A New Zinc-Nickel Electroplating Process

A New Zinc-Nickel
Electroplating Process:
Alternative to Cadmium Plating
Grace F. Hru
Boeing Materials Technolcgy
Boeing Commercial Airplane Ca.
Seattle. WA
equivalent process that can provide the unique
characteristics of LHE and retain the use of
conventional electroplating tank facilities.
ABSTRACT
New environmental regulations aU over
the world encourage the use of alternatives to
cadmium plating for corrosion-protection
systems used on steels. Boeing patents are
pending on a norrcyanide replacement zincnickel alloy electroplating process with
superior properties, including low hydrogen
embrittlement and good corrosion protection,
for use on highstrength steels and other
substrates. Another advantage of this process
is low cost because conventional electroplating tanlc facilities can be used and waste
treatment cost can be reduced. The feasibility of this zinc-nickel plating process has
been successfully demonstrated in the
laboratory and is scheduled for manufacturing
scaleup during 1983.
EVOLUTION OF LOW HYDROGEN EMBRITTLEMENT CADMIUM ELECTROPLATING
Hydrogen may be absorbed by metals
both during processing and when the finished
products are in use. Because hydrogen
adversely affects ductility, sufficiently high
levels of hydrogen can cause brittle failure in
metals subjected to sustained stress.
Hydrogen embrittlement is of primary concern
to the aerospace industry.
The vast majority of high-strength steel
landing gear parts used on jet aircraft are
cadmium plated using LHE processes. Figure
1 shows the evolution of LHE plating processes
for high-strength steels. The first LHE
process introduced in 1960, w a s accomplished
by plating in an unbrightened cadmium cyanide
solution at high current density. One of the
drawbacks of this process is the very uneven
deposit thickness, as shown in Figure Za. This
feature, plus the very porous plate, accounts
for the poor corrosion protection of the
substrate and the susceptibility to hydrogen
reembrittlement or "post-plating
embrittlement" (12,13,14).
ALTHOUGH THE CADMIUM A N D CYANIDE
HAZARDS to human health are well known
and documented (1P, cyanide cadmium
electroplating is widely used on steel for its
many beneficial properties (2.3.4). In the
United States alone, the annual cadmium
consumption for plating is approximately five
million pounds (5). Increasingly stringent
environmental regulations all over t h e world
encourage the use of alternatives to cadmium
plating for corrosion-protection systems used
on steel. For aircraft highstrength steel
parts, a substitute for cadmium plating must
ensure long-term corrosion protection and
provide low hydrogen embrittlement (LHE)
(6,7,8,9).
Mechanical plating, ion vapor deposition
(IVD) of aluminum, aqueous coating dispersion,
and bonded solid-film lubricants are mentioned
(10,lI) as possible alternative candidates to
cadmium plating. However, there is no
*Numbers in parentheses designate references
at end of paper.
'
3
Porous Cyanide Cadmium Plating
.L
Cyanide Cadmium-Titanium Plating
.L
NonCyanide Zinc-Nickel Alloy Plating.
-
1960
-
1962
-
1983
Figure 1. Evolution of Low Hydrogen Embrittlement
Cadmium and Replacement Electroplating
Boeing Proprietary
a.
Cyanide Porous Cadmium
Deposit
c.
Boeing Zinc-Nickel
Alloy Deposit
b.
Cyanide CadmiumTitanium Deposit
Figure 2. Scanning Electron Micrographs of Polished and Etched Low
Hydrogen Embrittlement Electroplating Deposit Cross-Sections (400X)
4
In 1962, a cyanide cadmium-titanium
(Cd-Ti) plating bath w a s adopted by Boeing for
coating high-strength structural steel (15,16).
Figure 2b illustrates that the cyanide
cadmium-titanium deposit is a more
continuous plating of less porosity than
cyanide porous cadmium deposit. One
interesting feature of Figures 2a and 2b is that
coarsegrained structures are exhibited in both
deposits.
Although not utilized by Boeing,
researchers at Beijing !nstitute in 1970
invented a noncyanide cadmium-titanium alloy
plating process which w a s stated to be LHE
single process is a viable alternative to Cd
plating for both high and low strength steels.
For high-strength steel parts, a flow chart of a
typical plating process sequence is shown in
Figure 3.
The microstructure of the zinc-nickel
deposit, as shown in Pigure 2c, is continuous
and level. The plate porosity has been
optimized to permit baking-out of hydrogen,
introduced during plating, and to minimize
potential re-embrittlement due to service
environment.
EXPERIMENTAL TESTING
(17).
-
LOW HYDROGEN EMBRITTLEMENT
Notched tensile specimens ( N E )
manufactured and tested in accordance with
ASTM F519 Type l a (26) w e r e used to evaluate
hydrogen embrittlement of plated highstrength steels. The plated and baked
specimens were tested by static tensile
loading t o 75 percent of established notch
ultimate tensile strength continuously for 200
hours. Thespecimens that withstand the
loading for more than 200 hours exhibit
satisfactory LHE characteristics.
More than 150 specimens, representing
more than 40 plating conditions, were
evaluated by dry notched tensile testing. Only
three conditions produced "IS failures:
o
Without proprietary additives in
the bath
o
Contamination of the bath with a
tvvical cvanide cadmium
biight en&
o
Without bakine after olatine
Initial correlation OF BoeiG platkg
porosity meter (BPPM) and N T S testing has
been established.
Hydrogen Analysis To further confirm
t h e LHE characteristics of the process, the
hydrogen contents in the above N T S were
determined by an ultrasensitive hydrogen
analyzer developed by Boeing (27). The data
shows that when the substrate hydr
content of 4340 steel (260 t o 280 ksi was
below 1.0 ppm, no N T S failures were observed.
Preliminary data indicates that the hydrogen
content of the substrate is the determining
factor for LHE characteristics, not the total
hydrogen or the hydrogen in the deposit. Even
when the Boeing zinc-nickel deposits were 4 to
6 times the nominal thickness (0.0005 inches),
hydrogen contents of the substrate were also
analyzed to be below 1.0 ppm. All NTS
failures correlate with high hydrogen contents
in the substrate.
ZINC-NICKEL ELECTROPLATING
BACKGROUND
Zinc-nickel alloy w a s commercially
deposited as early as 1905 (18). Since then,
many zinc-nickel alloys have been suggested
for electroplating onto steel to provide
corrosion protection (19,20,21). However,
most of the applications for these alloys have
been only suggested for high-speed plating
techniques, which are unsatisfactory for rack
or barrel platings.
S. la. Popov (22) proposed an ammoniacal
electrolyte to deposit a zinc-nickel alloy.
However, this process, which uses low current
densities, has led to a relatively high degree of
hydrogen embrittlement in plated highstrength steel parts.
Rynne (23) disclosed an alloy plating
containing 95% by weight or greater zinc with
the balance being nickel. Prom literature
(19.24.25) and the authofs experimental data,
the above alloys are not in the best alloy
composition range to provide corrosion
protection of steel parts.
-
BOEING'S ZINC-NICKEL ELECTROPLATING
PROCESS
\
Y
A noncyanide, zinc-nickel alloy
electroplating process has been developed at
Boeing t o ensure long-term corrosion
protection of aircraft steel parts. This zincnickel deposit provides low-hydrogenembrittlement and corrosion protection
properties equivalent or superior t o t h e
currently used Cd and Cd-Ti deposits. The use
or conversion of conventional electroplating
tank facilities is feasible. In addition, this
3
--
5
I
YaDor Degrease
I
Dilute Acid Activation j
;
I
J
I Cold Water Rinse I
Figure 3. Flow Chart of Typical Electroplating Process
for High-Strength Steel Psrrs
1
CORROSION PROTECTION -The
Boeing zinc-nickel deposit provides sacrificial
corrosion protection to steel, as does cadmium
or Cd-Ti deposit (fig. 4). However, the Boeing
zinc-nickel deposit provides longer sacrificial
corrosion protection to steel than Cd-Ti
deposit when plated to the same thickness
(0.0005 inches) (fig. 4). Uncoupled metals and
alloys are ranked in a galvanic series
according to their corrosion potentials in a
given environment, e+, seawater. Corrosion
potential is useful as an indication of general
trends in galvanic corrosion. After
approximately two months salt-spray test, the
electrode potential of Cd-Ti deposit in 3.5%
NaCl solution increases from -740 mV to -400
mV indicating that the deposit no longer
provides sacrificial corrosion protection to
steel. The electrode potential of the Boeing
zinc-nickel deposit, after approximately four
months saltspray test, increases only slightly
from -770 mV t o -650 mV. Therefore, it still
provides sacrificial corrosion protection to
st eeL
Figure 5 shows the excellent saltspray
corrosion protection of Boeing zinc-nickel
plating compared to Cd-Ti plating. Figure 6
demonstrates that most of the steel substrate
IS still protected by the Boeing zinc-nickel
deposit, while the Cd-Ti depasit has
disappeared after accelerated salt-spray test.
Accelerated saltspray tests w e r e
accomplished by (a) applying primer and
enamel over the plating, (b) scribing t h e test
panel t o expose the steel substrate, (c)
coupling with graphite using.titanium fastener,
and (d) testing in 5% salt-spray per ASTM
R117.
3
same trend of galvanic current increase w i t h
saltspray exposure is evident for both
deposits, the average galvanic current density
of long-term saltspray tested Zn-Ni deposit is
smaller than unexposed Cd-Ti deposit.
LOW HYDROGEN RE-EMBRI'lTLEMENT For high-strength steel protection, a
plating process must provide not only low
hydrogen embrittlement, but also low
hydrogen reembrittlement and good damage
tolerance. The hydrogen introduced into the
deposit and the substrate during plating must
be driven out during the bake cycle.' A porous
plate enhances the removal, but it also
enhances reembrittlement. This zinc-nickel
bath chemistry and plating parameters have
been optimized to establish a coating that will
have the least tendency to promote hydrogen
reembrittlement of the steel substrate, due
to corrosive environment or damaged plating,
and will still be within the parameters that
produce low hydrogen embrittlement and good
corrosion resistance.
ReEmbrittlement Test (Wet Notched
Tensile Test) -The ASTM PSI9 test orocedure
lor maintenance material (26) w a s modified to
determine re-embrittlement characteristics by
testing plated notched tensile specimens under
tensile stress whne exposed to water. The
zinc-nickel plating demonstrated less tendency
for re-embrittlement than did the Cd-Ti
plating, which in turn w a s less susceptible than
porous cadmium plating (fig. 7).
ReEmbrittlement and Damwe
ToleranceTest (Wet and Scratched Notched
Tensile Test) -The ASTM PSI9 test procedure
w a s further modified t o test a damaged plate
by scratching the test specimen in the notch
area prior to loading and exposing to water.
Several different Zn-Ni bath formulations (a,
b, and c) w e r e tested. Figure 8 shows that ZIP
Ni formulations a and b provide equal or
better low reembrittlement and damage
tolerance than Cd-Ti plating. The zinc-nickel
deposit plated in bath a is within the present
recommended bath formulation and operating
parameters. Bath c illustrates that hydrogen
re-embrittlement can occur when the zincnickel bath is operated outside of the Boeing
established bath parameters.
-
-
Compatibility with Aluminum
ExDerimental results show that the Dotential
difference of uncoupled dissimilar metals, is a
poor indicator of the extent (rate) of galvanic
corrosion of coupled dissimilar materials. The
values of the average galvanic current density
agree w e l l with the increase of dissolution
rates due to galvanic coupling (28). The
average galvanic current densities were
measured between coated steels (cathode) and
7075-T6 aluminum (anode) in 3.5% NaCl
solution at 2 5 W , as shown in Table 1. Data
indicates the zinc-nickel coated steel is more
compatible with 7075 aluminum than t h e CdTi coated steel. Galvanic corrosion of
aluminum alloy 7075 coupled t o zinc-nickel
coated steel is much less than when coupled to
unexposed Cd-Ti coated steel. Although the
7
Eoeing,Zn-Ni plating
- Irm
-am
SOhlUM
potential
(MVISCE)
I
I
I
2
I
0
4
6
Neutral salt spray test (months)
Figure 4. Long-Term Sacrificial Corrosion Protection of Boeing
Zn-Ni Plating Compared to Cd-Ti Plating
Cd-Ti PLATING
80EING Zn-Ni PLATING
WHITE
CORROSION
RED
RUST
4.1 MONTHS
(3000 HOURS)
2.3 MONTHS
(1848 HOURS)
1020 Steel: Plated, Baked, Chromated, and Tested in 5% Salt Spray
Figure 5. Excellent Salt Spray Corrosion Protection of Boeing Zn-Ni
Plating Compared to Cd-Ti Plating
8
Near scribe l i n e
blistered area
(paint removed
by tape t e s t )
Enamel
Primer
Cd-Ti plating
missing
4130 steel
Original mag. 400X
(a) Cd-Ti Plating - 336 Hours
Near scribe l i n e
blistered area
(paint removed
by tape test)
Enamel
Primer
Boeing
Zn-Ni
Plating
(Proprietary )
4130 Steel
Original mag. 400X
(b)Boeing Zn-Ni Plating - 672 Hours
Figure 6. Accelerated Salt-Spray Test Results of Cd-Ti and Zn-Ni
Plating Showing Improved Protection of t h e Boeing Zn-Ni Plating
3
9
Table 1. The Average Galvanic Current D e n s i t y 3 for AI 7075-T6 in 3.5% NaCl
:
~~~
Coupled To
Unatposed
Cd-Ti
Boeing Zn-Ni
3.6
0.012
1848
un*
564
-
3000
HI%*
1.0
*Exposed salt spray test hours.
i
aNo Fracture (removed from test
after indicated time)
Fracture after specification
minimum
-
mzzI Fracture
(at indfcated time)
specification
Minimum
A
BOElNG
Zn-Ni
d-Ti
POROUS Cd
Loaded to 45% of Ultimate and Notch Area Exposed to Water
Individual Results Shown
Notched Tensile Specimen Loading Results Showing L e s s Tendency to
Figure 7.
ReEmbrittlement of Boeing Zn-Ni Plating Compared to Cd-Ti and Porous Cd Platings
10
)
'1
I
577
No Fracture (removed from t e s t
a f t e r indicated time)
Zn-Ni Bath Variations
Loaded to 45% of Ultimate, Notch Area Scratched and Exposed to Water
Individual Results Shown
**Bath cis Outside of Boeing Zn-Ni Bath Parameters
Figure 8. Notched Tensile Specimen Loading Results Showing Equal Low
Hydrogen ReEmbrittlement and Damage Tolerance of Certain Zn-Ni Alloy
Plalinp Compared to Cd-Ti Plating
3
FASTENERS PLATING - Installation
torque is an important characteristic for
fasteners. Torquetension curves Cor several
fastener coatings are shown in Figure 9. The
Boeing zinc-nickel process has installation
torque equivalent to those of cadmium-plated
(QQ-P-416), diffused nickel-cadmium-plated,
or aluminum-filled epoxy-painted fasteners
when installed in interferencefit holes in
aluminum panels. IVD aluminum-plated
fasteners require higher installation torque
than the above four finishes (fig. 9) (29).
UNIFORMITY OF COATING -This zincnickel process provides good throwing power
and excellent plating coverage, both of which
are problem areas with the Cd-Ti and porous
Cd processes. Uniformity of the Boeing zincnickel deposit on a fastener is illustrated in
Fig. 10.
11
LORD VERSUS 10RDUE
Figure 10. Boeing Zn-Ni plating Thickness Distribution on a Fastener
Thread (1OOX)
CONCLUSIONS
The high performance of t h i s non-cyanide zinc-nickel plating process h a s been
successfully demonstrated in the laboratory and is a viable cadmium alternative for
both high and low strength steels. This process is scheduled for manufacturing scale
up during 1983. Specific features and benefits include:
Feature
-
o
Benefit
Norrcadmium, non-cyanide process
o
Exceeds EPA standard and
o
Minimizes waste treatment costs
o
Low hydrogen embrittlement
o
Protects highstrength steels
o
Low hydrogen re-embrittlement
o
Increases in-service protection
o
Sacrificial protection
o
Provides long-term corrosion
protect ion
o
Damage tolerance
o
Provides excellent service life
o
Compatible with aluminum
o
Provides galvanic protection to
aluminum alloys
o
Torque tension values
equivalent to cadmium
o
Can be used on fasteners
o
Conventional electroplating process
o
Minimizes facilities investment
o
Good paint adhesion
o
Further corrosion protection
o
Stablebath
o
Ease of control and
o
Fewer rejects
ACKNOWLEDGEMENTS
REFERENCES
The author thanks Mr. R.C. Colonel for
his valuable suggestions and Dr. J.H. Jones and
Mr. P.3. Saelid for their excellent technical
guidance.
1.
"Cadmium Colloquy," Plating and
Surface Finishing, Nov. 1979, pp. 8-14.
2.
R.E. Marce, ''Cadmium Plating
Still a Must," Industrial Finishing, Aprir 1978,
pp. 34-37.
P. Baeyens, "No More Cadmium
3.
Plating, Are There Processes to Replace It,"
Galvanotechnik, 68,7 (1977). pp. 590-597
(from German), U.S. Department of
Commerce. National Technical Information
Service, Nov. 1978.
4.
V.C.R. McLouEhlin. T h e
Replacement of Cadmium-for the Coating of
Fasteners in Aerospace Applications,"
Transactions of the Institute of Metal
Finishing, vol. 57, 1979, pp. 102-104.
APPENDIX
Licensing of this process will be
available after successful completion of
manufacturing feasibility. For information
concerning licensing, contact Mr. B.A.
Donahue (206-394-3101)or Mr.R.E. Suter (206394-3100). Mailing address: Patents and
Licensing, Boeing Commercial Airplane Co.,
P.O. Box 3707, MS 9H-82, Seattle, WA 98124
3
13
5.
22.
E.J. Dyckman, "Cadmium
S. Ia. Popov, Proceeding Fourth
Convention on Electrochemistry, Acad. Sci.
Utilization and Environmental Impact,"
Defense Industrial Resources Support Office,
J u n e 26, 1975.
6.
W.L. Cotton," Hydrogen Embrittlement of High Strength Steels During
Cadmium, Chromium and Electroless Nickel
Plating," Plating, vol. 47, Feb. 1960, pp. 169175.
7.
H.J. Read, "Hydrogen
Embrittlement in Metal Finishing," Reinhold
Publishing Corporation, 1961.
8.
W. Beck, E.J. Jankowsky, and P.
Fischer, "Hydrogen Stress Cracking of High
Strength Steels," center report NADC-MA7140, Naval Air Development Center,
Warminster, Pennsylvania, 1971.
A.W. Thompson, "Metallurgical
9.
Characteristics of Hydrogen Embrittlement,"
Plating and Surface Finishing, Sept. 1978, pp.
36-44.
10. "Alternatives toCadmilm Pisti!!!
Reflections Five Years Later," Plating and
Surface Finishing, Nov. 1982, pp. 1%3.
11. E.P. Cornwall. "Alternatives to
Cadmium Plating." Boeing Document. March
1979.
12. D.M. Eriwein, "Environmental
Effect on Notched Tensile Specimens," Boeing
Progress Report, 1962.
13. J.G. Rinker and R.F. Hochman,
"Hydrogen Embrittlement of 4340 Steel as a
Result of Corrmion of Porous Electroplated
Cadmium," Corrosion, voL 28, June 1972, pp.
231-232.
14. D. Altura, Tostplating
Embrittlement," Metal Finishim.
-. Smt. 1974.
pp. 45,46,50.
15. K. Takada, US. Patent No.
3.083.150.
. . 1963.
16. K. Takada, US. Patent No.
3,139,325, 1964.
17. S.S. Wane. J.K. Chai. Y.M. Shui
and J.K. Liang, "CbTi Eletmdeposits from a
Noncyanide Bath," Plating and Surface
Finishing, Dec. 1981. pp. 62-64.
18. C.B. Jacobs, "Some Observations
on the Deposition of Alloys from Mixed
Solutions," J. Am. Chem. Soc. 27, 1905, pp.
972-976.
19. D.H. Schantz, US. Patent No.
2,419,231, 1947.
20. E.J. Roehl. US. Patent No.
3,420,754, 1969.
21.
_ _ E.J. Roehl and R.H. Dillon. U.S.
Patent No. 3,558,442,1971.
US.S.R. Press, 1959.
23. G.B. Rynne, U.S. Patent No.
4,285,802, 1981.
24. L. Domnikov, Zinc-Nickel Alloy
Electroplated Coatings," Metal Finishing, Aug.
1963, pp. 49-54.
25. V.A. Averkin, "Electrodeposition of
Alloys," Israel Program for Scientific
Translation, Jerusalem, 1964, pp. 102-115.
26. ASTM P519, "Standard Method for
Mechanical Hydrogen Embrittlement Testing
of Platinp: Processes and Aircraft Maintenance
Chemic&."
27. K.B. Des. "An Ultrasensitive
Hydrogen Detector,; Hydrogen Embrittlement
Testing, ASTM STP 543, American Society for
Testing and Materials, 1974, pp. 106-123.
28. F. Mansfeid, D.H. Hengstenberg,
and J.V. Kenkel, "Galvanic Corrosion of 41
Alloys, 1. Effect of Dissimilar Metal,"
Corrosion, voL 30, no. 10, Oct. 1974, pp. 343353.
29. E.R. Pannin, "Ion Vapor Deposited
Aluminum Coatings for Improved Corrosion
Protection," MCAIR No. 78-007, presented at
AGARD Meeting, Florence, Italy, Sept. 26-28,
1978.
.
~
. 1
14
.'
1
SCOPE
a.
This specification establishes the requirements for the electro-deposition of zinc-nickel
alloy plating.
b.
Do not plate steels heat treated to strength levels above 220 ksi (1510 MPa). For steels
which are heat treated to strength levels above 220 Ksi (1510 MPa), contact Liaison
Engineering.
c.
Plating in accordance with this specification is compliant with
d.
Zinc-nickel alloy plating is considered a substitute for BAC 5701, cadmium plating and
AMs 2417.
QQ-P-416.
2
CLASSIFICATION
This process specification consists of the following Types, Classes, Grades, etc., as specified.
2.1
2.2
TYPE (POST-PLATE TREATMENT)
a.
Trpe I - As plated (no supplementary treatment)
b.
Type I1 - with supplementary treatment
..
CLASSES (THICKNESS)
a.
Class 1 - 0.0005 inch (13 pm) thick minimum
b.
Class 2 - 0.0003 inch (8 pm) thick minimum
c
Class 3 0.0002 inch (5 r m ) thick minimum
-
This process and bath are covered by U.S. Patent 4,765.871 and corresponding foreign
patents andlor applications. Articles made by this process a r e covered by U.S. Patent
4,765,871, U.S. Patent 4,818,632 and corresponding foreign patmts andlor applications.
Patent licenses are available. For further information contactr. Chief Patent Counsel,
Boeing Commercial Airplanes, P. 0. Box 3707. Mail Stop 6Y-25, Seattle, Washington,
98124. U S A .
- ..-
REFER TO NUMERICAL INDM FOR PSO A C T " INFORMATION
CVL.
,.
3
REFERENCES
The current issue of the following documents shall be considered a p a n of this specification to the
extent herein indicated.
I
ASTMB 117
ASIU B 374
' BAC 5034
BAC 5408
BAC 5617
BAC 5619
BAC 5625
BAC 5744
BAC 5746
BAC 5748
BAC 5749
BAC 5750
BAC 5751
BAC 5763
BAC 5771
BSS 7217
BSS 7235
4
Standard Method of Salt Spray (Fog)Testing
Standard Definitions of Terms Relating to Electroplating
Temporary Protection of Production Materials, Parts and Assemblies
Vapor Degreasing
Heat Treatment of Alloy Steels
Heat Treatment of Corrosion Resistant Steel
Surface Treatments for Ferrous Alloys
Manual Cleaning (Cold Alkaline, Solvent Emulsion and Foam Cleaners)
Nickel Plating (Electrodeposited)
Abrasive Cleaning, Deburring, and Finishing
Alkaline Cleaning
Solvent Cleaning
Cleaning. Descaling and Surface Preparation of Ferrous Alloys
Emulsion Cleaning (Immersion and Spray)
Stripping Inorganic Finishes
Air Cleanliness, Shop Compressed Air
Adhesion Test Method, Plating
CONTENTS
Section
-
Subject
1
SCOPE
CLASSIFICATION
TYPE (POST-PLATE TREATMENT)
CLASSES PHICKNESS)
REFERENCES
CONTENTS
MATERIALS CONTROL
FACILITIES CONTROL
GENERAL NOTES
PRECONDITIONING O F PLATING TANK
AND FILTER SYSTEM
ZINC AND NICKEL ANODE PRETREATMENT
DEFINITIONS
MANUFACTURING CONTROL
GENERAL NOTES
FLOW CHART
CLEANING PRIOR TO MASKING
2
2.1
2.2
3
4
5
6
6.1
6.2
6.3
I
a
8.1
8.2
8.3
1
1
1
1
2
2
4
6
6
I
I
8
8
9
10
11
i
4
CONTENTS (Continued)
Section
Subject
8.4
8.5
8.5.1
8.5.2
8.6
8.7
8.7.1
8.7.2
8.8
MASKING AND RACKING
8.9
9
9.1
9.2
9.3
9.4
9.5
9.5.1
9.5.2
10
11
11.1
11.2
11.3
11.4
11.5
11.6
RIGINAL ISSUE:
8-21-92
CLEANING PRIOR TO PLATING
LOW ALLOY STEELS
CORROSION RESISTANT STEELS
ZINC-NICKEL PLATING
HYDROGEN EMBRITTLEMENT RELIEF BAKE
GENERAL
FERROUS ALLOYS PARTS (INCLUDING COIL SPRINGS)
SUPPLEMENTAL TREATMENTICONVERSION COATING
(FOR TYPE 11 ONLY)
REWORK
MAINTENANCE CONTROL
ZINC-NICKEL PLATING SOLUTION
CONVERSION COATING
DILUTE ACID SOLUTION
ANODE PRETREATMENT SOLUTION
PROCESS WATERS
MAKE-UP WATER
RINSE W A E R
QUALITY CONTROL
REQUIREMENTS
STRESS RELIEF
WORKMANSHIP
THICKNESS
ADHESION
CORROSION RESISTANCE
TEST SPECIMENS
@
11.
11
11
12
13
13
13
13
14
14
15
15
17
18
18
19
19
19
19
19
19
19
20
20
20
20
REVISED:
5
MATERIALS CONTROL
Equivalent materials may be used provided that they meet all the requirements of this
specification. Approval from Boeing Materials Technology is required prior to use.
MATERIAL
a.
SOURCE
Abrasive Materials
b.
C.
d.
(1) Pumice
Open
(2) Tripoli Powder
Open
(3) Silicon Carbide Abrasive Paper
Open
(4) Scotch-Brite Pads, No. 744B. Silicon Carbide
3M Company, St. Paul,
Minn.
Ammonium chloride, (plating grade) free of
humectants. anti-caking agents or organic additives
SUPPIY
Ammonium hydroxide (aqua ammonia), 28 percent.
technical
3M Company, or other
plating
Open
Anodes
(1) Platinium plated titanium
Open
(2) Nickel anodes, 99 percent nickel rolled depolarized,
or carbon-nickel cast and rolled.
Open
(3) Platinum wire
Open
(4) Zinc anodes, high purity, ASTM B 6 (99.9 percent),
slab
Open
e.
Anode bags, Dynel or polypropylene
Open
f.
Anode hooks, titanium or monel
Open
g.
BOE-NIZ Additive LHE, Boeing proprietary
Pure Coatings, Inc.
West Palm Beach, Fl.
h.
Boric acid, crystals or powder, technical
Open
I.
Charcoal, activated, plating grade, such as
Darco S-51 or 6-60
Open
i.
Filter, 50 micron or finer polypropylene or Dynel
cloth filter
Open
k.
Filter aid, Diatomaceous Earth, filtering grade
Open
m.
Fluoboric acid, 48 percent, technical
Open
n.
Hydrochloric acid, 20 degree Be’. technical. 0-H-765
Open
I
5637
5
MATERIALS CONTROL (Continued)
P.
Maskants:
Other maskants may be used provided that production
experience has proven them to be satisfactory.
(1) AC-850
Adcoat, Inc.
(2) AC-854
Adcoat, Inc.
(3) Miccroshield Stopoff Lacquer
Michigan Chrome andl
Chemical Company
(4) ripe, yellow, pressure sensitive, platers
Sequoia Manufactunnl
Company, or other
plating supply
9.
Nickel chloride, hexahydrate, technical
Open
r.
Nickel sultate, hexahydrate, technical
Open
S.
NitTic acid, technical, 40 to 42 degree Be', 0-N-350
Open
t.
Supplemental 'Iteatment
U.
Supplemental Tkeatment - CorroBan IC-B
Pure Coatings, Inc.
West Palm Beach, Fl..
V.
Sodium hydroxide, flake, bead o r 50 percent liquid
concentrate, technical
Open
W.
Zinc dust, plating grade
Open
X.
Zinc oxide, 0.005 percent lead maximum, plating grade
Open
- CorroBan IC-A . .
Pure Coatings, Inc.
West Palm Beach, F1.
6
FACILITIES CONTROL
6.1
GENERAL NOTES
a.
All surfaces of t h e plating tank, filter and associated plumbing which are in continuous
contact with the plating solution shall be made of, or lined with, one of the following
materials:
(1) rigid polyvinyl chloride or polyvinyl dichloride
(2) unfilled polyethylene or polypropylene.
It is recommended to cover the tank, when idle, with one of the above materials.
NOTE: Mold releases on plastics are detrimental to the plating bath, and should not be
used when the tanks are fabricated.
b.
If filtration is used, the filter shall have sufficient capacity to turn the solution over one to
two tank volumes per hour. Filtration shall be through a 50micron or finer polypropylene
or Dyne1 cloth filter (Section Sj.). Diatomaceous earth (Section Sk.) may be used as a filter
media.
C.
The plating tank shall be equipped with a temperature indicating and controlling device(s),
if required, to maintain the temperature within Table.I.requirements.
d.
The plating solution should be agitated to minimize temperature and concentration
gradients. The maximum temperature gradient measured from the hottest to the coldest
points in t h e bath shall not exceed 10 F (6 C).
e.
Air used for solution agitation or for drying parts shall be free of oil, water, o r solid
particles when tested in accordance with BSS 7217.
f.
Power supplies shall have sufficient capacity to deliver the required current at the
minimum and the maximum anticipated plating tank loads without current interruption
during a strike or plating operation. The power supplies shall be capable of producing DC
current having less than ten percent ripple (100 times AC voltage divided by DC voltage)
over the desired plating range.
g.
The power supply control panel shall be equipped with an ammeter that is readable and
+ 5 percent of the current over the desired plating range.
accurate within -
ORIGINAL ISSUE:
- -
8 2 1 92
REVISED
6.2
PRECONDITIONING OF PLATING TANK AND FILTER SYSTEM
*
.
.
I
.
.
.
.
Ffi.? T;?.:
6.3
The presence of organic material in the plating tank or associated
plumbing will affect the quality of the plating.
a.
Fill tank with 1 otlgal(7.5 g/l) sodium hydroxide (Section 5v.) solution.
b.
Heat solution to 140 F (60 C) minimum and operate pump, heat exchanger, and filter
system for 6 hours minimum.
C.
Remove and discard t h e solution and rinse the tank thoroughly with water.
d.
Fill tank with approximately 3 percent by volume hydrochloric acid (Section 5n.) and
approximately 0.1 percent by volume BOE-NIZ additive LHE (Section 5g.)
e.
Operate the pump, heat exchanger, and filter system for 6 hours minimum a t ambient
temperature.
f.
Allow the above leaching solution 10 stand an additional 24 hours minimum at ambient
temperature.
g.
Remove and discard the solution and rinse the tank thoroughly with water.
h.
New or contaminated anode bags (Section 5e.) shall be treated in the above caustic and a c
solutions to leach out any organic contaminants.
ZINC AND
NICKEL ANODE PRETREATMENT
a.
Manual solvent clean in accordance with BAC 5750, vapor degrease in accordance with
BAC 5408 or emulsion clean in accordance with BAC 5763. Anodes shall be completely c
prior 10 further processing.
b.
Dry abrasive blast clean in accordance with BAC 5748, Type 11, Class
c.
Insen the anodes (Section 5d.(2) and Section S.d.(4)) in the leached anodes bags
(Section 5e. and Section 6.2h). Immerse the clean zinc and nickel anodes in the zinc-ano)
pretreatment solution (Table IV) for 2 to 3 hours to allow the formation of a dark-gray fii
on the surfaces.
Cold water immersion rinse. Handle the anodes carefully to prevent damaging the soft,
dark-gray film on the anodes. Transfer the anodes to the zinc-nickel plating bath.
d.
1.
NOTE: If the anodes become contaminated or are stored outside of the plating bath
a prolonged period of time (e& one month or longer) reconditioning in
accordance with the above procedure may be necessary.
.
-
.^^..* a
7 ,
"7
__
REVISED
.
7
DEFINITIONS
The following definitions shall apply to terms which are uncommon or have special meaning as
used in this specification.
Lot - any group of parts of approximately the same size, shape, and basis metal which have been
processed under the same conditions and submitted for inspection at the same time.
Nonfunctional Surface - a surface on which the presence of a slight plating imperfection will not
affect :he proper operation of the part.
Plating terms
- see ASTM B 374 for standard definitions.
-
Water-break-free
a surface which maintains a continuous water film for a period of at least 30
seconds after having been sprayed or immersion rinsed in dean water at a temperature below
100 F (38 C).
8
MANUFACTURING CONTROL
A
I
Some of the materials employed herein are toxic, flammable, andlor
corrosive to human tissue. Boeing personnel should refer to the
Hazard Communication Handbook (Dl-8301)located in your work area
for information contained in the tip sheets and material safety data
sheets concerning the health effects and proper control measures
associated with the use of hazardous materials. Consult the
responsible Security/Fire Protection Engineering organization
concerning appropriate facilities, equipment, and other requirements
for safe operation. For disposition of hazardous waste materials,
contact the responsible Pollution Control Monitor for appropriate
procedures.
Non-Boeing personnel should refer to manufacturer's material safely
data sheets, o r contact t h e manufacturer for safety and health
information pertaining to a hazardous material.
I
PAGE
5637OF 21
8
8.1
GENERAL NOTES
a.
For ferrous alloys, refer to Section 11.1 for stress relief requirements.
b.
Unless otherwise specified, the zinc-nickel alloy plating shall be applied after all basis,
metal heat treatments and mechanical operations (such as machining, brazing, welding,
forming and perforating) have been completed.
C.
Surfaces must be water-break-free following any immersion in any processing solution or
rinse, except following vapor degreasing, manual cleaning, emulsion cleaning o r solvent
cleaning. Reclean parts which develop a water break.
d.
Auxilliary anodes (such as platinum plated titanium Sd.(l) or platinum wire 5d.(3)) may be
used, as necessary, to meet the thickness requirements of Section 11.3.
e.
Place all contacts and electrode connections in a nonfunctional area. When in doubt,
consult the applicable design engineering department.
f.
Filtration may be used when necessary
bath.
g.
When t h e plating tank is inactive for more than 120 hours, the zinc anodes shall be
removed from the plaling bath. Removal is necessary to prevent degradation of the zinc
anodes.
tO
remove particulates from the zinc-nickel plating
i.2
FLOW CHART
I
I
Stress Relieve as Required
(Section 11.1)
Mask andRack
(Section 8.4)
I
I
Zinc-Nickel Plating
(Section 8.6)
Hydrogen Embrittlement Relief
Bake, As Required
(Section 8.7)
I
Supplemental Treatment
(Section 8.8)
I
Quality Control Inspection
(Section 10)
I
8.3
CLEANING PRIOR TO MASKING
If parts are greasy or oily, vapor degrease in accordance with BAC 5408, emulsion clean in
accordance with BAC 5763, solvent clean in accordance with BAC 5750, manual clean in
accordance with BAC 5744 or alkaline clean in accordance with BAC 5749. Descaling in .
accordance with Section 8.5.la. or 8.5.h. may be accomplished prior to or subsequent to masking
(Section 8.4).
'
8.4
MASKING AND RACKING
OPTIONAL
8.5
8.5.1
Parts may be masked and racked after Section 8.5.la.(l) provided the abrasively
cleaned surfaces are not contaminated (rusting, soiling or discoloration). If the
surfaces become contaminated, the parts shall be reprocessed in accordance with
Section 8.5.la.
a.
Mask area not to be plated using maskants listed in Section 5p.
NOTE: To reduce the effect of shadowing and/or robbing of current, it is recommendecc
to mask any area of a metal rack, with the exception of the contact points, whicc
may be immersed in the plating solution.
b.
Rack parts to prevent entrapment of gases generated during plating, and to facilitate
draining. Make firm electrical connections to the part@) to prevent arcing. Provide
sufficient contact to carry the required current.
CLEANING PRIOR TO PLATING
a.
Wet processed activated surfaces shall not be allowed to dry prior to immersion in the
zinc-nickel alloy plating bath.
b.
Parts which have been masked after descaling may be cleaned, if necessary, in accordance:
with BAC 5744 or BAC 5749 to remove any grease or oil from handling.
LOW ALLOY STEELS
a.
Descale by one of the followin'g methods:
(1) Method 1
(a) Abrasive clean in accordance with BAC 5748, l j p e 11, Class 1 using glass bead or'
aluminum oxide abrasive. Use of larger particles (e.&, 80 grit aluminum oxide) ttr
produce B rougher finish will improve plating adhesion.
@) Alkaline clean and rinse in accordance with BAC 5749. If parts require masking
return to Section 8.4, otherwise, transfer to activating step (Section 8.5.lb.) withii
minute.
(2) Method 2
Descale in accordance with BAC 5625, Method 1, or BAC 5751, Method 1. WatR
rinse thoroughly. If parts require masking, return to Section 8.4, otherwise,
transfer to activating step (Section 8.5.lb.) within 1 minute.
(3) Method 3
Descale in accordance with BAC 5749, Method 3. Water rinse thoroughly. 1 f . P
require masking, return to Section 8.4, otherwise, transfer IO activating Step
(Section 8.5.1b.) within 1 minute.
8.5.1
LOW ALLOY STEELS (Continued)
b.
Activate the surface by one of the following methods:
(1) Method I
(a) Immerse in dilute acid solution (hydrochloric acid or fluoboric acid in accordance
with Section 9.3) for 5 to 30 seconds.
(b) Cold water rinse for 10 to 60 seconds.
(2) Method 2
(a) Anodic clean in Isoprep 58 in accordance with BAC 5749.
@) Warm water rinse for 1to 3 minutes.
(3) Method3
(a) Periodic reverse clean in accordance with BAC 5749, Method 3. End with a I5 10
25 second anodic cycle.
@) Remove smut, if present, by scouring using abrasive material specified in
Section Sa. Rinse thoroughly with water.
(c) Continue periodic reverse cleaning until a water-break-free surface is obtained
(typically 2 to 10 minutes).
(d) Cold water rinse for 2 to 3 minutes.
C.
8.5.2
Proceed to Section 8.6. Do not allow parts 10 dry.
CORROSION RESISTANT STEELS
a.
Descale by one of the following methods:
(1) Method 1
(a) Abrasive clean in accordance with BAC 5748, q p e 11. Class 1 using glass bead or
aluminum oxide abrasive. Use of larger particles (e.& 80 grit aluminum oxide) to
produce a rougher finish will improve plating adhesion.
(b) Alkaline clean and rinse in accordance with BAC 5749. If parts require masking,
return to Section 8.4, otherwise transfer to activating step (Section 8.5.2b.) within 1
minute.
(2) Method2
Descale in accordance with BAC 5625. Method 111, or BAC 5751, "pe 11, Class 3.
Water rinse thoroughly. If parts require masking, return to Section 8.4, otherwise,
transfer to activating step (Section 8.5.2b.) within 1minute.
b.
Activate surface with a Nickel Strike in accordance with BAC 5746.
I
nalelw,,I
ISSUE:
8-21-92
.
.
,
.
5637
.-
8.6
ZINC-NICKEL PLATING
Immerse in zinc-nickel plating solution (Section 9.1) and then apply current at 10 to 40
a.
ASF (1.1 to 4.3 A/dmz)
OPTIONAL Strike parts at a current density of 60 to 90 ASF (6.5 to 9.7 Aldm2) for 15
seconds before regular plating. For CRES steels, nickel strike in
accordance with Section 8.5.2b.(1).
Plate to the required thickness. T h e plating time to apply 0.0005 inch (13 pm) (average) is;
estimated to be 40 minutes at a current density of 20 ASF (2.2 A/dmZ). (Every 160
ASF-min (17.2 A/dmz - min) will deposit approximately 0.001 inch (25 pm)).
b.
If required, plating may be interrupted for re-racking of parts to obtain 100 percent
coverage. Parts may be removed from the solution for re-racking, but do not allow the
parts to dry.
c.
Plate control specimens, when required, with the pans for subsequent adhesion and
corrosion tests as required by Sections 11.4 and 11.5, respectively.
d.
Cold water rinse for 1 to 10 minutes.
e.
Dry within 5 minutes. A rinse for 1 minute in hot water will facilitate drying.
8.5
HYDROGEN EMBRITTLEMENT RELIEF BAKE
8.7.1
GENERAL
8.7.2
a.
Unless otherwise specified, all steel parts requiring baking (See Section 8.7.2) shall be
baked within 8 hours after plating to provide hydrogen embrittlement relief. Records shah
be kept to provide evidence that each lot of processing has been properly baked.
b.
Do not flex springs prior to baking.
FERROUS ALLOYS PARTS (INCLUDING COIL SPRINGS)
Bake ferrous parts within 8 hours following plating according to the drawing. If not
a.
specified on the drawing, bake in accordance with the following schedule:
(1) Carburized parts and 440 series CRES: 5 to 8 hours a t 275 + 25 F (135 + 14 C).
-
(2) Externally threaded parts heat treated from 160 to 220 ksi (1100 to 1500 MPa), all coii
springs regardless of heat treat and all other parts heat treated from 1SO to 220 ksi
(1200 to 1500 MPa): 3 hours minimum a t 375
25 F (191 + 14 C).
+
-
(3) PH steels not specified in Section 8.7.2b. shall be baked for 12 hours minimum at 37.':
+ 25 F (191 14 C).
-
b.
+
-
The following ferrous alloys do not require baking:
(1) 17-4 PH. 15-5 PH, 17-7 PH; all below 180 ksi (1200 MPa), if not externally threaded
(2) 17-7 PH (CH 900 condition)
(3) A-286
(4) 300 series CRES
( 5 ) All other ferrous alloys with tensile strengths less than 160 ksi (1200 MPa), except a s
specified in Section 8.7.2a.(2).
I
ORIGINAL ISSUE
8-21-92
PLGE
13
REVISED:
-
8.8
SUPPLEMENTAL TREATMENT/CONVERSION COATING (FOR TYPE 11 ONLY)
If there is a delay prior to application of the conversion coating, dry the parts and protect
a.
the plated surface from contamination in accordance with BAC 5034,Type 11, Class 3,
Grade A. (Insure parts are kept dry while in contact with Kraft paper. Wet Kraft paper
can deposit sulfites on the part surface.)
s.9
b.
If parts have been allowed to dry because of a delay, alkaline clean prior to applying the
conversion coating in accordance with BAC 5749 using a medium duty alkaline cleaner (e.&
15 minute soak in Isoprep 58), and water rinse. Do not allow the surfaces to dry.
c.
Immerse pan(s) in conversion coating solution (Section 9.2) for 40 to 60 seconds.
d.
Immersion rinse in water (130 F maximum (54 C)) for 0.5 to 2 minutes.
e.
Within 5 minutes, air dry thoroughly at a maximum of 130 F (54 C). Blowing with
compressed air may be used to facilitate drying.
f.
Other conversion coating solutions may be used as a supplemental treatment of they meet
the requirements listed in Section 11of this specification. However, any solution not
specifically mentioned in this specification must have t h e prior approval of Boeing
Engineering and Quality Assurance.
REWORK
The following rework shall be documented a s required by the applicable quality assurance
provisions.
a.
Parts not meeting the requirements of this specification shall be stripped in accordance
with BAC 5771, Solution 46 or Solution 11.
....
.....
y!*v
BAC 5771, Solution 11 contains cyanide.
b.
+ 25 F (191
Parts heat treated above 160 Ksi (1100 MPa) shall be baked at 375 3 hours minimum after stripping is performed.
c.
Reprocess parts in accordance with this specification.
-+ 14 C) for
I
5637
9
MAINTENANCE CONTROL
9.1
ZINC-NICKEL PLATING SOLUTION
a.
The tank and filter system shall be preconditioned prior to the initial make-up of the
zinc-nickel plating bath (Section 6.2)
NOTE: Subsequent bath make-up do not require the tank and filter system to be
preconditioned.
b.
Clean tank thoroughly and fill approximately half full with warm water.
C.
For each 100 gallons (379 L) of final solution, add the appropriate chemical amounts in the
following order:
(1) 142 pounds (65 kg) of ammonium chloride (Section 5b.). Mix until completely
dissolved.
(2) 61 pounds (28 kg) of nickel chloride (Section 5q.). Mix until completely dissolved.
(3) In a separate tank or container, add 2.5 gallons (9.5 L) of hydrochloric acid
(Section 5n.) to 0.5 gallons (1.9 L) Of water. Add and dissolve 9.3 Ib (4.2 kg) of zinc
oxide (Section 5x.). Add this solution to the main bath.
(4) 17 pounds (7.7 kg) of boric acid (Section 5h.). Mix until completely dissolved.
13
d.
Fill the tank close to operating level with water.
e.
Check the pH of t h e bath. Adjust the pH, if required, to 6.2 to 6.3. Ammonium hydroxide?
(Section Sc.) is used to raise the pH, and hydrochloric acid is used to lower the pH.
f.
When the bath temperature has cooled 10 65 to 85 F (18 to 29 C)
add 3.0 gallons (11.5 L) of BOE-NIZ additive LHE (Section 5g.) per 100 gallons (379 L) off
total solution. Stir the bath thoroughly.
g.
h.
Add additional water if necessary. Recheck the pH and adjust to 6.2 to 6.3 if necessary.
1.
Maintain the plating solution within the ranges specified in Table I and adjust, when
necessary, as prescribed by the Quality Control lab.
Before placing a freshly prepared solution into production, dummy plate at 3 10 5 ASF (0.::
to 0.6 A/dm’) for a period of 8 10 12 hours. Analyze and adjust in accordance with Sectiorr
9.li.
N O T E Organic contamination occurs due to ineffective removal of oils and greases
during the cleaning operation. Treatment with activated carbon (Section 5i.) ii
usually effective in removing organic contaminants. The carbon treatment will
also deplete the BOE-NIZ additive. Thus, it must be replenished before
resuming plating.
3
5633
PAGE
ORIGINAL ISSUE:
8-21-92
--
REVISED
15
ZINC-NICKEL PLATING SOLUTION (Continued)
9.1
CONTROL
OPTIMUM
Zinc Metal
0.7 to 2.0 ozlgal
(5.2 to 15 gn)
1.2 ozlgal
(9.0 gl1)
qickel Metal
1.4 to 4.0 oz/gaI
(10.5 to 30.0 g/l)
2.5 to 6.0 oz/gaI
(19 to 45 g/l)
2.4 ozlgal
(18.0 gll)
3.6 ozlgal
(27
1.0 to 3.5
2.0
Chloride
16 to 20 ozlgal
(120 to 150 gll)
18.5 ozlgal
(139 g/l)
Boric Acid
1.6 to 3.7 oz/gal
(12to 28 g/l)
BOE-NIZ Additive LHE
1.9 to 11.5 oz/gal
(14 to 90 mlll)
MATERIAUCONDITION
~~
rota1 Metal Content
:Zn** + Nic2)
Nickel/Zinc Ratio
i
PH
Temperature
Cathode Current D'ensity
Nickel to Zinc Anode Area
Ratio I/ '2.
--
Anode to Cathode Area Ratio
5.9 to 6.5
6.30
65 to 95 F
(18 to 35 C)
(24 C)
10 to 40 ASF
(1.1 to 4.3 Aldm2)
75 F
20 to 30 ASF
, (2.2 t o 3.2
Aldm2)
1 to 3
2:1
-I/
Remove zinc anodes when the tank is not in use for more than 120 hours.
-2/
Use anode bags with all anodes. Leach new or contaminated bags in accordance with Section 6.2.
ORIGINAL ISSUE
- -- ---,*,ns
8-21-92
REVISED:
CONVERSION COATING
9.2
Clean tank thoroughly. Fill tank approximately one-half full of water.
a.
NOTE: lhnk material should be PVC or polypropylene. T h e tank should be equipped
such that heating and air agitation of the solution is possible (to minimize
temperature and concentration gradients).
b.
Make-up the solution in accordance with "mble 11.
c
Fill the tank to the operating level and check and adjust, if necessary, pH and CorroBan
IC-A (Section St.) concentration in accordance with the control values listed in
Table 11.
TABLE I1
CONVERSION COATING CONTROL
MAKE4
MATERIAL/
CONDITION
100 GALLONS
COLTOB~II
IC-A
75 Ibs
CorroBan IC-B
1percent by volume
PER
100 LITERS
CONTROL
10 to 13 oz/gal
(75 to 98 g/l)
1percent by volume
+ 0.2
100 + 5F
1.9
(38 r 2 C)
BAa
__
ORIGINAL
ISSUE:
.. -. -I
-
8 -21-92_
PACE
5637
17
REVISED:
1.3
DILUTE ACID SOLUTION
Make-up and control t h e bath as indicated in n b l e 1%
TABLE I11
DILUTE ACID MAKE-UP AND CONTROL
MATERIAUCONDITION
SOLUTION A
Balance
Water
Hydrochloric Acid, HCl
(Section 5n.)
Fluoboric Acid, HBF4
(Section 5m.)
Temperature
9.4
MAKE-UP PER 100 GALLONS
PER 100 LITERS)
1
SOLUTION B
Balance
SOLUTION A
---
0.8 to
1.6 ozlgal
(6.1 to 12.3 g/l)
3.0 gal
(3.0 I)
---
---
---
---
---
1.2 to 2.0 ozlgal
(9.3 to 15 gll)
.Ambient
Ambient
2.5 gal
(2.5 I)
---
SOLUTION B
:
ANODE PRETREATMENT SOLUTION
)
MAKE-UP PER
MATERIAL1
CONDITION
Ammonium Chloride
(Section 5b.)
Nickel Sulfate
(Section 5r.)
Water
Temperature
100 GALLONS
100 LITERS
CONTROL
208 lbs
25 kg
30.7 to 36 ozlgal
(230 to 270 g l l )
46 lbs
5.5 k.g
6.7 to 8.0 ozlgal
(50 to 60 gll)
Balance
Balance
---
---
---
Ambient
REVISED:
.
PROCESS WATERS
MAKE-UP
WATER
Water used for solution make-up shall not contain more than 100 ppm total solids.
9.5.2
RINSE WATER
Control the total solids in the rinse water to 500 ppm maximum.
10
QUALITY CONTROL
a.
Monitoring of the process and examination of end-items shall be in accordance with the
applicable Quality Assurance provisions which assure the requirements of this specification
are met.
b.
Testing shall be done with sufficient frequency to ensure compliance with the requirements
of this specification.
c
Analyze the solutions at intervals that have been determined through experience.
Prescribe and record any changes that are necessary for compliance with this specifcation.
__
11
REQUIREMENTS
11.1
STRESS RELIEF
a.
The plater must receive written verification from the parts fabricator that all stress
relieving has been accomplished in accordance with Section 1l.lb. and 11.1~.
b.
Ferrous alloy pans, heat treated to 180 Ksi (1240 m a ) (160 Ksi (1100 MPa) for externally
threaded parts) or higher, shall be stress relieved prior to plating if they have been
subjected to any of the following operations after heat treatment: Grinding, machining,
straightening, cold working, or proof loading. Parts which only have been honed, lapped, 011
shot peened do not require stress relief. When stress relief is required for parts it shall be
performed in accordance with BAC 5617 and BAC 5619.
c.
11.2
If more than one plating operation (including different plating or re-plating) is performed
on the pans, stress relief shall be accomplished only once.
WORKMANSHIP
a.
The zinc-nickel deposit shall be smooth, fine-grained, adherent and visibly free from
blisters, pits which expose the substrate, nodules. porosity, excessive edge buildup,
indications of burning and other defects when visually inspected without magnification.
Uniformity of color is not required.
b.
The Type !I supplemental treatmentlchromate conversion coating shall be continuous,
smooth, adherent, and free from powder. Loose coating which can be wiped off with a
clean cloth. exposing bare plating. is unacceptable.
I---
.n
11.3
THICKNESS
a.
b.
c.
11.4
.
11.5
Unless otherwise specified. the zinc-nidel alloy plating thickness shall be C ~ S1Sfor all
hardware, except fastener hardware shall be Class 2.
I
Pan surfaces designated on the drawing shall be completely covered with visible zinc-nickel
. I.
alloy plating, within the capability of the throwing power of the plating Solution. Unless
'
otherwise specified. measurements of plating thickness apply only to those surfaces which
can be touched by a ball 0.75 inch (1.9 cm)in diameter.
Unless otherwise specified, the mawimum thickness shall not exceed 0.0010 inch (25 pm).
ADHESION
T h e deposit shall be firmly adherent when tested in accordance with BSS 7235 after baking and
supplemental treatment, if required, is completed
-.
CORROSION RESISTANCE
Zinc-nickel alloy plating with the 'ljpe 11supplemental treatment shall show neither white
corrosion products of zinc nor base metal corrosion products at the end of 96 hours when tested in
accordance with ASIU B 117. The appearance of c o d o n produas, visible to the unaided eye
at normal reading distance, shall be a cause for rejection, exccpt that white corrosion products
within 0.25 inch (0.64 cm)from the edges of the specimens shall not constitute failure.
.,
11.6
TEST SPECIMENS
Test specimens may be used in lieu of parts provided they are processed in the same manner as the
parts they represent. For corrosion tests, low-carbon steel test specimens may be used to
represent low-alloy steel parts. For other than low-alloy steel parts, corrosion test specimens may
be of a generically similar material.