1、Designation: D 7087 05aStandard Test Method forAn Imaging Technique to Measure Rust Creepage at Scribeon Coated Test Panels Subjected to CorrosiveEnvironments1This standard is issued under the fixed designation D 7087; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of rust creep-age area from a
3、 scribe line on painted/coated flat test panelsafter exposure to corrosive environments. This test method hasthe advantage of simplicity and ease of use. Expensive equip-ment is not required, and the results are more accurate thanvisual evaluation but not as precise as advanced digitalimaging.1.2 Th
4、is test method uses visual imaging software to deter-mine the area damaged by rust creepage from the scribe.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety conc
5、erns, if any, associated with its use. 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:2B117 Practice for Operating Salt Spray
6、(Fog) ApparatusD 1014 Practice for Conducting Exterior Exposure Tests ofPaints and Coatings on Metal SubstratesD 1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive EnvironmentsD 4585 Practice for Testing Water Resistance of CoatingsUsing Controlled CondensationD 458
7、7 Practice for Fluorescent UV-Condensation Expo-sure of Paint and Related CoatingsD 5894 Practice for Cyclic Salt Fog/UV Exposure ofPainted Metal, (Alternating Exposures in a Fog/Dry Cabi-net and a UV/Condensation Cabinet)D 6695 Practice for Xenon-Arc Exposures of Paint andRelated CoatingsG85 Practi
8、ce for Modified Salt Spray (Fog) Testing3. Significance and Use3.1 This test method provides a means of evaluating andcomparing development of corrosion at scribe on painted/coated flat test panels after exposure to corrosive environ-ments.4. Apparatus4.1 Transparent Plastic SheetUse transparent pla
9、sticsheet with thickness approximately 0.085 mm (0.0034 in. or3.4 mil). The sheet material must be transparent enough foreasy tracing and must be sufficiently absorbent to provide goodink adhesion.34.2 Tracing PenA black permanent marker with ultrafinetip approximately 0.5 mm (0.02 in.) in diameter.
10、4.3 RulerAny transparent ruler with 1-mm black divi-sions. This length shall be shorter than either length or width ofglass surface of scanner.4.4 Computer and Scanning SystemAny computer andcompatible scanning system is applicable. A computer with atleast 32 MB of RAM is recommended.4Aflat bed scan
11、ner with1200 dpi optical, 120032400 dpi hardware resolution issuggested. The scanner must have a feature where it selects thebest possible resolution required for scanning. There is no needto calibrate or change settings while scanning.4.5 Image SoftwareUse any image software capable ofreading an im
12、age file generated from the computer andscanning system, calibrating length, and integrating area rap-idly and accurately.5. Specimen Scribing5.1 Scribe test specimens in accordance with Test MethodD 1654, section on Preliminary Treatment of Test Specimens.The panels should be scribed in a single st
13、raight line.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.25 on Evaluation of Weathering Effects.Current edition approved July 1, 2005. Published July 2005. Originally ap
14、provedin 2005. Last previous edition approved in 2005 as D 7087 05.2For 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 we
15、bsite.3The transparent plastic sheet material of one-gallon size zipper freezer bagwithout surface texture was found acceptable in round robin testing.4A PC compatible computer with the Windows 95, Windows 98, Windows ME,Windows NT, Windows 2000 or Windows XP operating system is applicable.1Copyrigh
16、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Exposure of Test Specimens6.1 Prior to exposure, measure the width of the scribe.Record this information.6.2 Expose test specimens in accordance with any of thefollowing Practices B117, D 101
17、4, D 4585, D 4587, D 5894,D 6695, and G85, or any other applicable test method, asagreed upon between the producer and the user. The exposurecycle, length of test and evaluation intervals shall be agreedupon prior to exposure of specimens.7. Procedure Evaluation of Scribed Specimens7.1 Prepare Speci
18、mens for EvaluationPrepare the scribedspecimens in accordance with Test Method D 1654.7.2 QuantificationQuantify the corrosion or loss of paintextending from a scribe mark, that is, manual tracing followedby an imaging analysis.7.2.1 Creepage Area Tracing TechniqueTrace the rustcreepage area based o
19、n the procedure described in 7.2.1.1 and7.2.1.2.7.2.1.1 Marking Test SpecimenPlace the ruler immedi-ately below and parallel to the scribe line ab of the test panel(refer to Fig. 1 for geometry terms). Use the tracing pen tomark points g and h on the test panel so that gh is the centerline that repr
20、esents 80 % of the scribe line. Mark points i, j, k,and l with the pen on the borderline of creepage area such thatlines ig and kh are perpendicular to the scribe line (See Fig. 1).Remove the ruler.7.2.1.2 Area TracingPlace a single sheet of the transpar-ent plastic that is 50 % larger than the pane
21、l over the entirecorroded side of the scribed panel. Do not stretch the plasticsheet and ensure there are no folds or creases. Press the sheettightly against the panel and fold the excess around the back ofthe panel. To avoid any sliding, tape the plastic sheet to theback of the panel.(a) Orient the
22、 panel so that the scribe line is vertical anddirectly in front. With one hand, hold the panel and the plasticsheet, and with the other hand, trace the creepage or undercut-ting outline on the sheet using the pen. The tracing must bemade smoothly and continuously by holding the pen at about a75 angl
23、e to the surface with the upper end of pen away fromcreepage. Position the pen so that only the tip is in contact withthe surface and is at the point where the raised creepage areabegins. Halfway through the tracing, rotate the panel and theplastic 180 degrees and complete the tracing on the other s
24、ideof the scribe. Ensure that the plastic does not move during therotation. Make sure the traced lines at both ends of scribe lineare connected. The traced line must have uniform intensity andgood continuity.(b) On the plastic sheet, mark points i, j, k, and l on theoutside edge of the traced line.
25、A typical trace of creepage areadeveloped around the scribe line (ab) and marking points i, j,k, and l for area integration are shown in Fig. 1. Note thatscribe line ab should not be traced. Remove the plastic sheetfrom the panel. With the tracing pen, use a ruler to draw linescd and ef on the plast
26、ic sheet.NOTE 1Stain beyond the creepage area should not be traced.NOTE 2The tracing must be conducted carefully under good lightcondition and by an operator with good eyesight.NOTE 3The intensity and continuity of traced line may be examinedwith a magnifying glass or an optical microscope.NOTE 4For
27、 some people, orienting the panel with scribe line hori-zontally may be easier. Trace the bottom side of the creepage area first andthen trace the topside of creepage area later. Make sure the traced lines atboth ends of the scribe line are connected.7.2.2 Trace ScanningPlace the transparent plastic
28、 sheetwith the traced creepage or undercutting area with markedpoints i, j, k, and l and lines cd and ef onto the glass of theflatbed scanner. Place a ruler next to the trace area with thedimension markings facing the light source. Back the tracingand the ruler with a sheet of white paper or cardsto
29、ck. Scan theimage that must include all the traced line and the ruler. Savethis image as a .xxx file in the computer with a uniquefilename.7.2.3 Imaging and Integrating Creepage AreaUse imagesoftware capable of capturing and opening image file of trace.Calibrate distance by selecting a known length
30、with the rulerimage (Fig. 1) such as 40 mm or 50 mm to obtain number ofpixels per mm, choose threshold for line contrast, then clickinside the region (ijlk) to be integrated to obtain rust creepagearea by following the instructions provided with the software.7.2.4 Obtaining Creepage Area and Mean Cr
31、eepageIntegrate the scanned area based on 7.2.4.1 and obtain meancreepage based on 7.3 or 7.4.7.2.4.1 Integrating Total Rust Creepage Area at ScribeIntegrate the total traced area in mm2including creepage areaat both sides of selected center scribe line (Aijlk). The areabeing integrated is the area
32、INSIDE the traced line.7.3 Calculating Mean Creepage (Including Area of OriginalScribe Line)Calculate mean creepage as follows:C 5 Aijlk/ 2L! (1)where:C = mean creepage in mm,Aijlk= integrated area inside the boundary of ijlk bytracing and imaging, andL = length of scribe line from which creepage (o
33、rundercutting) is extended and area is integrated.7.4 Calculating the Net Mean Creepage (Excluding Area ofOriginal Scribe Line)Calculate the net mean creepage asfollows:Cnet5 Aijlk A0! / 2L! (2)FIG. 1 The Scanned Trace and Markings for Area Integration ofCreepage Area Around the Scribe Line.D 7087 0
34、5a2where:Cnet= net mean creepage in mm,Aijlk= integrated area inside the boundary of ijlk bytracing and imaging,A0= integrated area of scribe line before exposure, andL = length of scribe line from which creepage (orundercutting) is extended and area is integrated.8. Report8.1 Report the following i
35、nformation:8.1.1 Rust creepage (also called undercutting) area of rec-ommended traces in mm2.8.1.2 Mean creepage, C, calculated from Eq 1, or net meancreepage, Cnet, calculated from Eq 2.8.1.3 Type of specimen and its dimensions.8.1.4 Length of scribe line around which creepage area isintegrated.8.1
36、.5 Exposure test to which the specimen was subjected to.8.1.6 Exposure cycle.8.1.7 Duration or interval of exposure.9. Precision and Bias9.1 PrecisionInterlaboratory round robin test results wereobtained by six laboratories; in each laboratory, three weath-ered coated panels were traced in duplicate
37、. For three sampleswith mean rust creepage of 2.2, 3.4, and 8.8 mm, within-laboratory relative standard deviation was found to be 4.3, 3.0,1.8 %, respectively, and between-laboratories relative standarddeviation was found to be 8.2, 10.4, and 2.2 %, respectively.Based on this, the following criteria
38、 should be used for judgingthe precision of results at the 95 % confidence level:9.1.1 RepeatabilityTwo results for the mean creepage of2.2, 3.4, and 8.8 mm obtained by the same operator should beconsidered suspect if they differ by more than 12.3, 8.3, and4.9 %, respectively. In other words, the me
39、asurements for themean creepage of 2.2, 3.4, and 8.8 mm should stay between 1.9and 2.5 mm, 3.1 and 3.7 mm, and 8.4 and 9.2 mm, respectively.9.1.2 ReproducibilityTwo results, each the mean of dupli-cates, obtained by operators in different laboratories should beconsidered suspect if they differ by mo
40、re than 22.9, 29.3, and6.3 % respectively, for the mean creepage of 2.2, 3.4, and 8.8mm. In other words, the measurements for the mean creepageof 2.2, 3.4, and 8.8 mm should stay between 1.7 and 2.7 mm,2.4 and 4.4 mm, and 8.3 and 9.4 mm, respectively.9.2 BiasBias cannot be determined as no reference
41、 mate-rial is available.NOTE 5The error increases as rust creepage area or mean creepagedecreases. More data are available in the publication cited.5NOTE 6Some factors affecting precision are:(a) Deviation of tracing line from actual outline of creepage area.(b) Low adhesion of pen ink to plastic sh
42、eet.(c) Discontinuity of tracing line.(d) Low intensity of tracing line.(e) Non-uniformity of tracing line.(f) Distance not accurately calibrated.(g) Sliding of transparent plastic sheet during tracing.(h) Poor light condition.(i) Poor operator eyesight.10. Keywords10.1 accelerated tests; coated pan
43、els; creepage area; imag-ing; outdoor exposure; quantification; rust creepage; undercut-ting; weatheringAPPENDIXES(Nonmandatory Information)X1. DOWNLOADABLE FREE IMAGE SOFTWAREX1.1 Downloadable Free Image Software A download-able free trial version of Scion Image software was used in theround robin
44、testing. Upon publication of this standard thecurrent version of the digital imaging program available was“Scion Image Beta 4.02.” The operating procedure of this freesoftware is described in X1.2-X1.7.X1.2 Download SoftwareGo to the website of“” and click “ Products” and then pagedown to “Software”
45、 and click “Scion Image Beta 4.02 Win.”Run set up “WinB402.exe” file (it takes about 7 minutes todownload, and save this file).X1.3 Open Image FileImage file needs to be a .tif or .bmptype (you can save the image in one of those formats directlyfrom the scanner). Two images are shown on computermoni
46、tor, one labeled “index color” and the other labeled“trace.” Delete the “Index color image.” The program does notwork the same for it as the other image.X1.4 Set Scale and Length CalibrationUnder “Analyze,”use the “measure line (dotted) tool” to determine the pixels inchosen number of mm on ruler, a
47、nd then open the “set scale”window. Select “mm” in the box of “Units” and then enter thechosen length in the box of “known distance.”X1.5 Analyze the Traced AreaUnder “Analyze,” go to“Options,” choose “Interior holes” and “Wand Auto-measure”and “Area,” deselect “density.”X1.6 Choose ThresholdUnder “
48、Options,” choose thresh-old; a default threshold will be selected that can be adjusted byputting mouse in LUT window. The threshold tool is automati-cally chosen.X1.7 Area IntegrationSelect the “magic wand tool” and5“An Imaging Technique to Measure Rust Creepage at Scribes on Coated TestPanels,” Jou
49、rnal of Protective Coatings and Linings, Vol. 19, No.1, p. 67, January2002.D 7087 05a3place inside the traced area Aijlktoward the vertical borderlinekl. The area (Aijlk) is displayed in the chart (can also use “showresults” under “Analyze” or “ctrl-2” to get the area).X2. COMMERCIAL IMAGE SOFTWAREX2.1 Use the particular image software to determine thearea of the creepage by following the instruction provided withthe image software.ASTM International takes no position respecting the validity of any patent rights asserted in c
