1、Designation: C614 10 (Reapproved 2011)1Standard Test Method forAlkali Resistance of Porcelain Enamels1This standard is issued under the fixed designation C614; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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 2011INTRODUCTIONAlthough all porcelain enamels are highly resistant to atttack by cold alkaline
3、 solutions, somecompositions are affected by hot solutions of the type encountered in automatic laundry anddishwashing equipment. Tests to eliminate porcelain enamels of poor resistance have been developedand used by various laboratories. In general, these tests consist of subjecting specimens to a
4、boilingsolution of either sodium pyrophosphate or sodium hydroxide for a period of two or more hours. Thespecimens are weighed before and after exposure to the test treatment and the loss-in-weight is takenas a measure of alkali attack. In some tests representing milder exposure conditions, the 45 d
5、egreespecular gloss is measured before and after exposure and the percentage of initial gloss retained is usedas an indicator of alkali resistance. While such tests have served a useful purpose in developing moreresistant porcelain enamel compositions and in manufacturing control operations, agreeme
6、nt betweenlaboratories has left something to be desired. The present test was designed to provide thereproducibility between laboratories that is so essential to any standard test procedure.1. Scope1.1 This test method2covers the measurement of the resis-tance of a porcelain enamel to a hot solution
7、 of tetrasodiumpyrophosphate. Although the specific alkali mentioned hereinis tetrasodium pyrophosphate the equipment and techniques areequally applicable to other alkali solutions.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematic
8、alconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health p
9、ractices and determine the applica-bility of regulatory limitations prior to use.2. Significance and Use2.1 This test method is intended specifically for testing theresistance to alkaline attack of porcelain enamels to be used asa final finish on washing machines, dishwashers, combinationwasher-drye
10、rs, and similar appliances where the surface isnormally exposed to an alkaline environment at elevatedtemperatures.3. Apparatus3.1 Test Chamber, of a type illustrated in Fig. 1, Fig. 3, andFig. 6. This part of the equipment consists of a stainless steelbeaker fitted with an O-ring sealed cover which
11、 supports animmersion heater, a stirring device, thermometer and thermis-tor wells; three specimen holders; a reflux condenser; a flowchanneling shield to slide over and be supported by theimmersion heater; and a stirring motor.3The beaker, heatersheath, stirring device, thermometer and thermistor w
12、ells,specimen holders, and the flow channeling shield shall be madefrom stainless steel alloys from the AISI 300 Series.3.2 Temperature Controller, thermistor-actuated, capable ofmaintaining the temperature of the alkali solution in the beakerat 96.00 6 0.20C.3.3 Thermometer, calibrated, approximate
13、ly 15 in. (380mm) long and932 in. (7.1 mm) in diameter, with 0.1 divisions.3.4 Drying Oven, electrically heated.3.5 Balance, having a sensitivity of 0.1 mg and a capacity ofnot less than 200 g.1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is t
14、he direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1968. Last previous edition approved in 2005 as C614 10. DOI:10.1520/C0614-10R11E01.2This test was developed
15、at the National Bureau of Standards under thesponsorship of The Porcelain Enamel Institute, Inc., and published as P. E. I.Bulletin T-25.3See the appendix for drawings of the equipment. This equipment may bepurchased from the Hoover Instrument Service, Inc., 401 N. Home Rd.,Mansfield,OH 44906.1Copyr
16、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.6 Desiccator.3.7 Hot Plate, or burner suitable for heating the test solu-tion.3.8 Sponge, soft, cellulose.3.9 Aluminum Alloy Sheets, approximately 312 by 312 by18in. (89 by 89 by 3.1 mm).4.
17、 Reagents and Materials4.1 Tetrasodium Pyrophosphate, hydrated (Na4P2O710H2O), recrystallized, reagent grade.4.2 Trisodium Phosphate (Na3PO412H2O).5. Test Specimens5.1 Preparation of Specimens The test specimens shallbe 312 in. (89 mm) square and may be prepared by enamelingmetal blanks of that size
18、 or by cutting from a larger piece.Hanging holes, if necessary for firing or weighing or both, maybe placed at the corners. The specimens shall be sufficiently flatto permit sealing in the holders. The edges of cut specimensshall be stoned or filed to remove any sharp or loosely adheringfragments of
19、 metal or porcelain enamel. It is recommended thatthe specimens be permanently marked on the back side foridentification.5.2 Number of SpecimensSix specimens shall be testedsimultaneously.5.3 Cleaning of Specimens Before Alkali ExposureThespecimens shall be rinsed with running tap water and washedwi
20、th a soft cellulose sponge dampened with a 1 % solution oftrisodium phosphate. A light pressure and a back-and-forthmotion in two directions, 90 apart, shall be used in thewashing.After washing, the specimens shall be rinsed first withrunning tap water, next with distilled water and then allowed tod
21、rain in a near vertical position prior to oven-drying at 110Cfor 15 min. The specimens shall be cooled in a desiccator for30 min prior to weighing.5.4 Weighing of Test SpecimensThe specimens shall beweighed immediately upon removal from the desiccator.Weights shall be recorded to 0.0001 g. The weigh
22、ed specimensshall be stored in a desiccator until tested.6. Procedure6.1 Preparation of Test SolutionPrepare the test solutionby adding 260 g of tetrasodium pyrophosphate to 4.940 litresof distilled water. Pour the entire amount of prepared solutioninto the beaker and cover the rectangular slots wit
23、h lids. Use afreshly prepared solution for each set of six specimens.6.2 Preheating Test SolutionPlace the temperature con-troller and stirrer in operation and preheat the solution to 96C.Heating may be expedited by placing the beaker on a hot plateor over a gas burner. When a temperature near 96C h
24、as beenreached, remove the beaker from the hot plate and place on aninsulated surface. Allow an equilibration period of 15 min forall parts of the equipment to achieve a stable temperature, andadjustment of the control point to yield the desired tempera-ture.6.3 Preparation for Alkali Exposure Place
25、 two clean,weighed specimens in each specimen-holder box. Shims maybe useful in the bottom of the specimen boxes to center thespecimens vertically about the exposure openings. Back-upeach specimen with a stress distributing aluminum alloybacking sheet and insert the clamping device between the twosh
26、eets. Tighten the clamping device only enough to give aNOTE 1Test solution is in stainless steel beaker.FIG. 1 Alkali Equipment in OperationC614 10 (2011)12leakproof seal. Test the seal by filling the specimen box withwater to confirm the absence of leaks. Next, remove the waterand preheat the speci
27、men holder assembly in an oven at 110Cfor about 15 min.6.4 Exposure of SpecimensWhen the test solution hasreached 96C and is under control, remove the lids and insertpreheated specimen holder assemblies in the proper openings.Expose six specimens for6hat966 0.20C. The exposuretime shall start upon i
28、nsertion of the specimen holders and shallend with their withdrawal. After removal from the holdersclean, dry and weigh the specimens as specified in 5.3 and 5.4.6.5 Measurement of Exposed AreaCalculate the area ofthe etched portion of the specimen using the average of twodiameters, approximately 90
29、 apart, which have been measuredto the nearest 0.01 in. (0.25 mm).7. Calculation7.1 Calculate the weight loss for each specimen as follows:L, mg/in.25 B C! 3 103/D (1)orL, mg/cm25 B C! 3 103/E (2)where:L = weight loss,B = original weight of specimen, g,C = final weight of specimen, g,D = area of etc
30、hed attack, in.2(0.155 3 cm2), andE = area of etched attack, cm2(6.45 3 in.2).Dimension in. mmA 9 229B14 6.4CThermistor well1132 8.7 OD818 206 lengthDThermometer well38 9.2 OD818 206 lengthE12 12.7F112 38.0GHeater chuck58 15.9H114 32.0I11732 39.0J158 41.5K78 22.2L378 98M11532 37.5N218 54FIG. 2 Cover
31、 for Alkali EquipmentC614 10 (2011)138. Treatment of Data8.1 Single DeterminationSix specimens shall constitute asample. The average of six values of weight loss (L), shall betermed the mean weight loss, L, for the sample. The statisticalerror of the determination shall be computed by the use of the
32、equation:e 5 1.15 s (3)where:e = the statistical error of the mean value for the sample,at the 95 % confidence level, ands = the standard deviation of the six individual weightlosses from the average of all six weights.NOTE 1The factor 1.15 is applied only when the number of specimensis six, and the
33、 confidence level is 95 %.8.1.1 This standard deviation shall be computed from thegeneralized equation:s5=(X2/n! X2(4)or if the number of specimens, n, is six, from:s5=(X2/6! X2(5)where:(X2= sum of the squares of the weight loss values of thesix individual specimens, andX2= the square of the mean we
34、ight loss of the sixspecimens.8.1.2 Illustrative calculations are given below. The recom-mended number of decimal places is given in each case:Specimen No. L, mg/in.2L21 7.7 59.292 7.5 56.253 6.9 47.614 8.0 64.005 7.7 59.296 7.9 62.41Sum 45.7 348.85Mean 7.6167 58.1417from Eq 3:s5=58.1417 2 7.6167!25
35、 =0.1276 5 0.357 (6)from Eq 1:A Empty specimen holder in position.B Immersion heater.C Thermometer well.D Thermistor well.E Stirrer.F Circular shield (lowered for clarity).FIG. 3 Cover AssemblyC614 10 (2011)14e 5 1.15 3 0.357 5 0.411 (7)The weight loss Lis reported as 7.66 0.4 mg/in28.2 Difference B
36、etween Two DeterminationsThe signifi-cance of a difference between two mean values shall be testedthrough the use of the ratio d:e8where:d = the difference in means, ande8 = the statistical error in the determination of d.8.2.1 The statistical error, e8, of the difference, d, betweentwo means shall
37、be determined from the following equation:e8 5 =e1!21 e2!2(8)Dimension in. mmA3116 78B 1 25.4C178 47.5D716 11.1E316 4.75F116 1.59G712 190H512 140I612 165J 9 229K 9.8 249L316 4.75M1014 260N12 12.7O516 7.9P12 12.7Q34 19.0R2 51FIG. 4 Alkali Test EquipmentC614 10 (2011)15Dimension in. mmA414 108B334 95C
38、1764 6.7D11132 34.0E178 47.5F 0.079 2.01G14 6.4H 6 152I 8 203J332 2.40K18 3.18L212 64M234 70N3 76P 0.060 1.52NOTE 1Box welded from 14-gage (0.079 in.) stainless steel.FIG. 5 Detail Specimen HolderAShowing a specimen.BThe back-up plate.CO-ring interior.DClamping plate (partly withdrawn).FIG. 6 Specim
39、en Holder AssemblyC614 10 (2011)16where:e8 = the error of the difference in means,e1= the error of one mean value, ande2= the error of the other mean value.8.2.2 An example to illustrate the use of Eq 4 is givenbelow:Assume:L1= 7.66 0.5,L2= 8.26 0.3, andd = 0.6.Then:e8 5 =0.5!21 0.3!25 =0.34 5 0.58
40、(9)d/e8 5 0.6/0.58 5 1.03When d:e8 is equal to or greater than 1.00, the difference issignificant at the 95 % confidence level.8.2.3 The following table shows the relation between valuesof d:e8 and the confidence level, for samples of six specimens.d:e8ConfidenceLevel, % InterpretationOver 1.50 99 o
41、r higher highly significantOver 1.00 but less 95 to 99 significantthan 1.50 90 to 95 indicativeOver 0.80 but lessthan 1.00The basing of conclusions on differences in which less than90 % confidence can be placed is not recommended.9. Precision and Bias9.1 The precision and bias of this method are bei
42、ngdeveloped.Dimension in. mmA314 83B118 28.5C18 3.18D14 6.4E1116 17.5F14 6.4G38 9.5H34 19.0I18 3.18J3716 87K34 19.0L516 7.9M158 41.5N12 12.7O258 67P14 6.4Q718 181R 0.060 1.52S 0.003 0.076T614 159FIG. 7 Stainless Steel Specimen Backup PlateC614 10 (2011)17ASTM International takes no position respecti
43、ng 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 responsibility.This stand
44、ard 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 ASTM Internation
45、al 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 address shown below.T
46、his 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/).C614 10 (2011)18
