1、BRITISH STANDARD BS1748-9: 1963 Method for The determination of zinc in copper alloys Methods for the analysis of copper alloysBS1748-9:1963 This British Standard, havingbeen approved by the Non-ferrous Metals Industry Standards Committee and endorsed by the Chairman of theEngineering Divisional Cou
2、ncil, was published under theauthorityof the General Council on 21February1963 BSI10-1999 The following BSI references relate to the work on this standard: Committee reference NFE/-/2 Draft for comment AB(NFE)6342 ISBN 0580018296 Co-operating organizations The Non-ferrous Metals Industry Standards C
3、ommittee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty Institution of Mechanical Engineers Aluminium Development Association* (Automobile Division) Aluminium In
4、dustry Council Institution of Mining and Metallurgy Association of Bronze and Brass Founders* Institution of Structural Engineers Association of Consulting Engineers Lead Development Association (Incorporated) Light Metal Founders Association British Bronze and Brass Ingot Manufacturers London Metal
5、 Exchange Association* Magnesium Industry Council British Electrical and Allied Manufacturers Ministry of Aviation Association Ministry of Transport British Lead Manufacturers Association National Brassfoundry Association British Non-ferrous Metals Federation Non-ferrous Metal Stockists British Non-
6、ferrous Metals Research Post Office Association* Royal Institute of British Architects Cable Makers Association Society of British Aircraft Constructors Copper Development Association Society of Motor Manufacturers and Traders Crown Agents for Oversea Governments and Ltd. Administrations Tin Researc
7、h Institute High Commission of India War Office* High Conductivity Copper Association Zinc Development Association Institute of British Foundrymen Individual manufacturers Institute of Metals The Government departments and scientific and industrial organizations marked with an asterisk in the above
8、list, together with the following, were directly represented on the sub-committee entrusted with the preparation of this British Standard: D.S.I.R. Laboratory of the Government Individual analysts Chemist Amendments issued since publication Amd. No. Date CommentsBS1748-9:1963 BSI 10-1999 i Contents
9、Page Co-operating organizations Inside front cover Foreword ii Introduction 1 Apparatus 1 Solutions required 1 Sampling 2 Method A. Volumetric Standardization 2 Procedure 2 Method B. Polarographic Calibration 3 Procedure 3BS1748-9:1963 ii BSI 10-1999 Foreword This standard makes reference to the fol
10、lowing British Standard: BS1499, Sampling non-ferrous metals. This method for the determination of zinc 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 cop
11、per alloys included in BS1400, “Schedule of copper alloy ingots and copper and copper alloy castings”, and those being included in the series of schedules of wrought copper and copper alloys BS2870BS2875, of which BS2870, BS2871, BS2872 and BS2874 have already been published, and the remainder are i
12、n course of preparation. The methods have been found to give reliable and reproducible results, 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. A British Standard does not purport to include
13、 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 cover, pagesi a
14、ndii, pages1 to4, 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 front cover.BS1748-9:1963 BSI 10-1999 1 Introduction a) Principle. The sample is dissolve
15、d in bromine-hydrobromic acid mixture and tin is volatilized. Bromides are decomposed with nitric acid and lead is separated as sulphate. Hydrochloric acid is added and the solution is passed through an ion-exchange column which retains zinc. In the volumetric procedure, using a solution of the diso
16、dium salt of diaminoethanetetra-acetic acid 1) , recovery of zinc from the column is made with dilute nitric acid. Where the amount of zinc does not exceed0.5per cent, the column is eluted with dilute hydrochloric acid and the determination is completed polarographically. b) Range. 0.01 to10percent
17、zinc. c) Reproducibility. Experiments 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. d) Application. The method has been shown to
18、 be particularly suitable for copper alloys containing1 to14percent of tin. The volumetric procedure is not applicable in the presence of cadmium. Apparatus a) Grade A volumetric glassware shall be used throughout. b) An ion-exchange column. This is essentially a1cm internal diameter glass tube,36cm
19、 long. A tap is attached to the base and a100ml separating funnel is connected to the top of the tube by means of a ground glass joint. A flat porcelain perforated disc is placed just above the tap to support the resin. The glass column is half-filled with an anion exchange resin 2) . The resin shal
20、l have been previously slurried with hydrochloric acid(5percent v/v) and then allowed to settle. The supernatant liquid is decanted and the slurry poured into the column, to give a depth of resin of about15cm. (At this stage, and throughout the procedure, a head of liquid sufficient to cover the res
21、in must be maintained.) Wash the resin successively with100ml of nitric acid(6.2percent v/v), then130ml of hydrochloric acid(20percent v/v) before use. It is strongly recommended that independent columns be used for the volumetric and polarographic procedures. c) Polarograph. Provided adequate sensi
22、tivity can be obtained, any polarograph capable of applying a potential over the specified voltage range may be used. Sensitivity varies between different instruments; the recommendations in the procedure are, therefore, intended only as a guide. Solutions required All reagents shall be of the highe
23、st purity obtainable and distilled water shall be used throughout. Solutions shall be freshly prepared and, where necessary filtered. Standard zinc A (1mlN 1mg of zinc). Weigh, as accurately as possible,1g of high purity zinc, dissolve in20ml of hydrochloric acid (sp. gr.1.161.18) and dilute to1litr
24、e in a volumetric flask. Standard zinc B (1mlN 0.01mg of zinc). Dilute10.0ml of standard zinc solution A to1litre in a volumetric flask. Copper sulphate (M/20). Dissolve12.49g of copper sulphate (CuSO 4 .5H 2 O) in water and dilute to1litre in a volumetric flask. Diaminoethanetetra-acetatic acid dis
25、odium salt (sodium ethylenediaminetetra-acetate E.D.T.A.) (M/20). Dissolve18.2g of the disodium salt of diaminoethanetetra-acetic acid E.D.T.A. in about400ml of water, and dilute to1litre in a volumetric flask. 1mlN 3.26mg of zinc (theoretical value). Base electrolyte. Dissolve125g of ammonium chlor
26、ide in about300ml of water, add180ml of ammonia solution (sp. gr.0.91),125ml of gelatine solution(2percent w/v) and dilute to1litre. Bromine-hydrobromic acid. To9 vol of hydrobromic acid (sp. gr.1.461.49) add, carefully,1vol of bromine and mix. Buffer. Dissolve54g of ammonium chloride in water. Add5
27、00ml of ammonia solution (sp. gr.0.91) and dilute to1litre. 1) Also known as sodium ethylenediaminetetra-acetate (E.D.T.A.). Zinc content Standard deviation per cent 0.025 0.25 2.00 7.50 per cent 0.002 0.01 0.02 0.05 2) De acidite FF and Amberlite, IRA,400 have been found suitable.BS1748-9:1963 2 BS
28、I 10-1999 Gelatine (2percent w/v). Dissolve4g of gelatine in warm water and dilute to200ml. Hydrochloric acid (50percent v/v). Dilute500ml of hydrochloric acid (sp. gr.1.161.18) to1litre. Hydrochloric acid (20per cent v/v). Dilute200ml of hydrochloric acid (sp. gr.1.161.18) to1litre. Hydrochloric ac
29、id (5percent v/v). Dilute50ml of hydrochloric acid (sp. gr.1.161.18) to1litre. Hydrochloric acid (0.05percent v/v). Dilute5ml of hydrochloric acid (sp. gr.1.161.18) to1litre. Dilute100ml of this solution to1litre. Nitric acid (6.2percent v/v). Dilute62ml of nitric acid (sp. gr.1.42) to1litre. P.A.N.
30、 indicator (0.10percent w/v). Dissolve100mg of1-(2-pyridyl-azo)2-naphthol (P.A.N.) in100ml of ethanol(95percent v/v). Sulphuric acid (50percent v/v). To500ml of water add, cautiously,500ml of sulphuric acid (sp. gr.1.84). Mix, cool, and dilute to1litre. Sulphuric acid (5percent v/v). To950ml of wate
31、r add, cautiously,50ml of sulphuric acid (sp.gr.1.84). Mix, cool and dilute to1litre. Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”. Method A. Volumetric (for zinc contents0.510percent) Stan
32、dardization E.D.T.A. solution (M/20). Transfer100ml of standard zinc solution A(1mlN 1mg of zinc) to a650ml conical beaker, add15ml of nitric acid (sp. gr.1.42) and dilute the solution to about250ml. Neutralize with ammonia solution (sp. gr.0.91) using litmus paper as indicator, then add15ml or the
33、buffer solution. Mix thoroughly after each addition. Add5 drops of P.A.N. indicator solution(0.10percent) and titrate with E.D.T.A. solution (M/20) until the colour of the indicator changes to yellow, than add a further5ml of the E.D.T.A. solution (M/20) and record the total volume of the E.D.T.A. s
34、olution (M/20) added. Back-titrate with copper sulphate solution (M/20) until one drop changes the colour of the test solution to violet. Deduct the corrected volume of copper sulphate solution (M/20) from the recorded volume of E.D.T.A. solution (M/20) added and calculate the equivalence in terms o
35、fmg of zinc per ml of the E.D.T.A. solution. Copper sulphate solution (M/20). Transfer200ml of water to a650ml conical beaker. Add15ml of the buffer solution,5 drops of P.A.N. indicator solution(0.10percent) and10ml of E.D.T.A. solution (M/20). Titrate with copper sulphate solution (M/20) until one
36、drop changes the colour of the indicator to blue-violet. Express the factor for the copper sulphate solution in terms of the E.D.T.A. solution, e.g.10.05ml of the copper sulphateN 10.00ml of the E.D.T.A. solution. Apply this correction (e.g.0.995) in all subsequent back-titrations. Procedure Weigh1.
37、000g of sample and transfer to a250ml squat beaker. Add10ml of the bromine-hydrobromic acid. Cover the beaker, warm gently to complete solution, then carefully evaporate to dryness (Note1). Cool, add a further10ml of the bromine-hydrobromic acid, warm to dissolve the residue, again evaporate careful
38、ly to dryness and bake at about200 C, until the residue is just decolorized (about15minutes). Cool, add dropwise,5ml of nitric acid (sp. gr.1.42), warm gently to decompose bromides, add10ml of sulphuric acid(50percent) and evaporate to fumes of sulphuric acid. Cool, add25ml of water and boil until a
39、ll soluble salts are in solution. Cool and allow to stand for one hour. Filter off the lead sulphate on to a paper pulp pad, wash five times with sulphuric acid(5percent) and twice with water. Add18ml of hydrochloric acid (sp. gr.1.161.18) to the filtrate and dilute to about100ml. Transfer the solut
40、ion to the separating funnel attached to the ion-exchange column and wash out the beaker four times with small volumes (each of about5ml) of hydrochloric acid(20percent). Adjust the outlet tap and pass the sample solution through the column at a flow rate of not more than6ml per minute until the vol
41、ume of solution remaining in the column is just sufficient to cover the resin. Pass150ml of hydrochloric acid(20percent) through the column at the same rate and discard the effluent.BS1748-9:1963 BSI 10-1999 3 Pass250ml of nitirc acid(6.2percent) through the column at a rate of6ml per minute and col
42、lect the eluted zinc in a650ml conical beaker. Neutralize (use litmus paper) with ammonia solution (sp. gr.0.91), add15ml of the buffer solution and continue as under “Standardization”, E.D.T.A. solution (M/20). (The colour changes are slightly different.) Deduct the corrected volume of copper sulph
43、ate solution (M/20) from the volume of E.D.T.A. solution (M/20) added and calculate the zinc content using the factor determined on the E.D.T.A. solution (M/20). Method B. Polarographic (for zinc contents0.010.50percent) Calibration Transfer, separately,2.5,5.0,10.0,15.0,20.0 and25.0ml of standard z
44、inc solution B to six50ml volumetric flasks, use a seventh flask for the blank. Add20ml of the base electrolyte and dilute to the mark. Transfer a convenient volume of each solution to separate polarographic cells then bubble nitrogen (oxygen-free) through the solution for5 minutes, to remove oxygen
45、. Prepare polarograms at20 C over the voltage range1.0 to1.5V ( mercury-pool anode), using a convenient sensitivity. Prepare a calibration graph relating step-height to zinc concentration. Procedure a) Zinc contents0.010.05percent. Proceed as in Method A paragraphs1 to3 but use a2.00g sample in a400
46、ml squat beaker and make additions of20ml of the bromine-hydrobromic acid. Pass three successive100ml of hydrochloric acid(20percent) through the column and discard the effluent. Pass450ml of hydrochloric acid(0.05percent) through the column, collect the effluent in a500ml volumetric flask, dilute t
47、o the mark and mix well. Transfer two100ml aliquots to250ml beakers. To one of these add a convenient volume of the standard zinc solution B and examine this prepared solution simultaneously with the sample solution thereby providing a check on the determined zinc content of the sample. In each case
48、 evaporate to about10ml, cool and transfer to a50ml volumetric flask washing the beaker twice with a total volume of10ml water. Add20ml of the base electrolyte, dilute to the mark and proceed as in “Calibration”. Using a convenient sensitivity, measure the step-height and calculate the zinc content
49、from the calibration graph. b) Zinc contents0.050.5percent. Proceed-as in Method A paragraphs13. Pass three successive100ml of hydrochloric acid(20percent) through the column and discard the effluent. Pass450ml of hydrochloric acid(0.05percent) through the column, collect the effluent in a500ml volumetric flask, dilute to the mark and mix well. Transfer two25ml aliquots to50ml volumetric flasks. To one of these add a convenient volume (Note2) of the standard zinc solution B and examine this prepared solution simultaneously with the sample solution, th
