ASTM B845-1997(2013)e2 Standard Guide for Mixed Flowing Gas (MFG) Tests for Electrical Contacts《电接触用混合流动气体(MFG)试验的标准指南》.pdf

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1、Designation: B845 97 (Reapproved 2013)2Standard Guide forMixed Flowing Gas (MFG) Tests for Electrical Contacts1This standard is issued under the fixed designation B845; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la

2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEFootnote 3 was corrected editorially in October 2014.2NOTEDocument IEEE P1156.1 in Section 2 was corrected editorially in Decem

3、ber 2017.1. Scope1.1 The techniques described in this guide pertain to mixedflowing gas (MFG) tests containing species that are applied toevaluate devices containing electrical contacts such as sliprings, separable connectors, electromechanical relays or switchcontacts. These techniques may be relev

4、ant to other devices,but it is the responsibility of the user to determine suitabilityprior to testing.1.2 The MFG tests described in this guide are designed toaccelerate corrosive degradation processes. These accelera-tions are designed such that the degradation occurs in a muchshorter time period

5、than that expected for such processes in theintended application environment of the device being tested.Application environments can vary continuously from benignto aggressively corrosive. Connectors and contacts withinclosed electronic cabinets may be affected by an environmentof different severity

6、 than the environment on the outside ofsuch cabinets. In general, indoor environments are differentthan outdoor environments. The MFG tests described herein,being discrete embodiments of specific corrosive conditions,cannot be representative of all possible application environ-ments. It is the respo

7、nsibility of the test specifier to assure thepertinence of a given test condition to the specifiers applica-tion condition.1.3 The MFG tests described herein are not designed toduplicate the actual intended application environment of thedevice under test. An extended bibliography that providesinform

8、ation which is useful to test specifiers to assist them inselecting appropriate test methods is included in this guide.The bibliography covers the scope from application conditioncharacterization, single and multiple gas effects, and materialand product effects to key application and test variables

9、as wellas discussions of atmospheric corrosion processes.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp

10、onsibility of the user of this standard to become familiarwith all hazards including those identified in the appropriateSafety Data Sheet (SDS) for this product/material as providedby the manufacturer, to establish appropriate safety, health,and environmental practices, and determine the applicabili

11、tyof regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the Worl

12、d Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B542 Terminology Relating to Electrical Contacts and TheirUseB808 Test Method for Monitoring ofAtmospheric CorrosionChambers by Quartz Crystal MicrobalancesB810 Test Method for Calibration ofAt

13、mospheric CorrosionTest Chambers by Change in Mass of Copper CouponsB825 Test Method for Coulometric Reduction of SurfaceFilms on Metallic Test SamplesB826 Test Method for Monitoring Atmospheric CorrosionTests by Electrical Resistance ProbesB827 Practice for Conducting Mixed Flowing Gas (MFG)Environ

14、mental Tests2.2 Other Documents:EIA-364B-TP65 Mixed Industrial Gas Test Procedure31This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Current edition approved Aug. 1, 2013

15、. Published August 2013. Originallyapproved in 1993. Last previous edition approved in 2008 as B845 97 (2008)2.DOI: 10.1520/B0845-97R13E02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume

16、 information, refer to the standards Document Summary page onthe ASTM website.3Available from IHS, 15 Inverness Way East, Englewood, CO 80112, http:/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was devel

17、oped in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1IEC Standard 68-242

18、 Basic Environmental TestingProcedures, Test KcSulphur Dioxide Test for Contacts andConnections4IEC Standard 68-243 Basic Environmental TestingProcedures, Test KdHydrogen Sulfide Test for Contactsand Connections4IEC Technical Trend Document 68-260 TTD Environmen-tal Testing, Corrosion Tests in Artif

19、icial Atmosphere atVery Low Concentration of Polluting Gas(es)4IEC 68-260 (second edition) Environmental TestingPart2: Teststest Ke: Flowing mixed gas corrosion test, 1995IEEE P1156.1 Environmental Specifications for ComputerModules (Draft 4 Approved June 17, 1993.)53. Terminology3.1 Terms relevant

20、to this guide are defined in TerminologyB542 except as noted in the following section.3.2 Other term:3.2.1 mixed flowing gas test, na laboratory test conductedin air that flows through a test chamber in which thetemperature, relative humidity, concentrations of gaseouspollutants, and other critical

21、variables are carefully defined,monitored and controlled.4. Significance and Use4.1 Preservation of a conducting surface on electrical con-tact is vital to the continued functioning of such contacts.Contamination of the surface with insulating layers formed bycorrosion processes is one potential haz

22、ard. Laboratory testingof contacts in MFG tests is used to assess the effectiveness ofdesign features and materials.4.2 MFG tests are used in development studies of processesand materials for contacts. For example, coupon specimensmay be exposed to MFG tests to evaluate new contactmaterials, layers

23、of new coating materials on a supportingsubstrate, reduced coating thicknesses, or protective surfacetreatments.4.3 MFG tests are also employed to test the durability of afinished product with respect to atmospheric corrosion. Forexample, finished connectors may be exposed to a MFG testand their per

24、formances compared against each other or againsta set of fixed requirements. Relays or switch contacts may beexposed in the operated and non-operated conditions to com-pare performance.4.4 MFG tests are useful for determining the effectivenessof connector housings and shrouds as barriers to ingress

25、ofatmospheric corrodants to the contact surfaces. These tests canalso be used to assess the screening of the metal-to-metalcontact areas of mated connectors.4.5 MFG tests are employed as qualification tests to deter-mine connector failure rates in application environments forwhich correlation betwee

26、n test and application has previouslybeen established.4.6 This guide provides test conditions which are to beapplied in conjunction with Practice B827 which defines therequired test operation and certification procedures, tolerances,and reporting requirements. Where the test specifier requirescertif

27、ications or tolerances different than those provided inPractice B827, the required certifications or tolerances shall bepart of the test specification. Differences from the specifica-tions in Practice B827 shall be reported in the test reportprovided by the test operator to the test specifier. Speci

28、ficationof one of the test conditions defined in this document in theform of a statement such as, “Parts shall be tested in accor-dance with ASTM B845 Method Z.”, implicitly requires testcondition, Z, applied according to Practice B827.5. Procedure5.1 Decide upon a test plan appropriate for the cont

29、actsbeing evaluated. Consider test parameters such aspreconditioning, performance measurement and other evalua-tion techniques, and experimental controls.5.2 Select a MFG test and exposure length appropriate forthe parts being evaluated. Table 1 lists a number of such teststhat have been documented

30、in the technical literature. The nextsection provides brief discussions of the origins and intendedpurpose of each of the methods.6. Abstracts of Methods6.1 Method AMethod A was originally developed as ahighly accelerated test to stress equipment that might beexposed to environments with high levels

31、 of air pollution fromcombustion of high sulfur coal (1).6The method is included inthis list for completeness. It is generally not consideredrealistic for evaluation of electronic equipment for the vastmajority of applications. Typical exposure time is 4, 10 or 21days, depending upon the specificati

32、on for the product undertest.6.2 Method BMethod B was originally developed as aEuropean standard, and has largely been replaced by methodswith lower levels of sulfur bearing gases (2). The method isincluded in this list for completeness. It is generally notconsidered realistic for evaluation of elec

33、tronic equipment forthe vast majority of applications. Typical exposure time is 4, 10or 21 days, depending upon the specification for the productunder test.6.3 Method CMethod C was developed in Europe as analternative to Method A in response to requests for a lessaggressive test that would simulate

34、exposures in less aggres-sive environments (3,4). Method C may simulate the majorityof usage environments better than Method A. Typical exposuretime is 4, 10 or 21 days depending upon the specification forthe product under test.6.4 Method DMethod D was developed in Europe as analternative to Method

35、B for the same reasons cited in the above4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-133

36、1, http:/www.ieee.org.6The boldface numbers in parentheses refer to a list of references at the end ofthis guide.B845 97 (2013)22discussion of Method C (3,4). Typical exposure time is 4, 10 or21 days, depending upon the specification for the productunder test.6.5 Method EMethod E was developed in Eu

37、rope as a firststep toward a test containing more than one pollutant gas (3,4).Typical exposure time is 4, 10 or 21 days depending upon thespecification for the product under test.6.6 Method G, H, and KGeneral InformationThesemethods are often called the Battelle Class II, III, and IV Tests7respecti

38、vely, since they were developed by the Battelle Colum-bus Laboratories after an extensive study of electronic equip-ment operating conditions (5). The test conditions were theresult of correlation studies between corrosion products andmechanisms, and test and application conditions, in order toobtai

39、n a valid estimate of the corrosion response in theexpected electronic service environments. From this study, itwas concluded that most operating or application environmentsfor electrical connectors and electronic components can becategorized by a limited number of Severity Classes, which canbe simu

40、lated, and their effects accelerated, by adjusting thecritical parameters of the MFG test.6.6.1 The descriptions in reference (5) of operating environ-ment Classes I through IV are as follows: Class I is character-ized by formation of oxides on copper coupons and no visibleattack on porous gold plat

41、ed, nickel underplated, coppercoupons (Au/Ni/Cu) Class II is characterized by pore corrosionof Au/Ni/Cu coupons and formation of oxides and complexcopper hydroxy chlorides on copper coupons. Class III ischaracterized by pore and tarnish creepage corrosion of Au/Ni/Cu coupons and the formation of oxi

42、des, sulfides and otherunknown corrosion products on copper coupons. Class IV ischaracterized by tarnish creepage on Au/Ni/Cu coupons andcopper coupon corrosion products similar to Class III exceptthat sulfide presence greatly exceeds oxide presence whereasfor Class III, the oxide presence is equiva

43、lent to the sulfidepresence (5).6.6.1.1 Method GMethod G accelerates the effects ofBattelle Class II environments. These correspond to conditionsthat are often found in business offices or control rooms that areassociated with light industrial areas or where environmentalcontrols are not operating e

44、ffectively and continuously (5,14).Light tarnish creepage corrosion has been reported to be found7It was found that the lack of electrical corrosion failure mechanisms in Class Ienvironments made it unnecessary to develop a Class 1 MFG Test.TABLE 1 Test Conditions of Mixed Flowing Gas TestsASTMMetho

45、dH2S ppbASO2ppbACl2ppbANO2ppb Temp. C RH %AirChanges(# /h)Air Velocity(m/h)Duration(days)Source Ref. NotesA 25,0005000252B75520-60 4, 10, 21 Kc(1)CB 12,5002500252B7553-5 20-60 4, 10, 21 Kd(2)C 500100251B7533-5 60 4, 10, 21 KeMethod A(3,4)D 10020251B7533-5 60 4, 10, 21 KeMethod B(3,4)E 10020500100251

46、B7533-10 60 4, 10, 21 KeIEC 68-2-60TestMethod 1(3,4)G10+0/410+0/2200253027023-8 BattelleClass II(5,6,7)(8)DH 10010205200253027523-8 BattelleClass III(5,6,7)(8)E,FK 20010505200255027523-8 BattelleClass IV(5,8)L405 %3505 %315 %6105 %300.57021832 G1(T) (9)M 105 20020 105 20020 251B75 3 3-10 10, 21 KeIE

47、C 68-2-60(3,4,10)(11)N10+0/42002510+ 0/220025302702perASTMB827perASTMB8275-30 Telecomcentraloffice(12,13)O 105 10020 103 20050 301 702 perASTMB827perASTMB82710, 20 Telecomcentraloffice(6,7)P 10020 20050 205 20050 301 702 perASTMB827perASTMB82720 Telecomuncontrolledenvironment(6,7)Notes:AGas concentr

48、ations in ppb refer to parts per billion (1 in 109) volume per volume (vol/vol) in air.BThe test temperature of 25C may require refrigeration in order to assure compliance with specified temperature and humidity variation limits.CCarbon dioxide, 4500 parts per million (vol/vol) maximum.DReferences (

49、6 and 7) show NO2level as 100 ppb and temperature as 25C while reference (5) shows the values in the table above; difference in corrosion of copperis minor between the two sets of conditions per private communication dated April 26, 1991, W. H. Abbott to E. Sproles.ERelative humidity of 75 % (as shown in References (6 and 7) is the recommended test condition for Class III per private communication dated April 26, 1991, W. H. Abbottto E. Sproles.FTest conditions are defined i