ASTM C703-72(2021)

Standard Test Methods for Spalling Resistance of Porcelain Enameled Aluminum

SIGNIFICANCE AND USE
3.1 It is difficult to overemphasize the importance of the spall test. Porcelain enameled aluminum that fails this test will probably spall in service if subjected to moisture or weathering.
SCOPE
1.1 These test methods cover accelerated determination of the resistance of porcelain enamel coatings on aluminum alloys to spalling from exposure to moisture or weathering. Test Method A,2 using a 5 % solution of ammonium chloride, requires 96-h immersion while Test Method B,3 using a 1 % solution of antimony trichloride, is completed after 20 h of immersion. The spalling tendency is evaluated by the same criteria in both methods. While either method is suitable for magnesium silicon alloys, such as 6061, Test Method B is preferred for simple alloys or commercially pure aluminum, such as 1100.  
1.2 The test methods appear in the following order:    
Sections  
Test Method A—Ammonium Chloride  
4 – 9  
Test Method B—Antimony Trichloride  
10 – 15  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2021
• ICS: 25.220.50 - Enamels
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.12 - Materials for Porcelain Enamel and Ceramic-Metal Systems

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C703 − 72 (Reapproved 2021)
Standard Test Methods for
Spalling Resistance of Porcelain Enameled Aluminum
This standard is issued under the fixed designation C703; 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 (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This test, using an ammonium chloride or antimony trichloride test solution, covers an accelerated
procedure for determining the resistance of porcelain enamel coatings on aluminum and aluminum
alloys to spontaneous loss of adhesion (spalling) resulting from exposure to moisture, weathering, or
other environmental stress.
1. Scope apparent external cause. Spalling can result from the use of
improper alloys or enamel formulations, incorrect pretreatment
1.1 These test methods cover accelerated determination of
of the base metal, or faulty application and firing procedures.
theresistanceofporcelainenamelcoatingsonaluminumalloys
to spalling from exposure to moisture or weathering. Test
2 3. Significance and Use
Method A, using a 5 % solution of ammonium chloride,
requires 96-h immersion while Test Method B, using a 1 % 3.1 It is difficult to overemphasize the importance of the
solution of antimony trichloride, is completed after 20 h of spall test. Porcelain enameled aluminum that fails this test will
immersion. The spalling tendency is evaluated by the same probably spall in service if subjected to moisture or weather-
criteria in both methods. While either method is suitable for ing.
magnesium silicon alloys, such as 6061, Test Method B is
TEST METHOD A—AMMONIUM CHLORIDE
preferred for simple alloys or commercially pure aluminum,
such as 1100.
4. Apparatus
1.2 The test methods appear in the following order:
4.1 Container, glass or plastic, large enough to immerse the
Sections
test area of the specimen completely and hold a minimum of 3
Test MethodA—Ammonium Chloride 4–9
Test Method B—Antimony Trichloride 10–15 mL of solution per square centimetre of the immersed surface.
No metal other than the base metal of the specimen may be
1.3 This international standard was developed in accor-
exposed to the test solution.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5. Reagent
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 Ammonium Chloride Solution (5 %)—The test solution,
Barriers to Trade (TBT) Committee.
freshly prepared, shall consist of 5 parts, by mass, of ammo-
nium chloride (NH Cl) (technical grade is adequate) dissolved
2. Terminology
in 95 parts, by mass, of water. Deionized or distilled water is
2.1 Definitions:
preferred, but in the case of very large production pieces, tap
2.1.1 spalling—a defect characterized by separation of the
water may be used. Sufficient solution shall be prepared to
porcelain enamel from the aluminum base metal without
permit complete immersion of the specimens.
These test methods are under the jurisdiction of ASTM Committee B08 on
6. Test Specimens
Metallic and Inorganic Coatings and are the direct responsibility of Subcommittee
6.1 Full-size production pieces should be tested. When this
B08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.
Current edition approved April 1, 2021. Published May 2021. Originally
is not practical, specimens approximately 4 by 6 in. (102 by
approvedin1972.Lastpreviouseditionapprovedin2016asC703 – 72(2016).DOI:
152 mm), cut from production parts should be tested. At least
10.1520/C0703-72R21.
2 one representative specimen from each “job” or each 1000 ft
Method A is based on Bulletin AL-1a, Recommended Test Methods for
Evaluation and Control of Quality of Porcelain Enamel on Aluminum ,ofthe (93 m ) of production, whichever is applicable, should be spall
Porcelain Enamel Institute.
tested. Spall-tested pieces should not be shipped.
Method B is based on Bulletin T-51, Antimony Trichloride Spall Test of
Porcelain Enameled Aluminum, of the Porcelain Enamel Institute. 6.2 Test production parts in as-produced condition.
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C703 − 72 (2021)
7. Procedure tested. It is necessary that the metal-enamel interface is
exposed to the test solution. Cut edges or the cracks in the
7.1 Immerse the test specimens completely in the NH Cl
enamel caused by bending over a mandrel usually accomplish
solution at room temperature. Large production pieces may be
this. If not, the interface should be exposed by scoring the
immersed in a container made by lining a packing box with
enamel. At least one representative specimen from each “job”
polyethylene plastic sheeting.
2 2
or each 1000 ft (93 m ) of production, whichever is
7.2 Make a visual inspection after 96 h of immersion.
applicable, should be spall tested.
NOTE 1—Variations of this test may be used for studies of processing
12.2 Test production parts in as-produced condition.
variables.These include scored or deformed samples, 24 h inspection, and
multiple cycles of 96 h each.
12.3 Wherever practical (such as porcelain enameled sheet
material) specimens cut from production pieces should be bent
8. Evaluation
toa45°angleovera ⁄2-in.(12.7-m
...