ASTM G85-2009 Standard Practice for Modified Salt Spray (Fog) Testing《改进的盐喷雾(雾化)试验的标准规范》.pdf

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1、Designation: G 85 09Standard Practice forModified Salt Spray (Fog) Testing1This standard is issued under the fixed designation G 85; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parentheses

2、 indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers and sets forth conditions for fivemodifications in sal

3、t spray (fog) testing for specificationpurposes. These are in chronological order of their develop-ment:1.1.1 Annex A1, acetic acid-salt spray test, continuous.1.1.2 Annex A2, cyclic acidified salt spray test.1.1.3 Annex A3, seawater acidified test, cyclic (SWAAT).1.1.4 Annex A4,SO2salt spray test,

4、cyclic.1.1.5 Annex A5, dilute electrolyte cyclic fog dry test.1.2 This practice does not prescribe the type of modifica-tion, test specimen or exposure periods to be used for a specificproduct, nor the interpretation to be given to the results.1.3 The values stated in SI units are to be regarded ass

5、tandard. 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. It is theresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter

6、-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray (Fog) ApparatusD 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD 1141

7、 Practice for the Preparation of Substitute OceanWaterD 1193 Specification for Reagent WaterD 1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsE70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. Significance and Use3.1 This practice i

8、s applicable to ferrous and nonferrousmetals; also organic and inorganic coatings. The variationsdescribed herein are useful when a different or more corrosiveenvironment than the salt fog described in Practice B117isdesired.4. Apparatus4.1 Cabinet:4.1.1 The apparatus required for salt spray (fog) t

9、estingconsists of a fog chamber, a salt solution reservoir, a supply ofsuitably conditioned compressed air, one or more atomizingnozzles, specimen supports, provision for heating the chamber,and necessary means of control. The size and detailed con-struction of the cabinet are optional, provided the

10、 conditionsobtained meet the requirements of this practice. The material ofconstruction shall be such that it will not affect the corrosive-ness of the fog. Suitable apparatus that may be used to obtainthese conditions is described in Appendix A1 of Practice B117with necessary modifications describe

11、d in each annex.4.1.2 Design the cabinet so that drops of solution thataccumulate on the ceiling or cover of the chamber do not fallon the specimens being tested. Do not return drops of solutionthat fall from the specimens to the solution reservoir forrespraying.4.1.3 Equip the cabinet with one or m

12、ore timing devices toprovide for intermittent spraying or periodic introduction of agas, or both.4.2 Air Supply:4.2.1 Make sure the compressed air supply to the nozzle ornozzles for atomizing the salt solution is free of oil and dirt andmaintain the air supply between 69 and 172 kPa (10 and 25psi).N

13、OTE 1The air supply may be freed of oil and dirt by passing itthrough a water scrubber or at least 610 mm (2 ft) of suitable cleaningmaterial such as asbestos, sheeps wool, or activated alumina.4.2.2 Temperature in the saturator tower (bubble tower)varies depending on the test method used.1This prac

14、tice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved July 1, 2009. Published August 2009. Originallyapproved in 1985. Last previous edition approved in 2002 as G 85021.

15、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 Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box

16、C700, West Conshohocken, PA 19428-2959, United States.4.3 Conditions in Salt-Spray Chamber:4.3.1 TemperatureThe temperature in the exposure zonevaries with the test method used. For recommended exposurezone temperatures for the various methods see theAnnex. Eachset point and its tolerance represents

17、 an operational controlpoint for equilibrium conditions at a single location in thecabinet which may not necessarily represent the uniformity ofconditions throughout the cabinet. Record the temperaturewithin the exposure zone of the closed cabinet at least twice aday at least 7 h apart (except on we

18、ekends and holidays, whenthe salt spray test is not interrupted for exposing, rearranging,or removing test specimens or to check and replenish thesolution in the reservoir).NOTE 2Suitable methods to record the temperature are a continuousrecording device or a thermometer which can be read from outsi

19、de theclosed cabinet. Obtain the recorded temperature with the salt spraychamber closed to avoid a false low reading because of wet-bulb effectwhen the chamber is open.4.3.2 Atomization and Quantity of FogPlace at least twoclean fog collectors within the exposure zone so that no dropsof solution fro

20、m the test specimens or any other source can becollected. Position the collectors in the proximity of the testspecimens, one nearest to any nozzle and the other farthestfrom all nozzles. Make sure that for each 80 cm2of horizontal-collecting area fog accumulates in each collector from 1.0 to2.0 mL o

21、f solution per hour based on an average run of at least16 h continuous spray.NOTE 3Suitable collecting devices are glass funnels with the stemsinserted through stoppers into graduated cylinders or crystallizing dishes.Funnels and dishes with a diameter of 100 mm have an area of about 80cm2.4.3.3 Dir

22、ect or baffle the nozzle or nozzles so that none ofthe spray can impinge directly on the test specimens.5. Test Specimens5.1 Define the type and number of test specimens to be used,as well as the criteria for the evaluation of the test results in thespecifications covering the material or product be

23、ing tested orupon mutual agreement between the purchaser and the seller.5.2 Preparation of Test Specimens:5.2.1 Clean metallic and metallic-coated specimens. Thecleaning method is optional depending on the nature of thesurface and the contaminants; however, when using a cleaningmethod do not include

24、 in the contents abrasives other than apaste of pure magnesium oxide nor of solvents which mayform corrosive or inhibitive films. The use of nitric acidsolution for the chemical cleaning, or passivation, of stainlesssteel specimens is permissible when agreed upon between thepurchaser and the seller.

25、 Take care that specimens are notrecontaminated after cleaning by excessive or careless han-dling.5.2.2 Prepare specimens for evaluation of paints and otherorganic coatings in accordance with applicable specification(s)for the material(s) being tested, or as agreed upon between thepurchaser and supp

26、lier. Otherwise, make sure the test speci-mens consist of steel meeting the requirements of PracticeD 609; clean and prepare the specimens for coating in accor-dance with applicable procedure of Practice D 609.5.2.3 Whenever it is desired to determine the developmentof corrosion from an abraded area

27、 in the paint or organiccoating, make a scratch or scribed line through the coating witha sharp instrument so that the underlying metal is exposedbefore testing. Use the conditions of making the scratch asdefined in Test Method D 1654, unless otherwise agreed uponbetween the purchaser and seller.5.2

28、.4 Protect the cut edges of plated, coated, or duplexmaterials and areas that contain identification marks or that arein contact with the racks or supports with a suitable coating thatis stable under the conditions of the test, such as ceresin wax,unless otherwise specified.NOTE 4Should it be desira

29、ble to cut test specimens from parts or frompreplated, painted, or otherwise coated-steel sheet, protect the cut edgesby coating them with paint, wax, tape, or other effective media so that thedevelopment of preferential attack or a galvanic effect between such edgesand the adjacent plated or otherw

30、ise coated-metal surfaces, is prevented.6. Salt Solutions6.1 Make the salt solutions by using either synthetic sea saltin accordance with Practice D 1141 or sodium chloride inaccordance with Practice B117, unless otherwise specified inthe appropriate annex. Make-up water shall be distilled ordeioniz

31、ed water conforming to Type IV water in SpecificationD 1193 (except that for this practice, limits for chlorides andsodium may be ignored).6.2 Synthetic Sea Salt Solution:6.2.1 Make the salt solution so that it consists of 42 g ofsynthetic sea salt in accordance with Practice D 1141 per litreof solu

32、tion (see Note 5).6.3 Sodium Chloride Solution:6.3.1 Prepare the salt solution by dissolving 5 6 1 parts byweight of sodium chloride in 95 parts of distilled water orwater containing not more than 200 ppm of total solids (seeNote 5). The sodium chloride shall be substantially free ofnickel and coppe

33、r and shall contain on the dry basis not morethan 0.1 % of sodium iodide and not more than 0.3 % of totalimpurities. Some salts contain additives that may act ascorrosion inhibitors; careful attention should be given to thechemical content of the salt. Upon agreement between pur-chaser and seller, a

34、nalysis may be required and limits estab-lished for elements or compounds not specified in the chemicalcomposition given above.NOTE 5A solution having a specific gravity of 1.0255 to 1.0400 at25C (77F) will meet the concentration requirement of 6.2.1 and 6.3.1.Itis suggested that a daily check be ma

35、de.6.4 The pH of the salt solutions will vary depending on thetest method used. Before the solution is atomized, free it ofsuspended solids (see Note 6). Take the pH measurementselectrometrically at 25C (77F) using a glass electrode with asaturated potassium chloride bridge in accordance with TestMe

36、thod E70.NOTE 6The freshly prepared salt solution may be filtered or decantedbefore it is placed in the reservoir, or the end of the tube leading from thesolution to the atomizer may be covered with a double layer of cheeseclothor suitable nonmetallic filter cloth to prevent plugging of the nozzle.7

37、. Procedure7.1 Position of Specimens During Test:G850927.1.1 Unless otherwise specified, support or suspend thespecimens between 6 and 45 from the vertical, and preferablyparallel to the principal direction of horizontal flow of fogthrough the chamber, based upon the dominant surface beingtested. No

38、te that test severity increases as angle from thevertical increases.7.1.2 Do not allow contact of the specimens between eachother, between any metallic material, or between any materialcapable of acting as a wick.7.1.3 Place each specimen so as to permit free settling of fogon all specimens. A minim

39、um spacing between specimens of30 mm is recommended.7.1.4 Do not permit the salt solution from one specimen todrip on any other specimen.7.1.5 It is recommended that placement of replicate speci-mens be randomized to avoid possible bias caused by differ-ence in spray patterns. Individual specimens m

40、ay also berotated daily for the same reason.7.1.6 Suitable materials for the construction or coating ofracks and supports are glass, rubber, plastic, or suitably coatedwood. Do not use bare metal. Support specimens preferablyfrom the bottom or the side. Slotted wooden, laminated plastic,or inert pla

41、stic strips are suitable for the support of flat panels.Suspension from glass hooks or waxed string may be used aslong as the specified position of the specimens is obtained, and,if necessary, by means of secondary support at the bottom ofthe specimens.7.2 Continuity of Test:7.2.1 Unless otherwise s

42、pecified, in the specifications cov-ering the material or product being tested, allow the test to becontinuous for the duration of the entire test period. Continu-ous operation implies that the chamber be closed except for theshort daily interruptions necessary to inspect, rearrange, orremove test s

43、pecimens, and to check and replenish the solutionin the reservoir.NOTE 7Operations shall be so scheduled that the maximum time forthese interrupting is held to 60 min or less per day. It is recommended tohave only one interruption per day if possible.7.3 Period of Test:7.3.1 Designate the period of

44、test in accordance with thespecifications covering the material or product being tested oras mutually agreed upon between the purchaser and the seller.Exposure periods of multiples of 24 h are suggested.7.4 Cleaning of Tested Specimens:7.4.1 Unless otherwise specified in the specifications cov-ering

45、 the material or product being tested, at the end of the test,specimens may be gently washed or dipped in clean runningwater no warmer than 38C (100F) to remove salt depositsfrom their surface, and then immediately dried. Dry with astream of clean, compressed air.NOTE 8Drying with compressed air may

46、 not be desirable for alumi-num specimens to be tested for exfoliation corrosion resistance.8. Evaluation of Results8.1 Make a careful and immediate examination for theextent of corrosion of the dry test specimens or for other failureas required by the specifications covering the material orproduct

47、being tested or by agreement between the purchaserand the seller.9. Report9.1 Record the following information, unless otherwiseprescribed in the specifications covering the material or prod-uct being tested:9.1.1 Type of salt and water used in preparing the saltsolution,9.1.2 All readings of temper

48、ature within the exposure zoneof the chamber,9.1.3 Weekly or daily records, see Note 9, (depending onwhich test annex is being performed) of data obtained fromeach fog-collecting device for volume of slat solution collectedin millilitres per hour of operation per 80 cm2of horizontalcollection area.9

49、.1.4 Weekly or daily records, see Note 9, (depending onwhich test annex is being performed) of data obtained fromfog-collecting devices for concentration or specific gravity at23 6 3C (73 6 5F) of solution collected (see Note 10) andpH of collected solution. Sample to be measured may be acomposite sample from multiple fog-collecting devices (withinone test chamber), if necessary to obtain sufficient solutionvolume for measurement.NOTE 9Except on Saturday, Sundays, and holidays, when the test isnot interrupted for exposing, rearranging, or removing test specimens