1、Designation: B636 84 (Reapproved 2010)B636/B636M 15Standard Test Method forMeasurement of Internal Stress of Plated Metallic Coatingswith the Spiral Contractometer1This standard is issued under the fixed designation B636;B636/B636M; the number immediately following the designation indicates theyear
2、of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the use of the spiral contractom
3、eter for measuring the internal stress of metallic coatings asproduced from plating solutions on a helical cathode. The test method can be used with electrolytic and autocatalytic deposits.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The val
4、ues stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated wi
5、th its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:E177 Practice for Use of the Terms Precision and Bias in ASTM Test Met
6、hodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 compressive stress ()stress that tends to cause a deposit to expand.3.1.2 internal stressthe net stress that remains in a deposit when it is free from external for
7、ces. The internal stress tends tocompress or stretch the deposits.3.1.3 tensile stress (+)stress that tends to cause a deposit to contract.4. Summary of Test Method4.1 The test method of measuring stress with the spiral contractometer is based on plating on the outside of a helix. The helixis formed
8、 by winding a strip around a cylinder, followed by annealing. In operation, one end of the helix is fixed and the otheris allowed to move as stresses develop. The free end is attached to an indicating needle through gears that magnify the movementof the helix. As the helix is plated, the stress in t
9、he deposit causes the helix to wind more tightly or to unwind, depending onwhether the stress is compressive () or tensile (+). From the amount of needle deflection and other data, the internal stress iscalculated.4.2 With instrument modifications, the movement of the helix can be measured electroni
10、cally instead of mechanically asdescribed in 3.14.1.5. Significance and Use5.1 The spiral contractometer, properly used, will give reproducible results (see 8.59.5) over a wide range of stress values.Internal stress limits with this method can be specified for use by both the purchaser and the produ
11、cer of plated or electroformedparts.1 This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on TestMethods.Current edition approved Nov. 1, 2010Nov. 1, 2015. Published November 2010 December 2015. O
12、riginally approved in 1978. Last previous edition approved in 20062010as B636 84(2006)(2010). e01. DOI: 10.1520/B0636-84R10.10.1520/B0636_B0636M-15.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the p
13、revious version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM
14、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Plating with large tensile stresses will reduce the fatigue strength of a product made from high-strength steel. Maximumstress limits can be specified to minimize this. Other properties affected b
15、y stress include corrosion resistance, dimensionalstability, cracking, and peeling.5.3 In control of electroforming solutions, the effects of stress are more widely recognized, and the control of stress is usuallynecessary to obtain a usable electroform. Internal stress limits can be determined and
16、specified for production control.5.4 Internal stress values obtained by the spiral contractometer do not necessarily reflect the internal stress values found on apart plated in the same solution. Internal stress varies with many factors, such as coating thickness, preparation of substrate, currentde
17、nsity, and temperature, as well as the solution composition. Closer correlation is achieved when the test conditions match thoseused to coat the part.6. Apparatus6.1 The spiral contractometer is described by A. Brenner and S. Senderoff.2NOTE 1Spiral contractometers are available from many of the sup
18、pliers of nickel sulfamate.6.2 Helices shall be stopped-off on the inside to prevent plating. Helices are available with or without a permanent inert coatingon the insides (see Appendix X1).6.3 The clamps holding the helix to the contractometer shall be coated with an inert nonconductive coating to
19、prevent theirplating and acting as thieves.6.4 For testing electroplating solutions, anodes are placed equidistant from the helix and symmetrically positioned to produceeven plate distribution. A minimum of four anodes is required. A concentric anode arrangement is preferred.6.5 Laboratory tests on
20、electroplating solutions shall utilize at least 3.7 L of solution. A 4-L beaker with an annular anodearrangement is convenient. Use of this volume or larger will minimize solution changes due to electrolysis during the test.6.6 Laboratory tests on autocatalytic plating solutions are done in a 1-L, t
21、all-form beaker. Obviously, no anodes are used.7. Factors Affecting Accuracy7.1 Variations in the preparation of the helix may cause substantial variations in results.7.1.1 Stop-off material shall be applied properly to the interior of the helix. The stop-off material shall be thin and flexible tope
22、rmit the helix to move freely during the test. A coating weight of less than 50 mg/dm3 mg/in.2 is satisfactory.NOTE 2The inside mustshall be stopped-off with some inert, flexible coating. One acceptable stop-off material is “Microstop.” One part of“Microstop” is diluted with two parts of acetone bef
23、ore use. Any nickel deposited on the inside of the helix will exhibit an opposing effect.7.1.2 Helices that have been permanently coated on the inside with TFE-fluorocarbon may give variable results when testingnear-zero stresses.7.1.3 Cleaning variations and surface preparation of the helix before
24、the test can produce varying results. For example,electrocleaning of the helix shall always be cathodic and controlled with respect to current, time, and temperature.Anodic cleaningat this stage can give wide variations. Abrasive cleaning of the helix and the use of etchants shall be avoided.7.1.4 V
25、ery thin deposits of less than about 3 m 1.18 104 in. are influenced more by the surface conditions and preparationof the helix than are thicker deposits.7.2 Internal stress varies with current density used in electroplating. The variation is not predictable and depends on the metalbeing deposited,
26、impurities or additives, and the current density range under consideration. It is important that the current bemeasured and controlled closely throughout the stress test. Variations in currents shall be held to less than 2 %.7.3 Because the temperature of the plating solution may affect the internal
27、 stress, it shall be maintained within 2C 6.5Fduring the test.The initial rest point of the indicator and the final rest point are both taken at the operating temperature of the platingsolution to eliminate thermal stresses.7.4 The solution composition shall not vary during the test. Usually, if the
28、 repeatability tests in 8.59.5 are met, the solution canbe assumed to be unchanged during the test runs. Conversely, when the repeatability tests are not met, the plating solution shallbe analyzed to determine if any changes in solution composition have occurred during the test.7.4.1 Tests run on el
29、ectroplating solutions using insoluble or inefficient anodes could result in significant solution changesduring the test.7.4.2 When testing autocatalytic plating solutions, the constituents of the plating solution may be significantly depleted duringthe test, unless replenished.2 Brenner, A., and Se
30、nderoff, S., Proceedings of the American Electroplaters Society, Vol 35, 1948, p. 53.B636/B636M 1527.5 A relationship between the surface area to be plated and the volume of autocatalytic plating solutions exists that may affectthe character of the deposit. In testing autocatalytic plating solutions
31、, the ratio of plated surface area to the volume of solution thatis normally used in the plating tank shall be maintained. When using proprietary solutions, the suppliers recommendation shallbe followed.8. Calibration8.1 Calibrate the instrument as directed in the manufacturers instructions.8.2 The
32、frequency of calibration will vary with use and extent of attack on the helices from the chemical stripping. When visibleattack is noted, discard the helix.8.3 The calibration procedure consists essentially of determining the force required per degree of dial deflection.Aknown massis suspended over
33、a small pulley on a lever arm with the helix mounted in place. The degree of deflection is read from the dial.The data required for the calibration calculations as expressed in metric units are as follows:w = mass used in calibrating, kg,a = length of lever arm, m,p = pitch of helix, m,t = thickness
34、 of the strip used to make the helix, m,degdef = degree deflection; difference in dial readings caused by mass,g = 9.8 m/s2 (acceleration of free fall), andZ = calibration constant of the helixS MPamdegdefDwhereZ 52w!a!g!pt!degdef310269. Procedure9.1 The procedure will vary with the solution being t
35、ested. Follow the instructions given by the supplier carefully. Variationsin the procedure can produce variations in results. Give appropriate attention to the factors in Section 67. A detailed procedure fornickel plating solutions appears in Appendix X1.9.2 Position the spiral contractometer in ele
36、ctroplating solutions so that it is equidistant from the anodes. Position the anodeson at least four sides when they are used in a production tank or use a concentric anode arrangement. Do not place the spiralcontractometer between the tank anodes and the work being plated in a production tank. A se
37、parate ammeter and current controlare required. If the test is run on a sample of the solution, use a 4-L beaker.9.3 When testing autocatalytic plating solutions, maintain the proper surface area-to-solution volume ratio (see 6.57.5).9.4 The conditions of the test are usually chosen to match those o
38、f the production parts as closely as practicable.9.4.1 The thickness of the deposit plated on the helix may not be required to be the same as the thickness plated on productionparts. This is especially true when production part thickness requirements are greater than about 15 m.m 5.9 in.9.4.2 The cu
39、rrent density used for the spiral contractometer is sometimes lower than that of production parts. Electroplating atthe lower current density will often indicate the cumulative effects of solution impurities before these have much effect on the workbeing plated at the higher currents. This informati
40、on can be used as a measure of the solution purity and will allow planning forcorrective or purification procedures.9.5 Repeatability:9.5.1 Consider the procedure repeatable if the results of three consecutive tests on the same solution sample produce internalstress values that do not vary more than
41、 610 % from the mean of the three values.9.5.2 For near zero stress values, 10 to +10 MPa, MPa 1450 to +1450 psi, it is more difficult to detect small changes withthe contractometer and an acceptable range for repeatability is 65 MPa.5 to +5 MPa 725 to + 725 psi.9.6 Solution adjustments may be made
42、during the test, especially when testing autocatalytic solutions and electroplatingsolutions using insoluble anodes.9.7 Clean the instrument after each use and before storage. This is to prevent solution that may creep up the shaft fromcrystallizing and binding or corroding the instrument.10. Stress
43、 Calculations10.1 Data Required:Z = calibration constant for the helix, MPa/(m degdef),B636/B636M 153D = change in dial reading during the test, deg, and = thickness of the deposit on the helix, m. can be calculated from the additional data:A = plated area, m2,W = mass of deposit, kg, andd = density
44、 of deposit, kg/m3.Then = W/(d)AInternal stress,S,in MPa5Z 3D (1)NOTE 3This value is an average stress and is uncorrected for the effects of the differences in Youngs modulus between the helix and the deposit.It also assumes a relatively thin deposit on the helix. If a corrected or truer stress, ST,
45、 is desired:ST 5SF11SE03tE 3DG (2)where:E0 = Youngs modulus of the deposit, andE = Youngs modulus of the helix.Normally, the correction made above is less than the experimental errors in the procedure and is infrequently used.11. Report11.1 When reporting internal stress values, it is necessary to i
46、nclude the following:11.1.1 Metal deposited and the plating solution composition,11.1.2 Instrument used (spiral contractometer),11.1.3 Thickness of deposit on helix,11.1.4 Current density (omit if autocatalytic deposits are being tested),11.1.5 Temperature, and11.1.6 pH (if it is a controllable vari
47、able).11.2 The unit for expressing internal stress is the megapascal (MPa). One megapascal is one meganewton per square metre(MN/m2), approximately 145 psi.12. Precision and Bias312.1 The precision of this test method is based on an interlaboratory study of Test Method B636/B636M for Measurement ofI
48、nternal Stress of Plated Metallic Coatings with the Spiral Contractometer conducted in 2013. Six laboratories tested triplicatespecimens of both bright and matte samples. Every “test result” represents an individual determination. Practice E691 wasfollowed for the design and analysis of the data; th
49、e details are given in ASTM Research Report No. B08-1008.12.1.1 Repeatability (r)The difference between repetitive results obtained by the same operator in a given laboratory applyingthe same test method with the same apparatus under constant operating conditions on identical test material within short intervalsof time would in the long run, in the normal and correct operation of the test method, exceed the following values only in 1 casein 20.12.1.1.1 Repeatability can be interpreted as the maximum difference between two results, ob
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