1、Designation: D5894 10Standard 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 andArtificial 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 Ac-celerated Test Devices that Use Laboratory Light S
8、ourcesG152 Practice for Operating Open Flame Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG154 Practice for Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic MaterialsG155 Practice for Operating XenonArc LightApparatus forExposure of Non-Metallic Materials3. Termi
9、nology3.1 DefinitionsThe definitions given in TerminologyG113 are applicable to this practice.4. Summary of Practice4.1 The test specimens are exposed to alternating periods ofone week in a fluorescent UV/condensation chamber and oneweek in a cyclic salt fog/dry chamber. The fluorescent UV/condensat
10、ion cycle is 4-h UV at 0.89 W/(m2 nm) at 340 nm at60C and 4-h condensation at 50C, using UVA-340 lamps.The fog/dry chamber runs a cycle of 1-h fog at ambienttemperature and 1-h dry-off at 35C. The fog electrolyte is arelatively dilute solution, with 0.05 % sodium chloride and0.35 % ammonium sulfate.
11、NOTE 1The irradiance target setpoint of 0.89 is based upon actualirradiance levels that have been historically widely used for coatings.5. Significance and Use5.1 The outdoor corrosion of painted metals is influenced bymany factors, including: corrosive atmospheres, rain, con-densed dew, UV light, w
12、et/dry cycling, and temperature1This 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 approved Dec. 1, 2010. Published January 2011. Origina
13、llyapproved in 1996. Last previous edition approved in 2005 as D5894 05. DOI:10.1520/D5894-10.2For 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
14、 Summary page onthe ASTM website.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 19428-2959, United States.cycling. These factors frequently have a synergistic effect onone another. This practi
15、ce 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 conditions.5.2 Results obtained from this practice can be used tocompare the relative durability of materials subjected to t
16、hespecific 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 conducted according to thispractice can be considered as representative of actual outdoorexposures only when the degree of
17、rank 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 i
18、f results from a specific artificial testcondition are found to be useful for comparing the relativedurability of materials exposed in a particular exterior envi-ronment, it cannot be assumed that they will be useful fordetermining relative durability for a different environment.5.4 Even though it i
19、s very tempting, it is not recommendedto calculate an “acceleration factor” relating xhours of labora-tory 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
20、 varies 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 e
21、xposure 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 ex
22、posure 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 paint
23、s on steel3,4,5,6,7and zinc-rich primers but itsapplicability has not yet been assessed for galvanized sub-strates.6. Apparatus6.1 Fluorescent UV-Condensation Exposure Chamber,complying with Practices G151 and G154.6.2 UVA-340 Fluorescent Lamps.6.3 Salt Fog/Dry Cabinet, complying with Practice G85,D
24、ilute Electrolyte Cyclic Fog/Dry Test Annex.NOTE 2Committee G03 is developing information to be published inAppendices of Practices G151, G152, G154, and G155 for guidance onuniformity of conditions in the test chambers and allowed operationalfluctuations of the set points.7. Test Specimens7.1 The c
25、omposition 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 PracticeD4587 on the preparation of specimens for the needs of thoseparticular exposures.7.2.1 Follow the guidelines of P
26、ractice 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 control specimen should have known durability and be ofsimilar composition to the test specimens. It is preferable toh
27、ave 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 variation within thechambers and variation between specimens.3Skerry, B. S. and Simpson, C. H., “Combined Corrosion/Weather
28、ing Acceler-ated Testing of Coatings for Corrosion Control,” Presented at Corrosion 91, TheNationalAssociation of Corrosion Engineers (NACE)Annual Conference 1991, andavailable from NACE, P.O. Box 218340, Houston, TX 77218.4Simpson, C. H., Ray, C. J., and Skerry, B. S., “Accelerated Corrosion Testin
29、gof Industrial Maintenance Paints Using a Cyclic Corrosion Weathering Method,”Journal of Protective Coatings and Linings, Vol 8, No. 5, May 1991, pp. 2836.5Cleveland Society for Coatings Technology, “Correlation of AcceleratedExposure Testing and Exterior Exposure Sites,” Journal of Coatings Technol
30、ogy,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 Linings, October 1994,pp. 5158.7Cleveland Society for Coatings Technology, “Correlation of AcceleratedExposure Testing and Exterior E
31、xposure Sites Part II: One-Year Results,” Journalof Coatings Technology, Vol 68 , No 858, July 1996, pp. 47-61.D5894 1028. Procedure8.1 Fluorescent UV-Condensation Exposure:8.1.1 Start the exposure in the fluorescent UV-condensationchamber.NOTE 3It has been found that in certain cases the exposure m
32、ust startin the fluorescent UV/condensation device in order to get 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 fluoresce
33、nt UV-condensation exposure incompliance with Cycle 2 of Practices D4587 and G151 andG154.8.1.3 Unless otherwise specified, set the irradiance level to0.89 W/(m2 nm) at 340 nm. Program a cycle of 4-h UV at60C and 4-h condensation at 50C. The temperatures specifiedrefer to the uninsulated black panel
34、 control sensor in thechamber, as described in Practice G154. The allowable opera-tional fluctuation at equilibrium is 63C.8.1.3.1 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 Use UVA-3
35、40 fluorescent lamps.8.1.5 Expose the specimens for a total of 168 h (1 week) inthe fluorescent UV-condensation chamber before transferringthem to the fog/dry chamber.8.1.6 Other cycles and lamps are acceptable if agreed uponprior to the test, and reported in compliance with Section 10.8.2 Cyclic Sa
36、lt Fog/Dry Exposure:8.2.1 Perform the cyclic salt fog/dry exposure according toPractice G85, Dilute Electrolyte Cyclic Fog/Dry Test Annex.8.2.2 Program a fog/dry cycle of 1-h fog at ambient tem-perature and 1-h dry-off at 35C at the chambers referencetemperature sensor.8.2.2.1 If the lab ambient tem
37、perature is above 30C,program a dry-off temperature at least 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 fo
38、g/dry chamber. Theallowable operational fluctuation at equilibrium 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 a total of 168 h in thefog/dry chamber before transferring them back to the fluores-cent UV-conden
39、sation chamber.8.2.5 Other cycles, temperatures, and electrolytes are ac-ceptable if agreed upon prior to the test, and reported incompliance with Section 10.NOTE 4Data from Electrochemical Noise Analysis tests indicate thatthe temperature of the fog/dry cabinet is not critical to the rate ofcorrosi
40、on, nor is the rate of 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.
41、3 Specimen Rotation When 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
42、 conditions within the 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
43、, D714, and D1654. Practice 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 Exp
44、osure) cycles only.9. Duration 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 spe
45、cimens or anagreed upon 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 inform
46、ation:10.1.1 Test cycle,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
47、(for example, 168 h in 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 8.1.4,10.1.3 Electrolyte solution (for example, 0.05 % sodiumchloride and
48、0.35 % ammonium sulfate 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/testingp
49、aints; corrosion; cycliccorrosion; rust; salt spray; ultravioletD5894 103SUMMARY OF CHANGESCommittee D01 has identified the location of selected changes to this standard since the last issue (D5894 - 05)that may impact the use of this standard. (Approved December 1, 2010.)(1) 5.6 Added Footnote 7.(2) 8.1.3 Expressed 63C as “operational fluctuation” as inPractice G151.(3) 8.2.2.1 and 8.2.2.2 were added.(4) Note 4 Clarified importance of frequency of drying andcompleteness of drying.ASTM International takes no position respecting the validity of
