ASTM B456-03 pdf free.Standard Specification for Electrodeposited Coatings of Copper Plus Nickel Plus Chromium and Nickel Plus Chromium.
The minimumthickness of the chromium deposit shall be 0.25 um onsignificant surfaces (see 3.1), except that for service conditionsc 1 (see 4.2.1) the minimum thickness may be reduced to0.13 um.The thickness of chromium is designated by the samesymbol as the type instead of by numerals as in the case ofcopper and nickel.When plating chromium over a nickel strike con-taining micro-particles used to induce microporosity in thesubsequent chromium deposit, excess chromium thickness willbridge the nonconductive particles within the nickel layer. Amaximum of 0.5 um is recommended.The coating shall be sufficiently adherent tothe basis metal, and the separate layers of multilayer coatingsshall be sufficiently adherent to each other,to pass theappropriate tests detailed in Test Methods B 571.The particulartest or tests to be used shall be specified by the purchaser.The elongation of copper shall be such thatit will not be less than stated in 6.2.3.i when tested by themethod given in Appendix X2.Greater elongation may berequested but shall be subject to agreement between thepurchaser and the manufacturer.The ductility of the composite nickel depositon a finished part is considered acceptable when foils platedout of the individual nickel processes meet or exceed the valueslisted in Table 6.See test details in Test Method B 490.
The minimum coating thickness shall be as designatedby the coating classification number.It is recognized that requirements may exist for thickercoatings than are covered by this specification.The thickness of a coating and its various layers shallbe measured at points on the significant surfaces (See 3.1.1 andNote 5). The coulometric method described in Test MethodB 504 may be used to measure thickness of the chromium, thetotal thickness of the nickel, and the thickness of the copper.The STEP test,Test Method B 764，which is similar to thecoulometric method,may be used to closely estimate thethicknesses of individual layers of nickel in a multilayercoating.The microscopial method described in Test MethodB 487 may be used to measure the thickness of each nickellayer and of the copper layer.The X-ray method described in Test Method B 568may be used when the total thickness of a copper/nickel/chromium composite coating is to be measured， without anyindication of the thickness of each individual layer.
Other methods may be used if it can be demon-strated that the uncertainty of the measurement is less than10 %, or less than that of any applicable method mentioned in6.6.3.Other methods such as B 499 and B 530, as outlined inGuide B 659,may be used if agreed upon between thepurchaser and manufacturer.
Coated articles shall be subjected to the corrosion testfor a period of time that is appropriate for the particular servicecondition number (or for the service condition number corre-sponding to a specified classification number) as shown inTable 5.The test is described in detail in the referenced ASTMdesignation.ASTM B456 pdf download.