1、BRITISH STANDARD BS3907-11: 1970 Method for The determination of silicon in magnesium and magnesium alloys (photometric method)BS3907-11:1970 This British Standard, having been approved by the Non-ferrous Metals Industry Standards Committee, waspublished under theauthorityofthe ExecutiveBoardon 20Ma
2、rch1970 BSI11-1999 The following BSI references relate to the work on this standard: Committee references NFE/23 and NFE/23/4 Draft for comment68/29128 ISBN 580 05658 9 Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under whose supervision this British Standard was p
3、repared, consists of representatives from the following Government departments and scientific and industrial organisations: Aluminium Federation Institution of Mechanical Engineers Association of Bronze and Brass Founders (Automobile Division) Association of Consulting Engineers Institution of Minin
4、g and Metallurgy Board of Trade Institution of Production Engineers British Bronze and Brass Ingot Institution of Structural Engineers Manufacturers Association Lead Development Association British Electrical Allied Manufacturers Light Metal Founders Association Association London Metal Exchange Bri
5、tish Lead Manufacturers Association Magnesium Industry Council* British Non-ferrous Metals Federation Ministry of Defence (Army)* British Non-ferrous Metals Federation Ministry of Defence (Navy) High Conductivity Copper Group National Brassfoundry Association British Non-ferrous Metals Research Non-
6、ferrous Metal Stockists* Association* Post Office Copper Development Association Royal Institute of British Architects Crown Agents for Oversea Governments and Society of Motor Manufacturers and Traders Administrations Ltd.* Electric Cable Makers Confederation Tin Research Institute Institute of Bri
7、tish Foundrymen Zinc Development Association Institute of Metals Individual manufacturers The Government department and scientific and industrial organisations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the prepar
8、ation of this British Standard: Institute of Sheet Metal Engineering Individual analysts Ministry of Technology Ministry of Technology Laboratory of the Government Chemist Amendments issued since publication Amd. No. Date CommentsBS3907-11:1970 BSI 11-1999 i Contents Page Co-operating organizations
9、Inside front cover Foreword ii 1 Introduction 1 2 Apparatus 1 3 Solutions required 1 4 Sampling 2 5 Procedure 2 6 Calibration 2 7 Calculation 2 8 Notes 3BS3907-11:1970 ii BSI 11-1999 Foreword This standard makes reference to the following British Standards: BS1499, Sampling non-ferrous metals. BS397
10、8, Water for laboratory use. This method for the determination of silicon in magnesium and magnesium alloys is the eleventh of a series which will form a complete British Standard under the collective title “Methods for the analysis of magnesium and magnesium alloys”, each being published as a separ
11、ate part. Other methods in the series are as follows: Part1: Aluminium (gravimetric method); Part2: Iron (photometric 1:10 phenanthroline method); Part3: Copper (photometric method); Part4: Manganese (photometric periodate method); Part5: Manganese (photometric periodate method) (low contents); Part
12、6: Zirconium (photometric method); Part7: Nickel (photometric method); Part8: Rare earths (gravimetric method) 1) ; Part9: Zinc (ion-exchange volumetric EDTA method); Part10: Manganese in magnesium alloys containing zirconium, rare earths or thorium (photometric method). The preparation of this seri
13、es of methods has been authorised by Non-ferrous Metals Industry Standards Committee as part of a general programme for the standardization of methods for the sampling and analysis of non-ferrous metals. The methods have been found to give reliable and reproducible results and while in some instance
14、s they may appear to be lengthy, it should be appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. This method is substantially the same as the corresponding method approved by ISO/TC79, which will be published as ISO/R 1) . A British Standard does not pu
15、rport 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. Summary of pages This document comprises a front cover, an inside front
16、 cover, pagesi andii, pages1 to3 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. 1) In course of preparation.BS3907-11:1970 BSI 11-1999 1 1 Introduction 1.1 Princi
17、ple. The sample is dissolved with sulphuric acid in the presence of bromine water and any remaining insoluble silicon compounds are decomposed and brought into solution with potassium fluoride. The excess fluoride is complexed with boric acid and the yellow oxidized silico-molybdate complex is forme
18、d at a pH between1.35 and1.50, then selectively reduced in a sulphuric acid medium of high acidity and in the presence of tartaric acid. The determination is completed photometrically. 1.2 Range. The method is recommended for silicon contents between0.01 and0.6%. 1.3 Reproducibility. Experiments hav
19、e been carried out independently by a number of analysts using this method. The degree of reproducibility that can be expected is shown by the following analysis of the results obtained. 1.4 Application. This method is not suitable for magnesium alloys containing rare earths or thorium. 2 Apparatus
20、2.1 Class A volumetric glassware complying with the appropriate British Standards shall be used throughout. All glassware should be carefully washed with hot chromic-sulphuric acid and rinsed thoroughly with water. Platinum vessels should be cleaned with fused sodium carbonate, then washed with boil
21、ing hydrochloric acid and thoroughly washed with water. 2.2 pH meter fitted with a glass electrode. 2.3 Any instrument suitable for measuring the optical density of the solution at a wavelength of810nm may be used with a1cm cell. Alternatively, when a filter photometer of the balanced two-cell type
22、is used, the following conditions have been found suitable: mercury vapour lamp, Ilford606 or equivalent filter, 4cm cell. 3 Solutions required All reagents shall be of the highest purity obtainable, and either distilled or demineralized water complying with BS3978 2)shall be used throughout. Soluti
23、ons shall be freshly prepared and where necessary filtered, and should be stored in plastic containers. Standard magnesium. (1mlN 0.01g of magnesium.) Weigh and transfer10g of high purity magnesium to a600ml tall-form beaker, add about200ml of water, then add in small portions140ml of sulphuric acid
24、(28%). When the reaction is complete, boil for5min, cool, transfer to a1litre volumetric flask, dilute to the mark andmix. Standard silicon. (1mlN 0.1mg of silicon.) Weigh0.2140g of finely ground pure silica (previously ignited to constant weight at1000 C) and fuse in a covered platinum crucible wit
25、h2g of a mixture of equal parts of anhydrous sodium carbonate and anhydrous potassium carbonate. Cool, dissolve the fused mass with hot water and transfer the solution to a plastics beaker. Dilute to about700ml, cool, transfer to a1litre volumetric flask, dilute to the mark and mix. Store in a plast
26、ics flask. Standard silicon. (1mlN 0.01mg of silicon.) Transfer50.0ml of standard silicon solution(1mlN 0.1mg of silicon) to a500ml volumetric flask, dilute to the mark and mix. This solution should be prepared immediately before use. Ascorbic acid. (2% w/v.) Dissolve2g of ascorbic acid in water, di
27、lute to100ml and mix. This solution should be freshly prepared. Boric acid (saturated). Dissolve40g of boric acid in hot water, dilute to about900ml, cool, dilute to1litre and mix. Bromine water (saturated). To100ml of water, add5ml of bromine, shake and allow to stand until saturated. Potassium flu
28、oride. (5% w/v.) Dissolve50g of potassium fluoride in water, filter if necessary, then dilute to1litre and mix. Sodium molybdate solution. (19.5% w/v.) Dissolve195g of sodium molybdate, Na 2 MoO 4 .2H 2 O, in hot water. Cool, dilute to1litre and mix. The pH of this solution should be about7. Sulphur
29、ic acid. (28% w/v.) To400ml of water, add cautiously280ml of sulphuric acid (sp.gr.1.84), mix, cool, dilute to1litre and mix. Sulphuric acid. (2.8% w/v.) Dilute100ml of sulphuric acid(28%) to1litre and mix. Silicon content Standard deviation % 0.02 0.2 0.001 0.01 2) BS3978 “Water for laboratory use”
30、.BS3907-11:1970 2 BSI 11-1999 Tartaric acid. (20% w/v.) Dissolve200g of tartaric acid in water, dilute to1litre and mix. 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”. 5 Procedure 5.1 Adju
31、st the weight of sample and quantities of bromine water (saturated) and sulphuric acid(28%) as follows: Transfer the appropriate weight of sample to a250ml tall-form beaker, add the appropriate volume of bromine water, then add in small portions the appropriate quantity of sulphuric acid(28%), cooli
32、ng if necessary during the addition. (Note8.1.) 5.2 Carry out simultaneously a blank determination, following the same procedure and using the same quantities of reagents as with the sample, except that when a1g sample is to be used,5ml of sulphuric acid(28%) should be added and when a0.5g sample is
33、 to be used,25ml of sulphuric acid(28%) should be added. 5.3 When the test sample is completely dissolved, boil the solution to remove excess of bromine, adjust the volume to about100ml with water and transfer to a plastics beaker. 5.4 Add5ml of potassium fluoride solution(5%), stir with a plastics
34、rod and allow to stand at60 to70 C for15 to20min. Then add50ml of boric acid solution (saturated) and shake. Cool, transfer to a250ml volumetric flask, dilute to the mark and mix. Transfer the solution to a plastics container. 5.4.1 For silicon contents 0.01 to 0.05%. Take a50.0ml aliquot of this so
35、lution. 5.4.2 For silicon contents 0.05 to 0.6%. Take a10.0ml aliquot of this solution. 5.5 Transfer the appropriate aliquot to a100ml beaker and where necessary dilute to50ml. Add5ml of sodium molybdate solution(19.5%) and stir. Check that the pH is between1.35 and1.50 and if necessary adjust to wi
36、thin this range by dropwise addition of sulphuric acid(2.8%). Dilute to a volume of about65ml and again check the pH. Note the volume of sulphuric acid(2.8%) used to adjust the pH to the required range. 5.6 Transfer a second aliquot of the sample solution to a100ml volumetric flask, if necessary dil
37、ute to50ml, then add the volume of sulphuric acid(2.8%) necessary to adjust the pH to the required range, dilute to about60ml and shake. Add5ml of sodium molybdate solution(19.5%) mix and allow to stand for10min. Add5ml of tartaric acid solution(20%),10ml of sulphuric acid(28%) and5ml of ascorbic ac
38、id solution(2%). Dilute to the mark and mix. 5.7 Allow to stand for at least10min but not more than40min, then measure the optical density against the reagent blank, using the conditions specified under Clause2, Apparatus. (Note8.2.) 6 Calibration 6.1 For silicon contents between0.01 and0.05% 6.1.1
39、To each of a series of six250ml plastic beakers transfer100ml of magnesium solution(1mlN 0.01g of magnesium) and then add to four of these: 0,5.0,10.0,25.0ml of standard silicon solution(1mlN 0.01mg of silicon), and to the remaining two: 5.0,7.5ml of standard silicon solution(1mlN 0.1mg of silicon).
40、 Continue from5.4 of the procedure. 6.1.2 Deduct the optical density for the solution containing no added silicon from the gross optical densities and prepare a calibration graph by plotting the net values against nominal silicon contents of the solution. 6.2 For silicon contents between0.05 and0.6%
41、 6.2.1 To each of a series of six250ml plastics beakers transfer50.0ml of magnesium solution(1mlN 0.01g of magnesium) and23.0ml of sulphuric acid(28%) then add: 0,2.5,5.0,12.5,25.0,37.5ml of standard silicon solution(1mlN 0.1mg of silicon), and dilute if necessary to100ml. Continue from5.4 of the pr
42、ocedure. 6.2.2 Deduct the optical density for the solution containing no added silicon from the gross optical densities and prepare a calibration graph by plotting the net values against the nominal silicon contents of the solution. 7 Calculation Convert the optical densities for the test sample cor
43、rected for blank to percentage silicon by means of the appropriate calibration graph. Silicon content Weight of sample Bromine water (saturated) Sulphuric acid(28%) % 0.01 to0.05 0.05 to0.6 g 1.0 0.5 ml 75 50 ml 14 30BS3907-11:1970 BSI 11-1999 3 8 Notes 8.1 If, during the attack, the orange colourat
44、ion due to bromine disappears, add more bromine water, noting the amount added for the purposes of the blank test. 8.2 To ensure that the Mo(V1) of the excess reagent has not been reduced, transfer a third aliquot of the sample solution to a second100ml volumetric flask, add the volume of sulphuric
45、acid solution(2.8%) necessary to adjust the pH to within the required range, then add10.0ml of sulphuric acid(28%),5ml of tartaric acid(20%)5ml of sodium molybdate solution(19.5%) and5ml of ascorbic acid solution(2%). Dilute to the mark and mix. Allow to stand for10min and check that the solution re
46、mains uncoloured and has a negligible optical density.BS3907-11: 1970 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 international level
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