ASTM C703 - 72 (2021)

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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

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,

using a 5 % solution of ammonium chloride,

requires 96-h immersion while Test Method B,

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 accor-

dance with internationally recognized principles on standard-

ization established in the Decision on Principles for the

Development of International Standards, Guides and Recom-

mendations issued by the World Trade Organization Technical

Barriers to Trade (TBT) Committee.

2. Terminology

2.1 Deﬁnitions:

2.1.1 spalling—a defect characterized by separation of the

porcelain enamel from the aluminum base metal without

apparent external cause. Spalling can result from the use of

improper alloys or enamel formulations, incorrect pretreatment

of the base metal, or faulty application and ﬁring procedures.

3. 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 weather-

ing.

TEST METHOD A—AMMONIUM CHLORIDE

4. Apparatus

4.1 Container, glass or plastic, large enough to immerse the

test area of the specimen completely and hold a minimum of 3

mL of solution per square centimetre of the immersed surface.

No metal other than the base metal of the specimen may be

exposed to the test solution.

5. Reagent

5.1 Ammonium Chloride Solution (5 %)—The test solution,

freshly prepared, shall consist of 5 parts, by mass, of ammo-

nium chloride (NH

Cl) (technical grade is adequate) dissolved

in 95 parts, by mass, of water. Deionized or distilled water is

preferred, but in the case of very large production pieces, tap

water may be used. Sufficient solution shall be prepared to

permit complete immersion of the specimens.

6. Test Specimens

6.1 Full-size production pieces should be tested. When this

is not practical, specimens approximately 4 by 6 in. (102 by

152 mm), cut from production parts should be tested. At least

one representative specimen from each “job” or each 1000 ft

(93 m

) of production, whichever is applicable, should be spall

tested. Spall-tested pieces should not be shipped.

6.2 Test production parts in as-produced condition.

These test methods are under the jurisdiction of ASTM Committee B08 on

Metallic and Inorganic Coatings and are the direct responsibility of Subcommittee

B08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.

Current edition approved April 1, 2021. Published May 2021. Originally

approved in 1972. Last previous edition approved in 2016 as C703 – 72(2016). DOI:

10.1520/C0703-72R21.

Method A is based on Bulletin AL-1a, Recommended Test Methods for

Evaluation and Control of Quality of Porcelain Enamel on Aluminum ,ofthe

Porcelain Enamel Institute.

Method B is based on Bulletin T-51, Antimony Trichloride Spall Test of

Porcelain Enameled Aluminum, of the Porcelain Enamel Institute.

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.

7. Procedure

7.1 Immerse the test specimens completely in the NH

solution at room temperature. Large production pieces may be

immersed in a container made by lining a packing box with

polyethylene plastic sheeting.

7.2 Make a visual inspection after 96 h of immersion.

NOTE 1—Variations of this test may be used for studies of processing

variables. These include scored or deformed samples, 24 h inspection, and

multiple cycles of 96 h each.

8. Evaluation

8.1 Any of the following types of spall that develop within

96 h shall constitute failure:

8.1.1 Any spall area (revealing bare metal) extending

⁄

in.

(3 mm), or more, in from an edge and more than 1 in. (25 mm)

in length,

8.1.2 Any spall area on the interior surface (not touching an

edge) that is more than

⁄

in. (3 mm) to its maximum

dimension, or

8.1.3 More than six visible spall spots per 1 ft

(929 cm

)on

the interior surface.

9. Report

9.1 The report shall include the following:

9.1.1 Evaluation of the specimen as passing or failing the

immersion test in 96 h,

9.1.2 Complete identiﬁcation of the specimen, including the

basis metal, metal pretreatment, enamel slip formulation, ﬁring

time and temperature, date, and any other pertinent processing

information, and

9.1.3 Size, description of part, number of specimens tested,

and ratio of parts tested to parts produced.

TEST METHOD B—ANTIMONY TRICHLORIDE

10. Apparatus

10.1 Container, glass or plastic, large enough to immerse all

or part of the test specimen and hold a minimum of 3 mL of

solution per square centimetre of specimen surface.

10.2 Steel Rod or Mandrel of

⁄

-in. (12.7-mm) diameter.

11. Reagent

11.1 Antimony Trichloride Solution (1 %)—The test

solution, freshly prepared, shall consist of 1 part, by mass, of

antimony trichloride (SbCl

) (technical grade is adequate)

dissolved in 99 parts, by mass, of water (10 g/L). Tap water

may be used. Stir the solution thoroughly to disperse the

antimony trichloride.

11.2 Discard the test solution when it becomes 3 days old or

when the 1 gal/195 in.

(3 mL/cm

) limit is reached, whichever

occurs ﬁrst.

12. Test Specimens

12.1 When practical, full-size production pieces may be

tested; otherwise, specimens approximately 4 by 6 in. (102 by

152 mm), cut from production parts or a 4-in. (102-mm) wide

cross-sectioned cut sample from a production piece should be

tested. It is necessary that the metal-enamel interface is

exposed to the test solution. Cut edges or the cracks in the

enamel caused by bending over a mandrel usually accomplish

this. If not, the interface should be exposed by scoring the

enamel. At least one representative specimen from each “job”

or each 1000 ft

(93 m

) of production, whichever is

applicable, should be spall tested.

12.2 Test production parts in as-produced condition.

12.3 Wherever practical (such as porcelain enameled sheet

material) specimens cut from production pieces should be bent

to a 45° angle over a

⁄

-in. (12.7-mm) diameter rod or mandrel.

13. Procedure

13.1 Immerse as much of the test specimen as practical in

the SbCl

solution at room temperature. If a sample has been

bent over a mandrel, the bent portion must be immersed in the

solution.

13.2 After 20 h of immersion, rinse the sample in water and

scrub with a sponge to remove loose glass ﬂakes (particularly

on the bent areas).

14. Evaluation

14.1 On ﬂat or non-deformed areas, any of the following

types of spall that develop within 20 h shall constitute failure:

14.1.1 Any spall area (revealing bare metal) extending

⁄

in.

(3 mm), or more, in from an edge and more than 1 in. (25 mm)

in length.

14.1.2 Any spall area on the interior surface (not touching

an edge) that is more than

⁄

in. (3 mm) in its maximum

dimension, or

14.1.3 More than six visible spall spots per 1 ft

(929 cm

)

on the interior surface. Disregard pinholes up to

⁄

-in.

(1.5-mm) diameter.

14.2 The evaluation of spall on the formed (bent) enamel

areas has not been standardized for all aluminum alloys used in

sheet form. While spalling on bends indicates a potential ﬁeld

failure of production pieces, absence of spalling on bends may

not be indicative of good porcelain adherence of all aluminum

alloys in sheet form. For 1100 clad alloy, the following spall

developing in 20 h shall constitute failure:

14.2.1 Any spall area on the bent portion (excluding the

edges) that is more than

⁄

in. (3 mm) wide or more than

⁄

in.

(12.7 mm) in length.

15. Report

15.1 The report shall include the following:

15.1.1 Evaluation of the specimens as passing or failing the

immersion test in 20 h, for the bent or deformed and ﬂat areas,

respectively,

15.1.2 Complete identiﬁcation of the specimen, including

the basis metal, metal pretreatment, enamel slip formulation,

ﬁring time and temperature, date, and any other pertinent

processing information, and

15.1.3 Size, description of parts, number of specimens

tested, and ratio of parts tested to parts produced.

C703 − 72 (2021)

16. Precision and Bias

16.1 No justiﬁable statements can be made regarding the

precision and bias of these test methods because it is designed

for application to full-size production parts, with the result that

variables due to design, metal composition, fabrication, and

metal processing, as well as porcelain enameling, are intro-

duced into the results.

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned

in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk

of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every ﬁve years and

if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards

and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the

responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should

make your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,

United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above

address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website

(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222

Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/

C703 − 72 (2021)

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摘要：

ASTM C703 - 72 (2021) 是美国材料与试验协会发布的一项标准规范，全称为《耐火砖抗崩裂性试验方法》。该标准最初于1972年批准，并于2021年进行了最新确认，规定了通过反复加热和冷却循环来评估耐火砖抗热震崩裂性能的试验程序。内容包括试样制备、加热炉条件、温度循环次数以及崩裂后质量损失或裂纹扩展的判定方法。该标准适用于高温工业窑炉用耐火材料，帮助用户评估材料在急冷急热工况下的耐久性，为材料选型、质量控制和工艺改进提供可靠依据。关键词为：ASTM C703, refractory

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