1、BRITISH STANDARD BS1748-7: 1960 Method for The determination of silicon in copper alloys (Photometric method)BS1748-7:1960 This British Standard, having been approved by the Non-ferrous Metals Industry Standards Committee and endorsed by the Chairman of theEngineering Divisional Council, was publish
2、edunder theauthorityofthe General Council on 20July1960 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference NFE/-/2 Draft for comment CZ(NFE)8590 ISBN 0 580 01809 1 Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under who
3、se supervision this British Standard was prepared, consists of representatives from the following Government departments, and scientific and industrial organizations: The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the f
4、ollowing, were directly represented on the sub-committee entrusted with the preparation of this British Standard: Admiralty* Institution of Mechanical Engineers Aluminium Development Association (Automobile Division) Aluminium Industry Council Institution of Mining and Metallurgy Association of Bron
5、ze and Brass Founders* Institution of Structural Engineers Association of Consulting Engineers, Lead Development Association Incorporated Lead Sheet and Pipe Manufacturers Association of Non-ferrous Metal Stockists Federation British Bronze and Brass Ingot Light Metal Founders Association Manufactur
6、ers Association* London Metal Exchange British Electrical and Allied Manufacturers Magnesium Industry Council Association Ministry of Aviation* British Non-ferrous Metals Federation National Brassfoundry Association British Non-ferrous Metals Research Post Office Association* Royal Institute of Brit
7、ish Architects Cable Makers Association Society of British Aircraft Constructors Copper Development Association Society of Motor Manufacturers and Traders Crown Agents for Oversea Governments and Limited Administrations Tin Research Institute High Commission of India War Office High Conductivity Cop
8、per Association Zinc Development Association Institute of British Foundrymen Individual manufacturers Institute of Metals D.S.I.R. Laboratory of the Government Chemist Individual firms Amendments issued since publication Amd. No. Date CommentsBS1748-7:1960 BSI 11-1999 i Contents Page Co-operating or
9、ganizations Inside front cover Foreword ii Introduction 1 Apparatus 1 Solutions required 1 Sampling 1 Calibration 2 Procedure 2BS1748-7:1960 ii BSI 11-1999 Foreword This standard makes reference to the following British Standards: BS410, Test sieves. BS1400, Copper alloy ingots and castings. BS1499,
10、 Sampling non-ferrous metals. This method for the determination of silicon is one of a series of methods for the analysis of copper alloys, which will form a complete British Standard issued in several parts. The methods are intended primarily for the analysis of the copper alloys included in BS1400
11、, “Copper alloy ingots and castings”, and those being included in the series of schedules of wrought copper and copper alloys BS2870 to BS2875, of which BS2871 has already been published, and the remainder are in course of preparation. The methods have been found to give reliable and reproducible re
12、sults, and while in some instances they may appear to be lengthy, it should be realized that they are put forward as referee methods to be used in cases of dispute. In the preparation of the calibration graphs an attempt has been made to define concentrations but because these are linked with the pa
13、rticular instrument used for determining optical density they should be used only as a guide. 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 n
14、ot of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the
15、 amendment table on the inside front cover.BS1748-7:1960 BSI 11-1999 1 Introduction a) Principle. The sample is dissolved in a mixture of nitric and hydrochloric acids. Ammonium molybdate is added to an aliquot of this solution, and the silico-molybdic acid is reduced at50 C with a solution containi
16、ng sodium sulphite, sodium metabisulphite and1-amino-2-naphthol-4-sulphonic acid. b) Range. 0.005 to0.2per cent silicon. c) Reproducibility. Experiments have been carried out independently by a number of analysts using the methods recommended in this standard. The degree of reproducibility that can
17、be expected is shown by the following analysis of the results obtained: d) Application. The method is suitable for application to phosphor bronze and gun metals. Apparatus a) Grade A graduated glassware shall be used throughout. b) Any instrument suitable for measuring the optical density of the sol
18、ution at a wave-length of820m may be used. If a filter photometer is used the filter combination should conform as closely as possible to the above wave-length. The following conditions have been found suitable: Ilford608 with Chance H503 or equivalent filters. 4cm and2cm cells. Solutions required A
19、ll reagents shall be of the highest purity obtainable, and double-distilled water shall be used throughout. Solutions shall be freshly prepared and temporarily stored in polythene 1)containers. Standard silicon. Solution A(1mlN 0.1mg of silicon). Weigh0.2141g of finely ground(100mesh) 2)pure silica,
20、 previously ignited at1000 C, into a platinum dish and fuse with2g of anhydrous sodium carbonate, cool and extract with100ml of water in a nickel beaker. Transfer to a1-litre graduated flask, dilute the clear solution to the mark and mix. Standard silicon. Solution B(1mlN 0.02mg of silicon). Dilute5
21、0ml of silicon Solution A to250ml in a graduated flask. Ammonium molybdate (10per cent w/v). Dissolve100g of ammonium molybdate(NH 4 ) 6 Mo 7 O 24 .4H 2 O) in about600ml of warm water, cool, dilute to1litre and filter through a fine textured paper before using. Citric acid (25per cent w/v). Dissolve
22、250g of citric acid(C 6 H 8 O 7 H 2 O) in water and dilute to1litre. Nitric-hydrochloric acid mixture. To275ml of water add75ml of nitric acid(sp. gr.1.42) and150ml of hydrochloric acid(sp. gr.1.161.18). Reducing solution. Dissolve2g of sodium sulphite in about25ml of water and add0.4g of1-amino-2-n
23、aphthol-4-sulphonic acid. Add this solution to25g of sodium metabisulphite dissolved inabout200ml of water. Dilute the mixture to250ml. Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”. Silicon
24、 content Standard deviation per cent per cent 0.005 0.2 0.0005 0.005 1) It should be noted that the name “polythene” is equivalent to the name “polyethylene”. 2) BS410, “Test sieves”.BS1748-7:1960 2 BSI 11-1999 Calibration Weigh0.25g of pure copper(Note1) into each of six polythene beakers(250ml), a
25、dd10ml of the nitric-hydrochloric acid mixture, cover with a polythene cover and warm very gently until the copper has dissolved. In the preparation of each graph, make additions of a standard silicon solution to5 of the beakers, as indicated in the table below, and use the sixth beaker for a blank
26、determination. Transfer each solution to a100-ml graduated flask, dilute to the mark and mix. Prepare duplicate aliquots(T) and(C) of each as follows: Graph1. Using a dry pipette, transfer50ml to a100ml graduated flask, then add5ml of water. Rinse the pipette with5ml of water and add the washings to
27、 the original flask. Graph2. Transfer25ml to each of two100ml graduated flasks, and add30ml of water. Graph3. Transfer10ml to each of two100ml graduated flasks and add45ml of water. To the aliquot(T) in each series, add10ml of ammonium molybdate solution(10per cent), allow to stand for5minutes at20
28、C, then add10ml of citric acid solution(25per cent). To the other aliquot(C) add10ml of citric acid solution(25per cent)(Note2) then10ml of ammonium molybdate solution (10percent) and allow to stand for5minutes at20 C. To both solutions add5ml of the reducing solution and place in a water-bath at50
29、C for15minutes. Cool, dilute to the mark and mix. Measure the optical density(Note3) of the solution at20 1 C against the compensating solution(C) using the conditions specified under “Apparatus”. Correct for the blank value on the pure copper and prepare a calibration graph by plotting these values
30、 against the equivalent percentage of silicon. Procedure Weigh0.250g of sample(Note1) and transfer to a polythene beaker(250ml), add10ml of the nitric acid-hydrochloric acid mixture, cover with a polythene cover and warm very gently until the sample has dissolved. Transfer to a100ml graduated flask,
31、 dilute to the mark and mix. Carry out simultaneously a blank determination on the reagents. Follow the same procedure without the sample and use the same quantities of reagents. Proceed to examine the sample as described under “Calibration” and compensate for the blank determination. Convert the co
32、rrected optical density to percentage silicon by means of the appropriate calibration graph. NOTE 1At no stage in the preparation of drillings should an abrasive be used. A preliminary quick immersion in nitric acid(50percent v/v) followed by washing and drying before weighing serves to minimize err
33、or due to extraneous silicon. NOTE 2Details for the preparation of these graphs are subsequently applied, in part, to the analysis of copper alloy samples, and in the examination of these, the amount of citric acid recommended is sufficient to react with the tin and molybdenum in solution and to pre
34、vent the formation of a blue-coloured compensating solution, after reduction. NOTE 3It is permissible to use4cm cells exclusively, but this will depend on the type of instrument used to determine optical density. It is desirable that the optical density of the sample solution should be within the ra
35、nge0.1 to0.85, although this range may be extended slightly in the preparation of the particular calibration graph. In applying Graph1 at the0.005 per cent silicon level, it is permissible to determine optical densities slightly lower than0.1. Graph Silicon content Cell size Standard silicon solutio
36、n Volume of standard silicon solution percent cm ml 1 2 3 0.0050.02 0.020.10 0.100.20 4 2 2 B A A 0.5 1.0 1.0 2.0 1.5 3.0 2.0 4.0 2.5 5.0 blankBS1748-7: 1960 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing British
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