ASTM B343-92a(1998)

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Endorsed by American
Designation: B 343 – 92a (Reapproved 1998) Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Practice for
Preparation of Nickel for Electroplating with Nickel
This standard is issued under the fixed designation B 343; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2.4 Surfaces that have been given a reverse-current treat-
ment in an alkaline solution for cleaning or possibly stripping
1.1 This practice summarizes well-known, generally practi-
an overplate of chromium (see 5.4).
cal methods for producing adherent electrodeposits of nickel
on nickel.
3. Cleaning
1.2 Electrodeposits of nickel on nickel are produced, for
3.1 The following cleaning treatments may be used for all
example, to improve the performance of decorative coatings, to
conditions and types of electrodeposited nickel. The choice of
reclaim electroplated parts that are defective, and to resume
the procedure will be governed largely by the condition of the
nickel electroplating after interruptions in processing. Interrup-
surface.
tions may be deliberate, for example, to machine the electrode-
3.1.1 Degreasing—Degreasing is used to remove the bulk
posit at an intermediate stage in the electrodeposition of thick
of grease, oil, and buffing compounds that may be present on
nickel coatings. The interruptions may be unintentional, for
the surface. The cleaning may be effected with vapor degreas-
example, resulting from equipment and power failures.
ing, organic solvents, emulsion cleaners, or soak cleaner.
1.3 To ensure good adhesion of nickel to nickel, precautions
3.1.2 Electrolytic Alkaline Cleaning—Removal of final
should be taken to avoid biopolar effects during nickel elec-
traces of dirt, grease, and oil is accomplished best with
troplating. This is of particular importance in return-type
electrolytic alkaline cleaning. The solution may be either a
automatic plating machines where one rack follows another
proprietary cleaner or a formulated one. Since a nickel surface
rack closely. Bipolar effects can be avoided by making the
forms an oxide coating if treated anodically in an alkaline
racks cathodic while they are entering or leaving the nickel
solution, this condition must be altered in subsequent steps if it
tank. Separate current control on entry and exit stations is
cannot be avoided.
desirable.
1.4 This standard does not purport to address all of the
4. Activating
safety concerns, if any, associated with its use. It is the
4.1 The procedure used for etching or activating the nickel
responsibility of the user of this standard to establish appro-
surface usually determines the soundness of the adhesion. The
priate safety and health practices and determine the applica-
choice of the procedure may be governed by the condition of
bility of regulatory limitations prior to use.
the surface and possibly the type of nickel. The milder etching
2. Types of Nickel treatment should be used in the case of highly finished
surfaces, but it may result in sacrificing maximum adhesion.
2.1 The types of nickel for which an overplate of nickel may
The thickness of the nickel may militate against the use of
be desired are dull nickel, semi-bright nickel, bright nickel, and
certain etching procedures, and therefore the thickness re-
nickel strike. Variations in these types may possibly require
moved is indicated for each procedure described in 4.2 to 4.8.
special handling.
4.2 Anodic Treatment in Concentrated Sulfuric Acid—
2.2 Surface conditions of the nickel may vary as follows:
(Nickel removed nil). A 70 mass % sulfuric acid solution
2.2.1 Freshly electroplated surfaces that are still wet with
containing 661 mL of concentrated, 96 mass % sulfuric acid
electroplating solution or rinse water (see 5.1),
(density 1.83 mL) diluted to 1 L may be used for activating the
2.2.2 Freshly electroplated surfaces that have been allowed
nickel surface provided the temperature of the solution is not
to dry (see 5.2),
over 30°C. (Caution—See Note 1.) When the initial mixture
2.2.3 Buffed, polished, or machine-ground surfaces (see
cools, dilute to exact volume. The time of treatment should be
5.3), and
about 1 min at a current density of 10 A/dm . At this current
density the nickel normally goes passive and a bright surface
This practice is under the jurisdiction of ASTM Committee B-8 on Metallic and
becomes only slightly dull. This type of passivity is removed
Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 on
by subsequent rinsing in water.
Substrate Preparation.
Current edition approved July 15, 1992. Published October 1992. Originally
published as B 343 – 60 T. Last previous edition B 343 – 92.
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B 343
NOTE 1—Caution: Slowly add the sulfuric acid with rapid stirring to
current densities from 15 to 20 A/dm . The electropolishing
the approximate amount of water required.
treatment is usually applied for 2 to 15 min. The cathodes may
be electrolytic nickel strip. Subsequent alkaline cleaning and
4.3 Anodic Etching in Sulfuric Acid—(Nickel removed
an acid dip are normally used before electroplating.
approximately 1.3 μm.) A 25 mass % sulfuric acid solution,
4.8 Cathodic Treatment—(Nickel removed nil.) These pro-
containing 166 mL of concentrated, 96 mass % sulfuric acid
cedures are recommended where the nickel surface has not
(density 1.83 g/mL), diluted to 1 L is used for this anodic
been severely passivated. Prior cleaning may be required, such
etching treatment in which the nickel surface is first etched at
as alkaline soak cleaning or electrocleaning, or both. If
a low current density of 2 A/dm for 10 min and then made
electrocleaning is employed, only cathodic current should be
passive at 20 A/dm for 2 min and finally cathodic for 2 or 3 s
used. In the following formulations, 96 mass % sulfuric acid
at 20 A/dm . See Caution in Note 1. The temperature of the
with a density of 1.83 g/mL, and 37 mass % hydrochloric acid
solution should be kept below 25°C. This treatment results in
with a density of 1.16 g/mL, are used.
excellent adhesion, but the amount of etching makes it less
4.8.1 Cathodic Treatment in Sulfuric Acid:
desirable for a highly finished surface.
Sulfuric acid 30 to 100 mL
4.4 Anodic Etching in Watts-Type Bath—(Nickel removed
Water to 1
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