2.73. )
?DF
83Q686
A New Zinc-Nickel
Electroplating Process:
Alternative to Cadmium Plating
Grace
F. Hsu
Boeing Materials Technology
Boeing Commercial Airplane
Co.
Seattle, WA
equivalent process that can provide the unique
characteristics of LHE and retain the use of
conventional electroplating tank facilities.
ABSTRACT
N e w environmental regulations all over
the world encourage the use of alternatives to
cadmium plating for corrosion-protection
systems used on steels. Boeing patents are
pending on a non-cyanide replacement z i n c
nickel 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 tank facilities can be used and w a s t e
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
scale-up 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 highstrength steel
landing gear parts used on jet aircraft are
cadmium plated using LHE processes. Figure
1 shows the evolution of LHE plating processes
for hightrength steels. The first LHE
process introduced in 1960, w a s accomplished
by plating in m 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 2a. This
feature, plus the very porous plate, accounts
for the poor corrosion protection of the
substrate and the susceptibility to hydrogen
re-embrit tlement or "post-lating
embrittlement" (12,13,14).
ALTHOUGH THE CADMIUM AND CYANIDE
HAZARDS to human health are well known
and documented W*, 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 a l l over the world
encourage the use of alternatives t o 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)
*Numbers in parentheses designate references
at end of paper.
(6,7,8,9).
Mechanical plating, ion vapor deposition
(IVD) of aluminum, aqueous coating dispersion,
and bonded solid-film lubricants are mentioned
(10,111 as possible alternative candidates t o
cadmium plating. However, there is n o
7
Porous Cyanide Cadmium Plating
-
1960
Cyanide Cadmium-Titanium Plating
-
1962
1 Non-Cyanide Zinc-Nickel Alloy Plating* -
1983
1
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 Embrit tlement Electroplating Deposit Cross-Sections (4UOX)
In 1962, a cyanide cadmium-titanium
(Cd-Ti) plating bath w a s adopted by Boeing for
coating high-strength structural steel (15,161.
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
(17).
ZINC-NIC KEL 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. Ia. Popov (22) proposed an ammoniacal
electrolyte t o deposit a zinc-nickel alloy.
However, this process, which uses low current
densities, has led t o 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. From literature
(19,24,25) and the author‘s experimental data,
the above alloys are not in the best alloy
composition range to provide corrosion
protection of steel parts.
BOEING’S ZINC-NIC KEL ELECTROPLATING
PROCESS
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-hydrogenembrit tlement and corrosion protection
properties equivalent or superior to the
currently used Cd and Cd-Ti deposits. The use
or conversion of conventional electroplating
tank facilities is feasible. In addition, this
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 Figure 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
LOW HYDROGEN EMBRITTLEMENT Notched tensile specimens (NTS)
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. The specimens 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 NTS failures:
o
Without proprietary additives in
the bath
o
Contamination of the bath with a
typical cyanide cadmium
brightener
o
Without baking after plating
Initial correlation of Boeing plating
porosity meter (BPPM) and N T S testing has
been established.
Hydrogen Analysis - To further confirm
the LHE characteristics of the process, the
hydrogen contents in the above-NTS w e r e
determined by an ultrasensitive hydrogen
analyzer developed by Boeing (27). The data
shows that when the substrate hydr
content of 4340 steel (260 to 280 ksr:a
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. A l l N T S
failures correlate with high hydrogen contents
in the substrate.
Dry Abrasive Blast
1
Cold Water R i n s e
1
Dilute Acid Activation
1
Cold Water Rinse
I Dry
1
I
H ydtogen Embrit t lement Relief Bake
I
L
I Chromate Treatment 1
F
Cold Water R i n s e
Figure 3. Flow Chart of Typical Electroplating Process
for High-Strength Steel Psrts
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 t o -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 salt-spray test, increases only slightly
from -770 mV to -650 mV. Therefore, it still
provides sacrificial corrosion protection t o
steel,
Figure 5 shows the excellent salt-spray
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 deposit has
disappeared after accelerated salt-spray test.
Accelerated salt-spray tests were
accomplished by (a) applying primer and
enamel over the plating, (b) scribing the test
panel t o expose the steel substrate, (c)
coupling with graphite using titanium fastener,
and (d) testing in 5% salt-spray per ASTM
9117.
Compatibility with Aluminum
Experimental results show that the potential
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 well 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 zincnickel coated steel is more
compatible with 7075 aluminum than the CdTi coated steel. Galvanic corrosion of
aluminum alloy 7075 coupled to zinc-nickel
coated steel is much less than when coupled to
unexposed Cd-Ti coated st eel. Although t h e
-
same trend of galvanic current increase w i t h
salt-spray exposure is evident for both
deposits, the average galvanic current density
of long-term salt-spray tested Zn-Ni deposit is
smaller than unexposed Cd-Ti deposit.
LOW HYDROGEN RE-E M B RITTLEMENT For highstrength steel protection, a
plating process must provide not only low
hydrogen embrittlement, but also low
hydrogen re-embrittlement 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 re-embrittlement. This zinc-nickel
bath chemistry and plating parameters have
been optimized to establish a coating that will
have'the least tendency to promote hydrogen
re-embrittlement of the steel substrate, due
to corrosive environment or damaged plating,
and w i l l still be within the parameters that
produce low hydrogen embrittlement and good
corrosion resistance.
Re-Embrittlement Test (Wet Notched
Tensile Test) The ASTM F519 test procedure
tor maintenance material (26) w a s modified t o
determine reembrit tlement characteristics by
testing plated notched tensile specimens under
tensile stress while exposed to water. The
zincnickel 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).
Re-Embrittlement and Damage
Tolerance Test (Wet and Scratched Notched
Tensile Test) The ASTM F519 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) were tested. Figure 8 shows that ZnN i formulations a and b provide equal or
better low re-embrittlement 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 z i n c
nickel bath is operated outside of the Boeing
established bath parameters.
-
-
-
~
Boeing,Zn-Ni plating
-loo0
SoI uti on
potential
-800
(MVISCEI
plating
\Cd-Ti
-dm
t
\
1
3.5% Na U solution at 25 C
I
i
Figure 4. Long-Term Sacrificial Corrosion Protection of Boeing
ZwNi Plating Compared to Cd-Ti Plating
Cd-Ti PLATING
BOEING Zn-Ni PLATING
WHITE
CORROSION
RED
RUST
..
.
.-
. -.. ..
2.3 MONTHS
(1848 HOURS)
4.1 MONTHS
(3000 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
Near scribe l i n e
b l i s tered area
(pa in t removed
by tape t e s t )
En amel
Pr imer
Cd-Ti plating
missing
4130 s tee1
Original mag. 400X
(a) Cd-Ti Plating - 336 Hours
Near s c r i b e l i n e
b l i s t e r e d area
(paint removed
Enamel
Primer
4130 Steel
O r i g i n a l mag. 400X
(b) Boeing Zn-Ni Plating - 672 Hours
Figure 6. A c c e l e r a t e d Salt-Spray Test R e s u l t s of Cd-Ti a n d Zn-Ni
P l a t i n g Showing Improved P r o t e c t i o n of t h e Boeing Zn-Ni P l a t i n g
n
Table 1. The Average Galvanic Current Density?
for A1 7075-T6 in 3.5% NaCl
ig ( A/cmZ)
Coupled To
Unexposed
C &Ti
3.6
Boeing Zn-Ni
0.012
1848 H&
564
3000 Hrs*
1.0
*Exposed salt spray test hours.
.,
No Fracture (removed from test
4-1
after indicated time)
mo-
8-
P
I
-
Fracture after specification
minimum
-
Exposure
Fracture
(at indicated time)
too-
Time
150
(Hr.)
loo
-
BOEING
Zn-Ni
Cd-TI
POROUS Cd
Loaded t o 45% of Ultimate and Notch Area Exposed to Water
Individual Results Shown
Figure 7.
Notched Tensile Specimen Loading Results Showing Less Tendency t o
Re-Embrittlement of Boeing Zn-Ni Plating Compared t o Cd-Ti and Porous Cd Platings
,
No F r a c t u r e (removed from t e s t
a f t e r i n d i c a t e d time)
J777
1-1
Fracture after specification
minimum
Fracture
( a t i n d i c a t e d time)
m
P
I
Bath a
Cd-TI
c
Instead o f notch,
shank area scratched
(1/4 inch from notch)
both scratched and
notch area exposed
t o water
Bath b
T
Bath c * *
I
Zn-NI Bath VarIatIons
Loaded t o 45% of Ultimate, Notch Area Scratched and Exposed t o Water
Individual Results Shown
**Bath c is Outside of Boeing Zn-Ni Bath Parameters
Figure 8. Notched Tensile Specimen Loading Results Showing Equal Low
Hydrogen Re-Embrittlement and Damage Tolerance of Certain Zn-Ni Alloy
Platings Compared t o Cd-Ti Plating
FASTENERS PLATING - Installation
torque is an important characteristic for
fasteners. Torquetension curves for several
fastener coatings are shown in Figure 9. The
Boeing zincnickel process has installation
torque equivalent to those of cadmium-plated
(QQ-P-4161, diffused nickel-cadmium-plated,
or aluminum-filled epoxy-painted fasteners
when installed in interference-fit 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
me problem areas with the Cd-Ti and porous
Cd processes. Uniformity of the Boeing zincnickel deposit on a fastener is illustrated in
Fig. 10.
LOCI0 VERSUS TORQUE
I
0
Figure 9. Comparison of TorqueTension Curves Between Various Finishes:
IVD Aluminum (IVD-Al), Diffused Ni-Cd (Ni-Cd), Boeing Z i n c N i c k e l (Zn-Ni),
Aluminum-Filled Epoxy (Al-Epoxy) and Cadmium (Cd)
Figure 10. Boeing Zn-Ni Plating Thickness Distribution on a Fastener
Thread (1OOX)
.
CONCLUSIONS
The high performance of this 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 scaleup during 1983. Specific features and benefits include
Feature
0
Non-cadmium, non-cyanide process
Benefit
0
Exceeds EPA standard and
0
Minimizes waste treatment costs
0
Low hydrogen embri t tlement
0
Protects high-strengt h st eels
0
Low hydrogen reembrittlement
0
Increases in-service protection
0
Sacrificial protection
0
Provides long-term corrosion
protect ion
0
Damage tolerance
0
Provides excellent service lit e
0
Compatible with aluminum
0
Provides galvanic protection to
aluminum alloys
0
Torque tension values
equivalent to cadmium
0
Can be used on fasteners
0
Conventional electroplating process
0
Minimizes facilities investment
0
Good paint adhesion
0
Further corrosion protection
0
Stable bath
0
Ease of control and
0
Fewer rejects
ACKNOWLEDGEMENTS
REFERENCES
The author thanks Mr. R.C. Colonel for
his valuable suggestions and Dr. J.H. Jones and
Mr. P.O. 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, April 1978,
pp. 34-37.
P, Baeyens, "No More Cadmium
3.
Plating, Are There Processes to Replace It,"
7 (1977), pp. 590-597
Galvanotechnik,
(from German), U.S. Department of
Commerce, National Technical Information
Service, Nov. 1978.
4.
V.C.R. McLoughlin, "The
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). MaiIing address: Patents and
Licensing, Boeing Commercial Airplane Co.,
P.O. BOX 3707, MS 9H-82, Seattle, WA 98124
s,
5.
E.J. Dyckman, "Cadmium
Utilization and Environmental Impact,"
Defense Industrial Resources Support Office,
June 26, 1975.
6.
W.L. Cotton," Hydrogen Embrittle
ment of High Strength Steels During
Cadmium, Chromium and Electroless Nickel
Plating," Plating, vol. 47, Feb. 1960, pp. 169175.
7.
H.J. Read, "Hydrogen
Embri t tlement 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, 1'971.
9.
A.W. Thompson, "Metallurgical
Characteristics of Hydrogen Embrittlement,"
Plating and Surface Finishing, Sept. 1978, pp.
36-44.
10. "Alternatives to Cadmkr?, P l S t k c
Reflections Five Y e a r s Later," Plating and
Surface Finishing, Nov. 1982, pp. 21-13,
11. E.P. Cornwall, "Alternatives to
Cadmium Plating," Boeing Document. March
1979.
12. D.M. Erlwein, "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 Corrosion of Porous Electroplated
Cadmium," Corrosion, vol. 28, June 1972, pp.
231-232.
14. D. Altura, "Postplating
Embrittlement," Metal Finishing, Sept. 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. SS. Wang, J.K. Chai, Y.M. Shui
and J.K. Liang, "Cd-Ti Eletrodeposits 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, U S . Patent No.
3,420,754, 1969.
21. E.J. R o d and R.H. Dillon, U.S.
Patent No. 3,558,442, 1971.
22.
S. Ia. Popov, Proceeding Fourth
Convention on Electrochemistry, Acad. Sci.
US3.R. Press, 1959.
23. G.B. Rynne, U.S. Patent No.
4,2a5,802,i981.
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 F519, "Standard Method for
Mechanical Hydrogen Embrittlement Testing
of Plating Processes and Aircraft Maintenance
Chemicals,"
27. K.B. Das, "An Ultrasensitive
Hydrogen Detector," Hydrogen Embrittlement
Testing, ASTM STP 543, American Society for
Testing and Materials, 1974, pp. 106-123.
28. F. Mansfeld, D.H. Hengstenberg,
and J.V. Kenkel, "Galvanic Corrosion of 41
Alloys, I. Effect of Dissimilar Metal,"
Corrosion, vol. 30, no. 10, Oct. 1974, pp. 343353.
29. E,R. Fannin, "Ion Vapor Deposited
Aluminum Coatings for Improved Corrosion
Protection," MCAIR No. 78407, presented at
AGARD Meeting, Florence, Italy, Sept. 26-28,
1978.
1
2
SCOPE
a.
This specification establishes t h e 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 AMs 2417.
d.
Zinc-nickel alloy plating is considered a substitute for BAC 5701, cadmium plating and
QQ-P-4 16.
CLASSIFICATION
This process specification consists of the following Types, Classes, Grades, etc., as specified.
2.1
2.2
TYPE (POST-PLATE TREATMENT)
-
a.
Type I As plated (no supplementary treatment)
b.
Type 11 - 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 pm) thick minimum
This process and bath are covered by U.S. Patent 4,765,871 and corresponding foreign
patents and/or applications. Articles made by this process are covered by U.S. Patent
4,765,871, U.S.Patent 4,818,632 and corresponding foreign patents and/or applications.
Patent licenses are available. For further information contact: Chief Patent Counsel,
Boeing Commercial Airplanes, P. 0. Box 3707, Mail Stop 6Y-25,Seattle, Washington,
98124. U.S.A.
REFER TO NUMERICAL INDEX FOR PSD ACTIVIW INFORMATION
-
3
REFERENCES
The current issue of the following documents shall be considered a part of this specification to the
extent herein indicated.
ASTMB 117
ASTM 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
Page
Section
Subject
1
SCOPE
CLASSIFICATION
TYPE (POST-PLATE TREATMENT)
CLASSES (THICKNESS)
REFERENCES
CONTENTS
MATERIALS CONTROL
1
6
6
8
FACILITIES CONTROL
GENERAL NOTES
PRECONDITIONING O F PLATING TANK
AND FILTER SYSTEM
ZINC AND NICKEL ANODE PRETREATMENT
DEFINITIONS
MANUFACTURING CONTROL
8.1
8.2
GENERAL NOTES
FLOW CHART
8.3
CLEANING PRIOR TO MASKING
2
2.1
2.2
3
4
5
6
6.1
6.2
6.3
7
1
1
1
2
2
4
7
7
8
8
9
10
11
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
CLEANING PRIOR T O PLATING
LOW ALLOY STEELS
CORROSION RESISTANT STEELS
ZINC-NICKEL PLATING
HYDROGEN EMBRITTLEMENT RELIEF BAKE
GENERAL
FERROUS ALLOYS PARTS (INCLUDING COIL SPRINGS)
SUPPLEMENTAL TREATMENT/CONVERSION COATING
(FOR TYPE I1 ONLY)
REWORK
MAINTENANCE CONTROL
ZINC-NICKEL PLATING SOLUTION
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
CONVERSION COATING
DILUTE ACID SOLUTION
ANODE PRETREATMENT SOLUTION
PROCESS WATERS
MAKE-UP WATER
RINSE WATER
QUALITY CONTROL
REQUIREMENTS
STRESS R E L I E F
WORKMANSHIP
THICKNESS
ADHESION
CORROSION RESISTANCE
TEST SPECIMENS
Page
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
BA
563
PAGE
3
5
MATERIALS CONTROL
Equivalent materials may be used provided that they meet all t h e requirements of this
specification. Approval from Boeing Materials Technology is required prior to use.
SOURCE
MATERIAL
Abrasive Materials
a.
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
SUPPlY
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),
Open
slab
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 Paim Beach, F1.
h.
Boric acid, crystals or powder, technical
Open
1.
Charcoal, activated, plating grade, such as
Darco S-51 or 6-60
Open
j.
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
BAC
5637
PAGE4
RFVISED:
OF2
-
~
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 and
Chemical Company
(4) B p e , yellow, pressure sensitive, platers
Sequoia Manufacturin
Company, or other
plating supply
q.
r.
Nickel chloride, hexahydrate, technical
Open
Nickel sulfate, hexahydrate, technical
Open
S.
Nitric acid, technical, 40 to 42 degree Be’, 0-N-350
Open
t.
Supplemental Treatment
- CorroBan IC-A . .
U.
Supplemental Treatment
- ComBan IC-B
v.
Sodium hydroxide, flake, bead or 50 percent liquid
concentrate, technical
Open
W.
Zinc dust, plating grade
Open
X.
Zinc oxide, 0.005 percent lead maximum, plating grade
Open
Pure Coatings, Inc.
West Palm Beach, Fl.
Pure Coatings, Inc.
West Palm Beach, F1.
I
PAGE
563
5
-
6
FACILITIES CONTROL
6.1
GENERAL NOTES
a.
All surfaces of the 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 a r e 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 b e through a 50 micron or finer polypropylene
or Dyne1 cloth filter (Section 5j.). Diatomaceous earth (Section 5k.) 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, or 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. T h e 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
accurate within + 5 percent of the current over the desired plating range.
6.2
PRECONDITIONING OF PLATING TANK AND FILTER SYSTEM
* * * 1 * 1 * 8 *
$>;.
6.3
T2p.V
T h e presence of organic material in the plating tank or associated
plumbing will affect the quality of t h e plating.
a.
Fill tank with 1 oz/gal (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 the 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 BO€-NIZ additive LHE (Section 5g.)
e.
Operate the pump, heat exchanger, and filter system for 6 hours minimum at ambient
temperature.
f.
Allow the above leaching solution to stand an additional 24 hours minimum at ambient
temperature.
g*
h.
Remove and discard t h e solution and rinseThe tank thoroughly with water.
New or contaminated anode bags (Section 5e.) shall be treated in the above caustic and ac
solutions to leach out any organic contaminants.
ZINC AND NICKEL A N O D E 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 to further processing.
b.
Dry abrasive blast clean in accordance with BAC 5748, Type 11, Class 1.
C.
Insert the anodes (Section 5d.(2) and Section 5.d.(4)) in the leached anodes bags
(Section 5e. and Section 6.2h). Immerse the clean zinc and nickel anodes in the zinc-an@
pretreatment solution (Xable IV)for 2 to 3 hours to allow the formation of a dark-gray fii
on the surfaces.
d.
Cold water immersion rinse. Handle the anodes carefully to prevent damaging the sok,
dark-gray film on the anodes. Transfer the anodes to the zinc-nickel plating bath.
NOTE: If the anodes become contaminated o r 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.
56.
PAGE
0
?_.
,.-
7
REVISED:
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 the 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 clean water at a temperature below
100 F (38 C).
MANUFACTURING CONTROL
A
I
Some of t h e materials employed herein are toxic, flammable, and/or
corrosive to human tissue. Boeing personnel should refer to the
Hazard Communication Handbook (D1-8301)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 SecuritylFire 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 safety
data sheets, or contact the manufacturer for safety and health
information pertaining to a hazardous material.
1
.
._^..C
0
q.l
nq
PAGE
8
REVISED:
20
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 5d.(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 to remove particulates from the zinc-nickel plating
bath.
g.
When the plating tank is inactive for more than 120 hours, the zinc anodes shall b e
removed from the plating bath. Removal is necessary to prevent degradation of the zinc
anodes.
..
I
PAGE
563’i
9
(
8.2
FLOW CHART
Stress Relieve as Required
(Section 11.1)
I
I
Clean Prior to Masking
(Section 8.3)
(Section 8.4)
7
Corrosion Resistant
Steels Clean and
Activate
(Secrion 8.5.2)
Low Alloy Steels
Clean and Activate
(Section 8.5.1)
-
Zinc-Nickel Plating
(Section 8.6)
*
I
-
I
Hydrogen Embrittlement Relief
Bake, As Required
(Section 8.7)
1
Supplemental Treatment
(Section 8.8)
I
I
t
1
1
Quality Control Inspection
(Section 10)
I
1
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
cieaned 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 recommended
to mask any area of a metal rack, with the exception of the contact points, whick
may be immersed in the pIating solution.
b.
Rack parts to prevent entrapment of gases generated during plating, and to facilitate
draining. Make firm electrical connections to the part(s) 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 o r BAC 5749 to remove any grease or oil from handling.
LOW ALLOY STEELS
a.
Descale by one of the following methods:
(1) Method 1
(a) Abrasive clean in accordance with BAC 5748,Type 11, Class 1 using glass bead or
aluminum oxide abrasive. Use of larger particles (e.g., 80 grit aluminum oxide) to
produce a 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.) withir
minute.
(2) Method 2
Descale in accordance with BAC 5625, Method 1, or BAC 5751, Method 1. Wate
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 BXC 5749, Method 3. Water rinse thoroughly. If-pa
require masking, return to Section 8.4, otherwise, transfer to activating step
(Section 8.5.lb.) within 1 minute.
PACE
5 6f
11
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.
(b) Warm water rinse for 1 to 3 minutes.
(3) Method3
(a) Periodic reverse clean in accordance with BAC 5749, Method 3. End with a 15 to
25 second anodic cycle.
(b) Remove smut, if present, by scouring using abrasive material specified in
Section Sa. Rinse thoroughly with water.
..
Continue periodic reverse cleaning until a water-break-free surface is obtained
(typically 2 to 10 minutes).
(C)
(d) Cold water rinse for 2 to 3 minutes.
c.
8.5.2
Proceed to Section 8.6. Do not allow parts to dry.
CORROSION RESISTANT STEELS
a.
Descale by one of the following methods:
(1) Method 1
(a) Abrasive clean in accordance with BAC 5748, Type 11, Class 1using glass bead or
aluminum qxide abrasive. Use of larger particles (e.g., 80 grit aluminum oxide) to
produce a rougher finish will improve plating adhesion. .
I
(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) Method 2
Descale in accordance with BAC 5625, Method 111, or BAC 5751, Q p e XI, 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.
1
BAC
5637
PAGE
-
12
R EVI s ED:
OF
20
..
~
8.6
ZINC-NICKELPLATING
a.
Immerse in zinc-nickel plating solution (Section 9.1) and then apply current at 10 to 40
ASF (1.1 to 4.3 A/dm2)
OPTIONAL
Strike parts at a current density of 60 to 90 ASF (6.5 to 9.7 A/dm2) for 15
seconds before regular plating. For CRES steels, nickel strike in
accordance with Section 8.5.2b.(l).
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/dm2). (Every 160
ASF-min (17.2 A/dm2 - 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 parts 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.
8.7
HYDROGEN EMBRITTLEMENT RELIEF BAKE
8.7.1
GENERAL
8.7.2
a.
Unless otherwise specified, all steel parts requiring baking (See Secrion 8.7.2) shall be
baked within 8 hours after plating to provide hydrogen embrittlement relief. Records shall
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)
a.
Bake ferrous parts within 8 hours following plating according to the drawing. If not
specified on t h e drawing, bake in accordance with the following schedule:
(1) Carburized parts and 440 series CRES: 5 to S hours at 275 + 25 F (135 + 14 C).
(2) Externally threaded parts heat treated from 160 to 220 ksi (1100 to 1500 MPa), all coil
springs regardless of heat treat and all other parts heat treated from 180 to 220 ksi
(1200 to 1500 MPa): 3 hours minimum at 375 + 25 F (191 + 14 C).
(3) PH steels not specified in Section 8.7.2b. shall be baked for 12 hours minimum at 375
+ 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 nor externally threaded
(2) 17-7 PH (CH900 condition)
(3) A-286
(4) 300 series CRES
( 5 ) All other ferrous alloys with tensile strengths less than 180 ksi (1200 MPa), except as
specified in Section 8.7.2a.(2).
I
1
ORIGINAL I S S U E
..
- .--,.^^. .-,"*
8 - 2 1- 9 2
563'
PACE
13
REV Is ED:
8.8
8.9
SUPPLEMENTAL TREATMENTKONVERSION COATING (FOR TYPE I1 ONLY)
a.
If there is a delay prior to application of the conversion coating, dry the parts and protect
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.)
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 part(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 11 of this specification. However, any solution not
specifically mentioned in this specification must have the prior approval of Boeing
Engineering and Quality Assurance.
REWORK
.. .
The following rework shall be documented as 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.
* * * . . . I . .
Ffi*v??p.? BAC 5771, Solution 11contains cyanide.
b.
Parts heat treated above 160 Ksi (1100 MPa) shall be baked at 375 + 25 F (191 2 14 C) for
3 hours minimum after stripping is performed.
c.
Reprocess parts in accordance with this specification.
BAC
5637
PACE
O R I G I N A LISSUE:
8 - 2 1- 9 2
14
REVISED:
OF
20
9
MAINTENANCE CONTROL
9.1
ZINC-NICKEL PLATING SOLUTION
a.
The tank and filter system shall b e preconditioned prior to the initial make-up of the
zinc-nickel plating bath (Section 6.2)
NOTE: Subsequent bath make-ups 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 completeiy
dissolved.
(2) 61 pounds (28 kg) of nickel chloride (Section 5q.). Mix until completely dissolved.
(3) In a separate tank o r container, add 2.5 gallons (9.5 L) of hydrochloric acid
(Section 5x1.) 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.
d.
Fill t h e tank close to operating level with water.
e.
Check the pH of the bath. Adjust the pH, if required, to 6.2 to 6.3. Ammonium hydroxide
(Section 5c.) is used to raise the pH, and hydrochloric acid is used to lower the pH.
f.
When the bath temperature has cooled to 65 to 85 F (18 to 29 C)
add 3.0 gallons (11.5 L) of BO€-NIZ additive LHE (Section Sg.) per 100 gallons (379 L)of
total solution. Stir the bath thoroughly.
g.
h.
Add additional water if necessary. Recheck the p H and adjust to 6.2 to 6.3 if necessary.
1.
Before placing a freshly prepared solution into production, dummy plate at 3 to 5 ASF (0.3
to 0.6 A/dm3) for a period of 8 to 12 hours. Analyze and adjust in accordance with Section
9. li.
Maintain the plating solution within the ranges specified in Table I and adjust, when
necessary, as prescribed by the Quality Control lab.
NOTE: Organic contamination occurs due to ineffective removal of oils and greases
during the cleaning operation. Treatment with activated carbon (Section 5.) is
usually effective in removing organic contaminants. T h e carbon treatment wil!
also deplete the BOE-NIZ additive. Thus, it must be replenished before
resuming plating.
563'
PAGE
ORIGINAL
ISSUE: 8
- . .-
- 2 1- 9 2
15
REVISED:
9.1
CONTROL
OPTIMUM
nc Metal
0.7 to 2.0 oz/gal
(5.2 to 15 g/l)
1.2 oz/gal
(9.0 g q
ckel Metal
1.4 to 4.0 odgal
(10.5 to 30.0 g/l)
2.5 to 6.0 odgal
(19 to 45 g/l)
2.4 oz/gal
(18.0 g/l>
3.6 ozlgal
(27 g/l)
1.0 to 3.5
2.0
hloride
16 to 20 oz/gal
(120 to 150 g/l)
18.5 odgal
(139 g/l)
,oric Acid
1.6 to 3.7 odgal
(12 to 28 g/l)
IOE-NIZ Additive LHE
1.9 to 11.5 odgal
(14 to 90 mlll)
3.8 odgal
(28.5 g n )
5.9 to 6.5
6.30
65 to 95 F
(18 to 35 C)
75 F
(24 C)
10 to 40 ASF
(1.1 to 4.3 A/dm2)
20 to 30 ASF
(2.2 to 3.2 Afdm2)
MATERIWCONDITION
,tal Metal Content
:n+Z + Nif2)
ickel/Zinc Ratio
,H
I'emperature
Cathode Current Density
Nickel to Zinc Anode Area
Ratio 1/ 2/
--
Anode to Cathode Area Ratio
1to 3
21
---
-1/
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.
CONVERSION COATING
9.2
Clean tank thoroughly. Fill tank approximately one-half full of water.
a.
NOTE: Thnk 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 n b l e 11.
c.
Fill the tank to the operating level and check and adjust, if necessary, pH and CorroBan
IC-A (Section 5t.) concentration in accordance with the control values listed in
Table 11.
TABLE I1
CONVERSION COATiNG CONTROL
MAKE-UP PER
MATERIAL/
CONDITION
100 GALLONS
100 LITERS
CONTROL
C O L T OIC-A
B~
75 lbs
9 kg
10 to 13 oz/gal
(75 to 98 g/l)
CorroBan IC-B
1percent by volume
1percent by volume
---
PH
1.9 + 0.2
100 + 5F
(38 F 2 C l
Temperature
BA(
563’7
PAGE
ORIGINAL ISSUE:
x-?d97 A
RFV 5IRS
8 - 2 1- 9 2
17
REVISED:
3.3
DILUTE ACID SOLUTION
Make-up and control t h e bath as indicated in liible 111.
TABLE 111
DILUTE ACID MAKE-UP AND CONTROL
CONTROL
MATERIAL/CONDI-
Water
SOLUTION A
Balance
---
Balance
---
Fluoboric Acid, HBF4
(Section 5m.)
---
---
1.2 to 2.0 oz/gal
(9.3 to 15 g/l)
Ambient
Ambient
2.5 gal
(2.5 1)
---
Temperature
SOLUTION B
0.8 to'
1.6 oz/gal
(6.1 to 12.3 g/l)
3.0 gal
(3.0 1)
Hydrochloric Acid, HCI
(Section 5n.)
9.4
SOLUTION A
ANODE PRETREATMENT SOLUTION
Make-up and control the bath as indicated in Table Iv.
TABLE IV
ANODE PRETREATMENT MAKE-UP AND CONTROL
MAKE-UP PER
MATERIAL/
ZONDITION
Ammonium Chloride
(Section 5b.)
Nickel Sulfate
(Section 5r.)
Water
Temperature
100 GALLONS
100 LITERS
CONTROL
208 lbs
25 kg
30.7 to 36 oz/gal
(230 to 270 g/l)
46 Ibs
5.5 k.g
6.7 to 8.0 oz/gal
(50 to 60 g/l)
Balance
Balance
---
---
---
Ambient
1
ORlGlNAL 1SSUE:
8 - 2 1 - 92
PAGE
18
REVISED:
OF
.
ZO
3.3
PROCESS WATERS
9.5.1
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 specification.
11
REQUIREMENTS
11.1
STRESS RELIEF
11.2
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 parts, heat treated to 180 Ksi (1240 MPa) (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, or
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.
If more than one plating operation (including different plating or re-plating) is performed
on the parts, 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 I1 supplemental treatmentkhromate 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.
113
THICKNESS
~
'fl
a.
b.
c.
11.4
11.5
Unless otherwise specified, the zinc-nickel ailoy plating thickness shall be Class 1 for all
hardware, except fastener hardware shall be Class 2.
Part surfaces designated on the drawing shall be completely covered with visible Zinc-nickel
.
alloy plating, within the capability of t h e 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 maximum thickness shall not exceed 0.0010 inch (25 pm).
ADHESION
The deposit shall be firmly adherent wbcn tested in accordance with BSS 7235 after baking and
supplemental treatment, if required, is completed.
--
CORROSION RESISTANCE
Zinc-nickel alloy plating with the 'Qpe II supplemental 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 corrosion products, visible to the unaided eye
at norma1 reading distance, shall be a cause for rejection, except that white corrosion products
within 0.25 inch (0.64 an)from the edges of the specimens shall not constitute failure.
11.6
T E S T 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.
BAC
5637
PACE
20
OF
2(