1、Designation: C 703 72 (Reapproved 2006)Standard Test Methods forSpalling Resistance of Porcelain Enameled Aluminum1This standard is issued under the fixed designation C 703; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover accelerated determination ofthe resistance of porcelain enamel coatings on aluminum alloy
3、sto 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 20 h ofimmersion. The spalling tendency is evaluated by the samecriteria in both
4、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 order:SectionsTest Method AAmmonium Chloride 4-9Test Method BAntimony Trichloride 10
5、-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 or enamel formulations, incorrect pretreatmentof the base metal, or faulty applic
6、ation 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 moisture or weather-ing.TEST METHOD AAMMONIUM CHLORIDE4. Apparatus4.1 Container, gla
7、ss 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 beexposed to the test solution.5. Reagent5.1 Ammonium Chloride Solution (5 %)The t
8、est 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 case of very large production pieces, tapwater may be used. Sufficient solution
9、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 production parts should be tested. At leastone representative specimen from each “j
10、ob” or each 1000 ft2(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 pie
11、ces may beimmersed 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 c
12、ycles of 96 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
13、touching anedge) 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.1These test methods are under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and are the direct responsibility of Subc
14、ommitteeB08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved April 1, 2006. Published April 2006. Originallyapproved in 1972. Last previous edition approved in 1999 as C 703 72 (1999).2Method A is based on Bulletin AL-1a, Recommended Test Methods forEvaluation
15、and Control of Quality of Porcelain 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 Consho
16、hocken, PA 19428-2959, United States.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 identification of the specimen, including thebasis metal, metal pretreatment, enamel slip formulation, firingtime a
17、nd 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 BANTIMONY TRICHLORIDE10. Apparatus10.1 Container, glass or plastic, large enough to immerse allor part of the te
18、st 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 (1 %)The test solu-tion, freshly prepared, shall consist of 1 part, by mass, ofantimony trichloride (SbCl3)
19、(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 solution when it becomes 3 days old orwhen the 1 gal/195 in.2(3 mL/cm2) limit is reached, whicheveroccurs first
20、.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) widecross-sectioned cut sample from a production piece should betested. It is necessary that the metal-enamel
21、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 theenamel. At least one representative specimen from each “job”or each 1000 ft2(93 m2) of production, whichever i
22、s 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 should be bentto a 45 angle over a12-in. (12.7-mm) diameter rod or mandrel.13. Procedure13.1 Immerse as mu
23、ch 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 immersion, rinse the sample in water andscrub with a sponge to remove loose glass flakes (particularlyon the bent
24、 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) extending18 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 th
25、e 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 pinholes up to116-in.(1.5-mm) diameter.14.2 The evaluation of spall on the formed (bent) enamelareas has no
26、t 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 of good porcelain adherence of all aluminumalloys in sheet form. For 1100 clad alloy, the following spalld
27、eveloping 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. Report15.1 The report shall include the following:15.1.1 Evaluation of the specimens as passing or failing theimmers
28、ion 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,firing time and temperature, date, and any other pertinentprocessing information, and15.1.3 Size, description o
29、f parts, number of specimenstested, and ratio of parts tested to parts produced.16. Precision and Bias16.1 No justifiable statements can be made regarding theprecision and bias of these test methods because it is designedfor application to full-size production parts, with the result thatvariables du
30、e to design, metal composition, fabrication, andmetal processing, as well as porcelain enameling, are intro-duced into the results.C 703 72 (2006)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users o
31、f 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 responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every fiv
32、e 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 ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical c
33、ommittee, 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 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 aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 703 72 (2006)3
