ASTM C282-1999(2005) Standard Test Method for Acid Resistance of Porcelain Enamels (Citric Acid Spot Test)《搪瓷耐酸的标准试验方法(柠檬酸斑点试验)》.pdf
《ASTM C282-1999(2005) Standard Test Method for Acid Resistance of Porcelain Enamels (Citric Acid Spot Test)《搪瓷耐酸的标准试验方法(柠檬酸斑点试验)》.pdf》由会员分享,可在线阅读,更多相关《ASTM C282-1999(2005) Standard Test Method for Acid Resistance of Porcelain Enamels (Citric Acid Spot Test)《搪瓷耐酸的标准试验方法(柠檬酸斑点试验)》.pdf(3页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: C 282 99 (Reapproved 2005)Standard Test Method forAcid Resistance of Porcelain Enamels(Citric Acid Spot Test)1This standard is issued under the fixed designation C 282; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers a
3、 procedure for evaluatingporcelain enamels in their resistance to citric acid exposure atroom temperature. No attempt is made to categorize porcelainenamels as to their acid-resistance or non acid-resistanceproperties, since the requirements in the several branches of theindustry differ.1.2 The test
4、 method is applicable for ware of various shapesproviding they contain a substantially flat area approximately50 mm in diameter.1.3 The test method is not applicable to finishes on chemicaland hospital ware, which may come in contact with strongmineral acids, nor to cooking utensils, which may come
5、inprolonged contact with hot acid solutions.1.4 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 practices and determine the applica-bility of regulat
6、ory limitations prior to use.2. Summary of Test Method2.1 The test method consists of a 15 min exposure of the testsurface to a small pool of 10 % citric acid, and an evaluation ofthe effect in terms of the change in appearance and the “relativecleanability” of the surface resulting from the treatme
7、nt.3. Significance and Use3.1 This test method is intended specifically for testing theporcelain enamel finish on stoves, refrigerators, table tops,sinks and other sanitary ware, laundry appliances, architecturalunits, etc., where the surface may come in contact with foodacids at room temperature.3.
8、2 Citric acid has been chosen as the test medium becauseit is one of the most common of the food acids and willgenerally provide a measurable result in its action on porcelainenamel.4. Apparatus4.1 Dropper Bottle, or medicine dropper,4.2 Watch Glass, 25 mm in diameter with fire polished edge,4.3 Tow
9、el, soft cotton, and4.4 Drafting Pencil, conventional graphite, degree 3B.5. Reagents and Materials5.1 Citric Acid SolutionDissolve 10 g of anhydrous citricacid crystals (H3C6H5O7) in 100 mL of water. Solution shall beprepared not more than 48 h prior to use.5.2 Cleaner SolutionDissolve 10 g of tris
10、odium phos-phate (Na3PO4) in 1 L of tap water.6. Sampling6.1 The test specimens may be articles of commerce, piecescut from articles of commerce, or laboratory specimens pre-pared especially for this test.NOTE 1Processing variables in the application and drying and firingoperations materially affect
11、 the degree of attack by the acid on the surfaceof porcelain enamels. Sample specimens used for classification of acidresistance must be processed under identical conditions to the commercialware they represent.7. Procedure7.1 Thoroughly wash area to be tested using a soft cottontowel moistened with
12、 a warm, 1 % solution of trisodiumphosphate. Rinse in warm, running tap water, and dry with asoft towel by blotting. Store the specimen at a temperature of26 6 1C (79 6 2F) for a time sufficient to bring it within thisrange prior to and during the test.NOTE 2If, when rinsing, the water gathers in dr
13、ops on the surface,repeat washing treatment until water spreads evenly.7.2 On articles of commerce, select areas that are horizontalor nearly horizontal in service. Place the specimen in a positionsuch that a flat area at least 38.1 mm in diameter is horizontal.1This test method is under the jurisdi
14、ction ofASTM Committee B08 on Metallicand Inorganic Coatings and 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 1951. Last previous edition approve
15、d in 1999 as C 282 99.This test method is based on the Test for Acid Resistance of Porcelain Enamels(Citric Acid Spot Test) Bulletin T-21, of the Porcelain Enamel Institute.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.With the spe
16、cimen and the citric acid solution at 26 6 1C (796 2F), place several drops of the solution on the test area toform a pool, and immediately cover with a clean watch glass inthe inverted position. Use a quantity of solution that is justsufficient to fill the inverted watch glass except for a small ai
17、rbubble (three to six drops are usually required, depending uponthe dropper and the curvature of the watch glass). After 15 minof treatment, remove the watch glass and immediately rinse thespot of solution from the surface. Dry the specimen with a dry,clean, soft cotton towel by blotting (not rubbin
18、g).NOTE 3The test surface must be thoroughly dry before grading. Thepresence of a slight film of water on the surface may change the rating ofspecimens near the borderline between classes.8. Grading8.1 Grade the test specimen within 2 h after exposure to thetest solution using the procedure outlined
19、 in the diagram, Fig.1. Rate each specimen with the appropriate classification grade,AA, A, B, C or D, as explained in Table 1. The criteria referredto in Fig. 1 and Table 1 are described as follows:8.1.1 Visual ExaminationView the specimen at variousangles with respect to the light source and eye,
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