1、Designation: D6132 13Standard Test Method forNondestructive Measurement of Dry Film Thickness ofApplied Organic Coatings Using an Ultrasonic CoatingThickness Gage1This standard is issued under the fixed designation D6132; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method describes the use of ultrasonic filmthickness gag
3、es to measure accurately and nondestructively thedry film thickness of organic coatings applied over a substrateof dissimilar material. Measurements may be made on fieldstructures, on commercially manufactured products, or onlaboratory test specimens. These types of gages can accuratelymeasure the d
4、ry film thickness of organic coatings on a varietyof substrates such as concrete, wood, wallboard, plastic, fibercomposites and metal.1.2 This test method is not applicable to coatings that willbe readily deformable under load of the measuring instrumentas the instrument probe is placed directly on
5、the coating surfaceto take a reading.1.3 The effective range of instruments using the principle ofultrasonics is limited by gage design.Athickness range of 8 mto 7.60 mm (0.3 to 300 mils) has been demonstrated.1.4 The values stated in SI units are to be regarded asstandard. No other units of measure
6、ment are included in thisstandard.1.5 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior
7、 to use.2. Referenced Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD4138 Practices for Measurement of Dry Film Th
8、ickness ofProtective Coating Systems by Destructive, Cross-Sectioning MeansE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 SSPCThe Society for Protective Coatings Standards:3P
9、A 2 Procedure for Determining Conformance to Dry Coat-ing Thickness RequirementsPA 9 Measurement of Dry Organic Coating Thickness onCementitious Substrates Using Ultrasonic Gages2.3 ASMEThe American Society of Mechanical Engi-neers:4B46.1 Surface Texture (Surface Roughness, Waviness, andLay)3. Termi
10、nology3.1 Definitions of Terms Specific to This Standard:3.1.1 accuracy, nthe measure of the magnitude of errorbetween the result of a measurement and the true thickness ofthe item being measured.3.1.1.1 DiscussionAn accuracy statement predicts theability of a coating thickness gage to measure the t
11、rue thicknessof a coating to be measured. Accuracy statements provide theperformance capability across the full functional measurementrange of the gage. Accuracy statements frequently include afixed portion that remains constant across the measurementrange, plus a variable portion that is related to
12、 the measurementresult for a particular thickness.3.1.2 adjustment, nthe physical act of aligning a gagesthickness readings to match those of a known thickness sample(removal of bias), in order to improve the accuracy of the gageon a specific coating.1This test method is under the jurisdiction of AS
13、TM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1997. Last previously edition approved
14、 in 2008 as D6132 08. DOI:10.1520/D6132-13.2For 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.3Available from So
15、ciety for Protective Coatings (SSPC), 40 24th St., 6th Floor,Pittsburgh, PA 15222-4656, http:/www.sspc.org.4Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.*A Summary of Changes section appea
16、rs at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2.1 DiscussionAn adjustment will affect the outcomeof subsequent readings.3.1.3 calibration, nthe high-level, controlled and docu-mented process of obta
17、ining measurements on traceable cali-bration standards over the full operating range of the gage, thenmaking the necessary gage modification (as required) to correctany out-of-tolerance conditions.3.1.3.1 DiscussionCalibration of coating thickness gagesis typically performed by the equipment manufac
18、turer, theirauthorized agent, or by an accredited calibration laboratory ina controlled environment using a documented process. Theoutcome of the calibration process is to restore/realign the gageto meet/exceed the manufacturers stated accuracy.3.1.4 certification, ndocumentation of the state of con
19、di-tion of the gage, which can (but not required by definition) beaccompanied by corrective action (such as adjustment orcalibration, or both, or the replacement of components) neces-sary to correct any out-of-tolerance conditions.3.1.5 coating thickness standard, ncoated metal plates, oruncoated sh
20、ims of flat sheet, with assigned values traceable toa National Metrology Institution.3.1.6 couplant, na substance such as water, oil, grease, orpaste used to avoid the retarding of sound transmission by airbetween the transducer and the test piece during ultrasonicexamination.3.1.7 dry film thicknes
21、s, nthe thickness of a coating (orcoating layers) as measured from the surface of the substrate.3.1.8 gage (gauge), nan instrument for measuringquantity, or an instrument for testing.3.1.8.1 DiscussionIn this test method, the term “gage”refers to an instrument for quantifying coating thickness.3.1.9
22、 manufacturers specifications, na statement or set ofstatements that describes the performance characteristics of thegage under a given set of conditions.3.1.9.1 DiscussionManufacturers specifications typicallyinclude the range of measurement, accuracy statement, oper-ating temperature range, power
23、source, dimensions and weight,and conformance to industry standards.3.1.10 measurement (reading), nthe value obtained whenplacing the probe of a thickness gage in contact with a surface.3.1.11 micrometer (micron), none one-thousandth of amilimetre (0.001 mm); 25.4 microns =1 mil.3.1.12 mil, na U.S.
24、term referring to the imperial unit ofmeasure of one one-thousandth of an inch (0.001 in.) referredto elsewhere in the world as “one thou;” 1 mil = 25.4 microns.3.1.13 reference sample, na specimen, coated with amaterial that is as close as possible in composition to theintended application, used to
25、 adjust and/or verify the accuracyof an ultrasonic coating thickness measuring gage for a specificproject.3.1.13.1 DiscussionA coated reference sample may ormay not have thickness values traceable to a National Metrol-ogy Institution. However, the reference sample should bemarked with the stated val
26、ue and the degree of accuracy. Thecoating thickness of the sample should be equal to or slightlygreater than the users coating thickness measurement require-ment and the coating material must have the same acousticvelocity and attenuation as the coating to be measured.3.1.14 substrate, nthe base mat
27、erial, the type of surface,or the component that is being coated.3.1.15 verification of accuracy, nobtaining measurementson coating thickness standards, comprising of at least onethickness value close to the expected coating thickness, prior togage use for the purpose of determining the ability of t
28、hecoating thickness gage to produce thickness results within thegage manufacturers stated accuracy.4. Summary of Test Method4.1 Instruments complying with this test method measurethickness by emitting an ultrasonic pulse into the coating thatis reflected back from the substrate to the probe. The tra
29、veltime is converted into a thickness reading. The instrumentsprobe must be placed directly on the coating surface to take areading.4.2 After verifying accuracy on a known coated part of theobject or material of the same kind, the instrument probe iscoupled with the coated specimen, after proper cur
30、e andconditioning according to the coating manufacturers instruc-tions.4.3 It should be recognized that the accuracy of the mea-surements can be influenced when:4.3.1 The coated object to be measured is not planar withrespect to the transducer face at the point of measurement,4.3.2 Coating density i
31、s not uniform, and4.3.3 The substrate peak-to-valley surface profile of thecoated specimen exceeds the coating thickness.NOTE 1The height of surface profile can be determined in accordancewith ASME B46.1.5. Significance and Use5.1 Many coating properties are markedly affected by thefilm thickness of
32、 the dry film such as adhesion, flexibility,wear, durability, chemical resistance, and hardness. To be ableto compare results obtained by different operators, it is essen-tial to measure film thickness carefully.5.2 Most protective and high performance coatings areapplied to meet a requirement or a
33、specification for the dry-filmthickness of each coat, or for the complete system, or both.Coatings must be applied within certain minimum and maxi-mum thickness tolerances in order that they can fulfill theirintended function. In addition to potential performancedeficiencies, it is uneconomical to a
34、pply more material thannecessary when coating large areas such as floors and walls.5.3 Low readings may occur occasionally on coatings withrough surfaces. The instrument may allow a user adjustment toprevent this.5.4 This test method may not be applicable to measureorganic coating thickness on all s
35、ubstrates. The instrumentsability to detect a distinct interface between the coating and thesubstrate may be impeded if the coating and the substrate areof similar composition, density or attenuation or if the coatingD6132 132is non-homogeneous. Verify operation on a known thickness ofthe coating/su
36、bstrate combination if these circumstances arethought to exist.5.5 Multilayered coatings have many interfaces and theinstrument will measure to the interface separating the twomost acoustically different materials. Some instruments havethe ability to detect and measure the individual layer thick-nes
37、ses in a multi-layer system.5.6 The use of this test method is not necessarily limited bythe type of substrate material.6. Apparatus6.1 Gage Bodyan electronic instrument that utilizes trans-ducer probes.6.2 Transducer Probea measurement probe (sensor) usingan ultrasonic principle and numerical techn
38、iques, attached tothe gage body. The appropriate transducer probe is selectedbased on the anticipated organic coating dry film thickness.The gage manufacturer may be contacted for a recommenda-tion.7. Test Specimen7.1 When this test method is used in the field, the specimenis the coated structure or
39、 article on which the dry film thicknessis to be evaluated.7.2 For laboratory use, apply the materials to be tested topanels of the same composition, structure or article on whichthe dry film thickness is to be evaluated. Cure the organiccoating in accordance with the coating manufacturers instruc-t
40、ion.NOTE 2Coatings should be applied in accordance with PracticesD823, or as agreed upon between the purchaser and the seller.8. Calibration, Verification and Adjustment of Apparatus8.1 Calibration of coating thickness gages is performed bythe equipment manufacturer, their authorized agent, or by an
41、accredited calibration laboratory in a controlled environmentusing a documented process. A certificate of calibration show-ing traceability to a National Metrology Institute can be issued.There is no standard time interval for re-calibration, nor is oneabsolutely required, but a calibration interval
42、 can be estab-lished based on experience and the work environment. Aone-year calibration interval is a typical frequency suggestedby many gage manufacturers.8.2 Verification of AccuracyBefore use, each instrumentscalibration accuracy shall be verified by the user in accordancewith the instructions o
43、f the manufacturer, employing suitablecoating thickness standards and, if necessary, any deficienciesfound shall be corrected. The probe should also be examinedfor cleanliness and excessive wear before verifying the accu-racy and before obtaining coating thickness measurements.8.2.1 If gage readings
44、 obtained during verification areoutside the combined accuracy of the coating thickness stan-dard and the manufacturers stated gage accuracy, the gageshould be returned to the manufacturer or their authorizedagent for calibration.8.3 AdjustmentMeasurement accuracy directly corre-sponds to the sound
45、velocity of the coating being measured.Because ultrasonic instruments measure the transit time of anultrasonic pulse, they may require an adjustment by the user foreach coating material. To determine if an adjustment isnecessary, the user should measure a known thickness of thecoating (reference sta
46、ndard) as determined by:8.3.1 Using a destructive, cross-sectioning method such asdescribed in Practice D4138,or8.3.2 Nondestructively (that is, not destroying film integ-rity) removing and measuring the coating with a micrometer inaccordance with Test Method D1005,or8.3.3 Cross sectioning the produ
47、ct and measuring the coat-ing thickness by imaging the coating cross-section under amicroscope or by using computerized image analysis. In thecase of variable coating thickness or coatings applied to roughsubstrate surfaces the average coating thickness should becalculated by computer image analysis
48、8.4 Best adjustment results are achieved on coatings with athickness equal to or greater than the coating thickness range tobe measured and on coating material having the same acousticvelocity and attenuation as the coating to be measured. Followthe manufacturers instructions.NOTE 3It has been repo
49、rted that the physical properties of somecoatings such as acrylic-melamine can vary over the time of the cure.9. Procedure9.1 Use the instrument only after calibration has beenverified in accordance with Section 8.9.2 Ensure that the coating is properly cured prior to use ofthe instrument.9.3 A couplant is often required to transmit the ultrasonicpulse from the gages probe into the coating. Water is ideal forcoatings with a smooth surface. For coatings with a roughsurface, a propylene glycol gel couplant is best, providing it isnot a co
