1、BRITISH STANDARD BS 6721-7: 1989 ISO 4742:1984 Sampling and analysis of copper and copper alloys Part 7: Method for determination of nickel in copper alloys: gravimetric method ISO title: Copper alloys Determination of nickel content Gravimetric method UDC 669.3:669.245:543.21:620.1BS6721-7:1989 Thi
2、s British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 28 February 1989 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference NFM
3、/34 Draft (ref. 86/38269) announced inBSI News January 1988 ISBN 0 580 17120 5 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Non-ferrous Metals Standards Committee (NFM/-) to Technical Committee NFM/34 upon which the following bodies w
4、ere represented: British Non-ferrous Metals Federation Copper Development Association London Metal Exchange Non-ferrous Metal Stockists Society of British Aerospace Companies Limited Coopted members The following bodies were also represented in the drafting of the standard, through subcommittees and
5、 panels: BNF Metals Technology Centre British Bronze and Brass Ingot Manufacturers Association Copper Smelters and Refiners Association Ministry of Defence National Brassfoundry Association Coopted members Amendments issued since publication Amd. No. Date of issue CommentsBS6721-7:1989 BSI 12-1999 i
6、 Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Publication referred to Inside back coverBS6721-7:1989 ii BSI 12-1999 Nation
7、al foreword This Part of BS 6721 has been prepared under the direction of the Non-ferrous Metals Standards Committee. BS6721 is a multi-part standard and describes methods of sampling and analysis for copper and copper alloys. It is intended that Parts1to3 of BS6721 will describe methods of sampling
8、 copper and copper alloys in various forms. The remaining Parts will give methods for the determination of individual elements in copper and copper alloys. This Part of BS 6721 is identical with ISO4742:1984 “Copper alloys Determination of nickel content Gravimetric method”, published by the Interna
9、tional Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; a
10、ttention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “P
11、art of BS 6721”. In British Standards it is current practice to use the symbol “L” for litre (and in its submultiples) rather than “l” and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. Cross-reference. The Technical Committee has reviewed the provisions of ISO1554, to which referenc
12、e is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard related to ISO1554 is BS1748-1-5:1961 “Methods for the analysis of copper, lead, iron, aluminium and nickel in copper alloys”, in particular “Part 1: Determination of copper”
13、. 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. Summary of pages This document comprise
14、s a front cover, an inside front cover, pages i and ii, 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 front cover.BS6721-7:1989 BSI 12-1999
15、 1 WARNING: Throughout this International Standard, normal precautions regarding the use of perchloric acid in laboratory work should be observed. 1 Scope and field of application This International Standard specifies a gravimetric method for the determination of the nickel content in all types of c
16、opper alloys listed in International Standards. The method is applicable to the determination of nickel contents between2and50% (m/m). 2 Reference ISO 1554, Wrought and cast copper alloys Determination of copper content Electrolytic method. 3 Principle Dissolution of a test portion in nitric acid an
17、d removal of tin and silicon, if present. Separation of copper by electrolysis and precipitation of nickel from the copper-free electrolysate by the sodium salt of dimethylglyoxime in the presence of citric acid. Separation of the precipitate by filtration. 4 Reagents During the analysis, use only r
18、eagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Nitric acid, 1,40g/ml. 4.2 Perchloric acid, 1,67g/ml. 4.3 Hydrobromic acid, 1,38g/ml. 4.4 Ammonia solution, 0,925g/ml. 4.5 Nitric acid solution,1+1. Dilute100ml of the nitric acid(4.1) with100ml of wat
19、er. 4.6 Sulfamic acid, 100g/l solution. 4.7 Citric acid, 250g/l solution. 4.8 Sodium dimethylglyoximate, 25,9g/l solution. 5 Apparatus Ordinary laboratory apparatus, and 5.1 Beakers, electrolytic, capacity300to400ml. 5.2 Electrolysis equipment, including current source and platinum electrodes, as sp
20、ecified in ISO1554. 5.3 Filter crucible, of fritted glass, pore size16to404m. 6 Procedure 6.1 Test portion 6.1.1 Nickel content between 2 and 4,25% (m/m) Weigh, to the nearest0,0001g, about2g of the test sample. The nickel content of the test portion will be40to85mg. 6.1.2 Nickel content between4and
21、8,5% (m/m) Weigh, to the nearest0,0001g, about1g of the test sample. The nickel content of the test portion will be40to85mg. 6.1.3 Nickel content between 8 and 50% (m/m) Weigh, to the nearest0,0001g, between0,25and1g of the test sample so that the nickel content of the test portion will be80to125mg.
22、 6.2 Dissolution of test portion 6.2.1 Test portions free of tin and silicon Transfer the test portion(6.1) to a250ml beaker. Add25ml of the nitric acid solution(4.5). Dissolve first at ambient temperature, then heat gently until dissolution is complete. When the test portion has completely dissolve
23、d, increase the temperature and allow the solution to boil for several minutes to expel the oxides of nitrogen. Remove from heat and add50ml of water. If the test solution is clear, transfer to an electrolytic beaker(5.1) and proceed as specified in6.3. 6.2.2 Test portions containing tin and silicon
24、 If the tin content is sufficiently high, the test solution(6.2.1) will be cloudy. In this case, let the test solution stand for1h at80 C to flocculate tin oxide. Remove from heat, add filter pulp, and filter through a close-textured filter paper. Collect the filtrate in an electrolytic beaker(5.1).
25、 Wash the precipitate several times with warm nitric acid solution (diluted1+99), adding the washings to the filtrate.BS6721-7:1989 2 BSI 12-1999 Transfer the filter paper and precipitate to the original beaker. Add15to20ml of the nitric acid(4.1) and10to15ml of the perchloric acid(4.2). Cover and h
26、eat to the evolution of copious white fumes. Continue heating until all organic matter is destroyed. Cool, rinse the cover and sides of the beaker, and add15ml of hydrobromic acid(4.3). Heat to the evolution of copious white fumes to volatilize tin. Repeat the hydrobromic acid addition and heating u
27、ntil the solution is clear, then evaporate the solution to near dryness. Cool, dissolve the residue in a small volume of water, and add the solution to the original filtrate in the electrolytic beaker. 6.3 Electrolysis Add 5ml of the sulfamic acid solution(4.6) to the test solution(6.2) and dilute t
28、o about200ml with water. Connect the electrolysis apparatus(5.2), introduce the platinum electrodes to the test solution, and electrolyse as specified in ISO1554. The current density may be increased by stirring the electrolyte vigorously. When deposition of copper is complete, remove the electrodes
29、 and reserve the electrolysate. 6.4 Precipitation 6.4.1 Add 5ml of the nitric acid(4.1) and10ml of the perchloric acid(4.2) to the electrolysate and evaporate the solution to the evolution of copious white fumes. Allow to cool and add100ml of water. Transfer to an800ml beaker, filtering if necessary
30、. Add10ml of the citric acid solution(4.7), then add the ammonia solution(4.4) until the test solution turns blue. Add1ml in excess. Dilute to400ml and heat to60to70 C. 6.4.2 In the case of nickel contents of40to85mg(6.1.1, 6.1.2), add44ml of the sodium dimethylglyoximate solution(4.8) to the test s
31、olution(6.4), stirring vigorously. Allow the test solution to cool to ambient temperature, with occasional stirring. 6.4.3 In the case of nickel contents of80to125mg(6.1.3), add60ml of the sodium dimethylglyoximate solution(4.8) to the test solution(6.4), stirring vigorously. Allow the test solution
32、 to cool to ambient temperature, with occasional stirring. 6.5 Filtration Filter the precipitate on a tared, medium-porosity fritted glass filter crucible(5.3), previously dried for1h at150 C and allowed to cool in a desiccator. Wash the precipitate 10to12times with small amounts of water, allowing
33、the filter to drain completely between washings. Dry the precipitate for1h at150 C. Allow to cool in a desiccator and weigh. 7 Expression of results The nickel content, expressed as a percentage by mass, in given by the formula where 8 Test report The test report shall include the following particul
34、ars: a) an identification of the sample; b) the reference of the method used; c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operation not included in this International Standard or in the International Standard to which reference is
35、made, or regarded as optional. m 0 is the mass, in grams, of the test portion(6.1); m 1 is the mass, in grams, of the precipitate(6.5). m 1 m 0 -20,32 BS6721-7:1989 BSI 12-1999 Publication referred to See national foreword.BS 6721-7: 1989 ISO 4742:1984 BSI 389 Chiswick High Road London W4 4AL BSIBri
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