ASTM B656-91

Standard Guide for Autocatalytic (Electroless) Nickel-Phosphorus Deposition on Metals for Engineering Use (Withdrawn 2000)

SCOPE
1.1 This guide gives information about the deposition of autocatalytic nickel for engineering uses (Note 1). It is not intended to be a standardized procedure, but rather a guide for obtaining smooth, adherent, and uniform coatings of a nickel-phosphorus alloy from acid-plating solutions (Note 2).  Note 1-Autocatalytic nickel is also known as electroless or chemical nickel. Note 2-Nickel-boron alloys are not covered in this document.
1.2 Autocatalytic nickel deposits covered in this guide are alloys of nickel and phosphorus produced by autocatalytic chemical reduction with hypophosphite. Because the nickel deposit is a catalyst for the reaction, the process is self-sustaining.  
1.3 The chemical and physical properties of the deposit vary with the pretreatment of the substrate, plating bath chemistry, phosphorus content, and subsequent heat treatment. For more details on such properties, see ASTM STP 265 (1) , (2), (3), (4), and (7).  Also, refer to Figs. X1.1, X1.2, and X1.3 in the Appendix.  
1.4 This guide covers the metal preparation and deposition process. The testing of autocatalytic nickel-phosphorus deposits is covered in Specification B733.  
1.5 This standard does not purport to address all of the safety problems 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. See 8.11 and 8.13 for specific safety precautionary statements.

General Information

• Status: Withdrawn
• Publication Date: 31-Dec-1990
• Withdrawal Date: 09-Nov-2000
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings

Relations

• Referred By: ASTM B607-21 - Standard Specification for Autocatalytic Nickel Boron Coatings for Engineering Use
• Effective Date: 01-Jan-1991
• Referred By: ASTM B851-04(2020) - Standard Specification for Automated Controlled Shot Peening of Metallic Articles Prior to Nickel, Autocatalytic Nickel, or Chromium Plating, or as Final Finish
• Effective Date: 01-Jan-1991

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:B656–91
Standard Guide for
Autocatalytic (Electroless) Nickel-Phosphorus Deposition on
Metals for Engineering Use
This standard is issued under the fixed designation B656; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
1. Scope A275/A275M Test Method for Magnetic Particle Exami-
nation of Steel Forgings
1.1 This guide gives information about the deposition of
B177 Guide for Chromium Electroplating on Steel for
autocatalytic nickel for engineering uses (Note 1). It is not
Engineering Use
intended to be a standardized procedure, but rather a guide for
B183 Practice for Preparation of Low-Carbon Steel for
obtaining smooth, adherent, and uniform coatings of a nickel-
Electroplating
phosphorus alloy from acid-plating solutions (Note 2).
B242 Practice for Preparation of High-Carbon Steel for
NOTE 1—Autocatalytic nickel is also known as electroless or chemical 4
Electroplating
nickel.
B252 Practice for Preparation of Zinc Alloy Die Castings
NOTE 2—Nickel-boron alloys are not covered in this document.
for Electroplating and Conversion Coatings
1.2 Autocatalytic nickel deposits covered in this guide are
B253 Practice for Preparation of Aluminum Alloys for
alloys of nickel and phosphorus produced by autocatalytic
Electroplating
chemical reduction with hypophosphite. Because the nickel
B254 Practice for Preparation of and Electroplating on
deposit is a catalyst for the reaction, the process is self-
Stainless Steel
sustaining.
B281 Practice for Preparation of Copper and Copper-Base
1.3 Thechemicalandphysicalpropertiesofthedepositvary
Alloys for Electroplating and Conversion Coatings
with the pretreatment of the substrate, plating bath chemistry,
B322 Practice for Cleaning Metals Prior to Electroplating
phosphorus content, and subsequent heat treatment. For more
B374 Terminology Relating to Electroplating
details on such properties, see ASTM STP 265 (1,2,3,4,7).
B480 GuideforPreparationofMagnesiumandMagnesium
Also, refer to Fig. X1.1, Fig. X1.2, and Fig. X1.3 inAppendix
Alloys for Electroplating
X1.
B481 Practice for Preparation of Titanium and Titanium
1.4 This guide covers the metal preparation and deposition
Alloys for Electroplating
process. The testing of autocatalytic nickel-phosphorus depos-
B678 Test Method for Solderability of Metallic-Coated
its is covered in Specification B733B733.
Products
1.5 This standard does not purport to address all of the
B733 Specification for Autocatalytic Nickel-Phosphorus
safety problems associated with its use. It is the responsibility
Coatings on Metals
of the user of this standard to establish appropriate safety and 5
E165 Test Method for Liquid Penetrant Examination
health practices and determine the applicability of regulatory
F519 Method for Mechanical Hydrogen Embrittlement
limitations prior to use. See 8.11 and 8.13 for specific safety
Testing of Plating Processes and Aircraft Maintenance
precautionary statements.
Chemicals
2.2 Military Specifications:
2. Referenced Documents
MIL-S-13165 Shot Peening of Metal Parts
2.1 ASTM Standards:
MIL-C-26074 Coating, Electroless Nickel, Requirements
for
This guide is under the jurisdiction ofASTM Committee B-8 on Metallic and
Inorganic Coatings and is the direct responsibility of Subcommittee B08.08 on Annual Book of ASTM Standards, Vol 01.05.
Engineering Coatings. Annual Book of ASTM Standards, Vol 02.05.
Current edition approved Mar. 15, 1991. Published May 1991. Originally Annual Book of ASTM Standards, Vol 03.03.
published as B656–79. Last previous edition B656–86. Annual Book of ASTM Standards, Vol 15.03.
2 7
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
B656–91
MIL-R-81841 Rotary Flap Peening of Metal Parts 4.7 After several metal turnovers the plating solution con-
2.3 Aerospace Materials Specifications (AMS): tainsconsiderableamountsofby-productsaltsandthedeposits
AMS-2404 Electroless Nickel Plating become more stressed and porous.
AMS-2405 Electroless Nickel Plating, Low Phosphorus
5. Metal Preparation
3. Significance and Use 5.1 Practices for the preparation of basis metals for electro-
plating have been published by ASTM. Generally, with some
3.1 This guide provides procedures for the inspection and
degree of variation, these practices are also applicable to the
preparation of the substrate and control of the plating process.
preparation for autocatalytic nickel deposition. Particularly
Thisguideisrecommendedtothemanufacturer,thepurchaser,
useful is Practice B322B322. The practices and guide listed
and the user of autocatalytic nickel.
below have sections that, when properly modified, are helpful:
3.2 Autocatalytic nickel-phosphorus coatings are used to
B 177B 177, B 183B 183, B 252B 252, B 253B 253,
improve the performance of the metal article by providing
B 254B 254, B 281B 281, B 322B 322, B 480B 480 and
corrosion resistance, wear resistance, solderability, or certain
B481B481
magnetic properties.
5.2 To ensure that an adherent corrosion resistant, essen-
tially pore-free deposit is produced, the metal surface must be
4. General Considerations
clean and uniform. Surface defects such as pores, pits, inclu-
4.1 Autocatalytic nickel will deposit uniformly on clean
sions, scale, crevices, burns, corrosion products, and oxides
wetted surfaces. The deposit may be applied to most metals.
will reduce the deposit integrity (see Test Methods
The as-plated coating is a hard nickel phosphorus alloy of
A275A275/A275M/A275M and E165E165). Surface con-
uniform thickness. The structure of alloys containing more
taminants that must be removed are: handling soils, environ-
than 8% phosphorus is predominantly amorphous as defined
mental matter, drawing oils or compounds, polishing abrasives
by X-ray diffraction.
and binders, rust preventatives, or protective coatings. Me-
4.2 Aluminum, beryllium, cobalt, copper, iron, nickel, tita-
chanical and chemical treatments must be used to properly
nium and their alloys can be plated directly. Other basis
prepare the substrate. Because each basis metal alloy reacts
materials can be plated by special processes (see 5.3).
uniquely, different pretreatments and various cleaning proce-
4.3 Articles that have blind holes, crevices, porosity, burrs,
dures must be used to produce a clean surface.
or have surfaces that have been burned or carbonized, require
5.3 On parts made from zinc, lead, cadmium, tin, bismuth,
special pretreatment and plating procedures for optimum
arsenic, antimony, and alloys containing high proportions of
deposit performance.
these metals (such as lead solders), apply a copper or nickel
4.4 The required thickness of autocatalytic nickel coatings
strike to prevent these metals from contaminating the bath.
can vary from as little as 1.0 µm to over 150 µm. The selected
Copper, brass, or bronze parts may be plated directly with
thickness will depend upon the application and service condi-
galvanic initiation. Magnesium parts require special pretreat-
tions to which the finished part is exposed, as well as the
ment and plating solution (see Guide B480B480).
surface condition of the basis metal. Rough surfaces require
5.4 Surface Conditions:
thickerdepositsforminimumporosityandmaximumcorrosion
5.4.1 Hardness—In hardened and high-strength steels, in-
resistance. The following are typical examples:
ternal stress may cause cracking during and after cleaning and
For soldering 1 to 7.5 µm
deposition. Articles made of severely cold-worked steel or
For preventing the rusting of steel in air 5 to 15 µm
steels with tensile strength greater than 1050 MPa are to be
For mild wear conditions 5 to 25 µm
For moderate corrosion wear 13 to 30µ m
stress-relieved according to Table 1 before cleaning.
For severe wear 30 to 75 µm
For severe corrosion 50 to 125 µm NOTE 3—Surface-hardened parts can be stress-relieved at 130–150°C
For salvage as required
for not less than 5 h. If required, the heat treatment shall not reduce the
surface hardness. Shorter times at higher temperatures may be used if the
The thickness of autocatalytic nickel coatings formed with
resulting loss of surface hardness of the substrate is acceptable. Stress-
good solution agitation and part movement is quite uniform.
relieving heat treatment is not normally required for nonferrous parts.
Thickness of less than 25 µm can be controlled to close
NOTE 4—Parts higher than 1050 MPa in tensile strength, which have
tolerances by controlling the operating parameters that influ-
been acid stripped for recoating, should be baked for embrittlement relief
encethedepositionrate.Smalldiameterholesareanexception before processing in accordance with Table 1.
and the thickness of the deposit therein may vary.
5.4.2 Autocatalytic nickel coatings will not fill in surface
4.5 Autocatalytic nickel-phosphorus coated products may
scratches, pits, tool marks, etc. The smoothness of the surface
be soldered, brazed, or welded. Inert gas welding methods are
necessary for optimum joint strength.
TABLE 1 Heat Treatment for Stress Relief Before Plating and
4.6 The basis metal composition and general surface con-
Hydrogen Embrittlement Relief After Plating
dition must be taken into account when selecting a pretreat-
Maximum Specified Tensile
Hours at 1906 15°C
ment procedure.
Strength (MPa)
1000 and below none
1051 to 1450 2
1451 to 1800 18
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B656–91
to be plated, therefore, must be equal to the surface finish 5.5.8 Smut Removal—When the hydrochloric acid treat-
required of the finished product. Avoid mechanical operations ment of steel results in the production of smut, it must be
that produce grinding checks or glazing. Welding spatter and
removed. Heavy smut can be removed by anodic treatment in
flux residues must be removed by mechanical means prior to a caustic solution (see A1.2 and Practice B242B242).
cleaning.
5.5.9 Anodic-Acid Etching:
5.5 Surface Preparation:
5.5.9.1 An anodic-acid etch with a subsequent rinse as the
5.5.1 Precleaning—Themetalsurfacemustbedegreasedor
final step in the preparation of high-carbon steel alloys is
soak-cleaned, or both, when grease, oil, and buffing com-
recommended in securing adhesion; it is not suitable where
pounds are present. For this purpose use vapor degreasing,
deep recesses are present. Without such an anodic treatment,
organic solvents, emulsion or spray cleaners. Whenever prac-
pooradhesionmayoccur.Theanodic-acid-treatmentiscapable
tical, supplement the degreasing by anodic or periodic reverse
of removing a small amount of smut or oxides formed by a
electrolytic alkaline cleaning. To remove heavy scale, sodium
preceding treatment. If more substantial amounts of smut must
hydride or some other molten salt bath may be used (5).
be removed, use the procedure described in A1.3.
5.5.2 Abrasive Cleaning—Oxideandscalemayberemoved
5.5.9.2 A250to1000g/Lsulfuricacid(94to96%)solution
by mechanical means, using abrasives such as fine emery on a
used at not more than 30°C is effective for anodic etching of
cloth or wheel, pumice slurry, or greaseless buffing com-
high-carbon steel.The addition of 125 g/Lof sodium sulfate is
pounds. Grit blasting, wet blasting, or vapor honing are
of benefit for most steel grades. The part is given an anodic
recommended on rough castings, corroded and other nonuni-
treatment in the acid for a time usually not exceeding 1 min at
form surfaces. Small parts can often be cleaned by barrel
a current density of 10 to 16 A/dm (see A1.3).
finishing with a mild abrasive.
5.5.9.3 High acid content, high current density, and low
5.5.2.1 Follow abrasive cleaning with a suitable cleaning
temperature (with reference to the ranges specified) will
procedure (for example, electrolytic alkaline cleaning) to
minimizetheattackonthebasismetalandproduceasmoother
remove all traces of the abrasives, which can reduce deposit
surface.
adhesion and corrosion performance. Abrasive material shall
befreeofmetalparticlesanddirttoavoidcontaminationofthe
NOTE 5—To obtain maximum coating adhesion it may be necessary to
surface.
etch highly finished metal surfaces.
5.5.3 Peening—Peen high-strength steels to induce com-
5.5.10 Stainless Steel—Stainless steels and other high-alloy
pressive stress within the substrate to minimize the loss of
substrates may require a nickel strike prior to autocatalytic
fatigue strength and of stress-corrosion resistance (see MIL-S-
nickel plating to obtain maximum adhesion (see A1.4).
13165 and MIL-R-81841).
5.5.11 Aluminum—The pretreatments of aluminum alloys
5.5.4 Masking—If required, apply masking after vapor
can vary widely and depend significantly on the alloy compo-
degreasing and mechanical cleaning. Test the masking com-
sition and the plating bath formulation. Zincating is frequently
pound and tape used for suitability (see 8.1).
usedafterdeoxidizinganddesmuttingofthealuminumsurface
5.5.5 Racking—Position racked or wired parts so as to
(see Practice B253B253).
minimizetrappingofhydrogengasincavitiesandholesandto
5.5.12 Titanium and titanium alloys are subject to stress
allow free circulation of solution over all surfaces to obtain
corrosion cracking after processing. Pretreatment solutions
uniform coating thickness. Significant surfaces shall not show
rackorwiremarks.Thelocationofrackorwiremarksshallbe including rinses should not contain methanol, halogenated
hydrocarbons, or more than 50 ppm chlorides, all which may
agreed upon between the purchaser and the producer.
cause subsequent halide stress corrosion cracking when the
5.5.6 Alkaline Cleaning—Final removal of dirt, abrasive
parts are heated to 260°C or higher (see Practice B481B481).
scale, grease, and oil is best performed by anodic alkaline
cleaning. Then, if this is impractical because of the size or
5.5.13 Oxidation—Topreventoxidationofthes
...