BS 6200-3 26 2-1991 Sampling and analysis of iron steel and other ferrous metals - Methods of analysis - Determination of silicon - Acid-resisting high silicon iron gravimetric met.pdf

1、BRITISH STANDARD BS 6200-3.26.2: 1991 Sampling and analysis of iron, steel and other ferrous metals Part3: Methods of analysis Section3.26 Determination of silicon Subsection3.26.2 Acid-resisting high silicon iron: gravimetric methodBS6200-3.26.2:1991 This British Standard, having been prepared unde

2、r the directionof the Iron and Steel Standards Policy Committee, waspublished under the authorityof the Standards Board and comes into effect on 29 November1991 BSI09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment91/35216 DC ISBN 0

3、 580 19943 6 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 which the following bodies were represented: BCIRA British Steel Industry Department of Tr

4、ade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS6200-3.26.2:1991 BSI 09-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Princip

5、le 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Calculation and expression of results 2 8 Test report 2 Publication(s) referred to Inside back coverBS6200-3.26.2:1991 ii BSI 09-1999 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards

6、Policy Committee and supersedes method2 for the determination of silicon in BSI Handbook No.19, to which it is technically equivalent. BS6200 is a multipart British Standard, covering all aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, together with

7、general information, is given in Part1. 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 obligations. S

8、ummary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2, 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 f

9、ront cover.BS6200-3.26.2:1991 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a gravimetric method for the determination of silicon in acid-resisting high silicon irons. The method is applicable to silicon contents from10% (m/m) to20% (m/m). NOTEThe titles of the publications referred to i

10、n this Subsection of BS6200 are listed on the inside back cover. 2 Principle The test portion is dissolved in a mixture of ammonium chloride, hydrobromic acid and bromine. After evaporation to dryness and extraction in acid, the precipitated silica is filtered off and the filtrate fumed with perchlo

11、ric acid, redissolved and filtered. The combined silica precipitates are ignited in a platinum vessel and silicon calculated from loss in weight with hydrofluoric acid. 3 Reagents During the analysis, use only reagents of recognized analytical grade and only grade3water as specified in BS3978. WARNI

12、NG. Suitable safety precautions should be taken during reagent preparation and use of bromine, hydrobromic acid and hydrofluoric acid, which are all highly irritant and corrosive. Perchloric acid vapour may cause explosions in the presence of nitrous fumes or organic material in general. 3.1 Ammoniu

13、m chloride 3.2 Bromine-hydrobromic acid. To100mL of hydrobromic acid, density =1.46g/mL to1.49 g/mL, add10mL of bromine and mix. 3.3 Hydrochloric acid, =1.16g/mL to1.18g/mL. 3.4 Hydrochloric acid, diluted1+4. To500mL of water, add200mL of hydrochloric acid(3.3), mix, dilute to1L and mix. 3.5 Hydrofl

14、uoric acid,40% (m/m) 3.6 Nitric acid, =1.42g/mL. 3.7 Perchloric acid, =1.54g/mL. 3.8 Sodium carbonate, anhydrous. 3.9 Sulfuric acid, =1.84g/mL. 3.10 Sulfuric acid, diluted1+3. To70mL of water add cautiously25mL of sulfuric acid(3.9), mix, cool, dilute to100mL and mix. 4 Apparatus 4.1 Ordinary labora

15、tory apparatus 4.2 Platinum vessel 4.3 Muffle furnace, operating at1100 C. 5 Sampling Carry out sampling in accordance with BS1837. NOTEBS6200-2, which will supersede BS1837, is currently in preparation. On its publication this Subsection will be amended to include sampling in accordance with BS6200

16、-2. 6 Procedure 6.1 Test portion For materials with up to15% (m/m) silicon, weigh to the nearest0.001g a test portion of1.0g. For higher silicon contents weigh a0.5g test portion. 6.2 Blank test In parallel with the determination and following the same procedure carry out a blank test, using the sam

17、e quantities of all reagents. 6.3 Determination 6.3.1 Preparation of the test solution Place the test portion in a250mL squat beaker. Add1g of ammonium chloride(3.1) and20mL of bromine-hydrobromic acid mixture(3.2), cover the beaker and allow to stand for30min. Heat on a steam bath until any remaini

18、ng sample has dissolved, evaporate to dryness and continue heating for1h. Add20mL of hydrochloric acid(3.3) and heat on the steam bath until soluble salts are dissolved. Dilute with100mL of cold water. 6.3.2 First separation of silica Filter through a paper-pulp pad into a600mL squat beaker, rinse t

19、he250mL beaker and cover with small washes of hot hydrochloric acid(3.4) and remove adherent particles of precipitate with the aid of a rubber-tipped glass rod. Wash the filter alternately with hot hydrochloric acid(3.4) and cold water, until freed from iron salts. Remove water from the pad using li

20、ght suction and then transfer the filter pad and silica to the platinum vessel(4.2), using small pieces of ashless filter paper, and reserve. 6.3.3 Recovery of soluble silica 6.3.3.1 Cover the600mL beaker, evaporate the filtrate to dryness, cool and add20mL of water. Add nitric acid(3.6) dropwise to

21、 decompose bromides and boil to expel free bromine. Rinse the cover glass. Add25mL of perchloric acid(3.7). 6.3.3.2 Evaporate until perchloric acid fumes appear and continue heating for10min to15min at a temperature sufficient to maintain a steady reflux of acid on the wall of the beaker. Allow to c

22、ool. Add20mL of hydrochloric acid(3.3), heat until soluble salts are dissolved and dilute with150mL of cold water. Filter and wash as described in6.3.2. Transfer the filter to the platinum vessel(4.2) containing the first filter.BS6200-3.26.2:1991 2 BSI 09-1999 6.3.4 Ignition and measurement of sili

23、ca Dry, ignite at as low a temperature as possible until carbonaceous matter is removed, and finally heat at not less than1100 C until a constant weight is obtained after cooling in a desiccator and weighing. Moisten the residue with water, add four drops of sulfuric acid(3.10) and5mL of hydrofluori

24、c acid(3.5). Evaporate to dryness and heat at not less than1100 C to constant weight. 6.3.5 Treatment of silicon carbide 6.3.5.1 For samples of high silicon iron containing silicon carbide, recognizable as a greyish-black residue insoluble after the hydrofluoric acid treatment, proceed as given in6.

25、3.5.2. 6.3.5.2 To the platinum vessel add4g of anhydrous sodium carbonate(3.8), fuse at1000 C, cool, and dissolve the fusion cake in the minimum volume of hydrochloric acid(3.4) in a150mL squat beaker. Rinse and remove the platinum vessel, add20mL of perchloric acid(3.7), and cover the beaker. Conti

26、nue from6.3.3.2, and treat the recovered silica as in6.3.4. 7 Calculation and expression of results 7.1 Calculation From the silica measured in6.3.4, calculate the silicon content expressed as a percentage by mass from the equation: If additional silica is recovered from silicon carbide in6.3.5, cal

27、culate the corresponding silicon content using the same equation and add to the main result. 7.2 Precision Replicate agreements in accordance with the following may be expected from this method: 0.15% for silicon contents of10% (m/m) to15% (m/m). 8 Test report The test report shall include the follo

28、wing 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 Subsection of BS6200; c) the results, and the form in which they are expressed; d) any unusual features noted during the determinatio

29、n; e) any operation not specified in this British Standard or any optional operation which may have influenced the results. where A is (m 1 m 2 ); m 1 is the mass of the platinum vessel and siliceous residue (ing); m 2 is the mass of the platinum vessel and residue after removal of silica with hydro

30、fluoric acid (ing); and B is (m 3 m 4 ); m 3 is the mass of the platinum vessel and blank residue (ing); m 4 is the mass of the platinum vessel after treatment of blank residue with hydrofluoric acid (ing); and m is the mass of the test portion (ing). silicon AB ()46.75 m - =BS6200-3.26.2:1991 BSI 0

31、9-1999 Publication(s) referred to BS1837, Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys. BS3978, Specification for water for laboratory use. BS5497, Precision of test methods. BS5497-1, Guide for the determination of repeatability and reproducibility for a standar

32、d test method by inter-laboratory tests. BS6200, Sampling and analysis of iron, steel and other ferrous metals. BS6200-1, Introduction and contents 1) . BS6200-2, Methods of sampling and sample preparation 2) . BSI Handbook No.19, Methods for the sampling and analysis of iron, steel and other ferrou

33、s metals 1) . 1) Referred to in the foreword only. 2) In preparation.BS 6200-3.26.2: 1991 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the

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