1、Designation: C703 72 (Reapproved 2011)1Standard Test Methods forSpalling Resistance of Porcelain Enameled Aluminum1This standard is issued under the fixed designation C703; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTETest Method was corrected editorially in 2011INTRODUCTIONThis test, using an ammonium chloride or antimony trichloride test
3、 solution, covers an acceleratedprocedure for determining the resistance of porcelain enamel coatings on aluminum and aluminumalloys to spontaneous loss of adhesion (spalling) resulting from exposure to moisture, weathering, orother environmental stress.1. Scope1.1 These test methods cover accelerat
4、ed determination ofthe resistance of porcelain enamel coatings on aluminum alloysto spalling from exposure to moisture or weathering. TestMethod A,2using a 5 % solution of ammonium chloride,requires 96-h immersion while Test Method B,3using a 1 %solution of antimony trichloride, is completed after 2
5、0 h ofimmersion. The spalling tendency is evaluated by the samecriteria in both methods. While either method is suitable formagnesium silicon alloys, such as 6061, Test Method B ispreferred for simple alloys or commercially pure aluminum,such as 1100.1.2 The test methods appear in the following orde
6、r:SectionsTest Method AAmmonium Chloride 4-9Test Method BAntimony Trichloride 10-152. Terminology2.1 Definitions:2.1.1 spallinga defect characterized by separation of theporcelain enamel from the aluminum base metal withoutapparent external cause. Spalling can result from the use ofimproper alloys o
7、r enamel formulations, incorrect pretreatmentof the base metal, or faulty application and firing procedures.3. Significance and Use3.1 It is difficult to overemphasize the importance of thespall test. Porcelain enameled aluminum that fails this test willprobably spall in service if subjected to mois
8、ture or weather-ing.TEST METHOD AAMMONIUM CHLORIDE4. Apparatus4.1 Container, glass or plastic, large enough to immerse thetest area of the specimen completely and hold a minimum of 3mL of solution per square centimetre of the immersed surface.No metal other than the base metal of the specimen may be
9、exposed to the test solution.5. Reagent5.1 Ammonium Chloride Solution (5 %)The test solution,freshly prepared, shall consist of 5 parts, by mass, of ammo-nium chloride (NH4Cl) (technical grade is adequate) dissolvedin 95 parts, by mass, of water. Deionized or distilled water ispreferred, but in the
10、case of very large production pieces, tapwater may be used. Sufficient solution shall be prepared topermit complete immersion of the specimens.6. Test Specimens6.1 Full-size production pieces should be tested. When thisis not practical, specimens approximately 4 by 6 in. (102 by152 mm), cut from pro
11、duction parts should be tested. At leastone representative specimen from each “job” or each 1000 ft21These test methods are under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and are the direct responsibility of SubcommitteeB08.12 on Materials for Porcelain Enamel and Cer
12、amic-Metal Systems.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1972. Last previous edition approved in 2006 as C703 72 (2006).DOI: 10.1520/C0703-72R11E01.2Method A is based on Bulletin AL-1a, Recommended Test Methods forEvaluation and Control of Quality of Por
13、celain Enamel on Aluminum ,ofthePorcelain Enamel Institute.3Method B is based on Bulletin T-51, Antimony Trichloride Spall Test ofPorcelain Enameled Aluminum, of the Porcelain Enamel Institute.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
14、 States.(93 m2) of production, whichever is applicable, should be spalltested. Spall-tested pieces should not be shipped.6.2 Test production parts in as-produced condition.7. Procedure7.1 Immerse the test specimens completely in the NH4Clsolution at room temperature. Large production pieces may beim
15、mersed in a container made by lining a packing box withpolyethylene plastic sheeting.7.2 Make a visual inspection after 96 h of immersion.NOTE 1Variations of this test may be used for studies of processingvariables. These include scored or deformed samples, 24 h inspection, andmultiple cycles of 96
16、h each.8. Evaluation8.1 Any of the following types of spall that develop within96 h shall constitute failure:8.1.1 Any spall area (revealing bare metal) extending18 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 ane
17、dge) that is more than18 in. (3 mm) to its maximumdimension, or8.1.3 More than six visible spall spots per 1 ft2(929 cm2)onthe interior surface.9. Report9.1 The report shall include the following:9.1.1 Evaluation of the specimen as passing or failing theimmersion test in 96 h,9.1.2 Complete identifi
18、cation of the specimen, including thebasis metal, metal pretreatment, enamel slip formulation, firingtime and temperature, date, and any other pertinent processinginformation, and9.1.3 Size, description of part, number of specimens tested,and ratio of parts tested to parts produced.TEST METHOD BANTI
19、MONY TRICHLORIDE10. Apparatus10.1 Container, glass or plastic, large enough to immerse allor part of the test specimen and hold a minimum of 3 mL ofsolution per square centimetre of specimen surface.10.2 Steel Rod or Mandrel of12-in. (12.7-mm) diameter.11. Reagent11.1 Antimony Trichloride Solution (
20、1 %)The test solu-tion, freshly prepared, shall consist of 1 part, by mass, ofantimony trichloride (SbCl3) (technical grade is adequate)dissolved in 99 parts, by mass, of water (10 g/L). Tap watermay be used. Stir the solution thoroughly to disperse theantimony trichloride.11.2 Discard the test solu
21、tion when it becomes 3 days old orwhen the 1 gal/195 in.2(3 mL/cm2) limit is reached, whicheveroccurs first.12. Test Specimens12.1 When practical, full-size production pieces may betested; otherwise, specimens approximately 4 by 6 in. (102 by152 mm), cut from production parts or a 4-in. (102-mm) wid
22、ecross-sectioned cut sample from a production piece should betested. It is necessary that the metal-enamel interface isexposed to the test solution. Cut edges or the cracks in theenamel caused by bending over a mandrel usually accomplishthis. If not, the interface should be exposed by scoring theena
23、mel. At least one representative specimen from each “job”or each 1000 ft2(93 m2) of production, whichever is appli-cable, should be spall tested.12.2 Test production parts in as-produced condition.12.3 Wherever practical (such as porcelain enameled sheetmaterial) specimens cut from production pieces
24、 should be bentto a 45 angle over a12-in. (12.7-mm) diameter rod or mandrel.13. Procedure13.1 Immerse as much of the test specimen as practical inthe SbCl3solution at room temperature. If a sample has beenbent over a mandrel, the bent portion must be immersed in thesolution.13.2 After 20 h of immers
25、ion, rinse the sample in water andscrub with a sponge to remove loose glass flakes (particularlyon the bent areas).14. Evaluation14.1 On flat or non-deformed areas, any of the followingtypes of spall that develop within 20 h shall constitute failure:14.1.1 Any spall area (revealing bare metal) exten
26、ding18 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 touchingan edge) that is more than18 in. (3 mm) in its maximumdimension, or14.1.3 More than six visible spall spots per 1 ft2(929 cm2)on the interior surface. Disregard
27、pinholes up to116-in.(1.5-mm) diameter.14.2 The evaluation of spall on the formed (bent) enamelareas has not been standardized for all aluminum alloys used insheet form. While spalling on bends indicates a potential fieldfailure of production pieces, absence of spalling on bends maynot be indicative
28、 of good porcelain adherence of all aluminumalloys in sheet form. For 1100 clad alloy, the following spalldeveloping in 20 h shall constitute failure:14.2.1 Any spall area on the bent portion (excluding theedges) that is more than18 in. (3 mm) wide or more than12 in.(12.7 mm) in length.15. Report15.
29、1 The report shall include the following:15.1.1 Evaluation of the specimens as passing or failing theimmersion test in 20 h, for the bent or deformed and flat areas,respectively,15.1.2 Complete identification of the specimen, includingthe basis metal, metal pretreatment, enamel slip formulation,firi
30、ng time and temperature, date, and any other pertinentprocessing information, and15.1.3 Size, description of parts, number of specimenstested, and ratio of parts tested to parts produced.C703 72 (2011)1216. Precision and Bias16.1 No justifiable statements can be made regarding theprecision and bias
31、of these test methods because it is designedfor application to full-size production parts, with the result thatvariables due to design, metal composition, fabrication, andmetal processing, as well as porcelain enameling, are intro-duced into the results.C703 72 (2011)13ASTM International takes no po
32、sition respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibi
33、lity.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to A
34、STM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the addres
35、s 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 aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C703 72 (2011)14
