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1、BRITISH STANDARD BS 6200-3.5.2: 1991 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.5 Determination of boron Subsection 3.5.2 Ferroboron: volumetric method Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolle
2、d Copy, (c) BSI BS 6200-3.5.2:1991 This British Standard, having been prepared under the direction of the Iron and Steel Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 20 December 1991 BSI 08-1999 The following BSI references relate to t
3、he work on this standard: Committee reference ISM/18 Draft for comment 91/38342 DC ISBN 0 580 20224 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/18, upon w
4、hich the following bodies were represented: BCIRA British Steel Industry Department of Trade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheff
5、ieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 BSI 08-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Principle1 3Reagents1 4Apparatus1 5Sampling1 6Procedure1 7Calculation and expression of results2 8Test report3 Table 1
6、 Precision data2 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 ii BSI 08-1999 Foreword This Subsection of BS 6200 has been prepared under the direction of the Iron and Steel St
7、andards Policy Committee and supersedes method 2 for the determination of boron in BSI Handbook No. 19, to which it is technically equivalent. BS 6200 is a multipart British Standard, covering all aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, toget
8、her with general information, is given in Part 1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obli
9、gations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, 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
10、the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 BSI 08-19991 1 Scope This Subsection of BS 6200 describes a volumetric method for the determination of boron in ferroboron. The method is applicable t
11、o the range of boron content normally found in ferroboron. NOTEThe titles of the publications referred to in this Subsection of BS 6200 are listed on the inside back cover. 2 Principle A solution of the test portion in sulfuric acid is passed through a column of cation exchange resin to remove iron
12、and interfering impurities and boron is determined in the eluate after addition of mannitol by titration with sodium hydroxide. 3 Reagents During the analysis use only reagents of recognized analytical grade and only grade 3 water as specified in BS 3978. 3.1 Boric acid, standard solution, 0.6 mg bo
13、ron per millilitre. Dissolve 3.429 g of boric acid in water. Transfer to a 1 L volumetric flask, dilute to the mark and mix. 3.2 Hydrochloric acid, density = 1.16 g/mL to 1.18 g/mL, diluted 1 + 1. 3.3 Hydrochloric acid, = 1.16 g/mL to 1.18 g/mL, diluted 1 + 9. 3.4 Hydrochloric acid, = 1.16 g/mL to 1
14、.18 g/mL, diluted 1 + 99. 3.5 Mannitol 3.6 Mixed indicator. Dissolve 0.05 g of methyl red, 0.1 g of bromocresol green, 0.3 g of phenolphthalein and 0.3 g of thymol blue in 100 mL of methanol. 3.7 Nitric acid, = 1.42 g/mL. 3.8 Sodium hydroxide, 100 g/L solution. Dissolve 100 g of sodium hydroxide cau
15、tiously, with stirring and cooling, in 600 mL of water, dilute to 1 L and mix. 3.9 Sodium hydroxide, 4 g/L solution, 0.1 M approximately. Dissolve 4 g of sodium hydroxide in water and cool. Transfer to 1 L volumetric flask, dilute to the mark and mix. Store in a a stoppered polyethylene bottle. 3.10
16、 Sodium peroxide 3.11 Sulfuric acid, 1.84 g/mL, diluted 1 + 1. To 400 mL of water add, cautiously, 500 mL of sulfuric acid, = 1.84 g/mL, with stirring and cooling. Cool, dilute to 1 L, and mix. 4 Apparatus IMPORTANT NOTE. Use only glassware which is known to give a low boron blank. 4.1 Ordinary labo
17、ratory apparatus 4.2 Volumetric glassware, in accordance with class A of BS 846, BS 1583 or BS 1792, as appropriate. 4.3 Reflux air condenser, comprising a 300 mm 6 mm diameter glass tube with a ground-glass joint fitting to a 250 mL round-bottomed flask. 4.4 Cation exchange column, comprising a gla
18、ss tube approximately 300 mm long 16 mm diameter, packed with a suitable sulfonated polystyrene cation exchange resin, particle size 0.3 mm to 1.18 mm, (14 mesh to 52 mesh). Wash the column with hydrochloric acid (3.2) when the resin is new, and also after every four determinations (to remove iron).
19、 Then wash with water until the washings are neutral. 4.5 pH meter, which may be used as an alternative to the mixed indicator (3.6). 5 Sampling Carry out sampling in accordance with BS 1837. Ferroboron is particularly prone to segregation because of the extended freezing range of the binary system;
20、 it is preferable to obtain the main sample when the melt is crushed. NOTEBS 6200-2, which will supersede BS 1837, is currently in preparation. On its publication this Subsection will be amended to include sampling in accordance with BS 6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest 0.00
21、1 g, a test portion of 1 g. 6.2 Blank test In parallel with the determination and following the same procedure carry out a blank test using the same quantities of all reagents. 6.3 Preparation of the test solution Place the test portion in a 250 mL round-bottomed flask (4.3) and add 75 mL of water,
22、5 mL of sulfuric acid (3.11), and 3.5 mL of nitric acid (3.7). Fit the reflux air condenser (4.3) and heat under gentle reflux until solvent action ceases. Continue to heat gently for a further 30 min. Cool, rinse and remove the condenser tube. Filter through a small paper-pulp pad into a 500 mL vol
23、umetric flask and wash with the minimum amount of hydrochloric acid (3.4). Reserve the solution in the 500 mL volumetric flask. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 2 BSI 08-1999 Transfer the filter to a platinu
24、m dish and ignite at a low temperature until carbonaceous matter is destroyed. Cool, transfer the residue to a nickel or iron crucible and fuse with the minimum amount of sodium peroxide (3.10) (0.5 g to 1.0 g is usually sufficient). Use a small flame until the reaction subsides and finally heat at
25、a bright red heat for 2 min. Cool and extract the fusion products in water, filter to remove iron or nickel oxide and wash with water. Add the filtrate to the main solution in the 500 mL volumetric flask. Dilute to the mark and mix. 6.4 Separation of boron by ion exchange Transfer a 50 mL aliquot of
26、 the solution to the top of the prepared ion exchange column and pass the solution through the column at a rate of approximately 5 mL per min. Wash several times with water, using 200 mL to 250 mL of water in all. Collect the eluate and washings in a 600 mL conical flask. 6.5 Titration of the boron
27、6.5.1 Using mixed indicator Add approximately 1 mL of mixed indicator (3.6) then sodium hydroxide solution (3.8) dropwise until a purple colour appears. Acidify with hydrochloric acid (3.3) dropwise from a burette to the appearance of a red colour, then add one drop in excess. Boil under a reflux co
28、ndenser for 5 min and cool. Neutralize the excess acid by adding sodium hydroxide solution (3.9) dropwise from a burette to the appearance of a green colour. IMPORTANT NOTE. The sodium hydroxide used up to this point does not count in the titration. Add 20 g of mannitol (3.5) and titrate with sodium
29、 hydroxide solution (3.9) to the appearance of a purple colour. Record the volume, Vt, of sodium hydroxide solution used. Titrate the blank test, following the same procedure, and record the volume, Vb, of sodium hydroxide (3.9) solution used. 6.5.2 Using a pH meter Adjust the boron solution with so
30、dium hydroxide solution (3.9), using the pH meter (4.5), to pH 6. Add 20 g of mannitol (3.5), and titrate with sodium hydroxide solution (3.9) to pH 8. Record the volume, Vt, of sodium hydroxide solution used. Titrate the blank test, following the same procedure, and record the volume, Vb, of sodium
31、 hydroxide solution (3.9) used. 6.5.3 Standardization of the sodium hydroxide solution Transfer 50 mL of boric acid solution (3.1) to a 600 mL conical beaker and dilute to approximately 250 mL. Add a few drops of hydrochloric acid (3.3) and then continue using the same procedure, 6.5.1 or 6.5.2, as
32、used in the boron determination. Record the volume, Vf, of sodium hydroxide solution (3.9) used. 7 Calculation and expression of results 7.1 Calculation Calculate c, the boron equivalent in milligrams per millilitre of the sodium hydroxide solution (3.9), from the equation: c = 30/Vc where Vc is the
33、 volume of sodium hydroxide solution (3.9) used in 6.5.3 (in mL). Calculate the boron content, B, expressed as a percentage by mass, from the equation: B = c(Vt Vb) where c is the equivalent concentration of boron of the sodium hydroxide solution (3.9) expressed as boron (in mg/mL); Vt is the volume
34、 of sodium hydroxide solution (3.9) used in the titration of the test portion (in mL); Vb is the volume of sodium hydroxide solution (3.9) used in the titration of the blank test (in mL). 7.2 Precision A planned trial of this method was carried out by 10 analysts each from a different laboratory; th
35、ree tests were carried out by each analyst on each of two samples. From the results obtained, the 95 % confidence limits (2s) have been calculated in accordance with BS 5497-1 and are given in Table 1. Table 1 Precision data The difference between two single results found on identical material by on
36、e analyst using the same apparatus within a short time interval will exceed the repeatability r, on average, not more than once in twenty cases in the normal and correct operation of the method. BoronRepeatability rReproducibility R % (m/m) 15.40.1700.48 19.30.2060.41 Licensed Copy: sheffieldun shef
37、fieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 BSI 08-19993 The difference between two single and independent results found by two operators working in different laboratories on identical test material will exceed the reproducibility, R, on average, no
38、t more than once in 20 cases in the normal and correct operation of the method. 8 Test report The test report shall include the following information: a) all information necessary for the identification of the sample, the laboratory and the date of analysis; b) the method used, by reference to this
39、Subsection of BS 6200; c) the results, and the form in which they are expressed; d) any unusual features noted during the determination; e) any operation not specified in this British Standard or any optional operation which may have influenced the results. Licensed Copy: sheffieldun sheffieldun, na
40、, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2:1991 BSI 08-1999 Publication(s) referred to BS 846, Specification for burettes. BS 1583, Specification for
41、 one-mark pipettes. BS 1792, Specification for one-mark volumetric flasks. BS 1837, Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys. BS 3978, Specification for water for laboratory use. BS 5497, Precision of test methods. BS 5497-1, Guide for the determination of re
42、peatability and reproducibility for a standard test method by inter-laboratory tests. BS 6200, Sampling and analysis of iron, steel and other ferrous metals. BS 6200-1, Introduction and contents1). BS 6200-2, Methods of sampling and sample preparation2). BSI Handbook No. 191) Methods for the samplin
43、g and analysis of iron, steel and other ferrous metals. 1) Referred to in the foreword only. 2) In preparation. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:06 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.5.2: 1991 BSI 389 Chiswick High Road London W4 4AL BSI British Standard
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