ASTM B808-97(2003)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:B808–97(Reapproved2003)
Standard Test Method for
Monitoring of Atmospheric Corrosion Chambers by Quartz
Crystal Microbalances
This standard is issued under the fixed designation B 808; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 The values stated in SI units are to be regarded as the
standard. The values in parentheses are for information only.
1.1 This test method monitors the reactivity of a gaseous
test environment in which metal surfaces (for example, elec-
2. Referenced Documents
trical contacts, assembled printed wiring boards, and so forth)
2.1 ASTM Standards:
and other materials subject to pollutant gas attack undergo
B 810 Test Method for Calibration of Atmospheric Corro-
accelerated atmospheric corrosion testing. This test method is
sion Test Chambers by Change in Mass of Copper Cou-
applicable to adherent corrosion films whose total corrosion
pons
film thickness ranges from a few atomic monolayers to
approximately a micrometre.
3. Summary of Test Method
1.2 The test method provides a dynamic, continuous, in-
3.1 A single crystal of quartz has various natural resonant
situ, procedure for monitoring the corrosion rate in corrosion
frequencies depending on the crystal’s size and shape. The
chambers; the uniformity of corrosion chambers; and the
decrease in natural frequency is linearly proportional to the
corrosion rate on different surfaces. Response time in the order
crystal mass and the mass of well-bonded surface films. For
of seconds is possible.
crystals with reactive metal films on the surface (usually
1.3 With the proper samples, the quartz crystal microbal-
driving electrodes), the mass of the crystal/metal film increases
ance (QCM) test method can also be used to monitor the
as the metal oxidizes or forms other compounds with gases
weight loss from a surface as a result of the desorption of
3,4
adsorbed from the atmosphere. Thus, by measuring the rate
surface species (that is, reduction of an oxide in a reducing
of resonant frequency change, a rate of corrosion is measured.
atmosphere). (Alternative names for QCM are quartz crystal
Non-adherent corrosion films, particles, and droplets yield
oscillator, piezoelectric crystal oscillator, or thin-film evapora-
ambiguousresults.Areviewoftheoryandapplicationsisgiven
tion monitor.)
in Lu and Czanderna.
1.4 Thistestmethodisnotsufficienttospecifythecorrosion
3.2 The chamber environmental uniformity and corrosion
process that may be occurring in a chamber, since a variety of
rate can be measured by placing matching quartz crystals with
pollutant gases and environments may cause similar weight
matching reactive metal films at various locations in the
gains.
chamber. If the chamber and corrosion rate have been stan-
1.5 This test method is generally not applicable to test
dardized, the corrosion rate on various surface materials that
environmentsinwhichsolidorliquidparticlesaredepositedon
have been deposited on the quartz crystal can be determined.
the surface of the quartz crystal.
1.6 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 Corrosion film growth with thicknesses varying from a
responsibility of the user of this standard to become familiar
monolayer of atoms up to 1 µm can readily be measured on a
with all hazards including those identified in the appropriate
continuous, real-time, in-situ, basis with QCMs.
Material Safety Data Sheet for this product/material as pro-
vided by the manufacturer, to establish appropriate safety and
health practices, and determine the applicability of regulatory
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
limitations prior to use.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
This test method is under the jurisdiction of ASTM Committee B02 on King, W. H. Jr., Analytical Chemistry, Vol 36, 1964, p. 173.
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee Karmarkar, K. H. and Guilbaut, G. G. Analytical Chemistry Acta,Vol 75, 1975,
B02.11 on Electrical Contact Test Methods. p. 111.
Current edition approved Nov. 1, 2003. Published November 2003. Originally Lu, C. and Czanderna,A.W. Eds., Applications of Piezoelectric Quartz Crystal
approved in 1997. Last previous edition approved in 1997 as B 808 – 97. Microbalances, Elsevier, c1984.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B808–97 (2003)
4.2 The test results obtained for this test method are be covered by the final electrode material so that less than 1 %
influenced by various factors, including geometrical effects, of the metallic area is of exposed sublayer material. Because of
temperature, humidity, film thickness, film materials, electrode the fragility of the metal electrode there should be multiple
conditions, gases in the corrosion chamber, and so forth. (three or more), spring-loaded contacts between the crystal and
Calibration of coated crystals and instrumentation and repro- electronics.
ducible crystal operating conditions are necessary for consis- 6.3 After metallization of the crystals, they should be stored
tent results. in desiccators. After two years storage or if the metallization
shows discoloration or staining, the crystals shall be discarded.
5. Apparatus
Crystal surfaces should not be chemically or mechanically
5.1 Apparatus can be a simple series circuit of crystal (with cleaned before use in the corrosion chamber. They should be
electrodes and sensing film), oscillator (typically 6 MHz) and blown clean with inert compressed gas. Chilling and conden-
frequency counter (610-Hz accuracy and stability), as sche- sation on the surface, as can occur with the use of pressurized
matically shown in Fig. 1. fluorocarbons, shall be avoided. Care shall be exercised so that
the crystals are only handled by clean tweezers or tongs and
never touched by hands.
7. Calibration
7.1 QCMs and its electronics shall be calibrated initially in
a given corrosion system and thereafter on an annual basis.
Calibration shall be performed with the same shape and size of
crystal holder to be used during operation. Recalibration shall
FIG. 1 Schematic of QCM and Related Electronics
be performed if the crystal holder geometry is changed.
Calibration can be done by comparison to a standard such as
5.2 Commercial, Thin-Film Monitors, incorporating those
actual gravimetric weighing on a microbalance (62 µg). Use a
functions that read out thicknesses or weight gain are also
sample of the same material as the sensing film with a
available and acceptable after they have been calibrated.
minimum area of 5 cm and a thickness of 0.1 to 0.6 mm (see
5.3 Balance, with an accuracy of 62 µg is needed for
Test Method B 810). Foil surface roughness should be within
calibration procedures.
620 % of the QCM sensing film roughness. The procedure for
5.4 Recording Devices or Computers are needed for real-
the generation (that is, evaporation) and cleaning of the
time, continuous measurements.
gravimetric sample should be the same as used for the sensing
films. The age a
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