NTERNATIONAL STANDARD 808 ISO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKIYHAPOIHAN OPIAHW3ALIMS IO CTAHIAPTH3ALIWIN.ORGANISATION INTERNATIONALE DE NORMALISATION Aluminium and aluminium alloys -- Determination of silicon -- Spectrophotometric method with the reduced silicomolybdic complex First edition - 1973-11-15 UDC 669.71 : 546.28 : 543.42 Ref. No. 1SO 808-1973 (E) ISO 808-1973 (E) Descriptors : aiuminium, aluminium alloys, chemical analysis, determination of content, silicon, photometry. Price based on 4 pages Not for Resale FOREWORD Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (ISO Member Bodies). The work of developing International Standards is carried out through ISo Technica! Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, governmental and non-governmental, in liaison with isO, also take part in the work. Draft International Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as International Standards by the ISo Council. Prior to 1972, the results of the work of the Technical Committees were published as iso Recommendations; these documents are now in the process of being transformed into International Standards. As part of this process, International Technical Committee ISO/TC 79, Light metals and their alloys. The Member Bodies of the following countries approved the Recommendation : South Africa, Rep. of Argentina India Austria Ireland Spain Belgium Israel Sweden Bulgaria Italy Switzerland Japan Turkey Canada Chile Korea, Rep. of United Kingdom U.S.A. Czechoslovakia Netherlands France U.S.S.R. New Zealand Norway Germany Yugoslavia Hungary Poland No Member Body expressed disapproval of the Recommendation. @ International Organization for Standardization, 1973 Printed in Switzerland Copyright International Organizatin for Standardization from IHS Not for Resa ISO 808-1973 (E) INTERNATIONAL STANDARD Aluminium and aluminium alloys -- Determination of silicon -- Spectrophotometric method with the reduced silicomolybdic complex 3.3 Basic solution for plotting the calibration curve 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies a photometric method Into a plastics vessel (for example polyethylene) of suitable for the determination of silicon in aluminium and capacity (for example 400 ml), introduce 40,0 ml of the sodium hydroxide solution (3.7), add approximately aluminium alloys. 200 ml of water, and acidify by means of 54,0 ml of the The method is applicable to the determination of silicon nitric acid (3.8) and 40,0 ml of the hydrochloric acid (3.9) content between 0,02 and 0,4 %. After cooling, transfer the solution to a 500 ml volumetric flask and make up to volume with water. The method does not apply to the special cases of aluminium alloys containing tin or bismuth. In this international Standard these special cases are not treated. 3.4 Molybdic solution Use either of the solutions indicated below 2 PRINCIPLE Attack of the sample with sodium hydroxide and oxidation with hydrogen peroxide. Acidification with nitric and 3.4.1 Sodium molybdate, 145 g/l solution. hydrochloric acids. Formation the yellow of silicomolybdic complex (at a pH of approximately 0,9) on Dissolve 145g sodium molybdate of dihydrate an aliquot of the test solution. (Na2 Mo04-2H20) in approximately 700 ml of warm water. Cool, filter if necessary through a medium texture filter, Increase of the acidity with sulphuric acid and reduction to collect the filtrate in a 1 000 ml volumetric flask and wash the blue silicomolybdic complex (using a reducing solution with cold water. Make up to volume with water and based 1-amino-2-naphthol-4-sulphonic acid on or, transfer to a polyethytene vessel. Check the pH of this alternatively, ascorbic acid solution).