1、 Standard Test Method Immersion Corrosion Testing of Ceramic Materials This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone, whether he or she has adopted
2、 the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or us
3、e in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requirements and should in no way be interpreted as a restriction on the use of better proc
4、edures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International assumes no responsibility for the interpretation or use of this standard by other par
5、ties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE International standard are resp
6、onsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not necessarily address all potential health and safety problems or environmental haza
7、rds associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate re
8、gulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technic
9、al committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication and subsequently from the date of each reaffirmation or revision. The user is cautioned to obtain the latest edition.
10、 Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Dr., Houston, Texas 77084-4906 (telephone +1 281-228-6200). Revised 2009-06-26 Approve
11、d 1999-10-22 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281-228-6200 ISBN: 1-57590-087-4 2009 NACE International NACE Standard TM0499-2009 Item No. 21239 TM0499-2009 NACE International i _ Foreword Ceramic materials are becoming increasingly important in manufactured prod
12、ucts and components as well as possible uses in power plants, high energy batteries, gas turbines, heat exchangers, and fuel cells. In many cases, the ceramic materials are exposed to highly aggressive service environments such as those found in the manufacturing and processing of industrial chemica
13、ls in which traditional metallic materials tend to be unusable because of extremely rapid corrosion. Therefore, corrosion resistance is an increasingly important aspect of the performance of advanced ceramics. While general corrosion of ceramic materials may occur, many real-world problems involve l
14、ocalized corrosion and/or corrosion-influenced mechanical failure. This standard test method is intended to provide for the development and reporting of corrosion data for ceramic materials. Widespread use of this standard should reduce variability in the immersion corrosion testing of ceramic mater
15、ials in both laboratory studies and field exposures. In addition to reducing the problem of incompletely documented corrosion test data and increasing the use of meaningful measurements to evaluate the effects of corrosion, this standard also provides a common basis for the evaluation and selection
16、of ceramic materials, thereby improving the ability of designers and users of ceramic materials to compare corrosion test data from different sources, and to have such data in units that do not distort or misrepresent performance and that are meaningful to practical applications. This standard was o
17、riginally prepared by Task Group (TG) T-3L-19, a component of Unit Committee T-3L, “Technologies for Corrosion Measurement,” and issued in 1999. It was revised in 2009 by TG 365, “Corrosion of Ceramics,” which is administered by Specific Technology Group (STG) 62, “Corrosion Monitoring and Measureme
18、nt: Science and Engineering Applications.” This standard is issued by NACE International under the auspices of STG 62. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must
19、are used to state a requirement, and are considered mandatory. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional. _ TM0499-2009 ii NACE International _ NACE International Standard Test Meth
20、od Immersion Corrosion Testing of Ceramic Materials Contents 1. General 1 2. Preparation of Test Specimens 2 3. Test Apparatus . 3 4. Test Exposure Conditions 4 5. Test Specimen Cleaning and Evaluation After Exposure 5 6. Calculation of Corrosion Rates 6 7. Reporting of Test Results 7 References 9 B
21、ibliography 10 Appendix A (Nonmandatory): Supplemental Evaluations . 10 _ TM0499-2009 NACE International 1 _ Section 1: General 1.1 This standard describes procedures for performing immersion corrosion tests for evaluation of ceramic materials. It is applicable to laboratory, field, or in-plant use
22、for the evaluation of a wide variety of ceramic materials. 1.2 The test procedures described in this standard include (1) preparation of test specimens, (2) test apparatus, (3) test exposure conditions, (4) test specimen evaluation after exposure, (5) calculation of corrosion rates, and (6) reportin
23、g of test results. 1.3 Modern ceramic materials vary widely in composition, processing, and properties. Various parts of this standard may be more or less applicable for specific ceramic materials, depending on their electrical conductivity, porosity, and hardness, as well as other physical and mech
24、anical properties and microstructural features. 1.3.1 Many ceramics can be brittle, and this must be considered during selection of a ceramic material for a given service. This standard, however, does not address applicability limits associated with the mechanical properties of ceramics beyond the p
25、ossible impact that corrosion may have on overall properties (e.g., decreased flexural strength). 1.3.2 See the NACE International Glossary of Corrosion-Related Terms1and NACE/ASTM(1)G 1932for definitions of many terms used in this standard. 1.4 The general description of procedures presented in thi
26、s standard for the corrosion testing of ceramic materials is as follows: 1.4.1 Obtain appropriate test specimens of the ceramic material; 1.4.2 Clean and weigh the test specimens; 1.4.3 Expose the test specimens to the corrosive environment for an appropriate amount of time; 1.4.4 Remove the test sp
27、ecimens from the corrosive environment; rinse, dry, and reweigh the exposed test specimens; 1.4.5 Document the appearance of the exposed (corroded) test specimens before cleaning; 1.4.6 Clean the test specimens of any corrosion products and reweigh the cleaned test specimens; 1.4.7 Document the appe
28、arance of the cleaned test specimens; 1.4.8 Calculate the general (mass-loss) corrosion rate (CR), the corrosion-product scale mass, and the maximum localized corrosion rate (LCR); 1.4.8.1 Absorption of the corrodent may make mass-loss measurements of porous ceramic materials meaningless if the corr
29、odent cannot be removed and the test specimen dried prior to performing the post-exposure evaluation. Similarly, if corrosion products cannot be effectively removed, the resultant mass-loss measurements can also be skewed. 1.4.8.2 Supplemental evaluations may be performed as discussed in Appendix A
30、(nonmandatory) to further quantify the nature of the corrosion or to assess its impact on the flexural strength of the ceramic material. (1)ASTM International (ASTM), 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959. _ TM0499-2009 2 NACE International 1.4.9 Report the results. 1.5 Important inf
31、ormation is needed to characterize ceramic test specimens. 1.5.1 Properties of the ceramic material such as density and porosity are used in the conversion of mass loss to the CR. It is often useful to have additional information regarding the composition, processing, and material microstructure (e.
32、g., phases present, morphology, and distribution). In the case of porous ceramic materials, apparent density is typically used, but this must be noted with the results. Some basic ceramic property tests can be found in the Annual Book of ASTM Standards, Volumes 15.013and 15.02.41.5.2 Test specimen d
33、imensions, shape, and surface roughness must be determined. 1.6 Many test methods used for the exposure of metallic test specimens to corrosive environments can be used with success for test specimens fabricated from ceramic materials. These test methods are given in several existing standards for l
34、aboratory and field evaluation as follows: 1.6.1 ASTM G 1;51.6.2 ASTM G 4;61.6.3 ASTM G 31;7and 1.6.4 NACE Standard TM0169.81.6.5 Visual and microscopic examination techniques for detection of localized corrosion on metallic test specimens following exposure to laboratory or field/plant environments
35、 are also suitable for the evaluation of ceramic materials. Test methods for examination and standardized reporting of localized corrosion are given in ASTM G 46.91.6.6 Test methods for determining the corrosion resistance of ceramic materials shall be consistent with the procedures described in the
36、 ASTM standards listed in Paragraphs 1.6.1 through 1.6.3, except as otherwise specified in this standard. 1.7 A corrosion test alone may not provide sufficient information to fully evaluate a ceramic material. Changes in mechanical properties after exposure could provide useful information, even if
37、no significant corrosion takes place. _ Section 2: Preparation of Test Specimens 2.1 Modern ceramic materials can be comprised of a single or multiple phases. Often the ceramic materials are blends or mixtures of various constituents to optimize physical or mechanical properties, processing, or fabr
38、ication. These individual constituents can combine to form various microstructures that may have varying degrees of chemical reactivity. Therefore, tests should be performed on ceramic materials that are as similar as possible to those intended to be used in service. Ideally, the test specimens shou
39、ld be prepared from the same stock, lot, and trade name or proven equivalent of the ceramic material to be used in service and should have been subject to the same manufacturing process and fabrication method. 2.2 The shape and size of the test specimens may vary depending on the product form of the
40、 ceramic material to be evaluated. The greatest sensitivity for determination of the CR is obtained with a test specimen that has a high surface-area-to-volume ratio. However, the as-produced part should be tested whenever possible. 2.3 As-produced surfaces may exhibit different corrosion resistance
41、 than surfaces exposed from the interior of the ceramic material. Therefore, when possible, all test specimens shall have a similar surface condition and finish. TM0499-2009 NACE International 3 Square edges should be avoided for most ceramic materials, unless specifically required, because of the t
42、endency of these brittle materials to spall or chip. 2.4 Multiple corrosion test specimens shall be used. If a high degree of scatter in the corrosion performance of a ceramic material is foreseen or noted, the number of test specimens shall be increased to improve the statistical significance of th
43、e test data, but a minimum of three replicates per time period shall be used. In cases of high data scatter, the average CR is not an accurate representation of material performance and should not be used. In these cases in which the coefficient of variation of the CR of multiple test specimens in t
44、he same test (standard deviation divided by the average) exceeds 20%, the investigator should attempt to determine the sources of scatter and note the maximum CR, unless that test specimen is not representative of the material of interest. 2.5 Test specimens shall be cleaned of surface contamination
45、, grease, and oil prior to exposure. The exact method of cleaning depends on the characteristics of the specific ceramic material, particularly if the ceramic material has open (interconnected) porosity as discussed in Paragraph 2.5.2. 2.5.1 Nonporous ceramic materials shall be cleaned first with wa
46、ter containing a detergent or nonbleaching cleaning powder containing a mild abrasive that is softer than the ceramic. This shall be followed by degreasing with a nonchlorinated, volatile solvent such as acetone, and air drying. NOTE: Even those ceramics that appear nonporous could have some measura
47、ble porosity. To ensure the test specimen is completely dry, oven drying as described in Paragraph 2.5.2 shall be used. 2.5.2 Porous ceramic materials may absorb moisture and hold small particle matter; therefore, cleaning shall be performed only with a volatile solvent such as acetone. The solvent
48、must be allowed to completely evaporate before the test specimens are weighed. If washing, grinding, or finishing must be performed on test specimens of porous ceramic materials, the test specimens shall be cleaned with a suitable solvent and ultrasonic agitation followed by drying in an oven until all moisture or solvent is removed. An oven temperature slightly above the boiling point of the solvent shall be used, provided the temperat
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