Designation:B487–85(Reapproved2002)
Standard Test Method for
Measurement of Metal and Oxide Coating Thickness by Microscopical Examination of a Cross Section1
This standard is issued under thefixed designation B487;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.
This standard has been approved for u by agencies of the Department of Defen.
1.Scope
1.1This test method covers measurement of the local thickness of metal and oxide coatings by the microscopical examination of cross ctions using an optical microscope. 1.2Under good conditions,when using an optical micro-scope,the method is capable of giving an absolute measuring accuracy of0.8µm.This will determine the suitability of the method for measuring the thickness of thin coatings.
1.3This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to u.(This is especially applicable to the chemicals cited in Table X
2.1.)
2.Referenced Documents
2.1ASTM Standards:
E3Methods of Preparation of Metallographic Specimens2
3.Summary of Test Method
3.1This test method consists of cutting out a portion of the test specimen,mounting it,and preparing the mounted cross ction by suitable techniques of grinding,polishing,and etching.The thickness of the cross ction is measured with an optical microscope.
N OTE1—The techniques will be familiar to experienced metallogra-phers but some guidance is given in Section5and in Appendix X1for less experienced operators.
4.Significance and U
4.1Coating thickness is an important factor in the perfor-mance of a coating in rvice and is usually specified in a coating specification.
4.2This method is suitable for acceptance testing.
体育锻炼心得
5.Factors Influencing the Measurement Result
5.1Surface Roughness—If the coating or its substrate has a rough surface,one or both of the interfaces bounding the coating cross ction may be too irregular to permit accurate measurement.(See X1.4)
5.2Taper of Cross Section—If the plane of the cross ction is not perpendicular to the plane of the coating,the measured thickness will be greater than the true thickness.For example, an inclination of10°to the perpendicular will contribute a 1.5%error.
5.3Deformation of the Coating—Detrimental deformation of the coating can be caud by excessive temperature or pressure during mounting and preparation of cross ctions of soft coatings or coatings melting at low temperatures,and also by excessive abrasion of brittle materials during preparation of cross ctions.
5.4Rounding of Edge of Coating—If the edge of the coating cross ction is rounded,that is,if the coating cross ction is not completelyflat up to its edges,the true thickness cannot be obrved microscopically.Edge rounding can be caud by improper mounting,grinding,polishing,or etching.It is usually minimized by overplating the test specimen before mounting.(See X1.2.)
5.5Overplating—Overplating of the test specimen rves to protect the coating edges during preparation of cross ctions and thus to prevent an erroneous measurement.Removal of coating material during surface preparation for overplating can cau a low-thickness measurement.
5.6Etching—Optimum etching will produce a clearly de-fined and narrow dark line at the interface of
two metals. Excessive etching produces a poorly defined or wide line which may result in an erroneous measurement.
5.7Smearing—Improper polishing may leave one metal smeared over the other metal so as to obscure the true boundary between the two metals.The apparent boundary may be poorly defined or very irregular instead of straight and well defined. To verify the abnce of smearing,the coating thickness should be measured and the polishing,etching,and thickness mea-surement repeated.A significant change in apparent thickness
1This test method is under the jurisdiction of ASTM Committee B08on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10on
General Test Methods.
Current edition approved Feb.22,1985.Published May1985.Originally
published as B487–68.Last previous edition B487–79.
2Annual Book of ASTM Standards,V ol03.01.
1
Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.公司催款律师函
indicates that smearing was probably prent during one of the measurements.
5.8Magnification—For any given coating thickness,mea-surement errors generally increa with decreasing magnifica-tion.If possible,the magnification should be chon so that the field of view is between1.5and33the coating thickness.
5.9Calibration of Stage Micrometer—Any error in calibra-tion of the stage micrometer will be reflected in the measure-ment of the specimen.Errors of veral percent are not unrealistic unless the scale has been calibrated or has been certified by a responsible supplier.The distance between two lines of a stage micrometer ud for the calibration shall be known to within0.2µm or0.1%,whichever is the greater.If a stage micrometer is not certified for accuracy,it should be calibrated.A generally satisfactory means of calibration is to assume that the stated length of the full scale is correct,to measure each subdivision with afilar micrometer,and to calculate the length of each subdivision by simple proportion.
5.10Calibration of Micrometer Eyepiece:
5.10.1Afilar micrometer eyepiece generally provides the most satisfactory means of making the measurement of the specimen.The measurement will be no more accurate than the calibration of the eyepiece.As calibration is operator depen-dent,the eyepiece shall be calibrated by the person making the measurement.
杨子扬
5.10.2Repeated calibrations of the micrometer eyepiece can be reasonably expected to have a spread of less than1%.
5.10.3Some image-splitting micrometer eyepieces have a nonlinearity that introduces an error of up to1%for short measurement distances.
5.11Alignment—Errors can be introduced by backlash in the movement of the micrometer eyepiece.If thefinal motion during alignment of the hairline is always made in the same direction,this error will be eliminated.
5.12Uniformity of Magnification—Becau the magnifica-tion may not be uniform over the entirefield,errors can occur if both the calibration and the measurement are not made over the same portion of thefield with the measured boundaries centered about the optical axis.
5.13Lens Quality—Lack of sharpness of the image contrib-utes to the uncertainty of the measurement.Poor quality lens could preclude accurate measurements.Sometimes image sharpness can be improved by using monochromatic light. 5.14Orientation of Eyepiece—The movement of the hair-line of the eyepiece for alignment has to be perpendicular to the boundaries of the coating cross ction.For example,10°misalignment will contribute a1.5%error.
5.15Tube Length—A change in the tube length of the microscope caus a change in magnification and if this change occurs between the time of calibration and the time of measurement,the measurement will be in error.A change in tube length may occur when the eyepiece is repositioned within the tube,when the focus of the eyepiece tube is changed,and,for some microscopes,when thefine focus is adjusted or the interpupillary distance for binoculars is changed.
赤壁之战真实历史6.Preparation of Cross Sections
6.1Prepare,mount,polish,and etch the specimen so that: 6.1.1The cross ction is perpendicular to the coating; 6.1.2The surface isflat and the entire width of the coating image is simultaneously in focus at the magnification ud for the measurement;
6.1.3All material deformed by cutting or cross ctioning is removed.
6.1.4The boundaries of the coating cross ction are sharply defined by no more than contrasting appearance or by a narrow, well-defined line.
N OTE2—Further guidance is given in Appendix X1.Some typical etchants are described in Appendix X2.
7.Procedure
7.1Give appropriate attention to the factors listed in Section 5and Appendix X1.
想做微商
7.2Calibrate the microscope and its measuring device with
a certified or calibrated stage micrometer.
7.3Measure the width of the image of the coating cross ction at no less thanfive points distributed along a length of the microction,and calculate the arithmetic mean of the measurements(e8.1.5and8.1.6).
8.Test Report
8.1The test report shall include the following information: 8.1.1The date of test;
8.1.2The number and title of this test method;
8.1.3The identification of the test specimens;
8.1.4The location on the coated item at which the cross ction was made;
8.1.5The measured thickness,in micrometres(millimetres if greater than1mm)at each point(7.3),and the length of ction over which the measurements were distributed;
8.1.6The local thickness,that is,the arithmetic mean of the measured thickness;
8.1.7Any deviations from this test method;金华有什么好玩的
8.1.8Any factors that might influence interpretation of the reported results;and
8.1.9The name of the operator and testing laboratory.
9.Precision and Bias
9.1The microscope and associated equipment,its u,its calibration,and the method of preparation of the cross ction shall be chon so as to allow the coating thickness to be determined to within1µm
or10%,whichever is the greater,of the actual coating thickness.Under good conditions,when using an optical microscope,the method is capable of giving an absolute measuring accuracy of0.8µm and for thickness greater than25µm a reasonable error is of the order of5%or
亲情作文
better.
APPENDIXES
(Nonmandatory Information)
X1.GUIDANCE ON THE PREPARATION AND MEASUREMENT OF CROSS SECTIONS
X1.1Introduction—The preparation of test specimens and measurement of coating thickness are greatly dependent on individual techniques and there is a variety of suitable tech-niques available.It is not reasonable to specify only one t of techniques,and it is impractical to include all suitable tech-
niques.The techniques described in this appendix are intended as guidance for metallographers not experienced in measure-ments of coating thickness.For additional guidance e Meth-ods E3.
X1.2Mounting:
X1.2.1To prevent rounding of the edge of the cross ction, the free surface of the coating should be supported so that there is no space between the coating and its support.This is usually achieved by overplating the specimen with a coating at least 10-µm thick of a metal of similar hardness to the coating.For hard,brittle coatings(for example oxide or chromium coat-ings)tightly wrapping the specimen in soft aluminum foil before mounting has proved successful.
X1.2.2If the coating is soft,overplating with a metal which is softer will make polishing more difficult,becau the softer metal tends to be polished away more rapidly.
X1.2.3Overplating of zinc or cadmium coatings with cop-per may cau difficulty becau of the tendency,during subquent etching,of dissolved copper to deposit on the coatings.It is better to overplate zinc with cadmium and vice versa.
X1.3Grinding and Polishing:
X1.3.1It is esntial to keep the cross-ction surface of the mount perpendicular to the coating.This is facilitated by incorporating additional pieces of a similar metal in the plastic mounting,near the outer edges,by periodically changing the direction of grinding(rotating through90°)and by keeping the grinding time and pressure to a minimum.If,before grinding, reference marks are inscribed on the side of the mount,any inclination from horizontal is easily measurable.
X1.3.2Grind the mounted test specimens on suitable abra-sive paper,using an acceptable lubricant,such as water or mineral spirits,and apply minimum pressure to avoid bevelling of the surface.Initial grinding should employ100or180grade abrasive to reveal the true specimen profile and to remove deformed metal.Subquently,u Grades240,320,500,and 600without exceeding grinding times of30to40s on each paper;alter the direction of scratches by90°for each change of paper.Afinal polish of2to3min on a rotating wheel charged with4to8-µm diamond paste particles and lubricated with mineral spirits should suffice to remove scratches forfinal examination.If an especially high degree of surfacefinish is required,a further treatment,using diamond paste of approxi-mately1-µm particles,may be employed.
X1.3.3If very soft materials are being prepared,abrasive particles may become embedded during grinding.This may be minimized by totally immersing abrasive papers in a lubricant during grinding o
r by using a copiousflow of lubricant.If abrasive particles do become embedded,they may be removed by applying a short,light hand polish with metal polish after grinding and before diamondfinishing or by one or more cycles of alternate etching and polishing.
X1.4Etching—Etching is usually advisable to promote contrast between the metal layers,to remove traces of smeared metal,and to develop afine line at the boundary of the coating. Some typical etchants are given in Appendix X2.
X1.5Measurement:
X1.5.1The measuring device may be afilar micrometer or a micrometer eyepiece.The latter has a lower precision.An image-splitting eyepiece is advantageous for thin coatings on rough substrate surfaces.Measurement of the image projected on to a ground-glass plate is usually less satisfactory becau of the lack of sharpness of the image and poor legibility of the ruler when the projected image is visible.
X1.5.2The measuring device should be calibrated at least once before and once after a measurement,unless repeated experience indicates otherwi.
X1.5.3When making calibration and coating measure-ments,both should be made by the same operator,the stage micrometer and the coating should be centered in thefield,and each measurement at a point should be made at least twice and averaged.
X1.5.4For critical and referee measurements,all steps for the preparation of cross ctions and measurement of coating thickness,from grinding with600grade or coarr abrasive,up to and including the determination,should be performed at least twice.With good techniques and equipment,and smooth coating and substrate surfaces,repeatability within2%or0.5µm,whichever is the greater,is reasonable.
X1.5.5Some microscopes are subject to a spontaneous movement of the stage relative to the objective,possibly due to nonuniform thermal effects from the light source.Such a movement during the measurement can cau an erroneous measurement at moderate and high magnifications.This can be minimized by completing the measurement quickly and by measuring each interval twice,once from left to right and once from right to
left.
X2.SOME TYPICAL ETCHANTS FOR USE AT ROOM TEMPERATURE
X3.LIMIT OF RESOLUTION
X3.1Resolution may be expresd as the minimum dis-tance by which two points must be parated before they can be revealed as parate points in the image.For a microscope there is a theoretical limit of resolution determined by the numerical aperture (NA)of the objective.This theoretical limit is approached by good quality microscopes.For practical purpos better resolution cannot be obtained regardless of the quality of the optics or of the total magnification.
X3.2Generally,the maximum uful magnification is about 10003the NA of an objective.That is,for practical purpos,greater magnification will not reveal additional information nor impart better definition.Such additional magnification is often referred to as “empty magnification.”
ASTM International takes no position respecting the validity of any patent rights asrted in connection with any item mentioned in this standard.Urs of this standard are expressly advid that determination of the validity of any such patent rights,and the risk of 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 and if not revid,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standards and should be addresd to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards,at the address shown below.
TABLE X2.1Etchants
Etchant
U and Remarks
Nitric acid (sp gr 1.42):5mL For nickel or chromium coatings on steel Ethanol (95%):95mL
Etches steel
Caution —This mixture can be explosively unstable,This etchant should be freshly prepared.
particularly if heated.Iron(III)chloride hexahydrate (FeCl 3·6H 2O):10g Hydrochloric acid (sp gr 1.16):2mL Ethanol (95%):98mL For gold,lead,silver,nickel and copper coatings on steel,copper,
and copper alloys.
Etches steel,copper,and copper alloys.
Nitric acid (sp gr 1.42):50mL Glacial acetic acid:50mL
For determination of thickness of individual layers of multilayer
coatings of nickel on steel and copper alloys;distinguishes each layer of nickel by identifying structures.
Etches nickel;excessive attack on steel and copper alloys.Ammonium persulfate:10g
For tin and tin alloy coatings on copper and copper alloys.Ammonium hydroxide (sp gr 0.88):2mL Etc
hes copper and copper alloys.
Distilled water:90mL
This etchant should be freshly prepared.
Nitric acid (sp gr 1.42):5mL
Hydrofluoric acid (sp gr 1.14):2mL Distilled water:93mL
For nickel and copper coatings on aluminum and its alloys.Etches aluminum and its alloys.
Chromium(VI)oxide (CrO 3):20g Sodium sulfate:1.5g Distilled water:100mL
For nickel and copper on zinc-bad alloys.Also suitable for zinc
and cadmium on steel.
Etches zinc,zinc-bad alloys and cadmium.Hydrofluoric acid (sp gr 1.14):2mL Distilled water:98mL
For anodized aluminum alloys.Etches aluminum and its alloys.
绘画自学
Ammonium hydroxide (sp gr 0.90):1part by volume Hydrogen peroxide (3%solution):1part by volume For nickel on copper and its alloys.Swab with a fresh solution.Etches the copper.
Sodium or potassium cyanide (10%solution):1part Ammonium persulfate (10%solution):1part Make up each solution fresh each time.
For silver and gold on copper and nickel alloys and
steel.
This standard is copyrighted by ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959, United States.Individual reprints(single or multiple copies)of this standard may be obtained by contacting ASTM at the above address or at610-832-9585(phone),610-832-9555(fax),or rvice@astm(e-mail);or through the ASTM website
(www.astm).
