1、Designation: C283 13Standard Test Methods forResistance of Porcelain Enameled Utensils to Boiling Acid1This standard is issued under the fixed designation C283; 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 () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe described method furnishes a means of quantitatively testing and grading glossy porcelainenamels with respect to their resis
3、tance to boiling citric acid at room temperature. Citric acid has beenselected because it is the most common and one of the more severe of the food acids in its action onconventional porcelain enamels.1. Scope1.1 These test methods cover the determination of theresistance of porcelain enamel coating
4、s used on utensils toattack by boiling acid.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to add
5、ress 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 practices and determine the applica-bility of regulatory limitations prior to use.2. Significance and Use2.1 Test Method A provides the pr
6、oducers of porcelainenameled utensils with a quality control method of testing forresistance to boiling acid for parts randomly selected from theproduction line.2.2 Test Method B provides the supplier of porcelainenamel raw materials with a laboratory method for testing theresistance of different co
7、atings (intended for use on utensils) toboiling acid.TEST METHOD A3. Apparatus3.1 Hot Plate, capable of maintaining over its entire surfacea uniform temperature that will keep the test solution at arolling boil (see section 7.5). The heating element shouldoccupy an area at least 8 in. (203 mm) in di
8、ameter.3.2 Chemical GlasswareBeakers, a desiccator, and a500-mL graduated cylinder.3.3 Drier, capable of maintaining a temperature of at least220F (104C).3.4 Boiling Acid Resistance Apparatus, as shown in Fig. 1.Three sets will be required.3.5 Cutting Equipment, suitable for cutting a 314-in. (82-mm
9、) diameter plate from the bottom of a porcelain-enameledsteel utensil, as follows:3.5.1 Punch and Die (Fig. 2),3.5.2 Shears,3.5.3 Abrasive Cut-off Wheel,3.5.4 Cutting Torch, or3.5.5 Any Other Suitable Equipment3.6 Analytical Balance, having a sensitivity of 0.0001 g.4. Reagent4.1 The test solution s
10、hall contain6gofACSgrade citricacid per 94 g of distilled water and shall be prepared fresh foreach test.5. Test Specimens5.1 The test specimens shall consist of three plates, 314 in.(82 mm) in diameter, cut from the bottoms of three identicalutensils.1These test methods are under the jurisdiction o
11、f ASTM Committee B08 onMetallic and Inorganic Coatings and are the direct responsibility of SubcommitteeB08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.Current edition approved May 1, 2013. Published July 2013. Originally approvedin 1951. Last previous edition approved in 2008 as
12、C283 97 (2008). DOI:10.1520/C0283-13.Test Method A is based on the boiling acid resistance test developed by theEnameled Utensil Manufacturers Council; see Section 16 of Commercial StandardCS100-47, Porcelain Enameled Steel Utensils, United States Department of Com-merce.Copyright ASTM International
13、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1“Identical utensils” signifies utensils of the same size, shape,and finish.6. Preparation of Test Specimens6.1 After the test specimens have been cut from the utensils,file their edges with a triangular file
14、to remove any looseenamel chips.6.2 Thoroughly wash the test specimens with soap andwater to remove any grease picked up in handling. Rinse withdistilled water. Place the specimens in a drier at 220F (104C).After 10 min, remove the test specimens and place them in adesiccator containing calcium chlo
15、ride.7. Procedure7.1 Level the hot plate, turn the switch on in the high heatposition, and allow to preheat for at least1htoobtain auniform temperature over the entire heating element.7.2 Remove the test specimens, one at a time, from thedesiccator, hold at the edges, and inspect the edges for loose
16、chips. Remove any chips found, before the initial weighing.7.3 Weigh each specimen on an analytical balance, record-ing its weight to the nearest 0.0001 g.7.4 Place the heat-resistant gasket above the hole in thebase-plate of the boiling-acid resistance apparatus (Fig. 1).Place the test specimen ove
17、r the gasket, with the surface fromthe inside of the utensil up. Next, place a rubber jar ring on thetest specimen. This serves as a seal between the test specimenand the heat-resistant glass tube, which shall be placed over it.Place another rubber jar ring on top of the glass tube, set thecover-pla
18、te on it, and clamp in place by tightening the wingnuts. Tighten the wing nuts until a seal is obtained between theglass tube and the test specimen. This can be determined byinspecting the seal ring, when the nuts are tight enough, theoutside edges of the rubber jar rings will lift from the testspec
19、imen. Use the bottom jar rings only twice (once on eachside); then discard for new ones.7.5 Bring approximately 500 mL of the citric acid solutionto boiling, pour 150 mL of the solution into each glass tube,and set the glass condensing tubes in position. Promptly centerthe three test units on the ho
20、t plate, as shown in Fig. 3, andleave the test units in place for a period of 212 h. After thesolutions begin to boil, decrease the wattage input so that thesolutions remain at a rolling boil for the remainder of the testperiod.in. mm in. mm in. mm in. mm116 1.6 114 32 2.5 64 4116 10318 3.2 12532 45
21、 314 82 418 10514 6.4 214 57 338 86 512 14038 9.5 2.31 59 4 102 14 356(a) Assembly (b) DetailsFIG. 1 Boiling-Acid Resistance ApparatusC283 1327.6 At the end of the test period, remove the units andcondenser tubes from the hot plate and pour out the solutions,then rinse the insides of the tubes and t
22、he test specimens withdistilled water, and dismantle the apparatus. Remove the testspecimens, rinse again with distilled water scrub the testspecimens gently with a nylon brush (10 to 12 strokes) toremove loose residue in the attack area, and dry in the drier at220F (104C) for 10 min. Place the spec
23、imens in a desiccatorand cool to room temperature.7.7 After the test specimens are cool, again weigh themseparately on the analytical balance.8. Calculations and Report8.1 The difference between the initial and the final weight ofeach specimen, divided by four, gives the loss in weight persquare inc
24、h of exposed area (wetted surface) (Note 2). Take theaverage loss per square inch for three specimens from threeidentical utensils for the boiling-acid resistance of the enamel.NOTE 2Wetted surface area is that surface which is attacked by thetest solution.8.2 If, however, any one of the three resul
25、ts does not agreewithin 610 % of the average, another set of three plates fromutensils identical with those of the first set shall be tested. Theindividual values of loss in weight per square inch for thesecond set of plates shall be averaged with the individualvalues of the first set, any individua
26、l value not within 610 %of the average for the six plates shall be discarded, and theaverage of the remaining values shall be taken as the boiling-acid resistance of the enamel.TEST METHOD B9. Apparatus9.1 Same as Section 3.10. Reagent10.1 See 4.1.11. Test Specimens11.1 The test specimens shall cons
27、ist of three plates 314 in.(82 mm) in diameter, cut from a sheet of raw Utensil Steelstock.12. Preparation of Test Specimens12.1 After the test specimens have been cut from the steelsheet, the edges are rounded with a file to insure uniformcoverage.12.2 The test specimens are then metal prepared by
28、the testusers preferred method (that is, cleaning or nickel flashpickling).12.3 One hole18 in. (3.2 mm) in diameter is punched ineach test specimen, the center of which is14 in. (6.4 mm) fromthe outer edge of the specimen plate. This hole is necessary forhanging the specimen during firing of the coa
29、ting being tested.12.4 The enamel coating to be tested may be applied to thethree test plates by dipping or spraying at 30 g/ft2dry (323g/m2). Spraying is the preferred method for minimizing edgebeading which may occur during dip application methods.Glass beads may chip off during the test leading t
30、o greaterweight losses for that specimen.12.5 The three test specimens (after drying if a wet appli-cation method is used) are fired at the optimum time andtemperature as established in the test users facility.12.6 Thoroughly wash the test specimens with soap andwater to remove any grease picked up
31、in handling. Rinse withdistilled water. Place the specimens in a drier at 220F (104C).After 10 min remove the test specimens and place them in adesiccator containing calcium chloride.13. Procedure13.1 See 7.1-7.7.14. Calculation and Report14.1 See 8.1 and 8.2.15. Precision and Bias15.1 The precision
32、 and bias of these test methods are beingestablished.in. mm in. mm in. mm in. mm116 1.6516 8114 32 31316 97332 2.438 9.5 2 51 4 10218 3.2916 14 314 82 478 12414 6.4 1 25 334 95FIG. 2 Punch and Die for Cutting Out Test SpecimensC283 13316. Keywords16.1 acid resistance; chemical resistance; coating; c
33、orrosionresistance; porcelain enamel; vitreous enamelASTM 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
34、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
35、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
36、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
37、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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).in. mm8 2039 22811 279FIG. 3 Position of Test Units of Boiling-Acid Resistance Apparatus on Hot PlateC283 134
