1、BRITISH STANDARDBS EN 12923-1:2006Advanced technical ceramics Monolithic ceramics Part 1: General practice for undertaking corrosion testsThe European Standard EN 12923-1:2006 has the status of a British StandardICS 81.060.99g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g
2、48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 12923-1:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 March 2007 BSI 2007ISBN 978 0 580 50457 0Nationa
3、l forewordThis British Standard was published by BSI. It is the UK implementation of EN 12923-1:2006. It supersedes DD ENV 12923-1:1998 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics.A list of organizations represen
4、ted on RPI/13 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued sin
5、ce publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 12923-1December 2006ICS 81.060.99 Supersedes ENV 12923-1:1997 English VersionAdvanced technical ceramics - Monolithic ceramics - Part 1:General practice for undertaking corrosion testsCramiques techniques avances -
6、 Cramiquesmonolithiques - Partie 1: Pratique gnrale destine auxessais de corrosionHochleistungskeramik - Monolithische Keramik - Teil 1:Allgemeines zur Durchfhrung von KorrosionsprfungenThis European Standard was approved by CEN on 25 November 2006.CEN members are bound to comply with the CEN/CENELE
7、C Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN m
8、ember.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members
9、are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and
10、United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12923-1:2006
11、: EEN 12923-1:2006 (E) 2 Contents Page Foreword4 1 Scope.5 2 Normative references 5 3 Terms and definitions6 4 Significance and use .6 5 Assessment of corrosive attack.7 5.1 Introduction 7 5.2 Method A: Depth of penetration .7 5.3 Method B: Mass change8 5.4 Method C: Change of test piece size .9 5.5
12、 Method D: Strength change 9 5.6 Method E: Change in surface roughness9 5.7 Method F: Change in hardness 9 6 Apparatus for laboratory corrosion testing 10 6.1 Container for corroding medium10 6.2 Heating device10 6.3 Thermocouple 10 6.4 Chemical balance.10 6.5 Oven 10 6.6 Dye penetrant equipment10 6
13、.7 Travelling microscope or optical microscope 11 6.8 Micrometer11 6.9 Vernier callipers .11 6.10 Surface roughness measuring equipment11 6.11 Flexural strength test facility 11 6.12 Hardness measurement equipment.11 7 Test pieces11 7.1 General requirements11 7.2 Specific requirements11 7.3 Number o
14、f test pieces12 8 Test procedure .12 8.1 Safety considerations12 8.2 Corrosion test.12 8.3 Procedure .12 9 Expression of results.14 9.1 Calculation of mass change (Method B)14 9.2 Change of component or test piece size (Method C).14 9.3 Calculation of flexural strength (Method D) 15 10 Test report 1
15、5 Annex A (informative) Appropriate container and specimen holder materials for corrosion testing17 A.1 Mineral acids, excluding hydrofluoric acid .17 A.2 Hydrofluoric acid (HF) .17 A.3 Aqueous-based alkaline solutions.17 A.4 Molten metal alloys17 A.5 Molten slags .18 EN 12923-1:2006 (E) 3 A.6 Corro
16、sive gases .18 Bibliography 19 EN 12923-1:2006 (E) 4 Foreword This document (EN 12923-1:2006) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by
17、 publication of an identical text or by endorsement, at the latest by June 2007, and conflicting national standards shall be withdrawn at the latest by June 2007. This document supersedes ENV 12923-1:1997. EN 12923 Advanced technical ceramics Monolithic ceramics consists of two parts: Part 1: Genera
18、l practice for undertaking corrosion tests Part 2: Oxidation test At the time of publication of this edition of Part 1, Part 2 was a European Prestandard. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this Eu
19、ropean Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN
20、 12923-1:2006 (E) 5 1 Scope This part of EN 12923 specifies guidelines to be employed when undertaking corrosion tests on advanced technical ceramics. The mechanisms of chemical attack on advanced ceramics are widely varied and depend on the chemical and phase composition and the phase morphology of
21、 the material, as well as the corrosive conditions imposed. For any particular engineering application it is usually necessary to model expected conditions of use in order to obtain quantitative data on the ability to withstand the proposed end-use conditions. This European Standard is not restricte
22、d to specific material types, nor does it prescribe particular test conditions or a test duration. The actual testing requirements might be very specific, for example, in order to investigate the suitability of a range of materials for a given application in which certain specified conditions occur.
23、 This European Standard provides recommended methods for undertaking the assessment of the effect of corrosion and provides guidance on practical issues related to undertaking the tests. 2 Normative references The following referenced documents are indispensable for the application of this document.
24、 For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 623-1, Advanced technical ceramics Monolithic ceramics General and textural properties Part 1: Determination of the presence of defects
25、by dye penetration EN 623-4, Advanced technical ceramics Monolithic ceramics General and textural properties Part 4: Determination of surface roughness EN 843-1, Advanced technical ceramics Mechanical properties of monolithic ceramics at room temperature Part 1: Determination of flexural strength EN
26、 843-4, Advanced technical ceramics Mechanical properties monolithic ceramics at room temperature Part 4: Vickers, Knoop and Rockwell superficial hardness ENV 1006, Advanced technical ceramics Monolithic ceramics Guidance on the selection of test pieces for the evaluation of properties EN 60584-1, T
27、hermocouples Part 1: Reference tables EN 60584-2, Thermocouples Part 2: Tolerances EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) ISO 3611, Micrometer callipers for external measurement ISO 6906, Vernier callipers reading to 0,0
28、2 mm EN 12923-1:2006 (E) 6 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 corrosion process of degradation induced by chemical attack by a surrounding medium on a ceramic body 3.2 oxidation process of reaction of a ceramic material with oxyg
29、en in the surrounding atmosphere, including any internal reactions as a result of the presence of open porosity or of diffusion of ions to or from the ceramic surface 4 Significance and use Advanced technical ceramic materials are widely regarded as being generally resistant to corrosion, and many t
30、ypes find applications in highly corrosive conditions where other materials are not viable. However, this is not always the case, and the selection of the most appropriate material requires some form of assessment to provide assurance that it has adequate resistance to the conditions to which it is
31、to be exposed. The rate of chemical attack is determined by: i) the chemical nature, phase composition, phase distribution and degree of continuous porosity in the material; ii) the temperature, pressure, composition, concentration and flow rate of the corroding medium and whether these are constant
32、 or vary with time; iii) the mechanical forces applied to the material in terms of internal stress condition and the degree of surface abrasion or wear due to contact with other surfaces, the presence of abrasive particles or the dissolving effect of the corroding medium itself; iv) the period for w
33、hich the test is performed, because it cannot be assumed that the rate of attack is constant with time. Adjusting test conditions to accelerate the corrosion process and extrapolating corrosion rates to times longer than that of the test should not be done. These factors need to be carefully selecte
34、d, clearly specified and reported in any corrosion test. The undertaking of corrosion tests is normally for two principal purposes: a. to simulate performance in an application, which will require careful consideration of all factors pertaining to the conditions under which corrosion is occurring, a
35、nd which will require these to be modelled in the test environment; b. to provide a comparative measure of performance of a range of materials under defined corrosion conditions. This European Standard provides a basis for undertaking corrosion tests and details the criteria which might be considere
36、d for determining whether attack has taken place and has significant consequences for subsequent use of a material. Since corrosion is dependent on a wide range of parameters, this European Standard does not prescribe particular environments or durations of attack, but provides guidance on the key f
37、actors that need to be considered or specified in undertaking tests and gives a general framework for conducting tests in a meaningful manner. EN 12923-1:2006 (E) 7 5 Assessment of corrosive attack 5.1 Introduction Chemical attack is manifest in a number of ways: a. change of dry mass; b. change of
38、section thickness; c. change of colour; d. penetration of corrodent into the material rendering the surface open porous; e. development of surface skins of altered composition; f. development of a surface skin of reaction product; g. change of surface finish; h. change in strength; i. change of hard
39、ness or wear resistance. Furthermore, attack might not be linear with time, notably if the diffusion path for corroding species increases with increasing corrosion. Table 1 summarizes the areas of validity of using these criteria for various types of corrosive attack. These criteria apply to passive
40、 conditions of corrosion, i.e. not when the component is under an externally applied stress. NOTE 1 Other situations might exist in which it is desirable to record changes in other properties, for example, thermal conductivity and thermal shock resistance, either whilst immersed in the corroding med
41、ium, or after extraction from it. Such methods are not specifically included in this European Standard and might require special equipment not covered by this European Standard. Change of colour might be subjective. NOTE 2 This European Standard does not lay down any recommended methods for determin
42、ing the quantity of test piece species dissolved in a corrodent (Method G). Reference should be made to standard analytical practices. Care should be taken in selection of the container material, corrosion of which may influence the results of such an analysis. 5.2 Method A: Depth of penetration 5.2
43、.1 For materials subjected to corrodents which result in grain boundary attack and penetration of the corrodent, the depth of penetration might be strongly influenced by the microstructural nature of the original test piece surface. Some as-fired surfaces might have better resistance to penetration
44、than bulk microstructures exposed by machining test pieces. When possible, testing should avoid as-fired surfaces unless the testing is specifically to evaluate the performance of such surfaces. 5.2.2 The depth of penetration might be variable if the microstructure is inhomogeneous. The greatest dep
45、th of penetration is to be recorded. 5.2.3 In materials with substantial pre-existing closed porosity, it might be difficult to determine the true depth of penetration if there is no major change in the appearance of the microstructure. Reliance should be placed on the use of penetrant dyes in accor
46、dance with EN 623-1. EN 12923-1:2006 (E) 8 Table 1 Appropriateness of methods of assessing corrosive attack Assessment method Aqueous based corrosion Corrosion by melts Corrosion by gases and vapours A. Penetration Appropriate Might be Appropriate in some appropriate cases B. Change of mass Appropri
47、ate, but Inappropriate Appropriate if non- sometimes inadequate slagging C. Change of cross- Not always appropriate Appropriate Appropriate section when change is small D. Change of strength Appropriate Might be Appropriate if non- appropriate if adherent slagging; might be material is removed appro
48、priate if adherent material is removed E. Change of surface Appropriate for slight Usually inappropriate Usually inappropriate roughness corrosion F. Change of hardness Appropriate Usually inappropriate Might be appropriate if non-slagging G. Change of Appropriate Usually inappropriate Appropriate c
49、orrodent composition 5.3 Method B: Mass change 5.3.1 Accurate determination of change in dry mass might not properly reflect the extent of attack as a result of either the adherence of solid surface deposits or the retention of corrosion products within porosity generated by corrodent penetration. A change in mass therefore indicates that some attack might have occurred, but other criteria need to be employed to quantify its overall effect on performance. 5.3.2 Assuming that the process of mass gain or mass loss is attributable to the t
