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1、 W - - - - - - - - 7- - 7- 7- - 77- 77- - 7 - 7 - - - - - - - - - - - $ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - W W D - w - - - - EN 623-5:2009 (E) 2 Contents page 1Scope 4 2Normative references 4 3Terms and definitions . 5 4Apparatus . 5 4.1Sectioning equipment . 5 4.2Moun
2、ting equipment 5 4.3Grinding and polishing equipment 5 4.4Microscope . 5 4.5Transparent grid 5 5Test piece preparation 6 5.1Sampling . 6 5.2Cutting 6 5.3Mounting . 6 5.4Grinding and polishing . 6 5.5Etching 6 6Photomicrography . 7 6.1General aspects . 7 6.2Inspection . 7 6.3Number of micrographs 7 6
3、.4Optical microscopy 7 6.5Scanning electron microscopy (SEM) . 7 7Measurement of micrographs 8 8Calculation of results 8 9Interferences and uncertainties . 9 10Test report 9 Annex A (informative) Grinding and polishing procedures . 11 Annex B (informative) Etching procedures . 13 Annex C (informativ
4、e) Use of automatic image analysis (AIA) 14 C.1Background 14 C.2Analysis techniques 14 C.3Micrograph requirements . 14 C.4Calibration 14 Annex D (informative) Setting Khler illumination in an optical microscope 15 D.1Purpose . 15 D.2Definition 15 D.3Setting up for Khler illumination 15 Annex E (info
5、rmative) Round robin verification of this procedure . 16 Annex F (informative) Results sheet 17 Bibliography 18 EN 623-5:2009 (E) 3 Foreword This document (EN 623-5:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is held by BSI. This
6、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of an identical text or by endorsement, at the latest by January 2010, and conflicting national standards shall be withdrawn at the latest by January 2010. Attention is drawn to the possibility that some of the
7、 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 rights. This document supersedes ENV 623-5:2002. EN 623 consists of five parts, under the general title “Advanced technical ceramics - Monolithic ce
8、ramics - General and textural properties“: Part 1: Determination of the presence of defects by dye penetration Part 2: Determination of density and porosity Part 3: Determination of grain size and size distribution (characterized by the Linear Intercept Method) Part 4: Determination of surface rough
9、ness Part 5: Determination of phase volume fraction by evaluation of micrographs 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, Cyprus, Czech Republic, Denma
10、rk, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 623-5:2009 (E) 4 1 Scope This part of EN 623 specifies a ma
11、nual method of making measurements for the determination of volume fraction of major phases in advanced technical ceramics using micrographs of polished and etched sections, overlaying a square grid of lines, and counting the number of intersections lying over each phase. NOTE 1 This method assumes
12、that the true phase volume fractions are equivalent to area fractions on a randomly cut cross- section according to stereological principles. NOTE 2 Guidelines for polishing and etching of advanced technical ceramics can be found in Annexes A and B. The method applies to ceramics with one or more di
13、stinct secondary phases, such as found in Al2O3/ZrO2, Si/SiC,or Al2O3/SiCw. If the test material contains discrete pores, these can be treated as a secondary phase for the purpose of this method provided that there is no evidence of grain pluck-out during polishing being confused with genuine pores.
14、 NOTE 3 If the material contains more than about 20 % porosity there is a strong risk that the microstructure will be damaged during the polishing process, and measurement of volume fraction of pores may become misleading. Secondary phase volume fractions or porosity present at levels of less than 0
15、,05 are subject to considerable error and potential scatter in results. A larger number of micrographs than the minimum of three is normally needed to improve the consistency and accuracy of the results. NOTE 4 Many ceramics contain small amounts of secondary glassy phases. In order to make a reason
16、able estimate of glassy phase content, the glass material between crystalline grains should be readily observable, and thus should be at least 0,5 m in width. The method in this European Standard is not considered appropriate for narrow glassy films around grains. This method assumes that the select
17、ed regions of a prepared cross-section are statistically representative of the whole sampled section. NOTE 5 Microstructures are seldom homogeneous, and the phase contents can vary from micrograph to micrograph. It is essential to survey a sufficiently wide area of the prepared section to ensure tha
18、t those areas selected for evaluation are representative, and do not contain eye-catching irregularities. Some users of this European Standard can wish to apply automatic or semiautomatic image analysis to micrographs or directly captured microstructural images. This is currently outside the scope o
19、f this European Standard, but some guidelines are given in Annex C. 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 doc
20、ument (including any amendments) applies. EN 1006, Advanced technical ceramics - Monolithic ceramics - Guidance on the selection of test pieces for the evaluation of properties EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) EN 6
21、23-5:2009 (E) 5 3 Terms and definitions For the purposes of this part of EN 623, the following terms and definitions apply. 3.1 phase volume fraction volume occupied by a distinct, identifiable phase present in a material expressed as a fraction of the whole 3.2 secondary phase one or more distinct
22、identifiable phases other than a primary crystalline phase in a material NOTE A secondary phase can be in the form of discrete grains, or as a continuous phase surrounding some or all the major phase grains. For the purposes of this European Standard, porosity may be treated as a secondary phase. 4
23、Apparatus 4.1 Sectioning equipment A suitable diamond-bladed cut-off saw to prepare the initial section for investigation. The saw shall be metal bonded with a diamond grit size of 125 m to 150 m and shall be cooled. NOTE This grit size is designated D151 according to ISO 6106, see 1. 4.2 Mounting e
24、quipment Suitable metallurgical mounting equipment and media for providing firm gripping of the test piece for polishing. 4.3 Grinding and polishing equipment Suitable grinding and polishing equipment, employing diamond abrasive media. NOTE A sequence of abrasives and techniques recommended for poli
25、shing are given in Annex A. 4.4 Microscope An optical or scanning electron microscope with photomicrographic facilities. NOTE Although the true magnification of the image is unimportant for making the measurement of volume fraction, it is advised that a reference graticule may be used to determine m
26、agnification in an optical microscope, or a reference grid or latex spheres may be used for calibration of magnification in a scanning electron microscope, and as a check on the homogeneity of magnification across the field of view. An optical microscope is additionally required for assessing polish
27、ing (see 5.4). 4.5 Transparent grid Transparent square grid on, e.g. acetate film, and with line thickness not exceeding 0,1 mm. NOTE 1 The grid spacing selected is not critical, but may conveniently be between 3 mm and 15 mm to minimise eyestrain. However, it is necessary that consideration of the
28、requirements of 6.3 is taken into account. NOTE 2 A suitable grid may be prepared as a computer plot with sufficient accuracy of line spacing for the purposes of this European Standard. EN 623-5:2009 (E) 6 5 Test piece preparation 5.1 Sampling The test pieces shall be sampled in accordance with the
29、guidelines given in EN 1006, and subject to agreement between parties. NOTE Depending on the objectives of performing the measurement, it is desirable to maintain knowledge of the positions within components or test pieces from which sections are prepared. 5.2 Cutting The required section of test-pi
30、ece shall be cut using the diamond saw (see 4.1). NOTE For routine inspection of materials, a small area of side no more than 10 mm is normally adequate as the section to be polished. 5.3 Mounting Mount the test piece using an appropriate mounting medium. If the ceramic is suspected to have signific
31、ant open porosity in some regions (see Clause 1) it is advisable to vacuum impregnate the test piece with liquid mounting resin before encapsulating as this will provide some support during grinding and polishing. NOTE It is not essential to encapsulate the test piece. For example, it could be affix
32、ed to a metal holder. However, encapsulation in a polymer-based medium allows easy gripping and handling, especially of small irregularly shaped test pieces and of weak friable test pieces. The method of mounting selected should take into account the etching procedure to be used; see Annex B. 5.4 Gr
33、inding and polishing Grind and polish the surface of the test piece. Care should be taken to ensure that grinding produces a planar surface with a minimum of damage. Employ successively smaller grit sizes, at each stage removing the damage from the previous stage until there is no change in appearan
34、ce when examined by an optical microscope (see 4.4) at high magnification. At least 90 % of the test piece area shall be free from optically visible scratches, or other damage introduced by polishing, which will interfere with the determination. In particular, discrete secondary phases may be plucke
35、d out from the surface giving the appearance of pores. This shall be avoided. NOTE Care should be taken in choosing the sequence of grits and lap types. It is impossible within the scope of this part of EN 623 to make specific recommendations for all types of material. The general principle to be ad
36、opted is the minimisation of subsurface damage, and its removal by progressively finer grits whilst retaining a flat surface. Some guidelines on polishing are given in Annex A. 5.5 Etching When a good quality polished surface has been achieved, the test piece shall be etched if necessary to reveal t
37、he individual phases. Any suitable technique shall be used, subject to agreement between parties. NOTE 1 Some general guidelines recommending etching procedures for various commonly available advanced technical ceramics are given in Annex B. NOTE 2 For optical evaluation, it is usually necessary to
38、etch oxide materials in such a way that the individual phases are distinguished by having different contrast levels. For evaluation by scanning electron microscopy (SEM), it may not be necessary to etch if a backscattered electron detector is used which has adequate resolution of net atomic number d
39、ifference between the phases such that contrast is generated. If a secondary electron detector is used, it will usually be necessary to etch to produce topographic contrast unless the atomic number difference between the phases is large. EN 623-5:2009 (E) 7 6 Photomicrography 6.1 General aspects If
40、it suspected that the average grain size of each phase or the widths of continuous glassy phases between grains is less than 2 m, it will be necessary to prepare the test piece for SEM. Between 2 m and 4 m either SEM or optical microscopy may be used. Otherwise, optical microscopy will normally be a
41、dequate. It is important to achieve sufficient contrast between phases in order to identify individual grains clearly and unambiguously. 6.2 Inspection Inspect the sampled cross-section in the microscope. If the microstructure appears homogeneous, prepare micrographs from randomly selected areas. If
42、 inhomogeneity of microstructure is suspected, select representative areas of relevance for measurement. 6.3 Number of micrographs At least three micrographs shall be prepared at a magnification sufficient to identify clearly all the phases to be counted. In addition, at least 100 features in total
43、of any given type shall be present to be counted in the set of micrographs. NOTE For a nominally homogeneous material, it may be sufficient to use a small number of micrographs analysed with a small grid spacing, but for an inhomogeneous material, results representative of the average for the sampled section can be prepared reliably only by selecting a large number of micrographs of different areas, with les