coatings and Lin
35、ings, October 1994,pp. 5158.7Cleveland Society for Coatings Technology, “Correlation of AcceleratedExposure Testing and Exterior Exposure Sites Part II: One-Year Results,” Journalof Coatings Technology, Vol 68, No 858, July 1996, pp. 47-61.D5894 1628.2.1 Perform the cyclic salt fog/dry exposure acco
36、rding toPractice G85 Annex 5, Dilute Electrolyte Cyclic Fog/Dry Test.8.2.2 Program a fog/dry cycle of 1-h fog at ambient tem-perature followed by 1-h dry-off at 35C at the chambersreference temperature sensor.8.2.2.1 If the lab ambient temperature is above 30C,program a dry-off temperature at least
37、5C above the labambient to provide positive dry-off. For instance if the labambient is 37C, program a dry-off temperature of at least42C.8.2.2.2 The dry-off temperatures specified in 8.2.2.1 refer tothe chamber air control sensor in the fog/dry chamber. Theallowable operational fluctuation at equili
38、brium is 63C.8.2.3 Prepare the salt solution with 0.05 % sodium chlorideand 0.35 % ammonium sulfate by weight.8.2.4 Expose the specimens for 84 cycles in the fog/drychamber before transferring them back to the fluorescentUV-condensation chamber. These 84 cycles equal a total of 168h (1 week).8.2.5 O
39、ther cycles, temperatures, and electrolytes are ac-ceptable if agreed upon prior to the test, and reported incompliance with Section 10.NOTE 2Data from Electrochemical Noise Analysis tests indicate thatthe temperature of the fog/dry cabinet is not critical to the rate ofcorrosion, nor is the rate of
40、 drying off critical to the rate of corrosion.What is critical is (a) the frequency of drying and (b) that the surface ofthe specimen does in fact dry off during the 1-h period. Longer fog/drycycles (for example, 2-h fog, 2-h dry) have been found to produce slowerdegradation.8.3 Specimen RotationWhe
41、n moving the specimens fromone chamber to another, reposition the specimens so that overthe course of the test each specimen spends equal amounts oftime in each area of the chamber: edges, center, top, bottom.This will help minimize variation in degradation due tovariations in conditions within the
42、chamber.8.4 Do not wash or clean specimens between tests or priorto completion of entire test, or as agreed upon betweenpurchaser and seller prior to testing.8.5 Evaluation of CorrosionMethods that may be usefulfor evaluating the corrosion of the specimens are Test MethodsD610, D714, and D1654. Prac
43、tice D4587 also references anumber of other standards that may be used for evaluating theappearance change of the specimens.8.5.1 Evaluate every 336-h or multiples thereof and aftercompletion of testing. Perform evaluation after complete 2-step(UV exposure and Salt Fog/Dry Exposure) cycles only.9. D
44、uration of Exposure9.1 Use one of the following methods to determine theduration of the exposure under this practice:9.1.1 A mutually agreed upon specified number of totalhours,9.1.2 The exposure required to produce a mutually agreedupon amount of change in either the test specimens or anagreed upon
45、 standard reference specimen, and9.1.3 If no information is available as to an appropriateexposure duration, expose the specimens for a total of 1008-h,or until significant differences in performance between speci-mens become apparent.10. Report10.1 Report the following information:10.1.1 Test cycle
46、,10.1.1.1 UV/condensation cabinet cycle (for example, 4-hUV at 60C and 4-h condensation at 50C),10.1.1.2 Fog/dry cabinet cycle (for example, 1-h fog atambient temperature and 1-h dry-off at 35C),10.1.1.3 Hours spent in each cabinet before transfer fromone cabinet to the other (for example, 168-h in
47、the fog/drycabinet and 168-h in the UV/condensation cabinet),10.1.1.4 The total hours of exposure,10.1.2 Manufacturers designation and wavelength of peakemission for fluorescent lamps, if different than 8.1.5,10.1.3 Electrolyte solution (for example, 0.05 % sodiumchloride and 0.35 % ammonium sulfate
48、 by mass),10.1.4 Specimen cleaning standards used or cleaning mate-rials and procedures, and10.1.5 Other information required in Report section ofPractice G85 and Periods of Exposure and Evaluation ofResults section of Practice D4587.11. Keywords11.1 accelerated aging/testingpaints; corrosion; cycli
49、ccorrosion; rust; salt spray; ultravioletSUMMARY OF CHANGESCommittee D01 has identified the location of selected changes to this standard since the last issue (D589410)that may impact the use of this standard. (April 1, 2016.)(1) 5.6 Removed reference to galvanized substrates, andreinforced that the standard has not been assessed for highlyUV-stabilized coating systems.(2) 6.3 Removed Note 2.(3) 8.1.3 Clarified the use of irradiance controlled devicesand added operational fluctuation for irradiance to harmonizewith other weathering standards.(4) 8
