Significance and Use
The ability of a multilayer nickel deposit to enhance corrosion resistance is a function of the difference in the electrode potentials of the nickel layers (as measured individually at a fixed current density in a given electrolyte versus a reference electrode) and the thicknesses of the layers. The potential differences must be sufficient to cause the bright nickel or top layer to corrode preferentially and sacrificially with respect to the semi-bright nickel layer beneath it.
This test procedure allows the measurement of these potential differences directly on an electroplated part rather than on separate foil specimens in such a way that time determines the thickness of each layer, while the potential difference between nickel layers is an indication of the corrosion resistance of the total nickel deposit.
The interpretation and evaluation of the results of this test should be by agreement between the purchaser and the manufacturer.
Note 1—This test may be used as a quality assurance test of the multilayer nickel coatings applied in production. It should be understood that due to many factors that influence the progress of corrosion during actual use of the part, the performance of different multilayer nickel deposits in the test cannot be taken as an absolute indicator of the relative corrosion resistance of these deposits in service.
1.1 This test method closely estimates the thickness of individual layers of a multilayer nickel electrodeposit and the potential differences between the individual layers while being anodically stripped at constant current density. ,
1.2 This test method does not cover deposit systems other than multilayer electroplated nickel deposits.
1.3 This standard does not purport to address all of the safety concerns, 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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
B456 Specification for Electrodeposited Coatings of Copper Plus Nickel Plus Chromium and Nickel Plus Chromium
B504 Test Method for Measurement of Thickness of Metallic Coatings by the Coulometric Method
D1193 Specification for Reagent Water
potential; STEP; thickness; Reference electrode; Step test; Stripping; Thickness--electrodeposited coatings; Agitating tube; Anodic coatings; Buffering action; Cathode coatings; Chromium electroplating; Corrosion--electrodeposited coatings; Coulometry--metallic materials; Current measurement; Density--metallic coatings; Deplating cell; Electrodeposited Ni coatings; Electrolytic determination; Metallic coatings; Multilayer nickel deposit; Nickel coatings; Purified water; Reagent water;
ICS Number Code 25.220.40 (Metallic coatings)
ASTM International is a member of CrossRef.
Citing ASTM Standards
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