1、Designation: C 614 74 (Reapproved 2005)Standard Test Method forAlkali Resistance of Porcelain Enamels1This standard is issued under the fixed designation C 614; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 This test method2covers the measurement of the resis-tance of a porcelain enamel to a hot solution of tetrasodiumpyrophosphate.
3、 Although the specific alkali mentioned hereinis tetrasodium pyrophosphate the equipment and techniques areequally applicable to other alkali solutions.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of thi
4、s standard to establish appro-priate safety and health practices 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
5、on washing machines, dishwashers, combinationwasher-dryers, 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 stainl
6、ess steelbeaker fitted with an O-ring sealed cover which supports animmersion heater, a stirring device, thermometer and ther-mistor wells; three specimen holders; a reflux condenser; aflow channeling shield to slide over and be supported by theimmersion heater; and a stirring motor.3The beaker, hea
7、tersheath, stirring device, thermometer and thermistor wells,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 beakera
8、t 96.00 6 0.20C.3.3 Thermometer, calibrated, approximately 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.3.6 Desiccator.3.7 Hot Plate, or burner suitable fo
9、r 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. Reagents and Materials4.1 Tetrasodium Pyrophosphate, hydrated (Na4P2O710H2O), recrystallized, reagent grade.4.2 Trisodium Phosphate (Na3PO412H2O).5. Test Speci
10、mens5.1 Preparation of Specimens The test specimens shallbe 312 in. (89 mm) square and may be prepared by enamelingmetal blanks of that size 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
11、flatto permit sealing in the holders. The edges of cut specimensshall be stoned or filed to remove any sharp or loosely adheringfragments of metal or porcelain enamel. It is recommended thatthe specimens be permanently marked on the back side foridentification.5.2 Number of SpecimensSix specimens sh
12、all be testedsimultaneously.5.3 Cleaning of Specimens Before Alkali ExposureThespecimens shall be rinsed with running tap water and washedwith 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
13、 used in thewashing.After washing, the specimens shall be rinsed first withrunning tap water, next with distilled water and then allowed todrain 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
14、of Test SpecimensThe specimens shall beweighed immediately upon removal from the desiccator.Weights shall be recorded to 0.0001 g. The weighed specimensshall be stored in a desiccator until tested.1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and
15、is the direct responsibility of Subcommittee B08.12 onMaterials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved Sept. 15, 2005. Published September 2005. Originallyapproved in 1968. Last previous edition approved in 1999 as C 614 74 (1999).2This test was developed at the Nati
16、onal 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 44906.1Copyright ASTM I
17、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 b
18、eaker and cover the rectangular slots with 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
19、gas burner. When a temperature near 96C has 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.
20、6.3 Preparation for Alkali Exposure Place 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 ins
21、ert the clamping device between the twosheets. Tighten the clamping device only enough to give aleakproof seal. Test the seal by filling the specimen box withwater to confirm the absence of leaks. Next, remove the waterand preheat the specimen holder assembly in an oven at 110Cfor about 15 min.6.4 E
22、xposure 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 insertion of the specimen holders and shallend with their wit
23、hdrawal. 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 apart, which have been measuredto the nearest 0.01 in. (0.2
24、5 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 etched attack, in.2(0.155 3 cm2), andE = area of etched attack,
25、 cm2(6.45 3 in.2).8. 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 theequation:e 5 1.15 s
26、 (3)NOTE 1Test solution is in stainless steel beaker.FIG. 1 Alkali Equipment in OperationC 614 74 (2005)2where: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
27、.NOTE 1The factor 1.15 is applied only when the number of specimensis six, and the 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 w
28、eight loss values of thesix individual specimens, andX2= the square of the mean weight loss of the sixspecimens.8.1.2 Illustrative calculations are given below. The recom-mended number of decimal places is given in each case:Dimension in. mmA 9 229B14 6.4CThermistor well1132 8.7 OD818 206 lengthDThe
29、rmometer 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 for Alkali EquipmentC 614 74 (2005)3Specimen 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 7.616
30、7 58.1417from Eq 3:s5=58.1417 2 7.6167!25 =0.1276 5 0.357 (6)from Eq 1:e 5 1.15 3 0.357 5 0.411 (7)The weight loss Lis reported as 7.66 0.4 mg/in28.2 Difference Between Two DeterminationsThe signifi-cance of a difference between two mean values shall be testedthrough the use of the ratio d:e8where:d
31、 = 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 be determined from the following equation:e8 5 =e1!21 e2!2(8)where:e8 = the error of the difference in means,e1= the error of one mean val
32、ue, 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 (9)d/e8 5 0.6/0.58 5 1.03A Empty specimen holder in position.B Immersion heater.C Thermometer well.D Thermistor
33、 well.E Stirrer.F Circular shield (lowered for clarity).FIG. 3 Cover AssemblyC 614 74 (2005)4When 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
34、of six specimens.d:e8ConfidenceLevel, % InterpretationOver 1.50 99 or 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.
35、 Precision and Bias9.1 The precision and bias of this method are beingdeveloped.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 EquipmentC 614 74 (2005)5Dimension in.
36、 mmA414 108B334 95C1764 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 withd
37、rawn).FIG. 6 Specimen Holder AssemblyC 614 74 (2005)6ASTM International takes no position 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 ri
38、ghts, 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 five years andif not revised, either reapproved or withdrawn. Your comments are invited either fo
39、r 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 committee, which you may attend. If you feel that your comments have not received a fair hearin
40、g 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 ma
41、y 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).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 PlateC 614 74 (2005)7
