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1、BRITISH STANDARD BS EN 12698-2:2007 Chemical analysis of nitride bonded silicon carbide refractories Part 2: XRD methods The European Standard EN 12698-2:2007 has the status of a British Standard ICS 71.040.40 ? BS EN 12698-2:2007 This British Standard was published under the authority of the Standa
2、rds Policy and Strategy Committee on 31 May 2007 BSI 2007 ISBN 978 0 580 50666 6 National foreword This British Standard was published by BSI. It is the UK implementation of EN 12698-2:2007. The UK participation in its preparation was entrusted to Technical Committee RPI/1, Refractory products and m
3、aterials. A list of organizations represented on this committee 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 im
4、munity from legal obligations. Amendments issued since publication Amd. No. DateComments EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12698-2 March 2007 ICS 71.040.40 English Version Chemical analysis of nitride bonded silicon carbide refractories - Part 2: XRD methods Analyse chimique des p
5、roduits rfractaires contenant du carbure de silicium liaison nitrure - Partie 2 : Mthodes de DRX Chemische Analyse von feuerfesten Erzeugnissen aus nitridgebundenem Silicumcarbid - Teil 2: XRD-Verfahren This European Standard was approved by CEN on 15 February 2007. CEN members are bound to comply w
6、ith 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 Management
7、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 Management Centre has the same status as the off
8、icial versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, S
9、lovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2007 CENAll rights of exploitation in any form and by any means reserved worldwide for C
10、EN national Members. Ref. No. EN 12698-2:2007: E EN 12698-2:2007 (E) 2 Contents Page Foreword .3 1 Scope4 2 Normative references4 3 Definitions 4 4 Apparatus.4 5 Sampling.5 6 Procedure.5 6.1 Sample preparation.5 6.2 Measuring parameters 5 6.3 Qualitative analysis.5 6.4 Quantitative analysis.6 7 Prec
11、ision.10 7.1 Repeatability 10 7.2 Reproducibility.10 8 Test report10 Annex A (normative) X-ray diffraction data for the determination of -SiAlON content.11 A.1 General .11 A.2 Example of calculation of z-value for -SiAlON12 Bibliography13 EN 12698-2:2007 (E) 3 Foreword This document (EN 12698-2:2007
12、) has been prepared by Technical Committee CEN/TC 187 “Refractory products and materials”, 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 September 2007,
13、and conflicting national standards shall be withdrawn at the latest by September 2007. 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,
14、 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 12698-2:2007 (E) 4 1 Scope This standard describes method
15、s for the determination of mineralogical phases typically apparent in nitride and oxy-nitride bonded silicon carbide refractory products using a Bragg-Brentano diffractometer. It includes details of sample preparation and general principles for qualitative and quantitative analysis of mineralogical
16、phase composition. Quantitative determination of -Si3N4, -Si3N4, Si2ON2, AlN, and SiAlON are described. NOTE For the refinement procedures the total nitrogen content, analysed in accordance with EN 12698-1 is needed. 2 Normative references The following referenced documents are indispensable for the
17、 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. EN 12475-4:1998, Classification of dense shaped refractory products Part 4: Special products EN 12698-1, Chem
18、ical analysis of nitride bonded silicon carbide refractories Part 1: Chemical methods ISO 836:2001, Terminology for refractories ISO 5022, Shaped refractory products Sampling and acceptance testing ISO 8656-1, Refractory products Sampling of raw materials and unshaped products Part 1: Sampling schem
19、e 3 Definitions For the purposes of this document the terms and definitions given in ISO 836:2001, EN 12475-4:1998 and the following apply. 3.1 nitride and oxynitride bonded silicon carbide refractories refractory products predominantly consisting of silicon carbide with minor amounts of nitride pha
20、ses as a matrix component NOTE In general, metallic silicon is used as a precursor material, which undergoes a phase transformation in an oxygen-free nitrogen atmosphere. 4 Apparatus Bragg-Brentano diffractometers with a copper X-ray tube, graphite monochromator and scintillation counter and the fol
21、lowing experimental setting for data collection are used: goniometer with a measurement uncertainty of 0,5 at a confidence level of 95 %; primary soller slit with a divergence 2,5 ; divergence slit 1 ; receiving slit 0,2 mm; EN 12698-2:2007 (E) 5 scatter slit 1 ; narrow line focus; tube settings 40
22、kV and 20 mA to 45 mA. 5 Sampling Sample shaped and unshaped products using the procedures given in ISO 5022 and ISO 8656-1. When sampling large fragments, take care to collect samples from different points of individual pieces. Homogenize the sample by reducing the maximum particle size to 150 m an
23、d take the test sample from this material. 6 Procedure 6.1 Sample preparation Grind the sample using a mill so that the resultant powder can pass through a 100 mesh sieve. NOTE Care should be taken not to grind the sample excessively as this has been found to cause the silicon nitride, and silicon p
24、hases in particular, to reduce in intensity. This is believed to be due to a build up of an amorphous layer on their particles due to damage induced by the silicon carbide. Press the powder into the cavity holder from the reverse side of the cavity to that which is to be presented to the x-ray beam
25、(to reduce preferred orientation). The depth of the cavity shall be sufficient to exceed the critical depth of CuK radiation for the sample analysed. 6.2 Measuring parameters Scan the sample on the instrument using the following parameters: start angle, 2 10 ; end angle, 2 70 , 130 if -SiAlON determ
26、ination is required; step-spec, 2 0,02 or continuous; integration time 4 s. An additional scan using the same conditions as above between 60 and 70 2 may be required if aluminium and/or iron is thought to be present. NOTE Parameters for tube settings should be: voltage 40 kV, excitation current 20 m
27、A to 45 mA. 6.3 Qualitative analysis Use an automatic or manual search to identify different phases in accordance with the ICDD, JCPDS and ASTM databases. NOTE 1 A deconvolution program should be used for overlapping peaks. EN 12698-2:2007 (E) 6 NOTE 2 The following phases are commonly found in nitr
28、ide bonded silicon carbide: -SiC, -SiC, -Si3N4, -Si3N4, Si (free), Si2ON2, SiO2 (cristobalite), FeSi2 and WC (from grinding). Less common phases include: FeSi, Fe, Al, AlN, C (graphite), SiO2 (quartz), SiAlON. Some potential line overlaps to be aware of include the (111) cristobalite at 28,4 with th
29、e (111) silicon and the (110) iron at 44,7 with the (200) aluminium, there is also an interference of monoclinic zirconia on silicon. 6.4 Quantitative analysis 6.4.1 General For quantitative analysis the net peak intensities of the test sample are compared to a sample of known concentration. The int
30、ensities shall be evaluated by measuring the peak height or preferably the peak area. For the determination of the net peak intensity, deduct the background from the total peak intensity. Certified reference material(s) should be used where available. If no reference material is available chemical a
31、nd mineralogical pure substances may be used instead. Calibration mixtures of 5 % and 10 % by mass in silicon carbide matrix shall be made up. Calibrations using the above mixes and one of 100 % by mass of silicon carbide by mass shall be constructed. The phases given in Table 1 can currently be qua
32、ntified by XRD. For quantification, the peak positions listed in Table 1 shall be preferably used. Ascertain that there are no line overlaps with other phases by performing a qualitative analysis in accordance with 6.3. Table 1 Phases which can currently be quantified by XRD Phase Available referenc
33、e material Diffraction angle 2 degrees Miller Indices -Si3N4 NIST656 BAM-S001 20,5 31,0 101 201 -Si3N4 NIST656 27,0 200 Si 28,4 47,3 56,0 111 220 311 Si2ON2 19,0 20,0 110 020 SiO2 (cristobalite) NBS SRM 1879 21,9 101 FeSi2 BCS 305/1 (50 % FeSi2, 50 % Si) 17,1 001 FeSi 28,0 69,4 79,9 110 311 321 Fe 4
34、4,7 82,3 110 211 Al 44,7 78,2 82,4 200 311 222 -SiC Used for calibration material NOTE 1 The limits of determination can be 5 % by mass even when using the recommended apparatus in clause 4 and measuring parameters in 6.2. EN 12698-2:2007 (E) 7 NOTE 2 Peak intensities should be measured as areas usi
35、ng computer software, taking into account peak overlaps where appropriate. Measuring the peak height and the background by hand is also possible. NOTE 3 It can be appropriate to use mass absorption coefficients based on bulk chemistry in the calculation of components particularly when non silicon ba
36、sed components are present. If so, it should be noted in the test certificate. 6.4.2 Calculation 6.4.2.1 General The net intensities are assumed to correlate linearly with the phase concentration. Therefore, the determination of the unknown phase concentration shall be calculated by the rule of prop
37、ortion. Where more than one peak per phase is measured, a mean result shall be quoted. The amount of each phase shall be taken from its individual calibration. 6.4.2.2 Calculation refinement for -Si3N4, -Si3N4, Si2ON2, and AlN The contents of -Si3N4, -Si3N4, Si2ON2, and AlN shall be normalized in pr
38、oportion to their molecular nitrogen contents to the total nitrogen concentration. Determine the total nitrogen content in accordance with EN 12698-1. EXAMPLE By XRD, the following results were obtained. -Si3N4 1,0 % by mass; -Si3N4 2,0 % by mass; Si2ON2 3,0 % by mass. The total nitrogen was determi
39、ned to be 2,10 % by mass from chemical methods (see EN 12698-1). Calculating the nitrogen content from the XRD results gives: nitrogen from -Si3N4 = %0,40 140,29 56,031,00 = by mass; nitrogen from -Si3N4 = %0,80 140,29 56,032,00 = by mass; nitrogen from Si2ON2 = %0,84 100,19 28,023,00 = by mass. The
40、refore the total nitrogen from XRD data = 2,04 % by mass; and therefore the correction factor is: 2,04 2,10 which gives the true nitride content as: -Si3N4 1,0 % by mass; -Si3N4 2,1 % by mass; Si2ON2 3,1 % by mass. EN 12698-2:2007 (E) 8 NOTE This method does not work if SiAlON or glassy phases of ni
41、trogen are present. 6.4.2.3 Calculation refinement for -SiAlON content 6.4.2.3.1 Determination of composition As the composition of the -SiAlON is variable, it is necessary to first accurately determine the composition and then the amount of -SiAlON and other nitride or oxynitride components. The de
42、termination of composition or z-value is made by XRD, for the stoichiometric formula Si(6z)AlzOzN(8z). Accurately determine the peak positions of all non-overlapped -SiAlON peaks using an appropriate CRM or standard such as NBS SRM 640 silicon powder to check alignment. Reference the -SiAlON diffrac
43、tion peaks on the basis of h, k, l Miller indices for a hexagonal structure. Annex A lists the calculated positions for -SiAlON for z = 3, along with Miller indices and some potential overlap peaks. Calculate the nitrogen content of the -SiAlON using the z value to give the composition. EXAMPLE z =
44、1 Si(6z)AlzOzN(8z) Si5AlON7 Nitrogen content = 34,8 % If no other nitride phases (-Si3N4, -Si3N4, AlN or SiON2) are present, determine the total nitrogen as in EN 12698-1, and calculate the -SiAlON content from the calculated nitrogen content of the SiAlON. For example: Total nitrogen 6 %, z value 1
45、, nitrogen content of -SiAlON 34,8 % 100 = N N S (1) where S is the -SiAlON content, in %; N is the total nitrogen content, in %; N is the nitrogen content of -SiAlON, in %; i.e. %17,2100 34,8 6,0 =S If other nitride phases are present, use XRD as described in Clause 6.4.1 and 6.4.2.2. Assign any re
46、sidual nitrogen to SiAlON and determine the -SiAlON content. NOTE It is possible that normalizing to the total oxygen content might not take into account the presence of silicate glass. Details of the X-ray diffraction data are given in Annex A. EN 12698-2:2007 (E) 9 6.4.2.3.2 Determination of z val
47、ue Determine the cell parameters using appropriate methods; proprietary software or other techniques may be used. NOTE Cohens least-squares method (see 6.4.2.3.3) is a suitable technique for a hexagonal SiAlON. From the a0 and c0 values, use the curves from Haviar and Johannesen 1 to determine the z
48、 value: () 0,278 7,605 0 = a z () 0,0248 2,91 0 = c z If the values of z differ, take the arithmetic mean. Apply the z value to the SiAlON formula: Si(6z)AlzOzN(8z) 6.4.2.3.3 Cohens Least Squares Method (Klung and Alexander (1959) 2). For each -SiAlON peak (in 2) calculate the following parameters: Sin2 (rads), Cos2 (rads) and from the reflection indices 22 khkh+= (2) 2 l= (3) = () + 1 sin 1 210sin21 (4) For each diffraction peak, calculate values of 2, , , 2, , 2, sin2 , sin2 and sum the individual factors over all the reflections. Set up and solve t