1、 Reference numberISO 22725:2007(E)ISO 2007INTERNATIONAL STANDARD ISO22725First edition2007-11-15Nickel alloys Determination of tantalum Inductively coupled plasma atomic emission spectrometric method Alliages de nickel Dosage du tantale Mthode par spectromtrie dmission atomique avec source plasma in
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6、ing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedISO 22725:
7、2007(E) ISO 2007 All rights reserved iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Principle. 1 4 Reagents 2 5 Apparatus 3 6 Sampling and sample preparation 4 7 Procedure 4 7.1 Test portion . 4 7.2 Preparation of test solution, TTa. 4 7.3 Optimisation of spectrometer 4 7.4 Pr
8、e-determination of the test solution 5 7.5 Preparation of calibration solutions for bracketing, Kl,Taand Kh,Ta. 5 7.6 Measurement of test solutions 6 8 Expression of results . 6 8.1 Method of calculation. 6 8.2 Precision 6 8.3 Trueness 7 9 Test report . 7 Annex A (normative) Checking the performance
9、 of an ICP instrument . 8 Annex B (informative) Notes on the test programme . 10 ISO 22725:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Intern
10、ational Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with
11、 ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical
12、 committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to
13、the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 22725 was prepared by Technical Committee ISO/TC 155, Nickel and nickel alloys, Subcommittee SC 3, Analysis of nickel,
14、ferronickel and nickel alloys. INTERNATIONAL STANDARD ISO 22725:2007(E) ISO 2007 All rights reserved 1Nickel alloys Determination of tantalum Inductively coupled plasma atomic emission spectrometric method 1 Scope This International Standard specifies an inductively coupled plasma atomic emission sp
15、ectrometric method for the determination of the mass fraction of tantalum between 0,1 % and 5 % in nickel alloys. 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 refere
16、nces, the latest edition of the referenced document (including any amendments) applies. ISO 648:1), Laboratory glassware Single volume pipettes ISO 1042:1998, Laboratory glassware One-mark volumetric flasks ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 5725-1:
17、1994, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard me
18、asurement method ISO 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results Part 3: Intermediate measures of the precision of a standard measurement method 3 Principle Dissolution of a test portion in a mixture of hydrofluoric, hydrochloric, nitric and phosphoric acid and
19、fuming after addition of perchloric acid. Addition of hydrofluoric acid and, if desired, of an internal reference element and dilution of the solution to known volume. Nebulization of the solution into an inductively coupled plasma atomic emission spectrometer and measurement of the intensity of the
20、 emitted light from tantalum, and eventually from the internal reference element, simultaneously. An example of the analytical line for tantalum is given in Table 1. The method uses a calibration based on a very close matrix-matching of the calibration solutions to the sample and bracketing of the m
21、ass fractions between 0,75 and 1,25 of the approximate concentration of tantalum in the sample to be analysed. The concentration of all elements in the sample has, therefore, to be approximately known. If the concentrations are not known, the sample has to be analysed by some semi-quantitative metho
22、d. The advantage of this procedure is that all possible interferences from the matrix will be automatically compensated, which will result in high accuracy. This is most important for spectral interferences, 1) To be published. (Revision of ISO 648:1977) ISO 22725:2007(E) 2 ISO 2007 All rights reser
23、vedwhich can be severe in very highly alloyed metals. All possible interferences shall be kept at a minimum level. Therefore it is essential that the spectrometer used meets the performance criteria specified in the method for the selected analytical lines. The line corresponding to 240,06 nm has be
24、en carefully investigated. If other lines are used, they shall be carefully checked. The analytical line for the internal standard should be selected carefully. The use of Scandium at 363,07 nm is recommended. This line is interference-free for the elements and concentrations generally found in nick
25、el alloys. Table 1 Example of analytical line for tantalum Element Analytical line Interferences nm Tantalum 240,06 Fe - Hf NOTE The use of an internal standard is not essential since no relevant differences between laboratories operating with or without internal standards were found. 4 Reagents Dur
26、ing the analysis, unless otherwise stated, use only reagents of recognised analytical grade and only grade 2 water as specified in ISO 3696:1987. 4.1 Hydrofluoric acid, HF, 40 % (mass fraction), = 1,14 g/ml, or 50 % (mass fraction), = 1,17 g/ml. WARNING Hydrofluoric acid is extremely irritating and
27、corrosive to skin and mucous membranes producing severe skin burns which are slow to heal. In the case of contact with skin, wash well with water, apply a topical gel containing 2,5 % (mass fraction) calcium gluconate, and seek immediate medical treatment. 4.2 Hydrochloric acid, HCl, = 1,19 g/ml. 4.
28、3 Nitric acid, HNO3, = 1,40 g/ml. 4.4 Phosphoric acid, H3PO4, = 1,70 g/ml. 4.5 Perchloric acid, HClO4, 60 % (mass fraction) = 1,54 g/ml or 70 % (mass fraction), = 1,67 g/ml. 4.6 Internal standard solution, 100 mg/l. Choose a suitable element to be added as internal reference and prepare a 100 mg/l s
29、olution. 4.7 Tantalum standard solution, 10 g/l. Weigh, to the nearest 0,000 5 g, 1 g of high-purity tantalum minimum 99,9 % (mass fraction), place it in a beaker and dissolve it in a mixture of 10 ml of hydrofluoric acid (4.1) and 10 ml of nitric acid (4.3). Cool and transfer quantitatively to a ca
30、librated 100 ml one-mark volumetric flask. Dilute to the mark with water and mix. NOTE 1 ml of this solution contains 10 mg of tantalum. 4.8 Tantalum standard solution, 1 g/l. Weigh, to the nearest 0,000 5 g, 0,1 g of high-purity tantalum minimum 99,9 % (mass fraction), place it in a beaker and diss
31、olve it in a mixture of 10 ml of hydrofluoric acid (4.1) and 10 ml of nitric acid (4.3). ISO 22725:2007(E) ISO 2007 All rights reserved 3Cool and transfer quantitatively to a calibrated 100 ml one-mark volumetric flask. Dilute to the mark with water and mix. NOTE 1 ml of this solution contains 1 mg
32、of tantalum. 4.9 Tantalum standard solution, 100 mg/l. Using a calibrated pipette (or burette), transfer 10 ml of the tantalum standard solution (4.8) into a calibrated 100 ml one-mark volumetric flask. Add 10 ml of hydrofluoric acid (4.1) and 10 ml of nitric acid (4.3). Dilute to the mark with wate
33、r and mix. NOTE 1 ml of this solution contains 0,1 mg of tantalum. 4.10 Standard solutions of interfering elements. Prepare standard solutions for each element whose mass fraction is higher than 1 % in the test sample. Use pure metal or chemical substances with mass fractions of tantalum less than 1
34、0 g/g. 5 Apparatus All volumetric glassware shall be class A and calibrated, in accordance with ISO 648 or ISO 1042, as appropriate. Ordinary laboratory apparatus and the following. 5.1 Polytetrafluoroethylene (PTFE) beakers or perfluoroalkyoxy-polymer (PFA) beakers with a graphite base. 5.2 Polypro
35、pylene volumetric flasks, of capacity 100 ml, calibrated in accordance with ISO 1042. 5.3 Atomic emission spectrometer (AES). The spectrometer shall be equipped with an inductively coupled plasma (ICP) and a nebulization system resistant to hydrofluoric acid. The ICP-AES used will be satisfactory if
36、, after optimising in accordance with 7.3, it meets the performance criteria given in this subclause. The spectrometer can be either a simultaneous or a sequential one. If a sequential spectrometer can be equipped with an extra arrangement for simultaneous measurement of the internal standard line,
37、it can be used with the internal reference method. If the sequential spectrometer is not equipped with this arrangement, an internal reference cannot be used and an alternative method without an internal standard should be applied. 5.3.1 Practical resolution of the sequential spectrometer. Calculate
38、 the bandwidth (full width at half maximum), in accordance with A.2 (see Annex A), for the analytical line used, including the line for internal reference. The bandwidth shall be less than 0,030 nm. 5.3.2 Short-term stability. Calculate the standard deviation of ten measurements of the absolute inte
39、nsity or intensity ratio corresponding to tantalum and to the internal standard, by using the most concentrated calibration solution for tantalum in accordance with A.3. The relative standard deviation shall not exceed 0,4 %. 5.3.3 Background equivalent concentration. Calculate the background equiva
40、lent concentration (BEC) in accordance with A.4, for the analytical line using a solution containing only the analyte element. The maximum values of BEC obtained should be 0,8 mg/l. ISO 22725:2007(E) 4 ISO 2007 All rights reserved6 Sampling and sample preparation 6.1 Sampling and preparation of the
41、laboratory sample shall be carried out by the normal agreed procedures or, in case of dispute, by the relevant International Standard. 6.2 The laboratory sample is normally in the form of millings or drillings and no further mechanical preparation is necessary. 6.3 The laboratory sample shall be cle
42、aned by washing with pure acetone and drying in air. 6.4 If brazed alloy tools are used in the preparation of the laboratory sample then the sample shall be further cleaned by pickling in 15 % (mass fraction) nitric acid for a few minutes. It shall then be washed several times with distilled water,
43、followed by washing in acetone and drying in air. 7 Procedure 7.1 Test portion Weigh, to the nearest 0,000 5 g, 0,25 g of the test sample. 7.2 Preparation of test solution, TTaA PTFE or PFA beaker (5.1) should be used when using HF (4.1). 7.2.1 Place the test portion in a PTFE or PFA beaker with a g
44、raphite base. 7.2.2 Add 5 ml of HF (4.1), 30 ml of HCl (4.2), 3 ml of HNO3(4.3) and allow the dissolution of the sample to take place overnight at room temperature. Then add 2,5 ml of H3PO4(4.4). If necessary, heat to complete dissolution. Add 7,5 ml of HClO4(4.5) and heat until the perchloric acid
45、starts to fume. Continue to fume for 2 to 3 min. NOTE 5 ml of H3PO4(4.4) and 5 ml of HClO4(4.5) can also be used, instead of 2,5 ml of H3PO4(4.4) and 7,5 ml of HClO4(4.5). 7.2.3 Cool the solution and add 10 ml of water to dissolve the salts. Some residues may remain undissolved. In this case, add 2
46、ml of HF (4.1) and heat gently for about 20 min until the residues dissolve completely. NOTE The following is an alternative dissolution procedure for 7.2.2 and 7.2.3. Add 30 ml of HCl (4.2), 3 ml of HNO3(4.3) and 5 ml of H3PO4(4.4), or 20 ml of HCl (4.2), 10 ml of HNO3(4.3) and 5 ml of H3PO4(4.4).
47、Let the dissolution begin at room temperature. If necessary, heat to complete dissolution. Add 2 ml of HF (4.1) and 5 ml of H2SO4( = 1,84g/ml) and heat until sulfuric acid starts to fume. Cool the solution and add 10 ml of water to dissolve the salts. Heat gently until the residues dissolve complete
48、ly. 7.2.4 Cool the solution to room temperature and transfer the solution quantitatively to a 100 ml volumetric polypropylene flask. If the internal standard solution (4.6) is used, add, with a calibrated pipette, 10 ml of this internal standard. 7.2.5 Dilute to the mark with water and mix. Proceed
49、as quickly as possible to the measurement. 7.3 Optimisation of spectrometer 7.3.1 Start the ICP-AES and let it run for at least 30 min for stabilisation before taking any measurements. 7.3.2 Optimise the instrument in accordance with the manufacturers instructions. ISO 22725:2007(E) ISO 2007 All rights reserved 57.3.3 Prepare the software to measure the intensity, mean value and relative standard deviation of the selected analytical lines. 7.3.4 If an internal standard is used, prepare the softwar
