1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright 2003 SAE InternationalAll rights reserved. No part of this publication may be
3、reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying,recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-
4、776-0790Email: custsvcsae.orgSAE WEB ADDRESS: http:/www.sae.orgSURFACEVEHICLESTANDARDJ2020REV.FEB2003Issued 1989-06Revised 2003-02Superseding J2020 SEP2002Accelerated Exposure of Automotive Exterior MaterialsUsing a Fluorescent UV and Condensation Apparatus1. Scope1.1 This test method specifies the
5、operating conditions for a fluorescent ultraviolet (UV) and condensationapparatus used for the accelerated exposure of various automotive exterior components.1.2 Specimen preparation, test duration, and performance evaluation procedures are addressed by eachautomotive manufacturers material specific
6、ations. 1.3 This SAE Standard may involve hazardous materials, operations, and equipment. This document does notpurport to address all of the safety problems associated with its use. It is the responsibility of whoever uses this document to consult and establish appropriate and health practicesand d
7、etermine the applicability of regulatory limitations prior to use.1.4 Significance and UseThis test method is designed to simulate extreme environmental conditionsencountered on the outside of an automobile due to sunlight, heat, and to provide an acceleration of exposurefor the purpose of predictin
8、g the performance of exterior automotive materials.1.5 Unless otherwise specified, all dimensions reported in this method are nominal.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein.2.1.1 ASTM PUBLICATIONSAvailable fr
9、om ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.ASTM E 207Standard Test Method for Thermal EMF Test of Single Thermoelement Materials ByComparison with a Reference Thermoelement of Similar EMF-Temperature PropertiesASTM E 220Method for Calibration of Thermocouples by Comparison Tech
10、niques ASTM G 113Standard Terminology Relating to Natural and Artificial Weathering Tests of NonmetallicMaterialsASTM G 154Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure ofNonmetallic MaterialsCopyright SAE International Provided by IHS under license with SAENot for Resa
11、leNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised FEB2003-2-2.1.2 CIE PUBLICATIONAvailable from Commission Internationale de Leclairage, 52 Bd Malesherbes, F-75008Paris, France.CIE Publication No. 85Solar spectral irradiance (1989)2.1.3 ISO P UBLICATIONAvailable
12、from ANSI, 25 West 43rd Street, New York, NY 10036-8002.ISO 9370PlasticsInstrumental determination of radiant exposure in weathering testsGeneralguidance and basic test method2.2 Related PublicationThe following publication is provided for information purposes only and is not a requiredpart of this
13、specification.2.2.1 ASTM P UBLICATIONAvailable from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.ASTM G 151Standard Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that UseLaboratory Light Sources3. DefinitionsThe terminology found in ASTM G 113 may be approp
14、riate to this procedure.3.1 Black Panel Thermometer, nA temperature measuring device consisting of a metal panel, having a blackcoating which absorbs all wavelength uniformly, with a thermal sensitive element firmly attached to the centerof the exposed surface. The black panel thermometer is used to
15、 control an artificial weathering device and toprovide an estimate of the maximum temperature of specimens exposed to a radiant energy source.3.2 Irradiance, nThe radiant power per unit area incident on a receiver, typically reported in watts per squaremeter, W/m2.3.3 Irradiance, Spectral, nThe dist
16、ribution of irradiance as a function of wavelength (W/m2/nm).3.4 Spectral Power Distribution (SPD), nThe absolute or relative radiant power emitted by a source, orincident upon a receiver as a function of wavelength.3.5 Fluorescent UV Lamp, nA lamp in which the irradiance from a low pressure mercury
17、 arc is transformed to ahigher wavelength UV by a phosphor. The spectral power distribution of a fluorescent lamp is determined bythe emission spectrum of the phosphor and the UV transmittance of the glass tube.4. Apparatus4.1 A more complete description of the apparatus may be found in ASTM G 154.4
18、.1.1 Test Chamber, constructed of corrosion-resistant materials enclosing eight fluorescent UV lamps, a heatedwater pan, test specimen racks, and provisions for controlling and indicating operating times andtemperatures.4.2 Lamps shall be rapid start, medium bi-pin fluorescent UV type with a length
19、of 1200 mm, and a nominal ratingof 40 W when operated from a ballast providing a controlled current of 430 mA at 102 V.4.2.1 The lamps shall be one of the following types:a. UVB lamps with a peak emission of 313 nm as described in Table 3 of ASTM G 154. A representativespectral power distribution of
20、 this lamp is shown in Figure 1. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised FEB2003-3-NOTE In devices that do not automatically control irradiance, “FS-40” or “F40UVB” type lamps
21、 havehistorically been used. In devices that automatically control irradiance, UVB-313 lamps may beused.FIGURE 1UVB LAMPS REPRESENTATIVE SPECTRAL POWER DISTRIBUTION4.2.2 Other fluorescent UV lamps meeting the size and electrical characteristics in 4.2 may be used by prioragreement, provided that the
22、 lamp and spectral power distribution are reported in conformance with theReport section. Use of lamps other than those specified in 4.2 may result in significant differences in testresults.a. UVA lamps with a peak emission of 340 nm as described in Table 1 of ASTM G 154. A representativespectral po
23、wer distribution of this lamp is shown in Figure 2.FIGURE 2UVA LAMPS REPRESENTATIVE SPECTRAL POWER DISTRIBUTIONCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised FEB2003-4-4.3 Lamp Spaci
24、ng and ArrangementThe lamps shall be mounted in two banks of four lamps each. The lampsin each bank shall be mounted in a flat plane on 70 mm centers.4.3.1 Lamp manufacturing techniques typically result in a slight gradient in light output from one end of a lamp tothe other end. To compensate for th
25、is, each lamp shall be positioned so that it is reversed 180 degrees fromthose mounted above it and below it.NOTE This can be accomplished by using the manufacturers stamps which are generally located on thesame end of every lamp.4.4 Test SpecimensThe test specimens shall be mounted in stationary ra
26、cks with the plane of the surfaceparallel to the plane of the lamps at a distance of 50 mm from the nearest surface of the lamps.4.5 Condensation MechanismWater vapor shall be generated by heating a water pan extending under theentire specimen area and containing a minimum water depth of 20 mm. Spec
27、imen racks and the testspecimens themselves shall constitute the side walls of the chamber. The back side of the specimens shall beexposed to cooling effects of ambient room air. The resulting heat transfer causes water to condensate on thetest surface.4.5.1 WATER S UPPLYSupply water with an automat
28、ic control to regulate the level in the water pan shall beprovided. Distilled, deionized, or potable tap water are equally acceptable for purposes of the test, since thecondensation process itself distills water onto the test surface.NOTE Use of distilled or deionized water is recommended. Using tap
29、 water may necessitate morefrequent cleaning of water pan.4.6 Cycle TimeA continuously operating cycle timer shall be provided to program the selected cycle of UVperiods and condensation periods.4.7 Temperature MeasurementSpecimen temperature shall be measured by a remote sensor attached to ablack p
30、anel 75 mm X 100 mm X 2.5 mm thick. The temperature sensor shall be accurate to 2 C through arange from 30 C to 100 C. The temperature indicator shall be located outside the test chamber. The blackpanel with the temperature sensor shall be positioned so that the sensor is subject to the same conditi
31、ons asthe specimens.4.8 Specimen Temperature Control-During UV exposure, the selected equilibrium temperature shall be maintainedwithin 3 C of set-point temperature by supplying heated air to the test chamber. During condensationexposure, the selected equilibrium temperature shall be maintained with
32、in 3 C of set-point temperature byheating the water in the water pan. The UV and condensation temperature controls shall be independent ofeach other.4.9 Test Chamber Location4.9.1 The apparatus shall be located in an area maintained between 18 C and 27 C. Ambient temperature shallbe measured at a ma
33、ximum distance of 150 mm from the plane of the specimen door of the apparatus and150 mm from the chamber air intake. Control of ambient temperature is particularly critical for properoperation of apparatus stacked one above the other, because the heat generated from one unit couldinterfere with the
34、operation of adjacent units.4.9.2 The apparatus shall be located at least 300 mm from walls or other apparatus. Nearby heat sources, such asovens or heated test apparatus, shall be avoided or shielded.4.9.3 The room where the apparatus is located shall be ventilated to remove the heat and moisture p
35、roduced andto maintain the temperatures specified in 4.9.1.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised FEB2003-5-4.10 To insure repeatability of test results, maintain and calibra
36、te the apparatus to the manufacturers specificationsas described in Appendix A.5. Test Specimens5.1 Specimen size shall be either 50 mm X 75 mm, 75 mm X 100 mm, 75 mm X 150 mm, 100 mm X 150 mm, oras agreed upon by concerned parties.NOTE Because of the geometry of some specimen holders, the previous
37、sizes may cause some problemsif, after inspection, they are replaced in a different orientation than the original. For example,improper replacement of 75 mm X 150 mm panel into a commonly used holder can cause the end1/3s to be shielded (i.e., exposed less than the center 1/3).5.1.1 For simultaneous
38、 exposures of original and repair coatings on one test specimen, 100 mm X150 mmspecimens have been found useful. In this situation, each coating should cover one half of the specimen andbe 50 mm X 150 mm area.5.2 Replicate specimens are desirable to provide a record of degradation at different time
39、intervals. Retention ofunexposed specimens in a controlled environment is recommended as it is difficult to mask a specimen toprevent exposure to condensation.5.3 For specimens of insulating materials, such as plastics or foams, maximum specimen thickness should be30mm to allow adequate heat transfe
40、r for condensation. Report any thickness greater than this in the testreport.5.4 To provide rigidity, flexible specimens should be attached to a backing panel made of aluminum, 0.635 mmthick, 3003 H14 alloy.5.5 Holes in specimens larger than 2 mm and any openings larger than 1 mm around irregularly
41、shapedspecimens shall be sealed to prevent loss of water vapor. Porous specimens, such as textiles, shall be backedwith a vapor barrier such as metal.6. Procedure6.1 Mount the test specimens in the specimen racks with the test surfaces facing the lamp. When the testspecimens do not completely fill t
42、he racks, the empty spaces must be filled with panels to maintain the testconditions within the chamber.6.2 The test specimens shall be exposed within an area 210 mm in height by 900 mm wide on each side of theapparatus located as shown in Figure 3. NOTE To avoid areas of variability in the specimen
43、 exposure area, do not use the extreme right- and left-hand specimen holders on the apparatus.FIGURE 3AREA OF MOST UNIFORM UV INTENSITYCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised
44、FEB2003-6-6.3 Set Condensation Cooling Timer to 15 min, if applicable. Report any variations in the test report Figure 4.FIGURE 4EXPOSURE REPORT FORMCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE
45、J2020 Revised FEB2003-7-6.4 Initiate all exposures at the beginning of the condensation cycle.6.5 Program the Cycle Timer to achieve the following test conditions: 8 h UV light exposure at 70 C, alternatingwith 4 h condensation exposure at 50 C.6.5.1 Operating continuously, repeating the cycle, exce
46、pt for servicing the instrument and inspection ofspecimens. Inspect specimens weekly during the condensation cycle for evidence of condensation.6.6 In order to minimize any effect from temperature or UV light variation, specimens shall be repositionedperiodically. As a minimum, specimens must be rot
47、ated horizontally once each week by (a) moving the twoextreme right-hand specimen holders to the far left of the exposure area and (b) sliding the remainingspecimen holders to the right (see Figure 5).FIGURE 5HORIZONTAL SPECIMEN HOLDER ROTATIONCopyright SAE International Provided by IHS under licens
48、e with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J2020 Revised FEB2003-8-6.7 UV Irradiance6.7.1 UV irradiance shall be maintained within a specified range by one of the methods shown in Appendix A. 6.7.2 For UVB lamps, the irradiance level shall be 0.48
49、15% W/m2/nm at 310 nm (0.41 to 0.55 W/m 2/nm at310nm). If the irradiance deviates beyond this tolerance, terminate the test until the cause of the deviationhas been determined and corrected.NOTE The previous edition of SAE J2020 specified an irradiance level of 0.43 W/m2/nm at 310 nm (0.37to 0.49 W/m 2/nm at 310 nm). The new 0.48 irradiance level is not an increase from the previouslyspecified 0.43 irradianc
