1、Designation: F520 10Standard Test Method forEnvironmental Resistance of Aerospace Transparencies toArtificially Induced Exposures1This standard is issued under the fixed designation F520; the number immediately following the designation indicates the year of originaladoption or, in the case of revis
2、ion, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the effects ofexposure to thermal shock, condensing humidity, an
3、d simu-lated weather on aerospace transparent enclosures.1.2 This test method is not recommended for quality controlnor is it intended to provide a correlation to actual service life.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisst
4、andard.1.3.1 ExceptionsCertain inch-pound units are furnished inparentheses (not mandatory) and certain temperatures in Fahr-enheit associated with other standards are also furnished.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is there
5、sponsibility 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:2D1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsD4329 Practic
6、e for Fluorescent UV Exposure of PlasticsF319 Practice for Polarized Light Detection of Flaws inAerospace Transparency Heating ElementsF521 Test Methods for Bond Integrity of Transparent Lami-natesF790 Guide for Testing Materials for Aerospace PlasticTransparent EnclosuresG53 Practice for Operating
7、Light-and Water-Exposure Ap-paratus (Fluorescent UV-Condensation Type) for Exposureof Nonmetallic Materials (Discontinued 2001)3G113 Terminology Relating to Natural andArtificialWeath-ering Tests of Nonmetallic MaterialsG151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices th
8、at Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Light Apparatusfor UV Exposure of Nonmetallic Materials3. Summary of Test Method3.1 Two types of test specimens, duplicating the aerospacetransparent enclosure design, are subjected to thermal shock,condensing humidity, and artif
9、icial weathering. Edge sealingmay be used if representative of the design.3.1.1 Type A specimens are used to determine the effect ofenvironmental exposure on electrical and optical properties.3.1.2 Type B specimens are used to determine the effect ofenvironmental exposure on bond integrity.4. Signif
10、icance and Use4.1 This test method, when applied to aerospace transpar-encies of either monolithic glass/plastic or laminated combi-nations, is a measure of the ability of the transparency towithstand the effects of artificially induced environments. Thetest may be used on configurations employing e
11、lectricallyconductive coatings, and also to evaluate the integrity ofnoncoated materials.4.2 The resistance of the transparent enclosure to environ-mental effects may vary appreciably depending on the size,geometry, material of construction, coating integrity, coatingdensity, and other factors.5. Te
12、st Specimens5.1 Each Type A specimen to be evaluated for externalcoating durability shall be a 250 by 250-mm (9.8 by 9.8-in.)1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and
13、 Materials.Current edition approved May 1, 2010. Published June 2010. Originallyapproved in 1977. Last previous edition approved in 2004 as F520 97 (2004).DOI: 10.1520/F0520-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. F
14、or Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、19428-2959, United States.cross section of the design and shall contain, as applicable,surface coatings of operational, electrically conducting coatingsystems complete with bus bars, braids, and temperaturesensors.5.1.1 Type A test specimens shall have a fully operationalcoating system, when applica
16、ble, with an average resistivityconsistent with the average resistivity of the representativedesign. Reproduction of multiphase electrical circuits is notrequired for these test specimens since this type of circuitry isonly a design technique used to accommodate limited voltageresources at installat
17、ion.5.1.2 Type A specimen testing exposure of an externalcoating only, are independent of size but shall be of sufficientsize to produce representative coatings. When testing externalcoatings the recommended specimen size is 250 by 250-mm(9.8 by 9.8-in.). Type A specimens which are monolithic, orlam
18、inated samples where only an external coating system isbeing tested shall be tested to the same exposure intervals as 50by 50-mm (2 by 2-in.), Type B specimens (5.2).5.1.3 Type A specimen testing for effects of exposure tocomponents within a laminated construction, such as electricalcomponents, heat
19、ing films, and interlayers, taking place due tomoisture ingress are dependent on size and shall receiveincreasing exposure levels as the length of the sides of thespecimen increase. 250 by 250-mm specimens shall be ex-posed to humidity 27 times the duration of 50 by 50-mmspecimens. Use of 150 by 150
20、-mm specimen shall be allowedwith exposure of 9 times that of corresponding 50 by 50-mmspecimens, or 1/3 the duration of 250 by 250-mm specimens.5.1.4 Type A that are both laminated and contain externalcoatings where both external and internal effects are to betested after exposure, must be tested i
21、ndependently as exter-nally coated samples, and as laminated samples, since theexposure durations will be different. To test effects on bothlayers of a particular design, the number of samples must bedoubled, the external coating tested on one set, and internalcomponents tested on a second set of sp
22、ecimens.5.2 Each Type B test specimen shall be 50 by 50 mm (2 by2 in.) and shall be of a cross section consistent with the edgeconfiguration of the representative design. Type B test speci-mens are not intended to be operational electrically, but theyshall be representative of the average resistivit
23、y of the design.6. Preparation of Test Specimens6.1 Prepare a minimum of three Type A specimens for eachdesign configuration. If the design contains an electricallyactivated coating, only one temperature sensor per specimen isrequired.6.2 Prepare a minimum of five Type B specimens for eachdesign con
24、figuration. Prepare the specimen in such a manner asto produce smooth edges and corners to prevent chippingduring testing. Polish at least one edge of each specimen toallow inspection of the internal bonded surfaces during tensileloading. Do not apply edge sealant to the specimens.6.3 Condition all
25、test specimens by exposing them to notless than 40 h at 23 6 2C (73.4 6 3.6F) and 50 6 5%relative humidity.7. Procedure7.1 Visual ExaminationCarefully examine Type A andType B specimens for any signs of material or manufacturingdefects. A microscope or magnifying lens, dark background,and cross ligh
26、ting may be used, as appropriate, to assist in theidentification and classification of visible defects.7.2 Optical TestsMeasure each Type A specimen forluminous transmittance and haze in accordance with ProcedureB ofTest Method D1003. Make at least two measurements, onein the center and one near the
27、 edge, on each specimen. Sixmeasurements are preferred. If greater than 1 % variationexists, prepare a template from polyester film or other suitablematerial to record these locations for indexing and correlationto readings to be taken after environmental exposure.NOTE 1Paragraphs 7.3-7.6 are applic
28、able to systems using electri-cally conductive coatings.7.3 Electrical Tests:7.3.1 Bus Bar-to-Bus Bar ResistanceMeasure each TypeA specimen for bus bar-to-bus bar resistance. Take precautionsto minimize the effects of variable contact resistance. Recordresults and repeat the measurement after enviro
29、nmental expo-sure prior to application of over-voltage power.7.3.2 Sensing ElementMeasure the resistance of the sens-ing elements at a specified temperature to assure conformanceto the temperature resistance ranges certified by the elementmanufacturer.7.3.3 Electrical InsulationTest the electrical i
30、nsulation bymeasuring leakage current on each test specimen. Apply analternating current potential between 1500 and 2500 V rms,depending upon the design application and specified require-ments, at 50 or 60 Hz for a period of 1 min between thefollowing:(1) each sensor lead and each heater lead;(2) ea
31、ch sensor lead and metal insert or spacer;(3) each heater lead and the metal insert or spacer;(4) each heater lead and metal strip placed in contact withthe edge of the glass panel; test the entire edge of the glasspanel;(5) each anti-ice and defog heater lead.Leakage current in excess of 1 mA at 15
32、00 V rms or 4 mA at2500 V rms is objectionable. Monitor the current during apreliminary low voltage application and terminate the test if thecurrent leakage exceeds the allowable amount prior to fullvoltage application. Determine the resistance and decidewhether to proceed to full voltage in conform
33、ance with the testprocedure.7.3.4 Monitor the current during gradual application of a dcvoltage. Current in excess of 5 A is objectionable. If thecurrent exceeds 5 A dc before 500 V dc is reached, suspendthe test and determine the resistance before deciding whether tocontinue. Gradually apply and re
34、move the potential at nogreater rate than 500 V rms/s.7.3.5 Electrically Conductive Coating TestTest each TypeA specimen for electrically conductive coating uniformity inaccordance with Test Method F319.7.3.5.1 For electrically conductive coatings on plastic ma-terials, apply a minimum of 110 % of t
35、he nominal designvoltage.F520 1027.3.5.2 For electrically conductive coatings on glass, applya minimum of 125 % of the nominal design voltage.7.3.5.3 Alternative voltage levels and power-on times maybe as specified by contractual documents.7.3.6 Overvoltage TestSubject each of the electrical heat-in
36、g circuits of Type A specimens to the application of anovervoltage of 150 % maximum operating voltage for thecircuit.Apply this voltage to the power leads for a minimum of5 s.After no less than a 2-min wait, apply the same voltage fora minimum of 5 s, observing the sample in a darkened roomwith spec
37、ific emphasis being on the bus bars for signs ofarcing.7.3.7 Bond Integrity TestTest individual Type B speci-mens in accordance with Test Methods F521.7.4 Specimens that fail due to some obvious, non-representative defect shall be disqualified and retests con-ducted.7.5 Environmental Exposure:7.5.1
38、Artificial WeatheringExpose test specimens to arti-ficial weathering in accordance with G154 for testing compo-nents internal to laminates. Test in accordance with G53 fortesting external coatings or surfaces exposed to the environ-ment.7.5.1.1 Practice G154 for Operating Light- and Water-Exposure A
39、pparatus (Fluorescent UV-Condensation Type) forExposure of Nonmetallic MaterialsUVA-340 is recom-mended when testing internal components of both glass andplastic laminates. The recommended G154 cycle is Cycle 4,UVA-340, UVA-340 bulbs operating at 1.35 W/m2/nm typicalirradiance, and a cycle of8hUVata
40、constant temperature of158F (70C) followed by 4 h condensation at a constanttemperature of 120F (50C). Exposure shall be a mutuallyagreed total number of hours and number of testing intervals.A suggested total exposure time is 1850 h (77 days) with aminimum of 7 test intervals of 264 h (15 days).App
41、ly the cyclecontinuously for 264 h (15 days) to constitute each interval.7.5.1.2 Practice G53 for Operating Light- and Water-Exposure Apparatus (Fluorescent UV-Condensation Type) forExposure of Nonmetallic MaterialsUse UVB-313 bulbs anda cycle of7hUVfollowed by 5 h condensation, all at aconstant tem
42、perature of 120F when testing external coatings,surfaces or surface treatments.Asuggested total exposure timeis 1176 h (49 days) with a minimum of 7 test intervals of 168h (7 days). Apply the cycle continuously for 168 h (1 week) toconstitute each interval.NOTE 2Practice G53 has been shown to produc
43、e acceptable acceler-ated weathering results. Practice G53 is used most extensively in theTransparency Community due to its simplicity, ease of use and lowoperational costs. The UVB-313 cycle of7hUVfollowed by 5 hcondensation, all at 120F have been standard practice for coatingsexposures, representi
44、ng a substantial database of test results.NOTE 3Accelerated weathering results may only be compared forsamples exposed using the same practice. Comparison of test resultsobtained using different practices may result in erroneous conclusions,particularly when comparing the relative performance of dif
45、ferent mate-rials.7.5.2 HumidityExpose Type B test specimens to a mini-mum exposure of 10 cycles of condensing humidity in achamber with a controlled temperature of 49 6 3C (120 65F) and relative humidity of 95 to 100 %.7.5.2.1 Type B specimens and Type A specimens testing anexternal coating or expo
46、sed surface shall be tested in intervalsof 10 cycles, a minimum of 1 interval is required, and testingshould be continued until the desired level of degradation isverified. Water used to maintain the humidity shall not containmore than 200 ppm total solids. Each cycle shall be a 24-hexposure in the
47、condensing humidity chamber and an 8-hexposure to ambient temperature and humidity. As an alterna-tive, continuous exposure to humidity may be used in cycles of24 h.7.5.2.2 Type A specimens exposed to test internal compo-nents using 150 by 150-mm laminated Type A specimens,intervals of 90 cycles are
48、 recommended with a minimum of 1interval exposure.7.5.2.3 Type A specimens exposed to test internal compo-nents using 250 by 250-mm laminated Type A specimens,intervals of 270 cycles are recommended with a minimum of 1interval exposure.7.5.3 Thermal ShockPlace the test specimen in an oven ata temper
49、ature of 71C (160F) and leave until stabilized at71C (160F) as determined by a thermocouple attached to thespecimen face.After the temperature has stabilized, transfer thespecimen as rapidly as possible (within 3 min) to a chambermaintained at 54C (65F). Let the specimen stabilizeat 54C (65F) and as rapidly as possible return it to theoven at 71C (160F). After each 54C (65F) cold soak,and while the specimen is stabilized at 54C (65F), ener-gize the conductive coating on Type A specimens using thedesign watt density until the tem
