ASTM B627-84(1992)e1
(Test Method)Test Method for Electrolytic Corrosion Testing (EC Test) (Withdrawn 1998)
Test Method for Electrolytic Corrosion Testing (EC Test) (Withdrawn 1998)
SCOPE
1.1 This test method covers a rigid and reproducible means for evaluating the corrosion durability characteristics of copper-nickel-chromium electrodeposits on steel and zinc-base die castings designed for outdoor service (1).
1.2 The suitability of this test method and the correlation of results with service experience should be determined before it is specified for coating systems or materials other than those described in 1.1 (2-5).
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Standards Content (Sample)
ASTM Bb27%EL 84 m 0759530 05043Y4 T m
AMERICAN SOCIETY FOR TESTING AND MATERIALS
Designation: B 627 - 64 (Reapproved 1992)“’
1016RaceSt.Philadelphla,Pa19103
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
If not listed in the current comblned index, will appear in the neti edtiion.
Standard Test Method for
Electrolytic Corrosion Testing (EC Test)’
This standard is issued under the fixed designation B 627; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision, A number in parentheses indicates the year of last reapproval. A
superscript epsilon (c) indicates an editorial change since the last revision or reapproval.
(I NOTE-Section I3 was added editorially in January 1992.
the substrate metal (area 0.01 % tested area). Cycling can be
1. Scope
done either manually or automatically (controlled by a small
1.1 This test method covers a rigid and reproducible
computer).
means for evaluating the corrosion durability characteristics
of copper-nickel-chromium electrodeposits on steel and
4. Significance and Use
zinc-base die castings designed for outdoor service (l).*
1.2 The suitability of this test method and the correlation
4.1 This test method simulates the actual corrosion pro-
of results with service experience should be determined
cess. In the potentiostatic mode, corrosion is under anodic
before it is specified for coating systems or materials other
control due to high-anode polarization at very low nickel-
than those described in l.l (2-5).
area exposure paralleling the initial stage of corrosion in
1.3 This standard does not purport to address all of the
service. As the anode area increases, particularly with the use
safety problems, if any, associated with its use. It is the
of microdiscontinuous chromium, current increases to the
responsibility of the user of this standard to establish appro-
specified maximum and control is changed to galvanostatic
priate sdety and health practices and determine the applica-
mode, corresponding to cathodic control in service (l-3).
bility of regulatory limitations prior to use.
NOTE I-The accumulated electrolysis time desired is determined by
the duration of service to LX simulated (see 9.8). A limited number of
2. Referenced Documents
observations has indicated that 2 min of electrolysis time approximates I
year of service exposure in Detroit, MI. This possible correlation is
2.1 ASTM Standards:
suggested only as an aid in determining the number of current cycles to
B 368 Method for Copper-Accelerated Acetic Acid-Salt
be conducted.
Spray (Fog) Testing (CASS Test)3
B 456 Specification for Electrodeposited Coatings of
5. Apparatus (See Fig. 1)
Copper Plus Nickel Plus Chromium and Nickel Plus
Chromium3 5.1 This test can be run optionally two ways: (1) by
B 65 1 Test Method for Measurement of Corrosion Sites in manually controlling current and potential, and on-off times
Nickel Plus Chromium or Copper Plus Nickel Plus with the aid of switches and a timer; (2) with the aid of a
Chromium Electroplated Surfaces with the Double-
small desk-top computer, which handles currents and
Beam Interference Microscope3 switching automatically.
G 3 Practice for Conventions Applicable to Electrochem- 5.2 Manual Control Apparatus:
ical Measurements in Corrosion Testing4
5.2.1 Potentiostat, capable of regulating an anode poten-
tial within k-2 mV and having a minimum capacity of 3.3
3. Summary of Test Method
mA/cm* (33 A/m*) of surface being tested, in accordance
with Practice G 3.
3.1 The plated test specimen is made anodic starting at a
5.2.2 Mode Switch, for galvanostatic or potentiostatic
predetermined fixed potential in a specified electrolyte for a
control (see Fig. 1 for schematic diagram).
predetermined time (usually 1 min). If the current density
5.2.3 Two-Channel Strip-Chart Recorder (recommended
reaches a predetermined value during electrolysis the poten-
option).
tial is reduced as required to maintain this value for the
5.2.4 On-OfS Switch, used for controlling power to
remainder of the test. Then the current is turned off and the
potentiostat and stirring motors.
potential versus reference electrode is monitored at the end
5.2.5 Electric Timer, used for reading total current-on
of a 2-min rest period: less than 350 mV indicate exposure of
time to accuracy of ~6 s.
5.3 Automatic Control Apparatus (see Fig. 2):
I This lust method is under the jurlsdiclion of ASTM Committee 8-g on 5.3.1 Small Desk-top Computer with Timer.
Mclallic and Inorganic Coatings and is the direct responsibility of Subcommittee
5.3.2 Programmable Power Supply.
BO8.03 on Decorative Copper, Nickel, Chromium, and Nickel-Chromium Coat-
5.4 Apparatus Common to Both Methods:
ings.
Current edition approved Aug. 3 I, 1984. Published February 1985. Originally 5.4.1 Input Scanner (two channels minimum).
published as B 627 - 79. Last previous edition B 627 - 79.
5.4.2 Digital Volt Meter (DVM).
2 The boldface numbers in parentheses refer to the list of references appended
5.4.3 Electrolysis Cell (see Fig. 3.)-Two types can be
to this test method.
used dependent on the size of the parts tested: (I) a
3 Annual Book a$ASTM Slandards, VolO2.05.
4 Attnrral Bwk oJASTM Standards, Vol 03.02. stationary tank for total immersion of the test specimen; and
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ASTM Bb27*Elr 84 m 0759530 0504345 IJ m
COMPUTER
POTENTIOSTAT
I I CONTROLLER
CELL
Nor&Best conflguratlon for longer tests Is (10 to 20 cycles); computer-
contrds test Includes onsff cycling,,stlrrer, and data storage. During potentiostatic
CELL
~ntr$ computer adjusts power supply output to maintain & W.E/ffE = 300 mV f
NoTE-T~~ on-off manual control stirrer is not shown, but It Is akio manually
controlled.
FIQ, 2 Schematic for Automatic Controlled EC Test
FIG. 1 Mode Switch Attached to Potentiostat and Two-Channel
Recorder for Manual Control Testing
Anode
CELL
Salt
Bridge
(a) Stationary-Type for Immersion of Test Specimen
(b) Portable-Type for Clamplng onto a Part
FIG. 3 Electrolysis Cells for EC Testing
5.4.3.2 Portable Clamp-On Cell (box with no bottom),
(2) a portable which can be clamped onto the test specimen,
isolating a small area. should also be made of a nonconductive material and shaped
to conform with the contours of the part. The surface of the
5.4.3.1 Stationary Tank, should be of suitable size to
contain enough electrolyte to cover the part. The cell can be test specimen is the “bottom” of the cell. Soft-rubber gaskets
are used on the edges to give a water-tight seal. The cell
made from nonconductive material, for example, polypro-
pylene. should contain a cathode and a reference electrode.
COPYRIGHT American Society for Testing and MaterialsCOPYRIGHT American Society for Testing and Materials
Licensed by Information Handling ServicesLicensed by Information Handling Services
ASTM Bb27*EL 84 m 0759530 0504346 3 m
.~
TO POTENTIOSTAT
SI = 4P 3T shorting switch
RI = Potentiometer (Note 1)
R2 = lOK, ‘Law
R3 = 10052, low
SI-D
TO CELL
NOTE l-Adjust to 300 mV between WE and RE for galvanostatic mode. (power rating bl W for currsnts ~1 A.)
NOTE P-The to/lowing are mode switch positions:
(1) Potentiostatio control of working electrode (WE).
(2) Galvanostatic control of working electrode.
(3) Current set.
FIG. 4 Mode Switch Schematic Description of Operating Positions Number of Discontinuities
6.1.2 Electrolyte B, for use when testing plated steel
5.5 Indicator Solution Tank, having flat transparent sides
specimens where corrosion sites are to be identified in the
and bottom with provision for uniformly illuminating the
electrolyte shall consist of the following:
sides and blacking out the bottom when plated zinc speci-
mens are tested (6).
Sodium nitrate, NaN03 10.0 g/L (10.0 kp/ms)
Sodium chloride, NaCl 1.0 g/L(l.O kg/m3)
5.6 Cathode, can be platinized zirconium of sufficient
Nitric acid (concentrated), HNO, 5.0 mL/L (5.0 dm3/m3)
area to permit an adequate anode current density. Nickel or
1, IO-Phenanthroline hydrochloride I.Og/L(I.O kg/ma)
nickel-plated copper may be used.
as required
Water-distilled or deionized
Path life 200 A*s/L (200 kA*s/ma) or until
NOTE 2-The nickel or nickel-plated copper cathodes must be
color of solution masks color
removed when not in use to avoid dissolution by the electrolyte.
originating at a corrosion site
6.2 Indicator Solutions:
5.7 Saturated Calomel Electrode (SCE), with a leak rate of
about 8 x 10e4 mm3/s (3 pL/h), for use as a reference 6.2.1 Solution C, for use when identifying corrosion sites
on plated zinc specimens after electrolysis shall consist of the
electrode, in external vessel connected with a salt bridge or a
following:
Luggin capillary tip to the cell.
5.8 Means to ensure positive electrical connection to the
Acetic acid (glacial), CH3CQQH 2 mL/L (2 dm3/m3)
Quinoline, CaH7N 8 mL/L (8 dm3/ma)
specimen. Any method of making a low-resistance contact is
Water-distilled or deionized as required
suitable.
Bath life until the solution turbidity masks
5.9 Masking Materials (paint or tape), for applying to
the cloudy streamer originating at
surfaces that are immersed in electrolyte, but that should not a corrosion site
be tested (such as cut edges and the reverse side of the part).
6.2.2 Solution D, for use when identifying corrosion sites
on plated steel specimens after electrolysis shall consist of the
following:
6. Reagents
Acetic acid (glacial), CH3CQQH 2 mL/L (2 dmYm3)
6.1 Electrolytes:
Potassium thiocyanate, KCNS 3 g/L (3 kg/m”)
6.1,l Electrolyte A (preferred), for use when testing either
Hydrogen peroxide (30 I), HaOe 3 mL/L (3 dma/ma)
plated zinc or steel specimens when corrosion sites are to be
Water-distilled or deionized as required
identified in a separate indicator solution shall consist of the
Bath life until the color of the solution
masks the color originating
following:
at a corrosion site
Scxiium nitrate, NaNOa 10.0 g/L (10.0 kg/m31
Sodium chloride, NaCl 1.3 g/L (1.3 kg/m’)
Nitric acid (concentrated), HNOJ
5.0 mL/L (5.0 dm3/m3)
7. Test Specimen
Water-distilled or deionized as required
Bath life 900 A*s/L (900 kA.s/ma) 7.1 Select the area of the specimen to be tested. If
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Licensed by Information Handling ServicesLicensed by Information Handling Services
ASTM Bb27*El 84 m 0759510 0504347 5 -
ds(E1 B 627
completely cover the significant surface to be tested. Place
reference electrode in its container connected to the cell with
a salt bridge, Make necessary connections. Adjust
potentiostat controls so that the specimen (anode) potential
POTENTIAL
is to,3 V versus SCE (8,2).
9,2 Manual Control:
9.2,1 Start electrolysis and the timer simultaneously.
Record the current density. (See Fig, 2 for suggested data-
mox
recording form,)
CURRENT
9.2.2 Electrolyze 1 min (8.3).
NOTE 4-The current density at the start of electrolysis is dependent
upon the original area of nickel exposed through pores or cracks in the
J chromium layer.
(a) Coating wtth Low Number of DlscontlnuiUes
9.2.2,1 If at any time the current density on the specimen
tends to exceed 3.3 f 0.05 mA/cm2 (33 A/m2), reduce the
applied potential enough to maintain this value. The mode
switch shown in Fig, 4 readily handles this step converting
the test from galvanostatic to potentiostatic control.
POTENTIAL
9,2.2.2 If a specimen is subjected to an anodic current
PI w
density sufficiently high to oxidize chromium anodically to
off off
Cr(V1) ion (evidenced by its characteristic orange color),
discard the specimen and the electrolyte,
9.3 Stop electrolysis and timer,
CURRENT
9,4 Allow the specimen to remain in the electrolyte for 2
mitt, Record potentiat versus saturated calomel for 2 min.
-I:
Repeat 9.2,l to 9,4 until desired electrolysis time has elapsed.
(I - mode change)
TIME
9.5 Remove the specimen and flush with clean running
J
water,
(b) Coating with High Number of Discontlnultles
FIG. 5 Characteristic Potential and Currents Recorded During the
9.6 Optional treatment after electrolysis to determine
On-Off Cycles of a Typical EC Test
whether or not corrosion has penetrated to the basis metal.
9.6.1 Transfer the plated zinc specimens to Indicator
necessary, cut the specimen to isolate the desired area, Select Solution C and the plated steel specimens to Indicator
the specimen from a significant surface as defined in the Solution D,
9.6.2 Observe the surface of the specimen for red
applicable specification.
streamers in the case of plated steel specimens or white
7.1.1 Construct the portable cell to conform with the
contours of the part to be tested. Water-tight gaskets applied precipitate streamers exuding from one or more corrosion
sites in the case of plated zinc specimens. These indicate
to the leading edges contacting the part define the test area,
penetration of the coating and corrosion of the basis mate-
7.2 If the test specimen has been cut from large parts, the
exposed edges and all insignificant surfaces must be pro-
rial,
tected before immersion into electrolyte. Insulating tape or
NOTE S---If a permanent visual record of the condition of a specimen
paint can be used. (The solution-air interface should also be
is desired, basis metal corrosion sites can be redeveloped in an
stopped off with tape to ensure a well-defined area,) accelerated corrosion test such as 1 to 4-h exposure in accordance with
Method B 368.
7,3 Determine the area of surface to be tested’ and
calculate the maximum value of current based on 3.3
9.7 Repeat 9.2 through 9.6.2 until the desired time of
mA/cm3 (33 A/m2).
electrolysis has elapsed. (See Note 1 J
7.4 Clean the test area by lightly scrubbing with magne-
9.8 Stop electrolysis and timer and record the total
sium oxide (MgO) slurry on a wad of cotton until the surface
current-on time.
is free of water breaks.
9.9 Automatic Computer Control:
7.5 Rinse thoroughly in clean running water,
9,g.l Program computer to perform cyclic operations
described in 9.3 to 9,4.
8. Operating Conditions
9.9.2 Input to Computer:
8.1 Maximum current density on the specimen-3,3 f
9.9.2.1 Type in sample identification.
0.05 mA/cm2 (33 A/m2).
9,9,2.2 Test area, S, (cm2).
8.2 Specimen potential (versus SCE)-i-0.3 V.
9.9.2,3 Test duration, cycles (N),
8.3 Current cycle-l min on and 2 min off,
...
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