1、CEN ENx29455-8 93 W 3404589 0053008 632 m EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 29455-8 August 1993 UDC 621.791.35.048 : 620.1 : 543.24 : 546.47 Descriptors: Soldering, soldering fluxes, chemical analysis, determination of content, zinc, volumetric analysis English version Soft solder
2、ing fluxes - Rst methods- Part 8 : Determination of zinc content (IS0 9455-8 1991) Flux de brasage tendre - Mthodes dessai - Partie 8: Dosage du zinc Flumittel zum Weichlten Prfverfahren - Ri1 8: Bestimmung des Zinkgehaltes (IS0 9455-8 : 1991) (IS0 9455-8 : 1991) This European Standard was approved
3、by CEN on 1993-08-02. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards
4、 may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the
5、Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN Europ
6、ean Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1993 Copyright reserved to CEN members Ref. No. EN 29455-8 : 1993 E CEN EN+29455-8 93 3404589 0053009 579 D Page 2 EN 29455-8 : 1993 Foreword In
7、1991, IS0 9455-8 : 1991 Soft soldemngflw - Ilrst methods - Alrt 8 : Determination of Zinc content was submitted to the CEN Unique Acceptance Procedure. The result of the UAP was positive. This European Standard shali be given the status of a national standard, either by publication of an identical t
8、ext or by endorsement, at the latest by February 1994, and conflicting national standards shal be withdrawn at the latest by February 1994. According to the CEN/CENEUC Internal Regulations, the foliowing countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, Fra
9、nce, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. CEN EN*:29455-8 93 m 3404589 0053010 290 m Page 3 EN294568 : 1993 Soft soldering fluxes - Test methods - Part 8: Determination of zinc content 1 Scope This par
10、i of IS0 9455 specifies a method for the de- termination of the zinc content of water soluble fluxes of type 3, as defined in lSO9454-1. The method is intended to apply to an aqueous solution of flux containing approximately 25 O/O of zinc, ex- pressed as zinc chloride (ZnCI,). For solid fluxes and
11、for solutions whose concentrations differ ap- preciably from those stated above, an appropriate adjustment should be made to the amount of sample taken for the test. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this
12、part of IS0 9455. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of IS0 9455 are encouraged to investi- gate the possibility of applying the most recent edi- tion of the standard indicated below. Member
13、s of IEC and IS0 maintain registers of currently valid International Standards. IS0 9454-1:1990, Soff soldering fluxes - Classifica- tion and requirements - Part 1: Classification, labelling and packaging. 3 Principle To an aqueous solution of the flux, containing sulfuric acid, ammonium chloride is
14、 added and the solution made alkaline by the addition of ammonia solution. Any precipitated iron is removed as hy- droxide. The zinc content of the flux is determined by titrating the solution using EDTA. 4 Reagents During the test use only reagents of recognized analytical quality and only distille
15、d, or deionized, water. 4.1 Disodium dihydrogen ethylenediaminetetra- acetate solution (EDTA) standard volumetric sol- utlon, c(EDTA) = 0,l mol/l. Dry approximately 10 g of disodium dihydrogen ethylenediaminetetra-acetate (C,H,N2Na,0,.2H,0) for 2 h at 80 “C. Dissolve 9,308 g of the dried salt in wat
16、er, transfer to a 250 ml volumetric flask, dilute to the mark and mix well. NOTE 1 0,006 54 g of zinc, or 0,013 63 g of zinc chloride. 1 ml of 0,l moll1 EDTA solution is equivalent to 4.2 Buffer solution (pH IO). Dissolve 7 g of ammonium chloride (NH,CI) in 20 ml of water. Add 57 ml of ammonia solut
17、ion (p 0,91 glml) and dilute to 100 ml. Mix well. 4.3 Sulfuric acid, 20 Yo (V/V) solution Add cautiously, with stirring, 200 ml of sulfuric acid (e 1,84 g/ml) to 400 ml of water and mix. Cool and dilute to 1000 ml and mix well. 4.4 Eriochrome black T mixture. Dissolve 0,25 g of eriochrome black T (a
18、lso known as mordant black 11 and solochrome black) and 2,25 g hydroxylammonium chloride in a mixture of 45 ml of water and 5 ml of triethanolamine. NOTE 2 a recently purchased batch of eriochrome black T. This solution should be freshly prepared from 4.5 Hydrochloric acid, p 1,16 gim1 or 1,18 g/ml.
19、 CEN ENs29455-8 93 9 3404589 0053011 127 9 Page 4 EN294558 : 1993 4.6 Ascorbic cid. 4.7 Ammonium chloride, (NH,CI). 4.8 Ammonia solution, p 0,91 g/ml. 5 Apparatus Ordinary laboratory apparatus is required. 6 Procedure Carry out the following procedure in triplicate. By means of a pipette, transfer 2
20、5,O ml of the flux sample to a 500 ml volumetric flask. NOTE 3 This method is intended for flux samples con- taining approximately 25 YO zinc in aqueous solution. For flux samples having a concentration appreciably different from this, make an appropriate adjustment to the volume of sample used for
21、the test. Solid fluxes should be dissolved in water to give a flux sample having a zinc content around 25 %. Add 10 ml of sulfuric acid solution (4.3), dilute to the mark with water and mix well. By means of a pipette, transfer 20.0 ml of this sol- ution to a 250 ml beaker, dilute to approximately 1
22、00ml and add a few drops of hydrochloric acid (4.5). Add approximately 10 g of ammonium chloride (4.7) and make alkaline with ammonia solution (4.8). If iron is precipitated, boil the solution and filter it through a rapid filter paper, washing the precipitate well with water containing a few drops
23、of ammonia solution (4.8). Combine the filtrate and washings and discard the precipitate. Add approximately 0,2 g of ascorbic acid (4.6) and 15 ml of buffer solution (4.2). Stir well and add dropwise sumcient eriochrome black T mixture (4.4) to produce a clearly visible red/purple colour. Titrate wi
24、th the EDTA solution (4.1) to a blue end point. NOTE4 The end point of the titration is more easily detected if the progress of the titration is viewed using an incandescent light source. 7 Calculation of results The percentage, by mass, of zinc in the original flux sample, expressed as zinc chlorid
25、e, is given by the following formula: 1,363 V d where V d is the volume, in millilitres, of EDTA sol- ution (4.1) used; is the density, in grams per millilitre, of the original flux sample at 20 OC, deter- mined by the use of a hydrometer. NOTE 5 if the original nux were in solid form, or if a diffe
26、rent sample volume were used for the test (see clause 6. note 3), then a suitable adjustment will need to be made to the calculation formula. 8 Precision Tests were carried out on three fluxes containing zinc covering the range 17 Oh (m/m) to 28 YO (mim). Four laboratories took pari in the tests and
27、 the esti- mates for precision data, expressed as a percentage of zinc chloride, were as follows: Standard deviations: - within laboratory s, 0,24 - between laboratories .r, 0,30 Repeatability r 0,66 Reproducibility R 0.84 9 Test report The test report shall include the following infor- m at ion: a) the identification of the test sample; b) the test method used (.e. reference to this pari of IS0 9455); c) the results obtained; d) any unusual features noted during the determi- nation; e) details of any operation not included in this part of IS0 9455. or regarded as optional.
