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1、BRITISH STANDARD BS 6783-12: 1992 ISO 9388:1992 Sampling and analysis of nickel, ferronickel and nickel alloys Part 12: Method for the determination of phosphorus in nickel alloys by molybdenum blue molecular absorption spectrometry UDC 669.245:543.422:546.18 Licensed Copy: sheffieldun sheffieldun,
2、na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 This British Standard, having been prepared under the direction of the Non-ferrous Metals Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 December 1992
3、BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference NFM/10 Draft for comment 91/39452 DC ISBN 0 580 21393 5 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Non-ferrous Metals Standards Policy
4、 Committee (NFM/-) to Technical Committee NFM/10, upon which the following bodies were represented: Association of Bronze and Brass Founders British Non-ferrous Metals Federation British Steel Industry Department of Trade and Industry (Laboratory of the Government Chemist) Engineering Equipment and
5、Materials Users Association Institute of British Foundrymen London Metal Exchange Ministry of Defence Nickel Development Institute Non-ferrous Metal Stockists Stainless Steel Fabricators Association of Great Britain Steel Casting Research and Trade Association Coopted members Amendments issued since
6、 publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 BSI 10-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Normative references1 3Principle1 4Reagents1 5
7、Apparatus2 6Sampling and sample preparation2 7Procedure2 8Expression of results4 9Interferences4 10Test report4 Annex A (informative) Examples of composition of some nickel alloys6 Table 1 Mass of sample to be taken2 Table 2 Nominal composition of test samples4 Table 3 Results of statistical analysi
8、s5 Table A.1 Examples of composition of some nickel alloys6 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 ii BSI 10-1999 National foreword This Part of BS 6783 has been prepared under the
9、 direction of the Non-ferrous Metals Standards Policy Committee. It is identical with ISO 9388:1992 Nickel alloys Determination of phosphorus content Molybdenum blue molecular absorption spectrometric method published by the International Organization for Standardization (ISO). At present this Briti
10、sh Standard consists of 12 Parts all concerned with analysis of nickel, ferronickel and nickel alloys. Further International Standards are in preparation on sampling and analysis of nickel, ferronickel and nickel alloys and, when available, these will be published as further Parts of this British St
11、andard. 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. Cross-references International St
12、andardCorresponding British Standard ISO 1042:1983BS 1792:1982 Specification for one-mark volumetric flasks (Identical) ISO 5725:1986BS 5497 Precision of test methods Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests (Id
13、entical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, 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
14、the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 BSI 10-19991 1 Scope This International Standard specifies a molecular absorption spectrometric method for the determination of the phosphorus content of
15、 nickel alloys in the range 0,001 % (m/m) to 0,025 % (m/m). Typical compositions of some nickel alloys are given in Annex A. Chromium(III) and silica cause interference which is eliminated in the procedure. See clause 9. 2 Normative references The following standards contain provisions which, throug
16、h reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applyi
17、ng the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 1042:1983, Laboratory glassware One-mark volumetric flasks. ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibil
18、ity for a standard test method by inter-laboratory tests. 3 Principle Dissolution of a test portion in nitric and hydrochloric acids. Removal of hydrochloric acid by fuming with sulfuric acid, and oxidation of chromium(III) to chromium(VI) with ammonium peroxydisulfate. Precipitation of iron(III) ph
19、osphate and redissolution of the precipitate in a hydrofluoric-nitric acid mixture. Addition of boric, tartaric, and sulfamic acids to complex free fluoride, eliminate arsenic interference, and remove oxides of nitrogen. Formation and extraction of molybdophosphoric acid into isobutyl alcohol, reduc
20、tion of the, heteropoly acid to molybdenum blue and back-extraction into an aqueous phase. Measurement of the absorbance of the aqueous solution at 700 nm. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of e
21、quivalent purity. 4.1 Nitric/hydrochloric acid, mixture. WARNING This acid mixture is highly corrosive and unstable. Noxious gases (chlorine) are liberated on standing. It shall be prepared and used in a fume cupboard and shall not be kept in a closed container. Carefully mix 25 ml of nitric acid (2
22、0 = 1,41 g/ml) and 125 ml of hydrochloric acid (20 = 1,18 g/ml). This mixture should be prepared just before use. 4.2 Hydrofluoric acid, 20 = 1,15 g/ml, 48 % (m/m) HF. WARNING Hydrofluoric acid is extremely irritating and corrosive to skin and mucous membranes, producing severe skin burns which are
23、slow to heal. In the case of contact with skin, wash well with water and seek medical advice. 4.3 Sulfuric acid, 20 = 1,84 g/ml, diluted 1 + 1. Slowly, and with constant stirring, add 100 ml of sulfuric acid to 100 ml of water. 4.4 Boric acid, solution. Dissolve 40 g of boric acid (H3BO3) in 1 litre
24、 of water and mix. 4.5 Oxalic acid, solution. Dissolve 1 g of oxalic acid dihydrate (COOH)22H2O in 100 ml of water and mix. 4.6 Sulfamic acid, solution. Dissolve 5 g of sulfamic acid (NH2SO3H) in 100 ml of water and mix. 4.7 Tartaric acid, solution. Dissolve 10 g of tartaric acid (CHOHCOOH)2 in 100
25、ml of water and mix. 4.8 Chloroform (CHCl3). 4.9 Isobutyl alcohol, (2-methyl-1-propanol) (CH3)2CHCH2OH. 4.10 Ammonia, solution, 20 = 0,89 g/ml. 4.11 Ammonium nitrate, solution. Dissolve 5 g of ammonium nitrate (NH4NO3) in 500 ml of water. 4.12 Ammonium peroxydisulfate, solution. Dissolve 20 g of amm
26、onium peroxydisulfate (NH4)2S2O8 in water and dilute to 200 ml. Prepare a fresh solution every three days. 4.13 Iron(III) nitrate, solution. Dissolve 7,2 g of iron(III) nitrate nonahydrate Fe(NO3)39H2O in about 75 ml of water containing 3 ml of nitric acid (20 = 1,41 g/ml), dilute to 100 ml with wat
27、er and mix. 4.14 Silver nitrate, solution. Dissolve 3 g of silver nitrate (AgNO3) in 200 ml of water. Store in a dark glass bottle. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 2 BSI 10-1999 4.15 Sodium molybdate, solution
28、. Dissolve 10 g of sodium molybdate dihydrate (Na2MoO42H2O) and 8 g of sodium hydroxide (NaOH) in 200 ml of water. 4.16 Sodium chloride, wash solution. Dissolve 23 g of sodium chloride (NaCl) in water, add 50 ml of hydrochloric acid (20 = 1,18 g/ml) and dilute to about 900 ml. Add 60 ml of isobutyl
29、alcohol (4.9) and shake to dissolve. Dilute to a final volume of 1 litre and mix. 4.17 Reducing solution 4.17.1 Dissolve 10 g of stannous chloride dihydrate (SnCl22H2O) in 25 ml of hydrochloric acid (20= 1,18 g/ml) and heat until dissolved. Cool to ambient temperature and dilute to 50 ml with water.
30、 The solution is stable for at least one week when kept in a stoppered flask. 4.17.2 Transfer 5 ml of this solution to a 250 ml one-mark volumetric flask, add 10 ml of the sulfuric acid (4.3), make up to the mark with water and mix. Prepare a fresh solution each day. 4.18 Phosphorus, standard refere
31、nce solution (100 mg/l). Transfer exactly 0,439 4 g of potassium dihydrogen phosphate (KH2PO4) to a 1 000 ml one-mark volumetric flask, add 100 ml of water and 5 ml of nitric acid (20 = 1,41 g/ml) diluted 1 + 1. Dissolve the salt, make up to the mark with water and mix. 5 Apparatus Ordinary laborato
32、ry glassware, and 5.1 Plastics beakers, of capacity 250 ml and usable up to 150 C. Polymethylpentene or fluorocarbon polymers have been found satisfactory. 5.2 Plastics filtration funnels 5.3 Separating funnels, of capacity 125 ml. Two funnels are required for the analysis of each test sample. Polyt
33、etrafluoroethylene stopcocks and plastics stoppers are preferred. 5.4 One mark volumetric flasks, complying with the requirements of ISO 1042, class A. 5.5 Mechanical micropipettes, of capacities 100 4l, 250 4l and 500 4l. 5.6 Molecular absorption spectrometer, suitable for measuring absorbance at 7
34、00 nm and equipped with optically matched 1 cm or 2 cm glass cells. 6 Sampling and sample preparation 6.1 Sampling and preparation of the laboratory sample shall be carried out according to normal agreed procedures or, in case of dispute, the relevant International Standard. 6.2 The laboratory sampl
35、e is normally in the form of millings or drillings and no further preparation of the sample is necessary. 6.3 If it is suspected that the laboratory sample is contaminated with oil or grease from the milling or drilling process, it shall be cleaned by washing with high purity acetone and drying in a
36、ir. 6.4 If the laboratory sample contains particles or pieces of widely varying sizes, the test portion should be obtained by riffling. 7 Procedure 7.1 Test portion and preparation of test solution 7.1.1 Weigh a test portion containing between 3 4g and 50 4g of phosphorus according to Table 1, and t
37、ransfer it to a 150 ml glass beaker. Table 1 Mass of sample to be taken 7.1.2 Add 7 ml of the acid mixture (4.1), cover the beaker and warm. Remove the beaker from the heat and allow the reaction to proceed and subside. Heat again to complete the dissolution. 7.1.3 Add 5 ml of the sulfuric acid (4.3
38、) and evaporate to dense fumes. Do not evaporate to dryness. Cool to room temperature and dissolve the salts in 5 ml of nitric acid (20 = 1,41 g/ml) and 30 ml of water. Transfer the solution, which may contain hydrolysed products of refractory metals, quantitatively to a 400 ml beaker. Use a rubber
39、policeman if necessary. NOTE 1Usually, the dissolution is rapid and no extensive heating is required. Some alloys, particularly those high in copper, are best dissolved in 7 ml of nitric acid (20 = 1,41 g/ml), diluted 1 + 1. In such instances, omit 7.1.3 and proceed as directed in 7.2. Expected phos
40、phorus content Mass of sampleWeighing accuracy % (m/m) gg 0,001 to 0,010,29 to 0,310,005 0,01 to 0,0250,19 to 0,210,002 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:52 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6783-12:1992 BSI 10-19993 7.2 Separation of chromium 7.2.1 Dilute the
41、solution to 150 ml, add 3 ml of the iron(III) nitrate solution (4.13), and heat almost to boiling. Add 10 ml of the silver nitrate solution (4.14) and 30 ml of the ammonium peroxydisulfate solution (4.12). Boil the mixture for 10 min to 15 min to decompose the excess oxidant. Dilute to 250 ml with w
42、ater and add, while stirring, the ammonia solution (4.10) until a permanent precipitate of iron(III) hydroxide forms. Add 15 ml of ammonia solution in excess and digest the hot mixture for about 15 min. Filter the precipitate through a fast filter paper containing some wet filter pulp. Wash the prec
43、ipitate and filter thorougly with the ammonium nitrate solution (4.11) until all of the yellow colour due to the chromate ions has been removed. 7.2.2 Transfer the filter with the precipitate to a plastics beaker (5.1) containing 2 ml of hydrofluoric acid (4.2). Wash the precipitation beaker with 10
44、 ml of nitric acid (20 = 1,41 g/ml) diluted 1 + 1 and add the washings to the plastics beaker. Heat carefully to dissolve the precipitate, and break up the filter with a plastics stirring rod. Filter through an 11 cm medium speed filter and plastics funnel into a 100 ml plastics beaker. Wash twice w
45、ith 5 ml portions of water and then once with 30 ml of the boric acid solution (4.4). Finish washing the filter with water so that the total volume of the filtrate does not exceed 60 ml to 70 ml. NOTE 2It is important to ensure that all the chromium is oxidized to chromium(VI) before the precipitati
46、on, and to wash the precipitate and filter until it is completely free of chromium(VI). The filtration and washing of the precipitate of hydrous oxides is very fast in the presence of filter pulp. 7.3 Extraction of molybdophosphoric acid 7.3.1 Transfer the filtrate to a separating funnel (5.3). Add
47、2 ml of the tartaric acid solution (4.7), 1 ml of the sulfamic acid solution (4.6), and 10 ml of the sodium molybdate solution (4.15). Mix by swirling, add 20 ml of the isobutyl alcohol (4.9) and extract by shaking the funnel vigorously for 2 min. Allow the phases to separate and transfer the lower
48、aqueous layer into a second separating funnel. Add, to this aqueous phase, 5 ml of sodium molybdate solution and 10 ml of isobutyl alcohol. Shake vigorously for 2 min, allow the phases to separate and discard the lower aqueous phase. Combine the remaining organic phase with that in the first separat
49、ing funnel. Swirl, allow to settle and discard any residual aqueous phase which may separate on standing. 7.3.2 Wash the combined extracts by adding 20 ml of the sodium chloride wash solution (4.16) and shaking for 30 s. Drain off and discard the lower aqueous phase. Repeat the washing of the organic phase twice more, each time using 20 ml of the sodium chloride wash solution. Discard the aqueous washings. 7.4 Molybdenum blue development To the washed extract add, in order, 40 ml of the chloroform (4.8), 30 ml of water, 10 ml o