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1、BRITISH STANDARD BS 6200-3.28.3: 1995 ISO 10701:1994 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.28 Determination of sulfur Subsection 3.28.3 Steel and iron: spectrophotometric method ICS 77.080.00 Licensed Copy: sheffieldun sheffieldun, na, We
2、d Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.28.3:1995 This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1995 BSI 08-1999 The followi
3、ng BSI references relate to the work on this standard: Committee reference ISE/18 Draft for comment 93/300210 DC ISBN 0 580 24932 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee ISE/18, Sampling and analysis of iron and
4、 steel, upon which the following bodies were represented: BCIRA British Iron and Steel Producers Association Ministry of Defence TWI Coopted members Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled C
5、opy, (c) BSI BS 6200-3.28.3:1995 BSI 08-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Normative references1 3Principle1 4Reagents1 5Apparatus3 6Sampling4 7Procedure4 8Expression of results5 9Special case6 10Notes on procedure6 11Test report7 Annex A (infor
6、mative) Additional information on the international cooperative tests8 Annex B (informative) Graphical representation of precision data9 Figure 1 Example of an apparatus for purification of the reducing mixture2 Figure 2 Example of an apparatus for reduction and distillation3 Figure B.1 Logarithmic
7、relationship between sulfur content (ws) and repeatability (r) or reproducibility (R and Rw)9 Table 11 Table 25 Table 36 Table A.18 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.28.3:1995 ii BS
8、I 08-1999 National foreword This Subsection of BS 6200 has been prepared by Technical Committee ISE/18. It is identical with ISO 10701:1994 Steel and iron Determination of sulfur content Methylene blue spectrophotometric method, published by the International Organization for Standardization (ISO).
9、The Technical Committee has reviewed the provisions of ISO 377-2, ISO 385-1 and ISO 648, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Related British Standards for ISO 385-1:1984 and ISO 648:1977 are, respectively, BS 846
10、:1985 Specification for burettes and BS 1583:1986 Specification for one-mark pipettes. Appropriate procedures from ISO 377 are incorporated in BS 6200-2:1993 Methods of sampling and sample preparation. A British Standard does not purport to include all the necessary provisions of a contract. Users o
11、f British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred toCorresponding British Standard ISO 1042:1983BS 1792 Specification for one-mark volumetric flasks (I
12、dentical) ISO 3696:1987BS 3978:1987 Specification for water for laboratory use (Identical) ISO 5725:1986BS 5497 Precision of test methods Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests (Identical) Summary of pages Thi
13、s document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Lice
14、nsed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.28.3:1995 BSI 08-19991 1 Scope This International Standard specifies a methylene blue spectrophotometric method for the determination of sulfur in steel and iron. The method is applicable
15、 to sulfur contents between 0,000 3 % (m/m) and 0,010 % (m/m). However, niobium, silicon, tantalum and titanium interfere in the determination of sulfur. Depending on the concentration of the interfering elements, the application ranges and test portion masses given in Table 1 apply. Table 1 2 Norma
16、tive references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Intern
17、ational Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 377-2:1989, Selection and preparation of samples and test pieces of wrought
18、steels Part 2: Samples for the determination of the chemical composition. ISO 385-1:1984, Laboratory glassware Burettes Part 1: General requirements. ISO 648:1977, Laboratory glassware One-mark pipettes. ISO 1042:1983, Laboratory glassware One-mark volumetric flasks. ISO 3696:1987, Water for analyti
19、cal laboratory use Specification and test methods. ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. 3 Principle Dissolution of a test portion in a mixture of hydrochloric and nitric acids. Evaporation wi
20、th perchloric acid until white fumes appear to remove hydrochloric and nitric acids. Dissolution of the salts in hydrochloric acid. Evolution of hydrogen sulfide by reducing with a mixture of hydroiodic and hypophosphorous acids in a nitrogen atmosphere, distillation, and absorption into zinc acetat
21、e solution. Formation of methylene blue by reacting with N,N-dimethyl-p-phenylenediamine and iron(III) solution. Spectrophotometric measurement at a wavelength of about 665 nm. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade with a very low s
22、ulfur content, and only freshly prepared grade 2 water as specified in ISO 3696. 4.1 Hydrochloric acid, about 1,19 g/ml. 4.2 Hydrochloric acid, about 1,19 g/ml, diluted 1 + 15. 4.3 Perchloric acid, about 1,54 g/ml. 4.4 Hydrobromic acid, about 1,48 g/ml. 4.5 Mixture of hydrochloric and nitric acids M
23、ix one volume of hydrochloric acid (4.1) and one volume of nitric acid, about 1,40 g/ml. Prepare immediately before use. 4.6 Reducing reagent solution Transfer 200 ml of hydriodic acid about 57 % (m/m) and 50 ml of hypophosphorous acid about 50 % (m/m) into the purifying apparatus (see Figure 1). Pu
24、rge with nitrogen (4.12) at a flowrate of 100 ml/min for 10 min, to mix the acids and expel air from the system. Switch on the electric heating mantle. Heat to boiling and boil gently for about 120 min at a temperature of about 115 C in a current of nitrogen. When purification is completed (see 10.3
25、), switch off the electric heating mantle. Then cool the solution and keep it in a brown bottle. 4.7 Absorbing solution Dissolve 5 g of zinc acetate dihydrate (CH3COO)2Zn.2H2O in 400 ml of water. Add 200 ml of sodium hydroxide solution, 30 g/l, and 70 g of ammonium chloride, and then dilute to 1 000
26、 ml with water. Maximum allowable content of the interfering elements Test portion Application ranges %ws % (m/m)% (m/m) NbSiTaTig 0,51,00,31,01,0 0,000 3 to 0,001 0 1,02,00,62,00,50 0,001 0 to 0,010 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (
27、c) BSI BS 6200-3.28.3:1995 2 BSI 08-1999 4.8 Iron, 10 g/l solution. Weigh, to the nearest 0,01 g, 1,00 g of pure iron which is free from sulfur as sulfate. Transfer to a 300 ml beaker, cover with a watch glass, dissolve by heating with an addition of 20 ml of hydrochloric acid ( about 1,19 g/ml, dil
28、uted 1 + 1) and boil gently for about 10 min. Then add 2 ml of nitric acid ( about 1,40 g/ml) drop by drop to oxidize iron. Remove the oxides of nitrogen by boiling, and cool to room temperature. Transfer to a 100 ml one-mark volumetric flask, dilute to the mark with water and mix. 4.9 Iron(III) chl
29、oride, solution. Dissolve 1 g of iron(III) chloride hexahydrate (FeCl3.6H2O) in about 40 ml of water. Add 10 ml of hydrochloric acid (4.1) and dilute to 100 ml with water. 4.10 N,N-dimethyl-p-phenylenediamine in hydrochloric acid medium Dissolve 0,5 g of N,N-dimethyl-p-phenylenediamine chloride NH2C
30、6H4N(CH3)2.2HCl in about 100 ml of water. Add 230 ml of hydrochloric acid (4.1) and dilute to 500 ml with water. Figure 1 Example of an apparatus for purification of the reducing mixture Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 620
31、0-3.28.3:1995 BSI 08-19993 4.11 Sulfur, standard solution. 4.11.1 Stock solution, corresponding to 1 g of S per litre. Weigh, to the nearest 0,000 1 g, 5,435 2 g of potassium sulfate minimum assay: 99,5 % (m/m), previously dried at 110 C for 2 h and cooled to room temperature in a desiccator. Dissol
32、ve in water, transfer to a 1 000 ml one-mark volumetric flask quantitatively, dilute to the mark and mix. 1 ml of this stock solution contains 1 mg of S. 4.11.2 Standard solution A, corresponding to 10 mg of S per litre. Transfer 10,0 ml of the stock solution (4.11.1) to a 1 000 ml one-mark volumetr
33、ic flask, dilute to the mark with water and mix. 1 ml of this standard solution contains 10 4g of S. 4.11.3 Standard solution B, corresponding to 1 mg of S per litre. Transfer 10,0 ml of the standard solution (4.11.2) to a 100 ml one-mark volumetric flask, dilute to the mark with water and mix. Prep
34、are the solution immediately before use. 1 ml of this standard solution contains 1 4g of S. 4.12 Nitrogen 5 Apparatus All volumetric glassware shall be class A, in accordance with ISO 385-1, ISO 648 or ISO 1042, as appropriate. Ordinary laboratory apparatus, and Figure 2 Example of an apparatus for
35、reduction and distillation Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.28.3:1995 4 BSI 08-1999 5.1 Apparatus for reduction and distillation Assemble the apparatus for reduction and distillation as shown in Figure 2. Close-fitti
36、ng ground-glass joints shall be used. When the apparatus is used for the first time, or after a long period of disuse, blank tests shall be carried out repetitively until stable low blank values are obtained. 5.1.1 Decomposition flask, about 300 ml in volume. 5.1.2 Reflux condenser, about 150 mm in
37、length. 5.1.3 Gas washing bottle, about 150 ml in volume. 5.1.4 Absorption flask, one-mark volumetric flask of capacity 20 ml or 100 ml. 5.2 Spectrophotometer, equipped to measure absorbance at a wavelength of about 665 nm. 6 Sampling Carry out sampling in accordance with ISO 377-2 or appropriate na
38、tional standards for steel and iron. 7 Procedure WARNING Perchloric acid vapour may cause explosions in the presence of ammonia, nitrous fumes or organic matter in general. 7.1 Test portion Weigh, to the nearest 1 mg, the mass given below as a function of the expected sulfur content: a) sulfur conte
39、nts from 0,000 3 % (m/m) to 0,001 0 % (m/m), mass of test portion about 1,00 g; b) sulfur contents from 0,001 0 % (m/m) to 0,010 % (m/m), mass of test portion about 0,50 g. 7.2 Blank test In parallel with the determination and following the same procedure, carry out a blank test using the same quant
40、ities of all the reagents. It is recommended that the blank value does not exceed 0,7 4g of sulfur for sulfur contents up to 0,001 % (m/m), or 1,5 4g of sulfur for sulfur contents from 0,001 % (m/m) to 0,010 % (m/m). 7.3 Determination 7.3.1 Preparation of the test solution Place the test portion (7.
41、1) in a decomposition flask (5.1.1). Add 15 ml of the mixture of hydrochloric and nitric acids (4.5). After standing at room temperature for about 30 min, heat gently until solvent action ceases. Then, using a pipette, add 5,0 ml of perchloric acid (4.3) and 1,0 ml of iron solution (4.8), heat and e
42、vaporate until white fumes appear. After cooling, add 5 ml of hydrochloric acid (4.1). (See clause 9 for a possible modification of this procedure.) Heat again and evaporate to fuming on a hotplate at a temperature of about 300 C. Then continue to evaporate until free from white fumes of perchloric
43、acid and dry. After cooling, add 10 ml of hydrochloric acid (4.1), heat to dissolve the salts and cool to room temperature. 7.3.2 Reduction and distillation Add 20 ml of the reducing reagent solution (4.6) to the decomposition flask (5.1.1) and allow to stand for 10 min. Pour 30 ml of water into the
44、 gas washing bottle (5.1.3). Place the appropriate volume of absorbing solution (4.7) in an absorption vessel (5.1.4), according to the expected sulfur content to be determined, as follows: a) for sulfur contents less than 0,001 0 % (m/m), introduce 10 ml of the absorbing solution (4.7) into a 20 ml
45、 absorption flask; b) for sulfur contents from 0,001 0 % (m/m) to 0,010 % (m/m), introduce 50 ml of the absorbing solution (4.7) into a 100 ml absorption flask. With water flowing through the reflux condenser (5.1.2), connect the decomposition flask (5.1.1) containing the test solution. Pass nitroge
46、n (4.12) through the apparatus at a flowrate of 100 ml/min, as shown in Figure 2. Heat the test solution to a temperature of 114 C to 118 C for 30 min. This will normally be achieved by setting the hotplate temperature to about 250 C (see 10.2). Evolved gases are conveyed by the nitrogen carrier gas
47、 through the gas washing bottle (5.1.3) to the absorption vessel. 7.3.3 Colour development 7.3.3.1 For sulfur contents up to 0,001 0 % (m/m) Disconnect the 20 ml absorption flask (5.1.4) and the gas inlet tube from the apparatus. Keeping the tip of the tube in the absorbing solution, add 1,0 ml of h
48、ydrochloric acid (4.2) from the upper end of the tube by using a micropipette to wash the inside surface of the tube, followed by rinsing with 1 ml of water. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:57 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.28.3:1995 BSI 08-19995 Re
49、move the gas inlet tube, gently swirl the 20 ml absorption flask, and allow to stand for 20 min at 25 C in a thermostat. Then add 2,0 ml of N,N-dimethyl-p-phenylenediamine solution (4.10) to the absorption flask (5.1.4) and shake gently. Immediately add 0,4 ml of iron(III) chloride solution (4.9), and shake vigorously for 1 min. Dilute to the mark with water and mix. Allow to stand for 15 min. 7.3.3.2 For sulfur contents from 0,001 0 % (m/m) to 0,010 % (m/m) Disconnect the 100 ml absorption flask (5.1.4) and the