1、BRITISH STANDARD BS1728-11: 1960 Method for The determination of silicon in aluminium and aluminium alloys (Perchloric acid method) Methods for the analysis of aluminiumand aluminium alloysBS1728-11:1960 This BritishStandard, having been approved by the Non-ferrous Metals IndustryStandards Committee
2、and endorsed bytheChairman of the Engineering Divisional Council,was published undertheauthority of the GeneralCouncil on 24May1960 BSI12-1999 The following BSI references relate to the work on this standard: Committee referenceNFE/3 Draft for commentCZ(NFE)8193 ISBN 0 580 01559 9 Co-operating organ
3、izations The Non-ferrous Metals Industry Standards Committee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty* Aluminium Development Association* Aluminium Industry
4、 Council* Association of Bronze and Brass Founders Association of Consulting Engineers (Incorporated) Association of Non-ferrous Metal Stockists British Bronze and Brass Ingot Manufacturers Association British Electrical and Allied Manufacturers Association British Non-ferrous Metals Federation Brit
5、ish Non-ferrous Metals Research Association* Cable Makers Association Copper Development Association Crown Agents for Oversea Governments and Administrations High Commission of India High Conductivity Copper Association Institute of British Foundrymen Institute of Metals Institution of Mechanical En
6、gineers (Automobile Division) Institution of Mining and Metallurgy Institution of Structural Engineers Lead Development Association Lead Sheet and Pipe Manufacturers Federation Light Metal Founders Association* London Metal Exchange Magnesium Industry Council Ministry of Aviation* National Brassfoun
7、dry Association Post Office Royal Institute of British Architects Society of British Aircraft Constructors Society of Motor Manufacturers and Traders Ltd. Tin Research Institute War Office Zinc Development Association Individual manufacturers The Government departments and scientific and industrial
8、organizations marked with an asterisk in the above list, together with the following, were directly represented on the Sub-committee entrusted with the preparation of this BritishStandard: Association of Light Alloy Refiners and Smelters Ltd. D.S.I.R. Laboratory of the Government Chemist Individual
9、analysts Amendments issued since publication Amd. No. Date CommentsBS1728-11:1960 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii Introduction 1 Solutions required 1 Sampling 1 Procedure 1 Calculation 2BS1728-11:1960 ii BSI 12-1999 Foreword This standard makes r
10、eference to the following BritishStandards: BS410, Test sieves. BS1499, Sampling non-ferrous metals. This method for the determination of silicon is the eleventh of a series which will form a complete BritishStandard under the collective title, “Methods for the analysis of aluminium and aluminium al
11、loys”, each method being published as a separate part. Other methods in the series are as follows: Part1: Copper; Part2: Magnesium; Part3: Zinc (mercuric potassium thiocyanate method); Part4: Zinc (polarographic method); Part5: Copper (absorptiometric method); Part6: Iron (volumetric: titanous chlor
12、ide method); Part7: Zinc (zinc oxide method); Part8: Iron (absorptiometric1:10-phenanthroline method); Part9: Manganese (volumetric: arsenite/nitrite method); Part10: Manganese (absorptiometric method). The preparation of this series of methods has been authorized by the Non-ferrous Metals Industry
13、Standards Committee as part of a general programme of the standardization of methods for the analysis of non-ferrous metals. These methods have been found to give reliable and reproducible results and, while in some instances the methods may appear to be lengthy, it should be realized that they are
14、put forward as “referee” methods to be used in cases of dispute. 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
15、from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2 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
16、 front cover.BS1728-11:1960 BSI 12-1999 1 Introduction a) Principle. The silicon is converted to insoluble silica by the dissolution of the metal with sodium hydroxide solution followed by evaporation with hydrogen peroxide, and fuming with excess of perchloric acid. If tin and antimony are present
17、they are volatilized as the bromides. After filtration, the silica obtained is determined by the loss of weight of the calcined precipitate after treatment with sulphuric and hydrofluoric acids. b) Range. The method is recommended for silicon contents from0.1per cent upwards. c) Reproducibility. Exp
18、eriments have been carried out independently by a number of analysts using the method recommended in this standard. The degree of reproducibility that can be expected is shown by the following analysis of the results obtained: Solutions required All reagents shall be of recognized analytical quality
19、 and distilled water shall be used throughout. Bromine-hydrobromic acid. Add10ml of bromine to100ml of hydrobromic acid (sp. gr.1.46 to1.49). Hydrochloric acid (1per cent v/v). Dilute10ml of hydrochloric acid (sp. gr.1.16 to1.18) to1litre. Perchloric acid (1:2). Mix100ml of perchloric acid(60per cen
20、t w/w, sp. gr.1.54) with200ml of water. Sulphuric acid (1:1). To100ml of water add cautiously100ml of sulphuric acid (sp. gr.1.84). Mixandcool. Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”.
21、 If powder accompanies the chips, the sample should be sieved through a30mesh sieve 1)and weights of the coarse and fine materials in proportion to their weights in the sample should be taken for analysis. Procedure NOTEAlthough the use of perchloric acid as described in this method has not been fou
22、nd hazardous, attention is drawn to the well-known danger of explosions which can arise if it is brought in contact under certain conditions with finely divided aluminium, silicon and organic matter (for instance, alcohol vapour). For further details, see “Analyst”, Vol.84,1959, p.214. Silicon conte
23、nt Standard deviation per cent per cent 0.1 0.01 1 0.015 5 0.04 12 0.10 17 0.18 24 0.28 1) BS410, “Test sieves”. Adjust the weight of sample and quantities of reagents as follows: Silicon content Sample weight Sodium hydroxide Water Perchloric acid60per cent w/w (sp. gr.1.54) per cent Over5 2.5to5 0
24、.25to2.5 0.1to0.25 g 0.5 1 2 5 g 6 6 6 12 ml 10 20 20 50 ml 40 55 65 110BS1728-11:1960 2 BSI 12-1999 Weigh the appropriate quantities of sample and sodium hydroxide and transfer to a nickel vessel(300-ml is suitable) covered with a nickel lid. Prepare a blank on the same quantities of reagents and p
25、roceed simultaneously with both sample and blank. Add cautiously the required volume of water in small portions, cooling if necessary, and when the reaction is complete, wash the lid and the sides of the vessel with a small jet of hot water. Evaporate cautiously to a syrupy consistency. Add5ml of wa
26、ter and10drops of hydrogen peroxide(100vol) and repeat the evaporation. If the sample contains more than10per cent of silicon, repeat the addition of water and hydrogen peroxide(100vol) and re-evaporate. Cool, dilute with20ml of water(50ml for a5g sample), warm gently and mix. Cool and pour into an
27、excess of perchloric acid(60per cent, see table) contained in a400-ml squat beaker of resistance glass(600-ml for a5g sample). Rinse the nickel vessel with hot water, add a few millilitres of dilute perchloric acid(1:2), transfer to the beaker any adhering particles with the aid of a rubber-tipped g
28、lass rod and finally rinse with hot water. Add5ml of nitric acid (sp. gr.1.42) and a few drops of hydrogen peroxide(100vol) to the solution, evaporate to dense white fumes, cover and fume for15minutes (Note1). Cool, add5ml of hydrochloric acid(sp.gr.1.161.18) and100ml(200ml for a5g sample) of hot wa
29、ter, stir well and heat until the salts are dissolved (Note2). Add paper pulp and filter on a double acid washed medium textured filter paper (Note3) or paper pulp pad. Remove and transfer to the filter any adhering particles with the aid of a rubber tipped glass rod. Wash10times with hot hydrochlor
30、ic acid(1per cent), and then with hot water until the filtrate is free from chloride, taking particular care if filter paper is used to wash the whole area of the paper (Note4). Reserve the filtrate and washings. To the filtrate and washings add10ml of perchloric acid(60per cent), evaporate to fumes
31、 and proceed as before. Place both the filter papers (or paper pulp pads) with the precipitates in a platinum crucible. Dry and ignite slowly at500 C with free access of air until free from carbon, then heat at1100to1150 C to constant weight. (See Note5.) Moisten the residue with a few drops of wate
32、r and sulphuric acid(1:1). Add a few millilitres of hydrofluoric acid 2) , evaporate to dryness, ignite at the same temperature as before, cool and weigh. Repeat the treatment with sulphuric and hydrofluoric acids and ignite to constant weight. The loss of weight represents silica. Correct this by d
33、educting the loss of weight found by hydrofluoric acid treatment of the blank. Calculation NOTE 1If the sample contains more than0.1per cent of tin or antimony, evaporate only until white fumes begin. Cool slightly, and cautiously add, while mixing,10ml of the bromine-hydrobromic acid mixture. Evapo
34、rate with the cover removed until there is abundant release of white fumes of perchloric acid and the brown colour is discharged from the solution. Allow to cool, again add10ml of bromine-hydrobromic acid mixture, evaporate to dense white fumes, and fume for15minutes, cool and dilute. If the solutio
35、n is opalescent (indicating incomplete volatilization of tin or antimony), the treatment should be repeated. NOTE 2If any manganese dioxide becomes apparent it should be cleared with a few drops of hydrogen peroxide(100vol). NOTE 3Whatman No.40 is suitable. NOTE 4If the paper is not washed completel
36、y free from perchloric acid there is risk of explosion occurring at a later stage. NOTE 5If the ignited precipitate is dark due to incomplete oxidation of the silicon, the determination should be repeated, and the time of digestion with the sodium hydroxide and the amount of hydrogen peroxide increa
37、sed. 2) This refers to the usual analytical reagent of40per cent w/w. Corrected loss of weight46.75 Weight of sample -percentage silicon =blankBS1728-11: 1960 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing Britis
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