4158 NTERNATIONAL STANDARDTSO INTERNATIONALORGANIZATION FOR STANDARDIZATIONMEKAYHAPOAHAR OPFAHM3AUMA NOCTAHAAPTM3ALWMORGANISATION INTERNATIONALEDENORMALISATION Ferrosilicon,ferrosilicomanganeseand ferrosilicochromium- Determinationofsiliconcontent-Gravimetricmethod Ferrosilicium,ferro-silico-manganeseetferro-silico-chrome-Dosagedu silicium-Methode gravimetrique Firstedition-1978-12-15 ISO4158-1978 (E) UDC669.15-198:543.21:546.28 Ref.No.1SO4158-1978(E) Descriptors; ferroalloys, ferrosilicon, chemical analysis,determination of content, silicon, gravimetric analysis. Price based on3pages FOREWORD ISo(the International Organization for Standardization)is a worldwide federation of national standardsinstitutes (iso memberbodies).Thework of developing International Standards is carried out through ISo technical committees.Every 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 StandardsbytheISOCouncil. International Standard ISO 4158 was developed by Technical Committee ISO/TC132,Ferroalloys,andwascirculated to thememberbodies inOctober1977. It has been approved by the memberbodies of the foilowing countries : Australia Italy Spain Austria Japan Sweden Bulgaria Korea, Rep.of Turkey Canada Mexico United Kingdom Czechoslovakia Norway U.S.A. France Philippines U.S.S.R. Germany,F.R. Poland Yugoslavia India Romania Iran SouthAfrica, Rep.of Nomemberbodyexpresseddisapprovalofthedocument. International Organizationfor Standardization,1978 PrintedinSwitzerland ISO4158-1978 (E) INTERNATIONALSTANDARD Ferrosilicon, ferrosilicomanganese and ferrosilicochromium Determination of silicon content -- Gravimetric method 1SCOPEANDFIELDOFAPPLICATION 4.7 Sulphuric acid, p 1,83 g/ml. This International Standard specifies a gravimetric method 4.8 Hydrochloric acid, p 1,19g/ml, diluted1+9. for the determination of the silicon content of ferrosilicon, ferrosilicomanganese and ferrosilicochromium. 4.9 Sulphuric acid, p 1,83 g/ml, diluted 1+1. The method is applicableto alloys containing from8 to 95% (m/m) of silicon. 4.10 Silver nitrate,10 g/l solution. 2 REFERENCE 5APPARATUS ISO3713, Ferroalloys- Sampling and preparation of Usual laboratory equipment,and in particular : samples - General rules. 1) 5.1Crucible, capacity 40 ml,of silicon-free iron,vitreous 3PRINCIPLE carbon, nickel or zirconium. Transformation of the silicon in a test portion into silicate 5.2 Beakers,for melt dissolution,of polytetrafluoro by oxidizing fusion with sodiumperoxide and taking up ethylene, stainless steel or high purity nickel. with acid. Double dehydration of the silicate by evaporation in a 5.3Platinumdish, capacity40ml. perchloric acid medium, and weighing of the impure silica. 5.4 Fluted glass funnel, diameter75mm. Double hydrofluoric-sulphuric volatilization of the silica, weighing of the residue, and determination, by difference, 5.5Glass beaker,capacity600ml or 800ml. ofthepuresilica. 5.6 Muffle furnace. 4REAGENTS During the analysis,use only reagents of recognized 5.7 Desiccator. analytical grade, and oniy distilled water or water of equivalent purity. 6SAMPLE 4.1 Sodiumperoxide. Use powder which will pass through a sieve with a mesh size of 160μm, prepared in accordance withIS0 3713. 4.2 Sodium carbonate (anhydrous). 7PROCEDURE 4.3Ammonia solution,p0,91g/ml. 7.1Testportion 4.4Perchloric acid2),p1,61g/ml. Forsiliconcontentslessthanorequal to50%(m/m),take 4.5 Hydrofluoric acid, p 1,14 g/ml. atestportion of0,50±0,0002g. NOTE-For silicon contents less than 25 % (m/m),it is possible to 4.6 Hydrochloric acid, p 1,19 g/ml. use atestportion of 1g. 1) At present at the stage of draft. 2) Attention is drawn to the hazards associated with perchloric acid when heated tofuming.