DIN EN ISO 28706-1-2011 Vitreous and porcelain enamels - Determination of resistance to chemical corrosion - Part 1 Determination of resistance to chemical corrosion by acids at ro.pdf

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1、August 2011 Translation by DIN-Sprachendienst.English price group 8No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS

2、25.220.50!$t2f“1811567www.din.deDDIN EN ISO 28706-1Vitreous and porcelain enamels Determination of resistance to chemical corrosion Part 1: Determination of resistance to chemical corrosion by acids atroom temperature (ISO 28706-1:2008)English translation of DIN EN ISO 28706-1:2011-08Emails und Emai

3、llierungen Bestimmung der Bestndigkeit gegen chemische Korrosion Teil 1: Bestimmung der Bestndigkeit gegen chemische Korrosion durch Suren beiRaumtemperatur (ISO 28706-1:2008)Englische bersetzung von DIN EN ISO 28706-1:2011-08maux vitrifis Dtermination de la rsistance la corrosion chimique Partie 1:

4、 Dtermination de la rsistance la corrosion chimique par les acides temprature ambiante (ISO 28706-1:2008)Traduction anglaise de DIN EN ISO 28706-1:2011-08SupersedesDIN EN 14483-1:2004-09www.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritati

5、ve.1307.11 DIN EN ISO 28706-1:2011-08 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee ISO/TC 107 “Metallic and other inorganic coatings” in collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” (Sec

6、retariat: BSI, United Kingdom). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Committee NA 062-01-63 AA Prfung von Emails und Emaillierungen. The DIN Standards corresponding to the International Standar

7、ds referred to in this document are as follows: ISO 1042 DIN EN ISO 1042 ISO 3696 DIN ISO 3696 ISO 4788 DIN EN ISO 4788 ISO 28764 DIN EN 15206 and E DIN EN ISO 28764 Amendments This standard differs from DIN EN 14483-1:2004-09 as follows: a) the text of ISO 28706-1:2008 has been adopted; b) the stan

8、dard has been editorially revised. Previous editions DIN 51150: 1957-03, 1966-11 DIN ISO 2722: 1982-11 DIN ISO 8290: 1987-10 DIN EN ISO 8290: 1998-10 DIN EN 14483-1: 2004-09 National Annex NA (informative) Bibliography DIN EN 15206, Vitreous and porcelain enamels Production of specimens for testing

9、enamel on sheet steel, sheet aluminium and cast iron DIN EN ISO 1042, Laboratory glassware One-mark volumetric flasks DIN EN ISO 4788, Laboratory glassware Graduated measuring cylinders Vitreous and porcelain enamels Production of specimens for testing enamels on sheet steel, sheet aluminium and cas

10、t iron DIN ISO 3696, Water for analytical laboratory use Specification and test methods E DIN EN ISO 28764, EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 28706-1 May 2011 ICS 25.220.50 Supersedes EN 14483-1:2004English Version Vitreous and porcelain enamels - Determination of resistance t

11、o chemical corrosion - Part 1: Determination of resistance to chemical corrosion by acids at room temperature (ISO 28706-1:2008) maux vitrifis - Dtermination de la rsistance la corrosion chimique - Partie 1: Dtermination de la rsistance la corrosion chimique par les acides temprature ambiante (ISO 2

12、8706-1:2008) Emails und Emaillierungen - Bestimmung der Bestndigkeit gegen chemische Korrosion - Teil 1: Bestimmung der Bestndigkeit gegen chemische Korrosion durch Suren bei Raumtemperatur (ISO 28706-1:2008) This European Standard was approved by CEN on 15 April 2011. CEN members are bound to compl

13、y with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

14、Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the sam

15、e status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Po

16、rtugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any mea

17、ns reserved worldwide for CEN national Members. Ref. No. EN ISO 28706-1:2011: EContents Page Foreword3 Introduction .4 1 Scope 6 2 Normative references 6 3 Principle6 4 Reagents.6 5 Materials and apparatus7 6 Test specimens7 7 Procedure .7 7.1 Attack by the test solution7 7.2 Determination.8 8 Class

18、ification of results 8 9 Citric acid test at room temperature9 9.1 Test solution.9 9.2 Test time .9 9.3 Test report 9 10 Sulfuric acid test at room temperature10 10.1 Test solution.10 10.2 Test time .10 10.3 Test report 10 11 Other test solutions at room temperature.10 11.1 Test solution.10 11.2 Tes

19、t time .10 11.3 Test report 10 DIN EN ISO 28706-1:2011-08 EN ISO 28706-1:2011 (E) 2 Foreword The text of ISO 28706-1:2008 has been prepared by Technical Committee ISO/TC 107 “Metallic and other inorganic coatings” of the International Organization for Standardization (ISO) and has been taken over as

20、 EN ISO 28706-1:2011 by Technical Committee CEN/TC 262 “Metallic and other inorganic coatings” the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 201

21、1, and conflicting national standards shall be withdrawn at the latest by November 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent right

22、s. This document supersedes EN 14483-1:2004. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Franc

23、e, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 28706-1:2008 has been approved by CEN as a EN ISO 2870

24、6-1:2011 without any modification. DIN EN ISO 28706-1:2011-08 EN ISO 28706-1:2011 (E) 3 Introduction Corrosion of vitreous and porcelain enamels by aqueous solutions is a dissolution process. The main component of the enamel, SiO2, forms a three-dimensional silica network. After hydrolysis, it decom

25、poses and forms silicic acid or silicates. These are released into the attacking medium. Other components, mainly metal oxides, are hydrolysed as well and form the corresponding hydrated metal ions or hydroxides. All corrosion products are more or less soluble in the attacking medium. The whole proc

26、ess results in a loss in mass per unit area. For some aqueous solutions, the attack on the enamel proceeds linearly during the corrosion time; for other aqueous solutions, the attack on the enamel proceeds in a logarithmic manner during the corrosion time. Only for the first series of solutions can

27、a scientifically exact rate of loss in mass per unit area (g/m2h) be calculated as well as a corrosion rate (mm/year). The most important parameters influencing aqueous corrosion of the enamel are the enamel quality, the temperature and the pH-value. Inhibition effects resulting from the limited sol

28、ubility of silica can also contribute. The following list describes different types of enamel attack for different corrosion conditions: a) In aqueous alkali solutions like 0,1 mol/l NaOH (see Clause 9 of ISO 28706-4:2008), the silica network of the enamel is considerably attacked at 80 C. Silicates

29、 and most of the other hydrolysed components are soluble in the alkali. Attack proceeds linearly during regular test times. Therefore, test results are expressed in terms of a rate of loss in mass per unit area (mass loss per unit area and time) and a corrosion rate (millimetres per year). b) At roo

30、m temperature, in weak aqueous acids like citric acid (see Clause 9 of ISO 28706-1:2008) or also in stronger acids like sulfuric acid (see Clause 10 of ISO 28706-1:2008), there is only minor attack on the silica network of the enamel. Other constituents are leached to some extent from the surface. H

31、ighly resistant enamels will show no visual change after exposure. On less resistant enamels, some staining or surface roughening will occur. c) In boiling aqueous acids (see ISO 28706-2), the silica network of the enamel is being attacked, and silica as well as the other enamel components are relea

32、sed into solution. However, the solubility of silica in acids is low. Soon, the attacking solutions will become saturated with dissolved silica and will then only leach the surface. The acid attack is inhibited and the rate of corrosion drops markedly. NOTE The glass test equipment also releases sil

33、ica by acid attack and contributes to the inhibition of the corrosion. Inhibition is effectively prevented in vapour phase tests. The condensate formed on the test specimen is free of any dissolved enamel constituents. Examples of enamel corrosion proceeding in a logarithmic manner see 1) and linear

34、ly see 2) are: 1) Boiling citric acid (see Clause 10 of ISO 28706-2:2008) and boiling 30 % sulfuric acid (see Clause 11 of ISO 28706-2:2008) Since only minute amounts of these acids are found in their vapours, the test is restricted to the liquid phase. The attack is influenced by inhibition effects

35、, and corrosion depends on the time of exposure. Therefore, test results are expressed in terms of loss in mass per unit area; no rate of loss in mass per unit area is calculated. 2) Boiling 20 % hydrochloric acid (see Clause 12 of ISO 28706-2:2008) Since this is an azeotropic boiling acid, its conc

36、entration in the liquid and the vapour phase are identical, and liquid phase testing need not be performed. Vigorous boiling supplies an uninhibited condensate, and the attack proceeds linearly with time of exposure. Therefore, test results are only DIN EN ISO 28706-1:2011-08 EN ISO 28706-1:2011 (E)

37、 4 expressed in terms of rate of loss in mass per unit area (mass loss per unit area and time) and the corrosion rate (millimetres per year). d) At high temperatures, with tests in the liquid phase under autoclave conditions (see ISO 28706-5), aqueous acid attack is severe. To avoid inhibition, the

38、test time is restricted to 24 h and the ratio of attacking acid to attacked enamel surface is chosen so that it is comparatively high (similar to that in a chemical reaction vessel). In addition, only low-silica water is used for the preparation of test solutions. Under these conditions, attack will

39、 proceed linearly with time of exposure. Therefore, test results with 20 % hydrochloric acid (see Clause 8 of ISO 28706-5:2008), artificial test solutions (see Clause 10 of ISO 28706-5:2008) or process fluids (see Clause 11 of ISO 28706-5:2008) are also expressed in terms of a rate of loss in mass p

40、er unit area (loss in mass per unit area and time). e) In boiling water (see Clause 13 of ISO 28706-2:2008), the silica network is fairly stable. The enamel surface is leached and silica is dissolved only to a small extent. This type of attack is clearly represented by the vapour phase attack. In th

41、e liquid phase, some inhibition can be observed with highly resistant enamels. However, if the enamel being tested is weak, leached alkali from the enamel can raise pH-values to alkaline levels, thus increasing the attack by the liquid phase. Both liquid and vapour phase testing can give valuable in

42、formation. f) Since the attack may or may not be linear, the results are expressed only in terms of loss in mass per unit area, and the test time should be indicated. g) For standard detergent solution (see Clause 9 of ISO 28706-3:2008), it will not be certain whether the linear part of the corrosio

43、n curve will be reached during testing for 24 h or 168 h. Calculation of the corrosion rate is therefore not included in the test report. h) For other acids (see Clause 14 of ISO 28706-2:2008) and other alkaline solutions (see Clause 10 of ISO 28706-3:2008 and Clause 10 of ISO 28706-4:2008), it will

44、 also not be known if a linear corrosion rate will be reached during the test period. Calculation of the corrosion rate is therefore not included in the test reports of those parts of this International Standard. For vitreous enamels fired at temperatures below 700 C, the test parameters (media, tem

45、peratures and times) of this International Standard are not appropriate. For such enamels, for example aluminium enamels, other media, temperatures and/or times should be used. This can be done following the procedures described in the clauses for “Other test solutions” in Parts 1, 2, 3 and 4 of thi

46、s International Standard. DIN EN ISO 28706-1:2011-08 EN ISO 28706-1:2011 (E) 5 1 Scope This part of ISO 28706 describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack by an acid at room temperature, and also specifies a method of classify

47、ing the results. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1042,

48、 Laboratory glassware One-mark volumetric flasks ISO 3696, Water for analytical laboratory use Specification and test methods ISO 4788, Laboratory glassware Graduated measuring cylinders ISO 28764, Vitreous and porcelain enamels Production of specimens for testing enamels on sheet steel, sheet alumi

49、nium and cast iron 3 Principle Part of the surface of a test specimen is exposed under defined conditions to attack by an acid solution. Resistance is assessed by methods based on the appearance and cleanability of the enamelled surface. 4 Reagents During the determination, use only reagents of recognized analytical grade, unless otherwise specified. 4.1 Water, conforming to the requirements of grade 3 of ISO 3696, i.e. distilled water or water of equivalent purity. 4.2 Degreasing solvent, such as ethanol, or water (