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 77.080.00BS6200-3.28.3:1995 This British Standard, havin
2、g been prepared under the directionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comes intoeffect on 15December1995 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference ISE/18 Draft for comment 93/300210 DC IS
3、BN 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 steel, upon which the following bodies were represented: BCIRA British Iron and Steel Producers Association Minist
4、ry of Defence TWI Coopted members Amendments issued since publication Amd. No. Date CommentsBS6200-3.28.3:1995 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 3 6 Sampling 4 7 Procedu
5、re 4 8 Expression of results 5 9 Special case 6 10 Notes on procedure 6 11 Test report 7 Annex A (informative) Additional information on the international cooperative tests 8 Annex B (informative) Graphical representation of precision data 9 Figure 1 Example of an apparatus for purification of the r
6、educing mixture 2 Figure 2 Example of an apparatus for reduction and distillation 3 Figure B.1 Logarithmic relationship between sulfur content (w s ) and repeatability (r) or reproducibility (R and R w ) 9 Table 1 1 Table 2 5 Table 3 6 Table A.1 8 List of references Inside back coverBS6200-3.28.3:19
7、95 ii BSI 08-1999 National foreword This Subsection of BS6200 has been prepared by Technical Committee ISE/18. It is identical with ISO10701:1994 Steel and iron Determination of sulfur content Methylene blue spectrophotometric method, published by the International Organization for Standardization (
8、ISO). The Technical Committee has reviewed the provisions of ISO377-2, ISO385-1 and ISO648, 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 ISO385-1:1984 and ISO 648:1977 are, respectively, BS84
9、6:1985 Specification for burettes and BS1583:1986 Specification for one-mark pipettes. Appropriate procedures from ISO377 are incorporated in BS6200-2:1993 Methods of sampling and sample preparation. A British Standard does not purport to include all the necessary provisions of a contract. Users of
10、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 to Corresponding British Standard ISO 1042:1983 BS 1792 Specification for one-mark volumetric flasks (I
11、dentical) ISO 3696:1987 BS 3978:1987 Specification for water for laboratory use (Identical) ISO 5725:1986 BS 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 T
12、his document comprises a front cover, an inside front cover, pages i and ii, pages1 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.BS62
13、00-3.28.3:1995 BSI 08-1999 1 1 Scope This International Standard specifies a methylene blue spectrophotometric method for the determination of sulfur in steel and iron. The method is applicable to sulfur contents between0,0003% (m/m) and0,010% (m/m). However, niobium, silicon, tantalum and titanium
14、interfere in the determination of sulfur. Depending on the concentration of the interfering elements, the application ranges and test portion masses given inTable 1 apply. Table 1 2 Normative references The following standards contain provisions which, through reference in this text, constitute prov
15、isions 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 International Standard are encouraged to investigate the possibility of applying the most recent editions of the standa
16、rds 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 steels Part 2: Samples for the determination of the chemical composition. ISO 385-1:1984, Laboratory glassware Bu
17、rettes 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 analytical laboratory use Specification and test methods. ISO 5725:1986, Precision of test methods Determination of repe
18、atability 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 with perchloric acid until white fumes appear to remove hydrochloric and nitric acids. Dissolution of the salts in
19、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 acetate solution. Formation of methylene blue by reacting with N,N-dimethyl-p-phenylenediamine and iron(III) solution.
20、Spectrophotometric measurement at a wavelength of about665nm. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade with a very low sulfur content, and only freshly prepared grade2 water as specified in ISO3696. 4.1 Hydrochloric acid, about1,19g/ml
21、. 4.2 Hydrochloric acid, about1,19g/ml, diluted1+15. 4.3 Perchloric acid, about1,54g/ml. 4.4 Hydrobromic acid, about1,48g/ml. 4.5 Mixture of hydrochloric and nitric acids Mix one volume of hydrochloric acid (4.1) and one volume of nitric acid, about1,40g/ml. Prepare immediately before use. 4.6 Reduc
22、ing reagent solution Transfer200ml of hydriodic acid about57% (m/m) and50ml of hypophosphorous acid about50% (m/m) into the purifying apparatus (seeFigure 1). Purge with nitrogen (4.12) at a flowrate of100ml/min for10min, to mix the acids and expel air from the system. Switch on the electric heating
23、 mantle. Heat to boiling and boil gently for about120min at a temperature of about115 C in a current of nitrogen. When purification is completed (see10.3), switch off the electric heating mantle. Then cool the solution and keep it in a brown bottle. 4.7 Absorbing solution Dissolve5g of zinc acetate
24、dihydrate (CH 3 COO) 2 Zn.2H 2 O in400ml of water. Add200ml of sodium hydroxide solution,30g/l, and70g of ammonium chloride, and then dilute to1000ml with water. Maximum allowable content of the interfering elements Test portion Application ranges %w s % (m/m) % (m/m) Nb Si Ta Ti g 0,5 1,0 0,3 1,0 1
25、,0 0,000 3 to 0,001 0 1,0 2,0 0,6 2,0 0,50 0,001 0 to 0,010BS6200-3.28.3:1995 2 BSI 08-1999 4.8 Iron, 10g/l solution. Weigh, to the nearest0,01g, 1,00g of pure iron which is free from sulfur as sulfate. Transfer to a300ml beaker, cover with a watch glass, dissolve by heating with an addition of20ml
26、of hydrochloric acid ( about1,19g/ml, diluted1+1) and boil gently for about10min. Then add2ml of nitric acid ( about1,40g/ml) drop by drop to oxidize iron. Remove the oxides of nitrogen by boiling, and cool to room temperature. Transfer to a100ml one-mark volumetric flask, dilute to the mark with wa
27、ter and mix. 4.9 Iron(III) chloride, solution. Dissolve1g of iron(III) chloride hexahydrate (FeCl 3 .6H 2 O) in about40ml of water. Add10ml of hydrochloric acid (4.1) and dilute to100ml with water. 4.10 N,N-dimethyl-p-phenylenediamine in hydrochloric acid medium Dissolve0,5g of N,N-dimethyl-p-phenyl
28、enediamine chloride NH 2 C 6 H 4 N(CH 3 ) 2 .2HCl in about100ml of water. Add230ml of hydrochloric acid (4.1) and dilute to500ml with water. Figure 1 Example of an apparatus for purification of the reducing mixtureBS6200-3.28.3:1995 BSI 08-1999 3 4.11 Sulfur, standard solution. 4.11.1 Stock solution
29、, corresponding to1g of S per litre. Weigh, to the nearest0,0001g, 5,4352g of potassium sulfate minimum assay: 99,5% (m/m), previously dried at110 C for2h and cooled to room temperature in a desiccator. Dissolve in water, transfer to a1000ml one-mark volumetric flask quantitatively, dilute to the ma
30、rk and mix. 1ml of this stock solution contains1mg of S. 4.11.2 Standard solution A, corresponding to10mg of S per litre. Transfer10,0ml of the stock solution (4.11.1) to a1000ml one-mark volumetric flask, dilute to the mark with water and mix. 1ml of this standard solution contains104g of S. 4.11.3
31、 Standard solution B, corresponding to1mg of S per litre. Transfer10,0ml of the standard solution (4.11.2) to a100ml one-mark volumetric flask, dilute to the mark with water and mix. Prepare the solution immediately before use. 1ml of this standard solution contains14g of S. 4.12 Nitrogen 5 Apparatu
32、s All volumetric glassware shall be class A, in accordance with ISO385-1, ISO648 or ISO1042, as appropriate. Ordinary laboratory apparatus, and Figure 2 Example of an apparatus for reduction and distillationBS6200-3.28.3:1995 4 BSI 08-1999 5.1 Apparatus for reduction and distillation Assemble the ap
33、paratus for reduction and distillation as shown inFigure 2. Close-fitting 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
34、flask, about300ml in volume. 5.1.2 Reflux condenser, about150mm in length. 5.1.3 Gas washing bottle, about150ml in volume. 5.1.4 Absorption flask, one-mark volumetric flask of capacity20ml or100ml. 5.2 Spectrophotometer, equipped to measure absorbance at a wavelength of about665nm. 6 Sampling Carry
35、out sampling in accordance with ISO377-2 or appropriate national 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 nearest1mg, the mass given below as a
36、function of the expected sulfur content: a) sulfur contents from0,0003% (m/m) to0,0010% (m/m), mass of test portion about1,00g; b) sulfur contents from0,001 0% (m/m) to0,010% (m/m), mass of test portion about0,50g. 7.2 Blank test In parallel with the determination and following the same procedure, c
37、arry out a blank test using the same quantities of all the reagents. It is recommended that the blank value does not exceed0,74g of sulfur for sulfur contents up to0,001% (m/m), or1,54g of sulfur for sulfur contents from0,001% (m/m) to0,010% (m/m). 7.3 Determination 7.3.1 Preparation of the test sol
38、ution Place the test portion (7.1) in a decomposition flask(5.1.1). Add15ml of the mixture of hydrochloric and nitric acids (4.5). After standing at room temperature for about30min, heat gently until solvent action ceases. Then, using a pipette, add5,0ml of perchloric acid(4.3) and1,0ml of iron solu
39、tion (4.8), heat and evaporate until white fumes appear. After cooling, add5ml of hydrochloric acid (4.1). (Seeclause9 for a possible modification of this procedure.) Heat again and evaporate to fuming on a hotplate at a temperature of about300 C. Then continue to evaporate until free from white fum
40、es of perchloric acid and dry. After cooling, add10ml of hydrochloric acid (4.1), heat to dissolve the salts and cool to room temperature. 7.3.2 Reduction and distillation Add20ml of the reducing reagent solution (4.6) to the decomposition flask (5.1.1) and allow to stand for10min. Pour30ml of water
41、 into the 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 than0,0010% (m/m), introduce10ml of the absorbing solution (4.7) into a20ml
42、 absorption flask; b) for sulfur contents from0,0010% (m/m) to0,010% (m/m), introduce50ml of the absorbing solution (4.7) into a100ml absorption flask. With water flowing through the reflux condenser(5.1.2), connect the decomposition flask(5.1.1) containing the test solution. Pass nitrogen (4.12) th
43、rough the apparatus at a flowrate of100ml/min, as shown inFigure 2. Heat the test solution to a temperature of114 C to118 C for30min. This will normally be achieved by setting the hotplate temperature to about250 C (see10.2). Evolved gases are conveyed by the nitrogen carrier gas through the gas was
44、hing bottle(5.1.3) to the absorption vessel. 7.3.3 Colour development 7.3.3.1 For sulfur contents up to0,0010% (m/m) Disconnect the20ml absorption flask (5.1.4) and the gas inlet tube from the apparatus. Keeping the tip of the tube in the absorbing solution, add1,0ml of hydrochloric acid (4.2) from
45、the upper end of the tube by using a micropipette to wash the inside surface of the tube, followed by rinsing with1ml of water.BS6200-3.28.3:1995 BSI 08-1999 5 Remove the gas inlet tube, gently swirl the20ml absorption flask, and allow to stand for20min at25 C in a thermostat. Then add2,0ml of N,N-d
46、imethyl-p-phenylenediamine solution (4.10) to the absorption flask (5.1.4) and shake gently. Immediately add0,4ml of iron(III) chloride solution(4.9), and shake vigorously for1min. Dilute to the mark with water and mix. Allow to stand for15min. 7.3.3.2 For sulfur contents from0,0010% (m/m) to0,010%
47、(m/m) Disconnect the100ml absorption flask (5.1.4) and the gas inlet tube from the apparatus, Keeping the tip of the tube in the absorbing solution, add1,0ml of hydrochloric 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
48、with1ml or2ml of water. Remove the gas inlet tube, gently swirl the100ml absorption flask, and allow to stand for20min at25 C in a thermostat. Then add10,0ml of N,N-dimethyl-p-phenylenediamine solution (4.10) to the absorption flask (5.1.4) and shake gently. Immediately add2,0ml of iron(III) chlorid
49、e solution(4.9), and shake vigorously for1min. Dilute to the mark with water and mix. Allow to stand for15 min. 7.3.4 Spectrophotometric measurement 7.3.4.1 For sulfur contents up to0,0010% (m/m) Carry out the spectrophotometric measurements with a cell of1cm optical path length at a wavelength of about665nm, after adjusting the spectrophotometer (5.2) to zero against water. 7.3.4.2 For sulfur contents from0,0010% (m/m) to0,010% (m/m) Carry out the spectrophotometric measurements with a cell of1cm optical path leng
