Standard Test Method for Sandwich Corrosion Test

SCOPE
1.1 This test method defines the procedure for evaluating the corrosivity of materials on aluminum alloys commonly used for aircraft structures. This test method is intended to be used in the qualification and approval of compounds employed in aircraft maintenance operations.
1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements appear in Section 9.

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Historical
Publication Date
31-Dec-1989
Current Stage
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ASTM F1110-90(1998) - Standard Test Method for Sandwich Corrosion Test
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1110 – 90 (Reapproved 1998)
Standard Test Method for
Sandwich Corrosion Test
This standard is issued under the fixed designation F 1110; 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 4. Summary of Test Method
1.1 This test method defines the procedure for evaluating 4.1 Aluminum coupons having clad or anodized nonclad
the corrosivity of materials on aluminum alloys commonly surfaces are sandwiched together with a filter paper saturated
used for aircraft structures. This test method is intended to be with the test material between the coupons. The sandwiched
used in the qualification and approval of compounds employed coupons are cycled between warm ambient air and warm
in aircraft maintenance operations. humid air for 7 days. The coupons are then inspected to
1.2 This standard may involve hazardous materials, opera- determine whether corrosion more severe than that caused by
tions, and equipment. This standard does not purport to reagent water has occurred on the surfaces exposed to the test
address all of the safety concerns, if any, associated with its material. This test method may be used for solutions of dry
use. It is the responsibility of the user of this standard to granular material or for liquid materials.
establish appropriate safety and health practices and deter-
5. Significance and Use
mine the applicability of regulatory limitations prior to use.
5.1 The data generated by this test method shall be used to
Specific hazard statements appear in Section 9.
determine whether aircraft structural aluminum alloys are
2. Referenced Documents
liable to be corroded or damaged by application of the test
2.1 ASTM Standards: material during routine maintenance operations.
D 1193 Specification for Reagent Water 5.2 Interpretation of the sandwich corrosion test results is
D 1748 Test Method for Rust Protection by Metal Preser- based on a comparison of the appearance of faying surfaces of
vatives in the Humidity Cabinet three sets of coupons. One set of test coupons is exposed with
G 46 Guide for Examination and Evaluation of Pitting reagent water only in the faying surfaces, to establish the
Corrosion baseline (controls) against which the panels exposed to the test
2.2 Federal Specifications: material are compared. Corrosion at cut edges of the test
QQ-A-250/4 Al Alloy 2024 Plate and Sheet coupons should be disregarded.
QQ-A-250/5 Al Alloy Alclad 2024 Plate and Sheet 5.3 The relative corrosion severity rating system is provided
QQ-A-250/12 Al Alloy 7075 Plate and Sheet in order to allow a numerical classification of the test results
QQ-A-250/13 Al Alloy Alclad 7075 Plate and Sheet and to eliminate the necessity for elaborate weight loss
2.3 Military Specification: measurements. Pitting corrosion, which is rated 4—extensive
MIL-A-8625 Anodic Coatings for Aluminum and Al Al- (severe) corrosion, may involve only a negligible weight loss.
4,5
loys 5.4 Relative corrosion severity rating system
0—No visible corrosion
3. Terminology
1—Very slight corrosion or discoloration
2—Slight corrosion
3.1 Definition of Term Specific to This Standard:
3—Moderate corrosion
3.1.1 sandwich corrosion test—a comparative accelerated
4—Extensive corrosion or pitting
environmental test of the corrosivity of liquid or solid materials
0—No corrosion
on structural aluminum alloys commonly used in aerospace
1—Up to 5 % of the surface area corroded
construction.
2—5 to 10 %
3—10 to 25 %
4—25 % or more
This test method is under the jurisdiction of ASTM Committee F-7 on
Aerospace and Aircraft and is the direct responsibility of Subcommittee F07.07 on
6. Interferences
Qualification Testing of Aircraft Cleaning Materials.
Current edition approved Jan. 26, 1990. Published March 1990. Originally
6.1 Tap water containing large amounts of dissolved solids,
e1
published as F 1110 – 86. Last previous edition F 1110 – 86.
especially chlorides, may cause relative severe corrosion of the
Annual Book of ASTM Standards, Vol 11.01.
aluminum control panels. For this reason a reagent water is
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 03.02. specified. For comparative purposes, a set of aluminum test
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
panels, with the locally available tap water applied to the filter
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1110
paper, may be run along with the reagent water panels. pairs of coupons of the same alloy and the same surface
6.2 Under certain conditions cellulose filter paper may react treatment, to provide four test coupon sandwiches for each test
with the test aluminum alloy and change the test results. Filter condition. Identify each coupon by impression stamping or
paper made from glass fibers is available, and should be used, other suitable permanent method.
except for fluoride-containing compounds. 11.2 Clean the panels by solvent wiping, or vapor degreas-
ing. Do not use acid or caustic cleaners. Remove ink stamped
7. Apparatus
markings from the panels. Do not use abrasive materials to
7.1 Humidity Test Cabinet, as specified in Test Method
clean the panels.
D 1748 or equal, capable of from 95 to 100 % relative 11.3 Prepare the test panel sets as follows for each alloy:
humidity at 37.7 6 1°C (100 6 2°F).
11.3.1 One set for the compound to be tested at use dilution,
7.2 Oven, forced air circulation, capable of maintaining 37.7 11.3.2 One set for the compound to be tested in concen-
6 1°C (100 6 2°F).
trated form and
7.3 Microscope, binocular, 103 to 403. 11.3.3 One set for controls using reagent water.
8. Reagents and Materials
12. Preparation of Apparatus
8.1 Purity of Water—Unless otherwise indicated, references 12.1 Verify that the humidity cabinet is operating at the
to water shall be understood to mean reagent water as defined
specified temperature and humidity.
by Specification D 1193, Type IV. 12.2 Verify that the air oven is operating at the specified
8.2 Aluminum Alloy Coupons:
temperature, with air circulation.
8.2.1 Aluminum alloy coupons shall conform to the follow-
13. Calibration and Standardization
ing Federal Specifications:
13.1 Since the test coupons include controls for comparative
QQ-A-250/4, 2024-T3 nonclad
QQ-A-250/5, 2024-T3 Alclad purposes, no special calibration or standardization procedures
are required.
QQ-A-250/12, 7075-T6 nonclad
QQ-A-250/13, 7075-T6 Alclad
14. Conditioning
8.2.2 Coupon Size—The recommended coupon size 50 by
14.1 Conditioning of the test materials or the sets of
100 by 1.0 to 1.5 mm (2 by 4 by 0.04 to 0.06 in.) has been
found to provide suitable results for comparative tests. Smaller prepared test coupons is not required. Thoroughly agitate the
test sample before application to the test coupons.
sizes are not recommended, because of the increased variations
due to edge effects. Larger coupons are acceptable,
...

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