1、Designation: D 5723 95 (Reapproved 2002)Standard Practice forDetermination of Chromium Treatment Weight on MetalSubstrates by X-Ray Fluorescence1This standard is issued under the fixed designation D 5723; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 practice covers the use of X-ray fluorescence(XRF) techniques for determinatio
3、n of the coating weight ofchromium treatments on metal substrates. These techniques areapplicable for determination of the coating weight as chro-mium or total coating weight of a chromium-containingtreatment, or both, on a variety of metal substrates.1.2 This standard does not purport to address al
4、l of thesafety concerns, 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. Summary of Practice2.1 ExcitationThe measurement of chromium
5、 treatmentcoating weights by XRF methods is based on the combinedinteraction of the chromium coating and substrate with anintense beam of primary radiation. Since each element fluo-resces at an energy characteristic of the particular element, thisinteraction results in the generation of X rays of de
6、fined energy.The primary radiation may be generated by an X-ray tube orderive from a radioisotope.2.2 DetectionThe secondary beam (fluorescent X rays ofthe elements and scattered radiation) is read by a detector thatcan discriminate between the energy levels of fluorescingradiations in the secondary
7、 beam. The detection system in-cludes the radiation detector with electronics for pulse ampli-fication and pulse counting.2.3 Basic Principle:2.3.1 A relationship exists between the treatment coatingweight and secondary radiation intensity. This relationship isusually linear within the desired coati
8、ng weights of thechromium treatments on metal substrates. The measurementsare based on primary standards of known coating weights andinstrument calibration that correlates the secondary radiationintensity with the coating weight quantitatively.2.3.2 The coating weight is determined by measurement of
9、the fluorescent X rays of the coating. The detection system isset to count the number of X rays in an energy region that ischaracteristic of X rays from the element of interest. Theelement of interest in this practice is chromium.2.3.3 If a linear relationship exists, the coating weight andnumber of
10、 counts of X rays of a chromium treatment on aparticular substrate can be expressed by a conversion factorthat represents the number of counts for a particular coatingweight unit/unit area. This is usually expressed in mg/ft2ormg/m2of chromium or total coating weight.2.3.4 The exact relationship bet
11、ween the measured numberof counts and corresponding coating weight must be estab-lished for each individual combination of substrate andchromium-containing treatment. Usually determined by thetreatment supplier, this relationship is established by usingprimary standards having known amounts of the s
12、ame treat-ment applied to the same substrate composition as the speci-mens to be measured.2.3.5 Some X-ray apparatus have a data handling systemwhereby a coating weight versus X-ray counts curve may beestablished within the system for the direct readout of coatingweight. If such apparatus does not p
13、ermit the entry of aconversion factor as described in 2.3.3, it is calibrated using abare, untreated specimen and a minimum of three specimenswith known coating weights of the treatment and substratecombination of interest. The coating weight to be measuredmust be within the range of these known coa
14、ting weights. Morethan three known specimens must be used if the relationship ofX-ray counts to coating weight is not linear over the range tobe measured. The treatment supplier should be consulted forrecommendations for establishing the curve in the instrumentfor the particular treatment and substr
15、ate combination ofinterest.3. Significance and Use3.1 The procedure described in this practice is designed toprovide a method by which the coating weight of chromiumtreatments on metal substrates may be determined.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coa
16、tings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved May 15, 1995. Published July 1995.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 This proced
17、ure is applicable for determination of thetotal coating weight and the chromium coating weight of achromium-containing treatment.4. Apparatus and Materials4.1 Measuring Instrument,2which is capable of determiningthe coating weights of chromium-containing treatments onmetal substrates by X-ray fluore
18、scence is required. The treat-ment supplier should be consulted for the suitability of theinstrumentation to be used.4.2 Calibration Standard,3necessary to calibrate the instru-ment. The count value of this standard must be specified by thetreatment supplier.4.3 Treated Coupon, on which the coating
19、weight is to bedetermined must be cut to the required size for the instrumentfrom the treated substrate.4.4 Blank (Bare and Untreated) Coupon should be asample of the same metal substrate on which the treatmentcoating weight is to be determined. It may be necessary toprepare a blank coupon from a tr
20、eated sample if an untreatedcoupon is not available. To best imitate a bare, untreated blank,abrade a treated coupon that is from the same metal specimenas the test specimen with a small abrasive pad.44.4.1 The first abrading is made parallel with the rollingdirection of the metal, the second abradi
21、ng is made perpen-dicular to the rolling direction of the metal, and the thirdabrading is made parallel with the rolling direction of themetal. This procedure should be repeated until constant read-ings are obtained. Always use the same side of the metalsubstrate from which the readings of the treat
22、ed coupon will betaken.5. Test Specimens5.1 All test specimens must be flat in the area of measure-ment and free of burrs and distortions that would preventproper seating in the specimen holder.5.2 The treatment on the substrate must be uniform in thearea of measurement.5.3 The area of measurement m
23、ust be maintained free offoreign materials. The specimen must be handled only by theedges that are outside of the area to be measured.5.4 The coated area of the specimen must be larger than themeasuring area.6. Procedure6.1 Operate the instrument in accordance with the manufac-turers instructions.6.
24、2 Set the instrument settings as follows:Dial and Arm Chromium PositionSeconds indicator per treatment supplierMultiplier switch per treatment supplierResponse switch per treatment supplierRange per treatment supplierMilliamps adjust for calibration of output per treatment supplier6.3 All specimens
25、must be seated firmly and securely overthe measuring opening. The distance between the measuringapparatus and specimen must be maintained the same as thatduring the calibration. The blank and treated specimens mustbe placed in the holder so that the rolling direction of the metalis in the same orien
26、tation. Whenever a sample tray holder is apart of the apparatus, the same opening of the slide must beused for the blank and treated specimen unless the openingshave been determined to produce equivalent results. If it isnecessary to use a backer to hold the test specimen firmlyagainst the window, m
27、ake sure that the backer is of untreatedcoupons of the same metal as the specimen. The same backermust be used for each set of measurements.6.4 Insert the chromium instrument calibration standard thathas been recommended by the treatment supplier into theinstrument, and obtain a count. Adjust the cu
28、rrent with thecontrol knob on the probe until the count value is within60.50 % of the counts provided by the treatment supplier witheach chromium calibration standard.6.5 Obtain the counts of a blank.6.6 Obtain the counts of the treated specimen.6.7 Consult the instrument manufacturers instructionma
29、nuals for calibrating and operating procedures if the X-rayapparatus has a data handling system for direct readout ofcoating weights.7. Calculation7.1 Use 7.2-7.5 for calculating the coating weight if anautomated data handling system is not available.7.2 The average of a minimum of three readings of
30、 both theblank and treated specimen is used to calculate the coatingweight.7.3 Calculate the delta (D) counts by subtracting the countsof the blank from the counts of the treated specimen.7.4 The coating weight is calculated by dividing the Dcounts by the conversion factor that is supplied by thetre
31、atment supplier for the particular substrate and treatmentcombination under study.Coating weight weight/unit area!5D countsconversion factor(1)Other methods as recommended by the treatment suppliermay be used to calculate the coating weight.7.5 The conversion factors supplied by the treatment sup-pl
32、ier are valid only for the instrument calibration procedurerecommended by the treatment supplier.8. Keywords8.1 chromium; coating weight; treatment; X-ray fluores-cence2A measuring instrument such as a Portaspect, or equivalent, available fromCianflone Scientific, 228 RIDC Park West Drive, Pittsburg
33、h, PA 15275, has beenfound suitable for this purpose.3The calibration standard may be a coupon of 316 stainless steel or otherchromium standard provided by the treatment supplier, Standard Reference Material1155 (AISI 316 stainless steel) from National Institute of Standards and Technology(NIST), Of
34、fice Standard Reference Materials, Gaithersburg, MD 20899, or otherchromium calibration standard as agreed upon between the purchaser and the seller.4An abrasive pad such as Scotchbritey No. 7447 General Purpose Hand Pad orNo. 96 General Purpose Commercial Scouring Pad, available from 3M, St. Paul,M
35、innesota, or equivalent, has been found suitable for this purpose.D 5723 95 (2002)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the
36、validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your
37、comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments h
38、ave not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 5723 95 (2002)3
