ASTM B636-84(2001)
(Test Method)Standard Test Method for Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
Standard Test Method for Measurement of Internal Stress of Plated Metallic Coatings with the Spiral Contractometer
SCOPE
1.1 This test method covers the use of the spiral contractometer for measuring the internal stress of metallic coatings as produced from plating solutions on a helical cathode. The test method can be used with electrolytic and autocatalytic deposits.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:B636–84 (Reapproved 2001)
Standard Test Method for
Measurement of Internal Stress of Plated Metallic Coatings
1
with the Spiral Contractometer
This standard is issued under the fixed designation B636; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This test method covers the use of the spiral contracto- 4.1 The spiral contractometer, properly used, will give
meter for measuring the internal stress of metallic coatings as reproducible results (see 8.5) over a wide range of stress
produced from plating solutions on a helical cathode. The test values. Internal stress limits with this method can be specified
method can be used with electrolytic and autocatalytic depos- for use by both the purchaser and the producer of plated or
its. electroformed parts.
1.2 This standard does not purport to address all of the 4.2 Platingwithlargetensilestresseswillreducethefatigue
safety concerns, if any, associated with its use. It is the strengthofaproductmadefromhigh-strengthsteel.Maximum
responsibility of the user of this standard to establish appro- stresslimitscanbespecifiedtominimizethis.Otherproperties
priate safety and health practices and determine the applica- affected by stress include corrosion resistance, dimensional
bility of regulatory limitations prior to use. stability, cracking, and peeling.
4.3 In control of electroforming solutions, the effects of
2. Terminology
stress are more widely recognized, and the control of stress is
2.1 Definitions: usuallynecessarytoobtainausableelectroform.Internalstress
2.1.1 compressive stress (−)—stress that tends to cause a
limits can be determined and specified for production control.
deposit to expand. 4.4 Internal stress values obtained by the spiral contracto-
2.1.2 internal stress—thenetstressthatremainsinadeposit
meterdonotnecessarilyreflecttheinternalstressvaluesfound
whenitisfreefromexternalforces.Theinternalstresstendsto onapartplatedinthesamesolution.Internalstressvarieswith
compress or stretch the deposits.
many factors, such as coating thickness, preparation of sub-
2.1.3 tensile stress (+)—stress that tends to cause a deposit
strate, current density, and temperature, as well as the solution
to contract. composition. Closer correlation is achieved when the test
conditions match those used to coat the part.
3. Summary of Test Method
5. Apparatus
3.1 The test method of measuring stress with the spiral
contractometer is based on plating on the outside of a helix.
5.1 The spiral contractometer is described by A. Brenner
2
The helix is formed by winding a strip around a cylinder, and S. Senderoff.
followed by annealing. In operation, one end of the helix is
NOTE 1—Spiral contractometers are available from many of the sup-
fixedandtheotherisallowedtomoveasstressesdevelop.The
pliers of nickel sulfamate.
free end is attached to an indicating needle through gears that
5.2 Helices shall be stopped-off on the inside to prevent
magnify the movement of the helix.As the helix is plated, the
plating.Helicesareavailablewithorwithoutapermanentinert
stress in the deposit causes the helix to wind more tightly or to
coating on the insides (see Appendix X1).
unwind, depending on whether the stress is compressive (−) or
5.3 Theclampsholdingthehelixtothecontractometershall
tensile (+). From the amount of needle deflection and other
be coated with an inert nonconductive coating to prevent their
data, the internal stress is calculated.
plating and acting as thieves.
3.2 With instrument modifications, the movement of the
5.4 For testing electroplating solutions, anodes are placed
helixcanbemeasuredelectronicallyinsteadofmechanicallyas
equidistant from the helix and symmetrically positioned to
described in 3.1.
produce even plate distribution. A minimum of four anodes is
required. A concentric anode arrangement is preferred.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
Test Methods.
2
Current edition approved Feb. 24, 1984. Published April 1984. Originally Brenner, A., and Senderoff, S., Proceedings of the American Electroplaters
published as B636–78. Last previous edition B636–78. Society, Vol 35, 1948, p. 53.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B636
5.5 Laboratory tests on electroplating solutions shall utilize 6.5 Arelationship between the surface area to be plated and
at least 3.7 L of solution.A4-L
...
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